ABSTRACT WANG, GUAN. Synthesis and Application of Bleach Activators

ABSTRACT

WANG, GUAN. Synthesis and Application of Bleach Activators Containing Various Cationic Groups and PET Fabric Decolorization using Fenton’s Reagent. (Under the direction of Dr. David Hinks.)

CBAs are quaternary ammonium salts (QAS) that are extensively used in various applications. Although most of the QAS are generally believed to be nontoxic to humans, they will harm aquatic life both animals and plants. CBAs are applied in textile bleaching process and the wastewater after bleaching contains chemicals including bleach activators. Even though wastewater contains CBAs will be treated in a wastewater treatment plant, the treated water still contain these chemicals. The study of acute toxicity and genotoxicity of CBAs to aquatic organisms was conducted in this study. Eight new bleach activators and two bench mark cationic bleach activators were investigated. New invented cationic bleach activator 3-

PBBC is 86 times less toxic in the Daphnia sp. Immobilization Test, 18 times less toxic in

Algae Toxicity assay and 10 times less mutagenic in the Salmonella/microsome microsuspension assay in comparison with the benchmark product (TBBC). This confirmed that replacing the cationic group in CBAs using low toxicity ammines can reduce the toxicity of CBAs to aquatic organisms.

An effective low temperature and neutral pH bleaching system was developed using

CBAs. A comparison life-cycle assessment for conventional and innovational bleaching system was conducted in this study. Their relative environmental performance was analyzed and compared. Based on data from industry, pre-published research, lab-scale experiments and the Ecoinvent database, the life-cycle-inventory (LCI) for both innovative and conventional bleaching process was developed. Seven impact categories from TRACI, USETox and IPCC

2007 were selected to evaluate the impact based on the results of the LCI. The innovative bleaching process has lower environmental impacts than conventional method. It consumes less electricity, steam, water, and process time by modifying the conventional bleaching process.

Polyester (polyethylene terephthalate; PET) fibers now exceed cotton as the largest volume textile substrate in commerce, owing to their economy, strength, and versatility.

Unlike cotton, PET fibers are not readily biodegradable, leading to their persistent if placed in a landfill environment following their useful lifetime. The modern-day corporate commitment to product stewardship has led to considerable interest in the recycle/reuse of textiles derived from synthetic fibers such as PET. It is generally recognized that the key step in the recycling process is color removal. Fenton’s chemistry was used in the present investigation as an approach to decolorizing PET fabrics containing a variety dye structural types, providing an indication of the versatility of this method. A full factorial design of experiments was used to establish the amount of FeSO4 and H2O2 needed to optimize fabric decolorization. In this study, an optimized method consisting of FeSO4 (0.18 mM), H2O2 (1235 mM), and water: acetone

(1:1), at 120 oC, for 15 min was found suitable for color removal from most PET fabrics.

Due to the technique barrier, the used PET garment cannot be recycled as simple as used

PET bottles. By developing the method which can be used to remove the dye in the used PET garments, it is possible to recycle used PET garments for PET fiber production. In this study, a life-cycle assessment was used to compare the environmental impacts of fiber production using post-consumer PET fabric and virgin PET fiber production. After analysis, using post- consumer PET fabric to produce fiber will release 5.45% to 44.61% less impacts to the environment compared to virgin PET production. Only emissions, which cause ozone depletion, released by recycled fiber production through chemical recycling process are more than the emissions released by virgin PET production. In order to reduce the environmental impacts of the post-consumer PET fabric to fiber production, the optimizations of PET fabric decolorization process, recycling process and chemical production are necessary. A decolorization process using less chemical and at lower temperature should be developed in the future. A more environmental friendly process for hydrogen peroxide production should be used.

by Guan Wang

A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy

Fiber and Polymer Science

Raleigh, North Carolina

2015

APPROVED BY:

______Dr. David Hinks Dr. Harold S. Freeman Committee Chair

______Dr. Peter J. Hauser Dr. Joseph F. DeCarolis

DEDICATION

Tong Yao

BIOGRAPHY

Guan Wang, the only son of Sifeng Wang and Ying Wang, was born on January 4th,

1989 in Zhejiang, China. He graduated from Huzhou High school in June, 2007, and received a Bachelor of Engineering degree in Textile Engineering from Donghua University, Shanghai,

China in June 2011. In undergraduate study, he conducted research on 3D-weaving ramie polypropylene enforced composite under the guidance of Dr. Yiping Qiu. He was one of the

Donghua “3+X” program students who took three years to complete the B.S. degree and then entered the Master of Science in Textile Chemistry in the College of Textiles at North Carolina

State University in August, 2010. After he got Master of Science degree in Textile Chemistry in May, 2012, Guan continue his education and studied for his Doctor of Philosophy degree in

Fiber and Polymer Science under the direction of Dr. David Hinks.

On June 29, 2015, Guan married Tong Yao in Xi’an, China. Tong is now pursuing her

Ph.D degree in Fiber and Polymer Science in the College of Textiles at North Carolina State

University.

iii

ACKNOWLEDGMENTS

Firstly, I would like to express my sincere gratitude to my advisor Dr. David Hinks for the continuous support of my Ph.D study and related research, for his patience, motivation, and immense knowledge. His guidance helped me in all the time of research and writing of this dissertation.

This dissertation could not be written to its fullest without Dr. Harold S. Freeman, who challenged and encouraged me throughout my time spent studying under him. He would have never accepted anything less than my best efforts, and for that, I thank him. Besides, I would like to thank the rest of my dissertation committee: Dr. Peter J. Hauser and Dr. Joseph F.

DeCarolis, for their insightful comments and encouragement, but also for the hard question which incented me to widen my research from various perspectives.

Also I thank my friends. Thank you so much for your time, your support, your well wishes and friendship.

Last but not the least, I would like to thank my family: my wife Tong Yao and my parents for supporting me spiritually throughout writing this dissertation and my life in general.

TABLE OF CONTENTS

LIST OF TABLES ...... ix LIST OF FIGURES ...... xi LIST OF SCHEMES ...... xi Chapter 1 Introduction...... 1 1.1 Dissertation Outline ...... 1 1.2 Research Objectives ...... 2 Chapter 2 Literature Review ...... 3 2.1 Natural color contents in cotton ...... 3 2.2 Peroxide-based bleaching ...... 4 2.3 Bleach activators ...... 6 2.3.1 Cationic Bleach Activators ...... 9 2.3.2 Synthesis of cationic bleach activators process ...... 14 2.3.3 Environmental properties of cationic compounds ...... 15 2.4 Structure analysis ...... 19 2.4.1 Time-of-flight mass spectrometry ...... 19 2.4.2 High-performance liquid chromatography ...... 19 2.4.3 NMR spectroscopy...... 20 2.5 Whiteness Measurement ...... 21 2.6 Whiteness ...... 21 2.7 The physical and chemical assesment of color ...... 22 2.7.1 Visible reflectance spectroscopy ...... 26 2.7.2 Color strength...... 27 2.8 History of colors and dyes ...... 28 2.9 Dyes in wastewater ...... 36 2.10 Dye wastewater treatment ...... 37 2.10.1 Adsorption and other physicochemical methods ...... 37 2.10.1.1 Inorganic adsorption systems ...... 37 Carbon-based inorganic adsorption agents ...... 37 Other inorganic adsorption agents ...... 38 2.10.1.2 Organic adsorption agents ...... 39 2.10.2 Chemical decolorization methods ...... 39

2.10.2.1 Ozonation...... 40

2.10.2.2 Oxidation with UV/H2O2 ...... 42 2.10.2.3 Fenton’s process ...... 43 a. Effect of pH ...... 44

b. Effect of H2O2 ...... 44 c. Effect of Fe(II) sulfate level ...... 45 2.11 Polyethylene terephthalate (PET) ...... 45 2.11.1 PET synthesis ...... 47 2.11.2 Recycled PET...... 48 2.11.2.1 Conventional recycling processes ...... 49 2.11.3 PET dyeing...... 50 2.11.4 PET decolorization...... 50 2.11.4.1 PET fiber and fabric ...... 50 2.11.4.2 PET plastic ...... 53 2.12 Life-cycle assessment ...... 55 Chapter 3 The toxicity of cationic bleach activators...... 57 3.1 Introduction ...... 57 3.2 Experimental ...... 60 3.2.1 Chemicals and media ...... 60 3.2.2 Daphnia sp. Immobilization Test ...... 61 3.2.2.1 Culture of aquatic organisms ...... 61 3.2.2.2 Experiment design ...... 61 3.2.3 Algae Toxicity assay ...... 62 3.2.3.1 Culture of aquatic organisms ...... 62 3.2.3.2 Experiment design ...... 62 3.2.4 The Salmonella/microsome assay ...... 63 3.2.4.1 Sample preparation ...... 63 3.2.4.2 Experiment design ...... 63 3.2.4.3 Data evaluation and potencies ...... 64 3.3 Results ...... 64 3.3.1 Daphnia sp. Immobilization Test ...... 64 3.3.2 Algae Toxicity assay ...... 67 3.3.3 The Salmonella/microsome assay ...... 68

3.4 Conclusion ...... 70 Chapter 4 A comparative life cycle assessment for bleaching process of cotton...... 71 4.1 Introduction ...... 71 4.2 Methods...... 72 4.2.1 Goal and scope ...... 72 4.2.1.1 Functional unit ...... 73 4.2.1.2 System boundaries ...... 73 4.2.2 Data collection and LCI analysis ...... 75 4.2.3 Impact assessment ...... 77 4.2.3.1 Normalization and weighting ...... 79 4.3 Results and Discussion ...... 80 4.3.1 Inventory analysis ...... 80 4.3.2 Life cycle impact assessment ...... 81 4.3.2.1 Comparative analysis ...... 81 4.3.2.2 Contribution analysis ...... 82 4.3.2.3 Normalization ...... 86 4.3.3 Sensitivity and uncertainty analysis ...... 88 4.4 Discussion ...... 90 4.5 Conclusions ...... 90 Chapter 5 Decolorization of colored PET using Fenton’s reagent in solvent/water solution ...... 91 5.1 Introduction ...... 91 5.2 Experimental ...... 95 5.2.1 Materials ...... 95 5.2.2 PET fabric dyeing ...... 95 5.2.3 Decolorization experiments ...... 96 5.2.4 Full factorial design of experiments ...... 97

5.2.5 Effect of FeSO4, H2O2 and solvent ratio ...... 98 5.2.6 Decolorization efficiency on different dyes ...... 98 5.2.7 UV-Vis measurements ...... 99 5.2.8 Reflectance and color strength ...... 99 5.2.9 Analysis of bath residuals ...... 100 5.2.10 Intrinsic viscosity ...... 100

vii

5.3 Results and discussion ...... 100 5.3.1 Full factorial design of experiments (FFD) ...... 100

5.3.2 Effects of FeSO4, H2O2 and solvent ratio ...... 104 5.3.3 Decolorization efficiency on different dyes ...... 109 5.3.4 TEM, EDS and XPS analysis...... 120 5.3.5 Polymer degradation ...... 122 5.4 Conclusion ...... 123 Chapter 6 A life-cycle assessment case study of post-consumer PET fabric-to-fiber recycling ...... 125 6.1 Introduction ...... 125 6.2 Methodology ...... 126 6.2.1 Goal, functional unit and system boundary ...... 126 6.2.1.1 Goal and functional unit ...... 126 6.2.1.2 System boundary ...... 126 6.2.2 General data and assumptions ...... 129 6.2.3 Environmental impact assessment ...... 131 6.2.4 Normalization and weighting ...... 131 6.3 Recycling PET garments into fiber ...... 133 6.3.1 Collection of used PET fabric ...... 133 6.3.2 PET fabric decolorization ...... 133 6.3.3 PET recycling...... 134 6.3.3.1 Semi-mechanical recycling ...... 134 6.3.3.2 Chemical recycling ...... 135 6.4 Life-cycle assessment results ...... 135 6.4.1 Comparative analysis ...... 135 6.4.2 Contribution analysis ...... 139 6.5 Discussion ...... 144 6.6 Conclusion ...... 144 Chapter 7 Conclusions and Recommendations for Future Research ...... 146 References ...... 148

viii

LIST OF TABLES

Table 2.1 Summary of main components present in raw cotton fibers ...... 3

Table 2.2 Summary of steps in the preparation of cotton ...... 4

Table 2.3. Toxicity classes: hodge and sterner scale ...... 17

Table 2.5. Chromaticity coordinates for the CIE standard illuminant and source used ...... 21

Table 2.6. Classification of Dyes [93] ...... 31

Table 3.1. EC50 values of each substance tested in D. similis acute toxicity test...... 65

Table 3.2. The GHS criteria for classification of a substance in acute categories ...... 66

Table 3.3. Algae toxicity test.results expressed in inhibition concentration 50%, 72h (IC50) for the selected chemicals ...... 67

Table 3.4. The GHS criteria for classification of a substance in chronic categories ...... 67

Table 4.1. Impact categories used in impact assessment ...... 78

Table 4.2. Normalization factors for all impact categories analyzed ...... 79

Table 4.3. Product flows for manufacture of dyed cotton fabric products through conventional and bleaching process...... 81

Table 4.4. Comparative LCIA results associated with conventional and modified new bleaching process ...... 82

Table 5.1. Factor levels used in DOEs ...... 97

Table 5.2. FeSO4, H2O2 and water: acetone levels used ...... 98

Table 5.4. Conditions and testing results of the FFD with actual levels of factors for decolorizing Basic Yellow 28 (0.75 owf) on cationic dyeable PET ...... 101

Table 5.5 ANOVA summary for the full factorial LS model ...... 102

Table 5.6 Parameter estimates (Adjusted R2 = 0.8912)...... 103

Table 5.7 The color coordinates of the original dyed fabric and fabric after decolorization...... 108

Table 5.8 EDS analysis of compound attached on fibril precipitate...... 120

Table 6.1. Product systems in this study, comparing type of fiber, property and application ...... 126

Table 6.2. Data and assumptions in this study ...... 130

Table 6.3. Impact categories used in impact assessment ...... 131

Table 6.4. Normalization factors for all impact categories analyzed ...... 132

Table 6.5. LCA results for 1000 kg of PET fiber production using virgin and used PET fabric ...... 136

LIST OF FIGURES

Figure 2.1. Proton NMR resonance signals of 3,5-dimethylbenzoic acid ...... 20

Figure 2.2. UV-visible spectrum of blue and yellow dye solution ...... 24

Figure 2.3. Same yellow dye solution with different dye concentration ...... 25

Figure 2.4. UV-visible spectrum of two yellow dye solution with different brightness...... 26

Figure 2.5. Reflectance spectrum of yellow and red fabric...... 27

Figure 2.5. Structure comparison between compounds resulting from PET depolymerization process...... 49

Figure 2.6. Life Cycle Stages [154] ...... 55

Figure 3.1. EC50, 48h in mg/L-1 of each substance tested in D. similis acute toxicity test and the respective confidence interval of 95%...... 66

Figure 4.1. System map for the conventional bleaching process. Two processes were considered within the system boundary, including bleaching and rinsing & neutralizing. For each process, chemicals, water, energy (electricity and steam) and other material consumption were indicated as inputs ...... 74

Figure 4.2 System map for the modified new bleaching process. One process was considered within the system boundary. In contrast to the conventional method, the rinsing & neutralizing process after bleaching was eliminated since neutral pH was used for bleaching ...... 75

Figure 4.3(a-g). Results of contribution analysis for conventional and modified new cotton wet processing ...... Error! Bookmark not defined.

Figure 4.4. Normalized impacts of all categories for conventional and modified new bleaching process ...... 87

Figure 4.5. Normalized impacts of conventional and modified new wet processing with the same assumed weight loss (5%) during bleaching ...... 89

Figure 5.1. Structures of dyes used in PET decolorization studies ...... 94

Figure 5.2. Schematic of the dyeing procedure employed for cationic dyeable PET...... 96

Figure 5.3. PET fabric decolorization procedure used in this study...... 97

Figure 5.4. Actual Vs. predicted plot of K/S values for decolorizing Basic Yellow 28 dyed cationic dyeable PET ...... 102

Figure 5.5. Σ K/S (400-750nm) for Basic Yellow 28 dyed cationic PET fabric treated with Fenton’s reagent contaning various [FeSO4]...... 105

Figure 5.6. Σ K/S (400-750nm) for Basic Yellow 28 dyed cationic PET fabric treated with Fenton’s reagent contaning various [H2O2]...... 105

Figure 5.7. Σ K/S (400-750nm) for Basic Yellow 28 dyed cationic PET fabric treated with Fenton’s reagent in various water:acetone ratios...... 106

Figure 5.8. Calculated fabric samples containing Basic Yellow 28 before and after Fenton’s treatment...... 108

Figure 5.9. Σ K/S values of fabrics colored by basic yellow 28 before and after decolorization using Fenton’s reagent under different conditions...... 109

Figure 5.10. Fabric samples containing disperse dyes before and after Fenton’s treatment at high and low Fe(II) levels...... 110

Figure 5.11. Σ K/S values of fabrics before and after decolorization using Fenton’s reagent at different Fe(II) levels (0.10 and 1.8 mM)...... Error! Bookmark not defined.

Figure 5.12. UV-Vis spectrums of solution collected at the end of stage I (extraction) and stage II (decolorization) in decolorization process ...... Error! Bookmark not defined.

Figure 5.13. (A-D) TEM images of insolubles produced during Fenton’s decolorization, at normal (A&B) and high (C&D) magnification; EDS image (E) of solid precipitate in image (C)...... 121

Figure 5.14. XPS survey of original PET fabric (left) and decolorized PET fabric (right) by using Fenton’s reagent method...... 122

Figure 5.15. Intrinsic average molecular weight of PET fabric dyed by Disperse Blue 56 and decolorized using optimum method ...... 123

Figure 6.1. Cradle-to-factory gate system boundary of recycling PET fibers from waste PET fabric, splitting the fiber life and the second life based on the “Cut-off” approach ...... 128

Figure 6.2. The PET fabric decolorization process ...... 134

Figure 6.3. The normalized environmental impacts of three PET fiber production systems 138

Figure 6.4. Results of contribution analysis for PET fiber production using virgin PET and used PET fabric through chemical & semi-mechanical recycling ...... Error! Bookmark not defined.

xii

LIST OF SCHEMES

Scheme 1. Reaction of TBBC with H2O2 to produce a cationic peracid...... 12

Scheme 2. A proposed sorption-activation peroxide bleaching model for TBBC [20]...... 13

Scheme 3. Process for making 4-chloromethyl benzoyl lactam ...... 14

Scheme 4. Process for making the lactam based bleach activator...... 14

Scheme 5. Free radical generation by ozone...... 41

Scheme 6. PET synthesis reactions: (a) trans-esterification reaction and (b) condensation reaction...... 48

xiii

Chapter 1 Introduction

1.1 Dissertation Outline

This dissertation consists of seven chapters. In chapter 1, the dissertation outline and research objectives are described. In chapter 2, literature pertaining to the physical and chemical basis preliminaries to conduct this research is reviewed. In chapter 3, the toxicity of ten cationic bleach activators is reported using Daphnia sp. Acute Immobilization Test and

Ames Test. In chapter 4, a comparative life cycle assessment of conventional and innovational bleach processing is reported. The environmental impacts of conventional bleaching and innovational bleaching are compared and discussed. In chapter 5, the design and optimization of PET fabric decolorization process using Fenton’s reagent in water/acetone solution is reported. The decolorization conditions are reported using 24 full factorial design of experiment. The applicability of this process is reported through comparing the process decolorization performance on PET fabric containing different type of dye. The residual on fabric and in solution after decolorization is reported using TEM, EDS and XPS. The polymer degradation of PET fabric after decolorization is report. In chapter 6, a life cycle assessment case study of post-consumer PET fabric-to-fiber recycling is reported. The environmental impacts of PET fiber production using virgin PET and decolorized PET fabric are compared and discussed. In chapter 7, the conclusions drawn from the study are listed and the needs of future work are discussed.

1.2 Research Objectives

1. Obtain the toxicity data of the new bleach activators and compare it with toxicity of

TBBC.

2. The life cycle assessment comparison between cotton fabric bleached with TBBC-

activated H2O2 system and conventional rapid bleaching will be conducted. The

environmental impacts of novel bleaching method will be studied.

3. Develop a novel solvent-based Fenton’s reagent process for PET fabric decolorization

method. This method should be used to decolorize PET fabric efficiently. In order to

get recyclable PET after decolorization, the differences of degree of polymerization

between untreated PET and decolorized PET will be measured.

4. Optimize the recipe of Fenton’s reagent process for PET decolorization. A full

factorial design of experiments will be made for obtaining the key factors and the best

processing condition. The factors could be: Fenton’s reagent concentration; treatment

time and temperature; liquor to goods ratio; pH.

5. Study the feasibility of the optimum decolorization process on fabric colored by

different types of dyes. Three dye categories: Azo, Nitro and Anthraquinone will be

used.

6. A life cycle assessment of recycled PET garment which made by decolorized PET

fiber will be conducted. It will be compared with the LCA of PET garment made by

virgin PET materials.

Chapter 2 Literature Review

2.1 Natural color contents in cotton

Cotton is the most widely used natural fiber by far, owing to its perceived comfort, relatively low cost, bright hues and good fastness properties when dyed. It is grown and processed into commercial products in various locations throughout the world. Approximately 116.7 million of 480 lb bales of cotton were processed in 2013/14 [1].

Table 2.1 shows the main components present in cotton [2]. Most of the content is cellulose and the other contents that may affect dyeing and finishing process take up around 1%.

Table 2.1 Summary of main components present in raw cotton fibers Components Percentage

Cellulose 91.00%

water 7.85%

Protoplasm,pectins 0.55%

Waxes, fatty substances 0.40%

Mineral salts 0.20%

Preparation, dyeing and finishing are three stages commonly used in wet processing of textiles. Preparation is a critical phase in the wet processing of fibers, yarns, fabrics or garments that aims to remove some or all of the impurities in the fiber, thereby enabling effective dyeing and finishing in the subsequent stages. In some cases, fibers are not dyed,

but are left in a whitened state. Table 2.2 shows the primary stages of preparation for cotton

[3].

Table 2.2 Summary of steps in the preparation of cotton Process Description

For woven fabrics only, size is removed most commonly via amylase for Desizing starch and hot water for PVA

Surface fibers are burned off fabric Singeing to give a smooth surface

Scouring Oils and waxes are saponified and emulsified to improve absorbency

Bleaching Fibers are treated with oxidizing agent to improve whiteness

A treatment for cellulosic materials. It causes increase in the surface area Mercerization and reflectance and give the fiber s softer feel

2.2 Peroxide-based bleaching

Whiteness is one of the major properties of fabrics in textile industry. It is very important not only for daily application but also for post processing of textile such as dyeing and finishing.

However the impurities remaining in most of the textile materials will cause white appearance detraction [4-7]. Bleaching is a key process used to remove colored impurities present in natural fibers such as cotton, ramie, and wool. Bleaching may be performed using a continuous or batch process [8]. A rapidly process performed at elevated temperature and a relatively slow process at room temperature are two common methods used in textiles bleaching. Perhydroxyl anion is the primary oxidative species for conventional bleaching process. The generation of the perhydroxyl group may be obtained in a number of ways,

using H2O2 and sodium perborate (NaBO3·nH2O) [16]. Of these, H2O2 is the most commonly used in diluted form (e.g. 35% w/w), owing to its very low cost, abundance, and ease of application from a solution.

H2O2 is a weak acid that exists in equilibrium with its conjugate base, as shown in Equation 3.

+ - H2O2 H + HOO (3)

In order to shift the equation to the right so that the perhydroxyl anion is established in high concentration, alkaline conditions are required, typically in the range pH 10.5-12 [12]. The perhydroxyl anion destroys many impurities via oxidation in substrates, although the exact mechanism is unclear [13-15].

Rapid bleaching is undertaken at relatively high pH and at elevated temperatures, typically

95°C or even higher to obtain better whiteness. These conditions consume significant amounts of energy and lead to reduction of fiber strength up to approximately 10% [11], via reduction in degree of polymerization. Furthermore, neutralization of the alkaline bleach bath is required at the end of the process, which generates electrolytes that have a negative environmental impact. In large dyeing and finishing mills, the effluent must be treated in lagoons prior to discharge to receiving waters. Hence, conventional bleaching is significantly costly.

Over the last 40 years, attempts have been made to increase bleaching efficiency of textile materials and reduce the environmental impact of bleaching processes. One approach that has been made commercial in laundry detergent formulations and is showing promise as a new

method of bleaching textiles during the manufacturing process is the use of so-called bleach activators.

2.3 Bleach activators

Bleach activators are compounds with O- or N-bounded acetyl groups which are able to react with the perhydroxyl anion to yield a peroxy acid functional group. Since 1970 sodium perborate has been used as a bleaching compound in European laundry detergents. Sodium perborate decomposes rapidly in aqueous solution to yield H2O2, as shown in Equation 4.

(4)

Sodium perborate by itself is active at temperatures above 80°C, but less so at 40-60°C. Hence, the bleach activators in the presence of which sodium perborate acts as a bleaching agent already at temperatures below 80°C were developed [21].The peroxy acid is decomposed in weakly basic media in a bimolecular reaction forming singlet oxygen[21], as shown in

Equation 5.

(5)

Today, two peroxyl activators are in widespread commercial use: tetraacetylethylenediamine

(TAED, 1), mostly used in Europe, Asia and South America, and the sodium salt of

nonanoylbenzenesulphonic acid (NOBS, 2), used mainly by The Procter & Gamble Company

(P&G) in the US, Japan and certain other countries.

H3C O CH3 O N N O CH3 O CH3

O SO3Na H3C O

Cai et al. [30] reported a new class of bleach activators and their application in the textile bleaching process. The new activators are guanidine derivatives, in which at least one amine hydrogen atom is substituted with an alkyl or acyl group. Suitable acyl groups include the benzoyl, formyl and acetyl groups.

3 4 5 6

Examples of the activators described in this paper include 1,1-dimethylguanidine sulphate (1,1-

DMG, 3), 1,1-dimethylbiguanide hydrochloride (1,1-DMBG, 4), 1-benzoylguanidine

hydrochloride (1-BOG, 5) and 1-acetylguanidine (1-ACG, 6).The performance of each new activator was evaluated on various cellulosic textiles and compared with the performance of

TAED. The results demonstrated that the whiteness of the substrate bleached using any of the alkyl-substituted guanidine additives is higher than that obtained without an activator. Among the alkyl guanidines and biguanides evaluated, 1,1-DMG and 1,1-DMBG were found to be the most effective activators and performed better than TAED.

2.3.1 Cationic Bleach Activators

TAED and NOBS are anionic bleach activators, and have certain limitations considering the negative charge on cellulosic fibers. Compared to anionic bleach activators, cationic bleach activators have potential to exhibit better performance because they exhibit inherent substantivity to the negatively charged surface of cellulosic fibers in neutral to alkaline conditions to provide enhanced bleaching efficiency, especially in low temperature [27]. They can react with peroxide to produce a peracid. It is a stronger oxidative specie for bleaching compared to the perhydroxyl anion obtained from the ionization of H2O2 under alkaline conditions.

Cationic bleach activators have high water solubility because it contains at least one cationic group. Cationic bleach activators can be applied in cold pad-batch or rapid hot peroxide bleaching for cotton [27,28]. In the late 1990s, Miracle and co-workers at P&G patented a series of new activators with cationic groups [37]. N-[4-(triethylammoniomethyl) benzoyl] caprolactam chloride (TBCC, 7) was one of them and it exhibited satisfactory bleaching performance in a shorter time and at lower temperatures than conventional peroxide bleaching.

The performance of TBCC was superior to that of NOBS, possibly due to its higher substantivity toward cotton in the bleach solution. Also the bleach activator system produced substantially less fiber damage than conventional bleaching [27]. The prior art shows that

TAED and NOBS both need alkaline condition for effective fabric bleaching, which requires neutralization, and reduces fabric strength. TBCC, on the other hand, has been shown to be effective when applied under neutral conditions. Also, as cationic compound, TBCC has a better absorption on the cellulose than TAED and NOBS, which likely contributes to enhanced

bleach performance. However, TBCC was found to be unstable in aqueous solution and the instability makes it hard to store for industry use.

O O

Cl N N

In order to improve the hydrolytic stability and bleaching performance, Lee et al. [25] synthesized, characterized and tested five cationic bleach activators containing lactam-based leaving groups of varying ring size. Their structures are listed below:

n=1, 2, 3, 4 and 5

The hydrolytic stability of each activator was determined via HPLC- based analysis of hydrolysis products, titration of AvO and whiteness assessment of cellulosic fibers using a peroxide-activator bleaching system following solution storage for various times under controlled conditions. All the cationic bleach activators exhibited good oxidative power before aqueous storage, as exhibited by CIE Whiteness Index measurement of cellulosic fibers bleached with each activator and alkaline H2O2. After comparing the effect, stability and cost of each lactam, N-[4-(triethylammoniomethyl)benzoyl] butyrolactam chloride

(TBBC, CH2 group n=1) was determined to be the most promising practical substitute to the more hydrolytically unstable TBCC.

TBBC has a similar structure to TBCC, except for the leaving group. The bleach mechanism for these cationic activators is the same, whiles the stability and, to a certain extent bleach performance of TBBC is better than TBCC.

TBCC (7) and TBBC (8) increase the reactivity of a H2O2 bleach bath by reacting with perhydroxyl anions (OOH-) to form a reactive peracid oxidant. It has potential to be a more effective bleaching system than H2O2 alone. A leaving group is expelled in the process. In

TBCC, caprolactam is the leaving group while in TBBC, the butyrolactam is the leaving group.

Incorporating a cationic group facilitates the potential inherent affinity for negatively charged substitutes in addition to water solubility. Scheme 1 shows the reaction of TBBC with H2O2 to produce a cationic peracid.

O O Cl N N

Scheme 1. Reaction of TBBC with H2O2 to produce a cationic peracid.

Scheme 2. A proposed sorption-activation peroxide bleaching model for TBBC [20].

Xu et al. [20] reported the sorption of a novel cationic bleach activator TBBC on regenerated bamboo fiber (Scheme 2). At the sorption equilibrium, bleaching was initiated by addition of sodium perborate to liberate H2O2, which reacted with TBBC to generate a peracid that is a more kinetically active oxidant than peroxide. The result supports their hypothesis that the cationic group brings the activator in close proximity of cellulosic fibers and associated colored impurities and that this proximity is important for efficient oxidation to take place. 13

Sang-Hoon Lim et al. [28] reported and compared the bleaching performances of NOBS activated and TBCC activated peroxide system.

2.3.2 Synthesis of cationic bleach activators process

Lee et al. reported the synthesis method for making lactam-based cationic bleach activators

[21]. The first step is to make the intermediate: 4-chloromethyl benzoyl lactam. Scheme 3 summarizes the process.

Scheme 3. Process for making 4-chloromethyl benzoyl lactam

In the second step the intermediate is reacted with triethylamine to get the final bleach activators: the 4-chloromethyl benzoyl lactam was dissolved in acetonitrile under argon and reacted with triethylamine. The solution was stirred under reflux for 4 hours then cooled to room temperature. The solvent was evaporated and the mixture was washed using acetone.

Scheme 4 summarizes the process.

O O O O Cl N N + (CH ) Cl (CH2)n CH3CN N 2 n

Scheme 4. Process for making the lactam based bleach activator.

2.3.3 Environmental properties of cationic compounds

Toxicity is a key characteristic of all new compounds developed for commercial application.

LC50 and LD50 are the two key indexes of toxicity. LC stands for “lethal concentration”, LC50 values refer to the concentration of a chemical that kills 50% of the test animals in a given time, such as 24h or 48h. LD stands for “Lethal Dose”. LD50 is the amount of a material, given all at once, which causes the death of 50% of a group of test animals. LD50 is one way to measure the short-term toxic potential of a material dose. Cationically charged compounds are often flagged by the US Environmental Protection Agency as being potentially toxic to aquatic organisms [159]. The cationic group in TBCC and TBBC is triethylamine, which is a toxic chemical. Additional research to discover reduced toxicity bleach activators may be necessary.

Bleach activators are consumed during bleaching and therefore cannot be recycled after use.

The cationic chemical will exist in the waste water and it is important to minimize its the impact on the environment for industry use. The cationic groups in both TBCC and TBBC are triethylamine. Triethylamine is LC50 60mg/L and LD50 460mg/kg. Table 2.3 summarizes toxicity classifications of molecules. The toxicity rating of triethylamine is a rating of two, or highly toxic. Therefore, it is desirable to replace triethylamine with a low toxicity cationic group to help make the bleach activator more environmentally responsible. Table 2.4 shows several amine groups with relatively low toxicity. It is feasible that the toxicity of bleach activators may be decreased by replacing triethylamine with a low toxicity tertiaryamino group.

The nicotinoyl series of tertiary amines could be employed as the substituent that confers cationic character to a molecule with relatively low toxicity. The toxicity of 1,4-

Diazabicyclo(2.2.2)octane is also relatively low. 3-Picoline is the main precursor of niacin, one of the B vitamins. Nicotinamide is also one of the B vitamins. Although pyridine is a highly toxic chemical, it is still less toxic than triethylamine. These chemicals can be incorporated into bleach activators as the cationic group during synthesis. The reaction sequence for the synthesis of new cationic bleach activators is similar to the synthetic method for the preparation of to TBBC. The chlorine substituent in the benzoyl chloride moiety will react with the nitrogen in the amine group to produce cationic chemicals. After synthesis of the new cationic bleach activators, optimizing the bleach recipe, comparing the toxicity and bleach performance with current bleach activators are necessary.

Table 2.3. Toxicity classes: hodge and sterner scale Toxicity rating Description Lc50(mg/l) Ld50(mg/kg)

1 Extremely Toxic 1 or less 10 or less

2 Highly Toxic 1-50 10-100

3 Moderately Toxic 50-500 100-1000

4 Slightly Toxic 500-5000 1000-10,000

5 Practically Non-toxic 5000-15,000 10,000-100,000

6 Relatively Harmless 15,000 or more 100,000 or more

Table 2.4. Toxicity of selected tertiary amines

Name Structure Lc50(mg/l) Ld50(mg/kg)

Triethylamine N 600 460

Pyridine N 4000 866

1,4-Diazabicyclo(2.2.2)octane N N 1510-1980 1700

O Nicotinamide NH2 1000 3500 N

3-Picoline 3300 400 N

Note: mg/kg = 0.001/1000 = 0.000001 = 1/1000000 = ppm

2.4 Structure analysis

2.4.1 Time-of-flight mass spectrometry

Time-of-flight Mass Spectrometry (TOFMS) was first introduced by Wiley et al. in 1955 [38].

TOFMS can determine the mass-to-charge ratio (m/Q) of an ion via a highly accurately measured time measurement. In TOFMS, ions are accelerated by an electric field. The ions that have the same charge will have the same kinetic energy and the velocity of ion depends on the mass-to-charge ratio. The time that the ion subsequently takes to reach a detector at a known distance is measured. From this time and the known experimental parameters one can find the mass-to-charge ratio of the ion. Based on this technique, some other methods such as matrix-assisted laser desorption/ionization (MALDI), californiumplasma desorption, static secondary ion mass spectrometry (SIMS) [39-42] were developed and are now quite widely used. An important enhancement to mass spectrometry is combining it with chromatographic separation techniques. The chromatographic separation system will separate the components of a mixture first followed by ionization, and passing the components into the mass spectrometer’s analyzer for detection.

2.4.2 High-performance liquid chromatography

HPLC is a separation technique that involves a liquid mobile phase and a stationary phase.

The mobile phase can be manipulated easily to accommodate a variety of chemical compositions. In 1966, Horvath developed reverse-phase separations to high-performance liquid chromatography (HPLC) [43]. Reverse-phase HPLC is especially useful for quantifying and purifying hydrophilic components in a mixture.

2.4.3 NMR spectroscopy

Nuclear magnetic resonance (NMR) is a physical phenomenon. It was first described and measured in molecular beams by Rabi et al. in 1938 [44]. NMR spectroscopy is one technique to obtain structural information on molecules. 1H is the most common element characterized in NMR analysis, because hydrogen is highly abundant and it is the nucleus most sensitive to a NMR signal. By studying the peaks of nuclear magnetic resonance spectra, the structure of many compounds can be inferred. Figure 2.1 shows the proton NMR resonance signals of 3, 5-dimethylbenzoic acid. The proton in different location has different chemical shift value and the height of the signal represents the number of the proton at same location.

Figure 2.1. Proton NMR resonance signals of 3,5-dimethylbenzoic acid

2.5 Whiteness Measurement

2.6 Whiteness

In colorimetry, whiteness is the degree to which a surface is perceived to be as white [47].

Whiteness is fundamentally an attribute of the human visual system of whose “color” is devoid of hues and grayness [11].

2.6.1 Whiteness index

In 1931, the CIE (the International Commission on Illumination) introduced the instrumental color measurement for specifying color numerically. All colors, including white, can be defined by tristimulus values. Whiteness index is a single scale of whiteness and allows users to identify and compare the level of whiteness of two or more objects, shown as Equation 8

[49].

WI CIE = Y + 800 (xn - x) + 1700 (yn - y) (8)

Where Y, x, y are the luminance factor and chromaticity coordinates of the specimen, and xn and yn are the chromaticity coordinates for the CIE standard illuminant and source used.

These values are provided in the Table 2.5 below based on the illuminant and observer used.

Whiteness Index can only be calculated for illuminants C, D50, and D65. Currently, no additional illuminants are incorporated into the standard.

Table 2.5. Chromaticity coordinates for the CIE standard illuminant and source used VALUE C/2° D50/2° D65/2° C/10° D50/10° D65/10°

xn 0.3101 0.3457 0.3127 0.3104 0.3477 0.3138

yn 0.3161 0.3585 0.3290 0.3191 0.3595 0.3310

2.7 The physical and chemical assesment of color

To see color, three things are required: a source of illumination, a human eye to observe the effect and an object to interact with the light which comes from this source [151].

And these three things are related to three natural science disciplines: physics, biology and chemistry.

Human experience colors though interpreting signal by brain. The signal comes from the optical nerve from the eyes in response to stimulation by light. Human eyes are only sensitive to light with a very narrow wavelength range 360-780 nm. Beyond this range extremes are the ultraviolet (UV) region (below 360 nm) and the infrared (IR) region (above

780 nm).

The most familiar nature light source is daylight. The daylight contains the complete visible wavelength range although the exact composition is variable. Tungsten lamps and fluorescent lights are two types of artificial illumination used as white light source in daily life. The composition of the light from these sources varies depending on the type of lamp.

For example, tungsten lamp appear yellowish because the light it emits is deficient in the blue region of the spectrum. In this case, same object will have a different color under different illumination sources.

There are fifteen specific causes of color which can be collected into five groups

[151]:

a) Color from simple excitations: color from gas excitation, and color from vibrations

and rotations;

b) Color from ligand field effects: color from transition and metal compounds and from

transition metal impurities;

c) Color from molecular orbitals: color from organic compounds and from charge

transfer;

d) Color from band theory: color in metals, in semiconductors, in doped semiconductors

and from color centres;

e) Color from geometrical and physical optics: color from dispersion, scattering,

interference and diffraction.

For dyes and pigments, color is generated by the mechanism described in group (c). In order to make sure dye and pigment have color, which means the light can interact with them, they must to able to absorb and scatter light. One substance can absorb light means that the radiant energy can raise its molecular to higher energy states. Scattering is occurred when light is re-directed as the results of multiple refractions and reflections. If only absorption happens, this substance will be transparent. If only scattering happens, the object will appear either translucent or opaque.

The color of dye is based on the wavelengths of visible light absorbed and the wavelengths of light reflected. There are various of ways to describe color in scientific terms. One useful method involves UV-visible spectroscopy. UV-visible spectra of dye solution can provide important information to enable relationship between the color and molecular structure of the dyes. UV-visible spectrum can define the color in three attributes: hue, strength and brightness. The hue of a dye is determined by the specific range of wavelength of light it absorbed. The hue can be characterized to a reasonable approximation by the λmax value obtained from the UV-visible spectrum. Figure 2.2 shows the UV-visible spectrum of blue

and yellow dye solution. The λmax value of blue dye solution is around 584 nm and the λmax value of yellow dye solution is around 424 nm.

UV-visible spectrum 2 1.8 1.6 1.4 1.2 1 0.8 Absorption 0.6 0.4 0.2

626 710 360 374 388 402 416 430 444 458 472 486 500 514 528 542 556 570 584 598 612 640 654 668 682 696 724 738 752 766 780 794 wavelength

blue yellow

Figure 2.2. UV-visible spectrum of blue and yellow dye solution

The strength of the dye is given by the molar extinction coefficient (ε) at its λmax value. It can be obtained from UV-visible spectrum by using the Beer-Lambert Law, showed below:

A=εcl where A is the absorbance of the dye in a particular wavelength, ε is the molar extinction coefficient at that wavelength, c is the concentration of the dye and l is the path length of the cell used for measurement of the spectrum. Figure 2.3 shows two yellow dye solution with same hue but different color strength.

UV-visible spectrum 2

1.5

Absorption 0.5

15 29 43 57 71 85 99

267 351 113 127 141 155 169 183 197 211 225 239 253 281 295 309 323 337 365 379 393 407 421 435 wavelength

yellow light yellow

Figure 2.3. Same yellow dye solution with different dye concentration

The brightness of color is characterized by the absence of wavelength of transmitted light. In terms of the UV-visible spectrum, the dyes with bright color show narrow absorption bands and broad absorption bands are characteristic of dull color. Figure 2.4 shows two yellow dye solution with different brightness.

UV-visible spectrum 2.5

1.5

1 Absorption 0.5

547 649 360 377 394 411 428 445 462 479 496 513 530 564 581 598 615 632 666 683 700 717 734 751 768 785 wavelength

yellow bright yellow

Figure 2.4. UV-visible spectrum of two yellow dye solution with different brightness.

2.7.1 Visible reflectance spectroscopy

Visible reflectance spectroscopy is used to measure the color of opaque object

such as textile fabrics. For example, in Figure 2.5, a yellow color has the low

reflectance in the 400-500 nm but high reflectance of the yellow wavelengths (500-

600 nm). And a red color has the low reflectance in the 400-600 nm but high

reflectance in 600-700 nm.

Reflectance spectrum 100 80 60 40 20 0

400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 Reflectance Reflectance percentage wavelength

yellow red

Figure 2.5. Reflectance spectrum of yellow and red fabric.

2.7.2 Color strength

Kubelka developed numerous formulas for correlating reflectance with concentration by making scattering and surface difference corrections. It was found that the ratio of light absorption to light scattering at a given wavelength is proportional to the concentration of the dye in the sample. The theory works best for optically thick materials. The relationship shown here is derived from the Kubelka-Munk equation [152].

(1−푅)2 K/S= 2푅

Where R= 1.0 at 100% reflectance; K is the absorption coefficient and S is the scattering coefficient.

Color strength is defined as:

Color strength = [(K/S) batch / (K/S) standard] × 100

2.8 History of colors and dyes

Colored substrnces such as minerals and oches have been used since ancient human history. Their uses ranged from decorating the body to painting on natural or constructed walls. The color they produced were quite stable and have survived for thousands of years.

Natural dyes used for textiles can be dissolved or dispersed in a medium and coloring the fiber or surface of a textile. Because ancient textiles are so biodegradable, few evidence of dyed fabric can be survived. The earliest record of natural dyes was made by Pliny the

Elder, a 1st-centry AD Roman encyclopedist. He wrote that the Egyptian dyers used indigo,

Kermes (source of red or purple, made from parts of the cochineal insect), archil ( a red- producing lichen, also called orchil or cudbear), alkanet (an herb whose root produces red), buckthorn berries and saffron (for yellow) [52]. Dyes were pretty precious in the ancient time because of their complex extraction process from nature materials and low yield. At that time, dyed fabric was only used by the wealthy.

In 18th and 19th centuries, dyeing developed from the boom in new research and processes. As the textile industry throughout Europe and America grew more mechanized, processes for dyeing fabric also evolved. Cotton became the most widely used material at that time but process for dyeing fabric with many color was complex and difficult.

Indigo was widely used from the 18th century because it was the most lightfast and fade proof color in that time, compared with other vegetable dyes [52]. In the 19th century, the British developed indigo factories in India and became the foremost producers in the world. Some regions of India, such as Bengal, became heavily dependent upon indigo

production, and this led to periodic famines and revolts in regions of monoculture, such as the 1860-1867 Indigo War [53]

In 1853, William Henry Perkin, a 15-year-old Englishman discovered mauve (9) during the experiment in which he attempted to synthesize quinine from aniline. In 1856, he patented mauve which is the first synthetic dye in the world and began to manufacture it.

Many organic chemists such as Hofmann, Charles-Adolphe Wurtz and Emil Fischer also chose to develop and study the structures and properties of dyes. Currently, the dye manufacturing industry is declining in Europe and the United States. Much of the world market in synthetic colors is controlled by Japanese companies [52].

A dye is a colored organic compound comprised of two key components: chromophores and auxochromes. Dyes can strongly absorb light in the visible region and can attach to the fiber by chemical and physical bonding between the groups on dye and groups on the fiber. Chromophores are the groups consisting conjugated double bonds containing delocalized electrons, which can produce color. Most of the chromogens are aromatic structures containing benzene, naphthalene or anthracene rings. Auxochromes not only can support chromophore but also make dyes be soluble in water and give enhanced affinity to

fibers [91]. –NH3, -COOH, -HSO3, and –OH are the most common auxochrome groups [92].

Dyes can be classified through many ways. Table 2.6 shows the chemical classification of dyes according to their chemical structures and method of application [93].

Table 2.6. Classification of Dyes [93] Dye type Example Characteristics

I. According to chemical structure

Derivatives of phenols containing at least

1 Nitro dyes one nitro group ortho or para to the

hydroxyl group

The azo dyes represent the largest and the

most important group of dyes. They are

2 Azo dyes characterized by the presence of one or

more azo groups (-N=N-), which form

bridges between two aromatic rings.

Dyes in which the central carbon

connecting two phenyl groups lacks an 3 Diphenylmethane dyes amino group; the chromophore is the

quinoid ring

Table 2.6. Continued Central carbon atom is joined to two

benzene rings and to p-quinoid group.

Triphenylmethane dyes are not fast to light

or washing, however, except when applied 4 Triphenylmethane dyes to acrylic fibers. They are used in large

quantities for coloring paper, and typewriter

ribbons where fastness to light is not so

important.

Dyes having xanthene central to their 5 Xanthene dyes molecular structure.

Phthalein dyes are dyes containing

6 Phthalein dyes phthalein structure. And they are insoluble

in water and are soluble in alcohol.

Table 2.6. Continued

Indigoid is the parent compound of indigoid 7 Indigoid and Thioindigoid dyes dyes.

A p-quinoid group is fused to two other 8 Anthraquinone dyes benzene rings

II. According to method of application

Any of a class of colored and water soluble

compounds which have the affinity for fiber

1 Direct dyes and can be dye color a fabric directly when

the fiber is immersed in a hot aqueous

solution of the dye.

Table 2.6. Continued

This class of dyes requires a pretreatment of

2 Mordant dyes the fiber with a mordant material designed

to bind the dye.

These dyes are insoluble in water, but on

reduction with sodium hydrosulfite yield 3 Vat dyes alkali soluble forms (Leuco-compounds)

which may be colorless.

These dyes contain a substituent which can 4 Reactive dyes reacts with the substrate.

Table 2.6. Continued These are sparingly soluble in water, but are

capable of dissolving in certain synthetic

5 Disperse dyes fibers. Disperse dyes usually exist in the

dye bath as a suspension or dispersion of

microscopic particles.

2.9 Dyes in wastewater

The discovery of the synthetic dyes overwhelmed the role of natural dyes in the society due to its low production cost, brighter colors, better resistance towards environmental factors (light, oxygen), and easy to apply factor [94]. Many industries like textiles, leather, cosmetics, paper, printing, plastics use synthetic dyes to color their products.

Thus, effluents from these industries contain various kinds of synthetic dye. Over 100,000 commercially available dyes existed and more than 7 × 105 t per year were produced in 2005

[95, 96]. It is reported that 10-15% of the used dyes enter the environment through wastes

[97, 98]. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) are two approaches to environmental impact. Typically, the waste water coming from textile industry has COD ranging from 150 to 12,000 mg/L and BOD ranging from 80 to 6,000 mg/L. The

BOD/COD ratio is around 0.25 which shows that it contains significant levels of nonbiodegradable organic compounds [99].

For environmental and health reasons, dyes as well as the degradation products in the waste water from dyeing process should be removed before they reach the effluent stream going out to the discharge water supply. Significant amounts of dyes are lost during the dyeing process, with the actual values depend on the class of dyes. The overall average loss is 15% [149]. The dye effluent will discolor water and increase the BOD of the contaminated water, creating anoxic conditions which may be lethal to aquatic species.

Color removal is a complex issue in the textile industry. In 1970’s, the color removal question first arose from a formal regulatory standpoint. Around 1972, the Federal Register contained guidelines for color removal in textile waste water. However, because of the testing methods lacked accuracy, no universal treatment technology emerged for color

removal and no evidence pointed to color toxicity, the issue of color removal standards received sporadic attention up until 1990’s [150].

A wide range of methods has been developed for removal of dyes from wastewater to decrease their impact on the environment. The methods can be generally classified in to three main categories: physical, chemical and biological treatment [100].

2.10 Dye wastewater treatment

2.10.1 Adsorption and other physicochemical methods

Adsorption methods can remove the color by simply adsorbing dyes from water and then change or destroy the dye chromophore [54]. However it cannot remove the residual dye completely, so the treated wastewater may still pose environmental problems.

2.10.1.1 Inorganic adsorption systems

Carbon-based inorganic adsorption agents

Activated carbon is the most often used adsorbents in conventional adsorption agent

[55]. It can be made from coal, wood, peat and other carbonaceous starting materials. Due to its strong binding with organic substances, it is very effective in treating organic-laden wastewater. The disadvantage of this adsorbent is the cost and the regeneration requirements.

The efficiency of the activated carbon depends on the type of dye [56]. For cationic, mordant and acid dyes, high removal levels (over 90%) are achieved by using activated carbon.

Moderate removal levels (over 40%) can be obtained for direct, sulfur, dispersed and reactive dyes. While the removal level is very low (under 20%) for vat dyes.

Other inorganic adsorption agents

Clays are widely used as catalysts, adsorbents and ion exchanges because of their low cost. Clay minerals such as kaolinite and montmorillonite are used as adsorbents for dyes

[57]. It was reported that basic, acidic, disperse, direct and reactive dyes in the wastewater could be removed by the use of acid-activated clay. Basic dyes have the highest adsorption capacity and this agent was proposed for their removal from aqueous media [58]. At acidic pH, low temperature, small particle size of clay can increase the efficiency Omega Chrome

Red ME (10) removal [59].

Silica and alumina were also used for removal of dyes in effluents [60-62]. Through the analysis of thermodynamical parameters, the adsorption of Rhodamine B, Acid Red 4 and

Nile blue on alumina was found to be more favorable at high temperature. Adsorption followed the Langmuir isotherm.

2.10.1.2 Organic adsorption agents

Organic adsorption agent mostly comes from the waste or by-product of industrial processes, which has no other commercial value. Compare with inorganic adsorption agent, its manufacturing cost is much lower or can be considered as no cost.

Biogas waste can be used for remove of Rhodamine B from the wastewater of a textile plant. The adsorption followed the Freundlich isotherm and the optimum pH was

2.3[63]. Chitosan was found to have high capacities for removal of anionic dyes such as direct yellow 4 [64]. Waste banana pith was used for the removal of Rhodamine B from aqueous solutions. At pH 4, it had the highest adsorption capacity, 84 % of the dyes were removed [65].

2.10.2 Chemical decolorization methods

Chemical decolorization methods are used to break down the dye structure through oxidation or reduction reactions. Table 2.7 contains some common agents for dyes decolorization with their advantages and disadvantages.

Table 2.7. Comparison of decolorization based on active oxygen species Agent Advantages Disadvantages Relatively high toxicity compared Simple equipment and process NaOCl with other agent Rapid decolorization Salt formation High equipment cost Short reaction times Not applicable for all dye types O 3 No salt and sludge formation No COD reduction Toxicity and hazard handing Short reaction time Not applicable for all dye types UV/H2O2 Reduction of COD Relatively high energy and equipment No salt and sludge formation cost Simple equipment and easy operation Long reaction time FeSO /H O Reduction of COD 4 2 2 Salt and sludge formation Increase of dissolved oxygen in water

2.10.2.1 Ozonation

Ozonation has found application in the decolorization of synthetic dyes due to its effective oxidation process. It has been reported that ozonation is effective for azo dyes decomposition in textile wastewater. The decomposition rate was considerably higher at acidic pH, while the influence of temperature and UV light on the decomposition level was negligible [130]. The effect of ozonation on the toxicity of wastewater effluents has been investigated using the nematode Caenorhabditis elegans. The data indicated that the toxicity depended on the type of dye decomposed [131]. The influence of operating parameters on the decolorization of reactive orange 14 by ozone has been studied in detail. The results indicated that the decomposition level increased with increasing pH and temperature [132].

The reaction mechanism of ozonalytic decomposition was made free radical generation, showed in scheme 5 [144].

Scheme 5. Free radical generation by ozone.

Ozone will rapidly decompose and yield hydroxyl radicals (2.8 V) which was reported by Lopez-Lopez et al [146], during ozonation of sulphonated some azo dyes.

Ozonolysis, the reaction of ozone with a carbon–carbon double bond (C=C), is well known. The C=C bonds are very attractive centers for addition reactions by ozone to yield reactive intermediates. Therefore, stoichiometric relationship may be considered between ozone and the double bonds. Kusvuran et al. [147] recently reported that relation between ozone and double bonds, C=C, C=N and N=N, in the decolorization study of some dyes

(basic yellow 28, reactive black 5 and reactive red 198). Decolorization stoichiometry must be different from degradation stoichiometry since the double bonds may be still present in dye molecule after decolorization.

The ozone concentration in water is limited by its solubility and is inversely proportional to ionic strength intermediates or final products that may be formed during the ozonation of dye molecules. Because the dissolved ozone in water reacts with Dye, the ozone

concentration is constant and is related to the partial pressure and Henry’s constant [148].

The concentration of dissolved ozone can be written as:

P = KH [O3] (9)

where P is the partial pressure of ozone and KH is Henry’s constant of ozone. If it is written as a second-order kinetic equation, Eq. (10) is obtained: d[Dye] - = K[Dye][P/KH] (10) dt

2.10.2.2 Oxidation with UV/H2O2

Hydrogen peroxide is widely used for bleaching in the textile industry. It also can be used applied to the decolorization of synthesis dyes in effluent. The combinantion of UV light and H2O2 gives the hydroxyl radical (OH˙), the second most powerful oxidant after fluorine, which oxidizes and destroys dye structures. It can attack most organic molecules and is not highly selective [87, 88]. The hydroxyl radical produces new oxidized intermediates with lower molecular weight or carbon dioxide and water in case of complete mineralization by abstracting a hydrogen atom or adding hydrogen atom to the double bonds

[89].

UV light was the one of the agents used to initiate the process which produces OH˙

[66-68]. The Fenton reaction is a catalytic process for the generation of hydroxyl radicals from hydrogen peroxide and is based on an electron transfer between H2O2 and iron irons acting as homogeneous catalyst [90].

However, it is difficult to develop a general oxidation method for a mixture of dyes because the optimum method for decolorization is different for each dye. UV/H2O2 could be successfully used for the decolorization of acid dyes, direct dyes, basic dyes and reactive dyes but it is not suitable for vat and disperse dye decolorization [69].

2.10.2.3 Fenton’s process

The Fenton process is widely studied and reported as an interesting method for the treatment of industrial wastewater containing nonbiodegradable organic pollutants [101]. The mechanism of organic compounds degraded by Fenton process is shown below [102-104]:

2+ 3+ - Fe + H2O2 →Fe +OH + HO˙ (11)

RH + HO˙ → R˙ + H2O (12)

RH represents the dye

R˙ + Fe3+ → R+ + Fe2+ (13)

Fe2+ + HO˙ → Fe3+ + OH- (14)

2+ 3+ Fe ions can be regenerated by the reaction between Fe ion and H2O2 (Eqs. (15) and (16)) under acidic condition [105-107]. These reactions make Fe2+ can be re-used after decolorization and keep the process going by adding H2O2 continuously.

3+ 2+ + · Fe + H2O2 → Fe + H + HO2 (15)

3+ · 2+ + Fe + HO2 → Fe + O2 + H (16)

The hydroxyl radical can also be produced by employing Fe3+ salts instead of Fe2+ salts in Fenton process. The process involves a slow reaction between Fe3+ ion and hydrogen peroxide (Eqs. (17) and (18)) and rapid reaction between the produced Fe2+ ion and additional hydrogen peroxide [55,56].

3+ 2+ + Fe + H2O2 → FeO2H + H (17)

2+ · 2+ FeO2H → HO2 + Fe (18) a. Effect of pH

2+ The optimal pH for Fenton reagent process is pH 2-3.5 [65, 143]. H2O2 and Fe ions are more stable when the pH value is lower than 3.5 and can give best decolorization ability under acidic condition. If the pH is higher than 4, Fe2+ ions are unstable and will form Fe3+

- ions, which have a tendency to produce hydroxyl complex. It will further generate [Fe(OH)4]

- when the pH value is higher than 9.0. However, for wastewater treatment, the [Fe(OH)4] can coagulate dyes and enhance the effluent treatment.

b. Effect of H2O2

The decolorization ability of Fenton reagent will increase with increasing H2O2 levels [65].

The effective amount of H2O2 is different depend on the dye: 584 mg/L for reactive dyes,

875 mg/L for acid dyes, and 292 mg/L for other. The optimal concentration is 0.001M.

Excess H2O2 will cause high COD values in the effluent. Also, excess H2O2 may form an inert iron oxide film (e.g. Fe2O3 ) on the iron powder surface, which prevents more iron

powder to dissolve into solution [143]. So the efficiency will decrease when H2O2 concentration is greater than 0.001M. c. Effect of Fe(II) sulfate level

The optimal amount of Fe2+ sulfate depends on the dyes. For reactive dyes, decolorization ability increased until the Fe2+ sulfate level reduced to 1 g/L, then the decolorization performance will drop by adding more Fe2+ sulfate. The low concentration of Fe2+ sulfate cannot generate enough sufficient Fe2+ ions for Fenton’s reaction but if the concentration is too high, the excess Fe2+ will scavenge the hydroxyl radical formed. For acid dyes, such as

Acid Blue 40 (11) which has two oxygen and two nitrogen atoms may serve as the ligand for

Fe2+ and Fe3+ on the Fe2+ sulfate powder surface, chemisorption is expected to be stronger than azo dyes. Therefore, the higher the iron powder concentration is, the greater the decolorization rate constants will be [143].

2.11 Polyethylene terephthalate (PET)

Polymers are macromolecules which consist of several hundred covalently bonded atoms and have at least 103 g/mol molar mass [84]. Most of the polymer properties in

solution and in bulk depend on the degree of polymerization (P) and the molecular weight

(M), which are the most important characteristics of macromolecular substances.

Degree of polymerization is the number of monomers in polymer chain. The molecular weight of a homopolymer is given by Eq. 19

M = P · Mru (19)

where Mru stands for the molar mass of the monomer repeating unit.

Polyethylene terephthalate, having repeat unit (12), is widely used in the past two decades due to its excellent tensile and impact strength, chemical resistance, clarity, process ability and reasonable thermal stability [69]. The short ethylene group and ρ-phenylene group make PET have low flexibility, and the inflexibility affects PET structure-related properties, such as high glass-transition point and melting point.

2.11.1 PET synthesis

There are two ways to make the PET repeat unit: 1. Reacting terephthalic acid with ethylene glycol (EG) by an esterification reaction; 2. Reacting dimethyl terephthalate (DMT) with EG by trans-esterification. Trans-esterification scheme.6 (a) is the much preferred process because it is easier to purify [70]. The initial product of both these process is bis(hydroxyethyl) terephthalate (BHET). The BHET is polymerized to a degree of polymerization (DP) up to 30 through pre-polymerization [70]. Then DP is further increased to 100 through polycondensation process [71]. PET with this DP is suitable for application which do not need high molecular weight such as fiber and sheets.

Scheme 6. PET synthesis reactions: (a) trans-esterification reaction and (b) condensation

reaction.

2.11.2 Recycled PET

In order to improve waste management and considering the low rate of PET natural decomposition, PET recycling is of interest. What is more, as the price of virgin PET remains stable, the technologies of PET recycling can provide the industry with relatively inexpensive

PET. The first recycling effort of PET bottles was in 1977 [72].

Certain minimum requirements are necessary for achieving successful PET recycling.

The major factor affecting the suitability of recycled PET is the level and nature of contaminants present in it, such as acid producing contaminants, water, colored contaminants, acetaldehyde [70, 73, 74].

2.11.2.1 Conventional recycling processes

PET recycling includes chemical and mechanical recycling. Chemical recycling is achieved by depolymerizing the PET to monomers or partially depolymerizing to oligomers. Water

(hydrolysis), methanol (methanolysis) and EG (glycolysis) are used for the depolymerization of PET [75-77]. Figure 2.5 shows the structure of compounds resulting from the depolymerization of PET with comparison to PET structure. However, chemical recycling is a high cost recycling process [73].

Figure 2.5. Structure comparison between compounds resulting from PET depolymerization process.

The mechanical recycling of PET consists of contaminants removal by sorting and washing, drying and melt processing. Mechanical recycling PET is a relatively simply, environmental friendly and cost efficient process. While the main issue by using this method is that the MW of PET will be reduced during the process. Researchers have worked on solution of this problem for three decades, such as reprocessing under vacuum [78], adding stabilizer during processing for reducing the contamination effect and maintain the thermal

stabilization [73, 79], using di- or poly-functional low MW material react with PET to rejoin the broken chain [80-82].

2.11.3 PET dyeing

Polyethylene terephthalate fibers, as a hydrophobic substrate with a very dense structure, are very difficult to dye. Disperse dyes, such as Disperse Blue 79 (13), Disperse

Orange 30 (14), and Disperse Red 60 (15), are used for PET dyeing.

13 14 15

PET is mostly exhaust dyed at high temperature in pressurized vessels. Atmospheric carrier dyeing and thermo-fixation processes mainly for polyester/cellulose blends are the alternative PET dyeing methods [110-114].

2.11.4 PET decolorization

2.11.4.1 PET fiber and fabric

The disperse dyes used for PET were designed to be stable under high temperature and

UV light. In this case, decolorization of dyed PET fiber will require stronger oxidation or reduction process to decompose the dye structure. There are a few of research on fiber and fabric decolorization specifically. H2O2 was used for hair bleaching and patented by Gillette

Co [161]. Sodium formaldehyde sulfoxylate was used to bleaching composition for permanently dyed hair [162] and decolorizing blue dyed denim jeans [163]. A similar principle used to decompose disperse dye is after clearing by ozone, Fenton reagent and other reducing agent for wash fastness. Disperse dyes aggregate and deposit at the surface of the fiber. The deposited disperse dyes at the surface decrease the wash, sublimation and crock fastness results.

After clearing with reducing agents is the most preferred choice to remove the deposited disperse dyes at the surface. Disperse dye molecules adsorbed on surfaces are broken down into smaller, often colorless and more readily water-soluble fragments by reduction clearing.

Reduction clearing involves treating the dyed fiber in a strong reducing bath, usually made up of sodium dithionite and sodium hydoxide [115-118]. Oxidative clearing of PET, with hydrogen peroxide, as a cleaner alternative to reduction clear was used [119]. Higher wash fastness results comparable with conventional reductive clearing and lower chemical oxygen demand values were reported by the oxidative clearing process. The oxidation potential of hydrogen peroxide is 1.77 V. and ozone (O3) has a higher oxidation potential of 2.07 V.

Decomposition of O3 is pH dependent. At acidic pH, O3 is available as molecular O3 and at

· · · · alkaline pH, it decomposes into secondary oxidants, such as HO , HO2 , HO3 and HO4 . Ozone has been studied for color removal from textile effluent and successful results have been reported for decolorization of disperse dyes [120-124]. Decolorization occurs by breaking down the dye into colorless fragments. The drawbacks associated with sodium dithionite in the conventional reduction clearing include strongly alkaline conditions, requirement of large amounts of water and discharge of sulfur with the wastewater [125]. Substitution of the conventional reduction clearing step with an ozonation step may lead to a decrease in

environmental pollution and savings in water and energy. The effectiveness of ozonation as the clearing phase for disperse dyed fabric has been examined by some researchers [126, 127].

2.11.4.2 PET plastic

Colorants used in PET packaging include both organic dyes and inorganic pigments, with organic dyes most commonly belonging to the azo and anthraquinone families, such as

Pigment Orange 64 (16), Pigment Red 177 (17) [134,135].

16 17

Previous work carried out in this field demonstrate the use of chemical processing steps, such as glycolysis or methanolysis, for the depolymerization of PET bottle, followed by repolymerization of the constituent monomers/ oligomers [136,137] as well as the use of highly toxic and expensive reagents, such as a 1,1,1,3,3,3-hexafluoroisopropanol solution containing silica gel as an absorbent, or extraction of colorants from the polymer in hot dichloromethane

[138-140]. Such processes tend to be expensive and generate significant quantities of hazardous waste, and to date have not been commercialized. Hydrogen peroxide (H2O2) could represent a more economical, lower toxicity reagent for the decolorization of colored PET bottle; peroxide is used extensively as an oxidant for a wide range of organic and inorganic oxidations at the present time [141]. Few references to the utilization of H2O2 for decolorization of PET resins exist, being primarily focused on bleaching of yellow catalysts residues generated from titanium catalysts [142]. Gupta et.al [160] developed a process to decolorize green and blue color PET bottle by soaking bottles in to 50 wt % H2O2 aqueous

solution at 130 ̊C. This process required from 2 to 15 hours to completely decolorize the bottle and it could generate potentially explosive pressurization. The H2O2 consumption rates per gram PET bottle decolorized were 0.3 to 0.9 g.

2.12 Life-cycle assessment

Life cycle assessment is a “cradle-to-grave” approach which used to analyze the impacts of a product to environment. The analysis “begins with the gathering of raw materials from the earth to create the product and ends at the point when all materials are returned to the earth” [153]. The Figure 2.6 shows the life cycle stages in an LCA and typical inputs and outputs measured.

Inputs Outputs Atmospheric Raw materials Raw material acquisition Energy Emissions Waterborne Manufacturing Wastes Solid Waste Coproducts Use/Reuse/Maintenance Other release

Recycle/Waster Management

System boundary Figure 2.6. Life Cycle Stages [154] LCA is a technique to assess the environmental aspects and potential impacts associated with a product, process, or service. LCA process consists of four component [153]:

1) Goal Definition and Scoping: Make definition and description of the product, process

and activity which LCA will be evaluated. Establish the context in which LCA is to be

made. Identify the system boundaries and environment effects to be reviewed for the

assessment.

2) Inventory Analysis: Identify and quantify inputs and outputs elements

3) Impact Assessment: Assess the potential human and ecological effects of the elements

in inventory analysis.

4) Interpretation: Obtain the preferred product, process or service by evaluating the results

of the inventory analysis and impact assessment.

To ensure LCA of a product, process and service is consistent and high-quality, a standard rules should be followed. The ISO 14040 and 14044 standards [156] provide the indispensable framework for life cycle assessment. However it leaves the individual researchers with a lot of choice which will affect the legitimacy of the results of an LCA study. The life cycle data system (ILCD) handbook was developed to give a guidance for consistent and quality assured life cycle assessment data and studies [153].

Chapter 3 The toxicity of cationic bleach activators.

The experiments were conducted in School of Technology, UNICAMP, Limeira, SP, Brazil. This chapter was reported with the help from Gisela de Aragão Umbuzeiro, Josiane Aparecida Vendemiatti, and Francine Inforçato Vacchi.

3.1 Introduction

Quaternary ammonium salts (QAS) are extensively used in various applications. They are major class of cationic surfactants used as the ingredients in industry, biotechnology, medicine and biocide production [165-166]. The structure of QAS contains at least one hydrophobic hydrocarbon chain linked to a positively charged nitrogen atom, and other alkyl groups with the mostly short-chain substituents such as methyl or benzoyl groups. The main source of QAS released into the environmental are the discharge of effluents and sludge from sewage treatment plant [167-172]. Other local point sources, such as hospitals and laundry wastewater also lead to its presence in the environment. QAS is generally considered to be biodegradable in an activated sludge system and its degradation depending on the QAS concentration, chemical structure, etc [173-177]. However, adsorption usually outcompete biodegradation in activated sludge system. Therefore, QAS is enriched in sewage sludge and the QAS containing biosolids will cause environmental risk when they are recycling on land.

The QAS in the surface water downstream from wastewater treatment plants in the US in the range of 2.7 to 5.8 μg/L and 6.3 to 36.6 μg/L [178]. Although most of the QAS is generally believed to be safe for humans, it will harm organisms that live in water and affects both animals and plants [179].

TBBC, TBCC and eight newly synthesized cationic bleach activators are QASs. They are applied in textile bleaching process and the wastewater after bleaching contains chemicals including bleach activator. Even though the wastewater will be treated in a wastewater

treatment plant, the effluent of the treatment plant still contains these chemicals. In this chapter, the study of their acute toxicity, chronic toxicity and genotoxicity to aquatic organisms is reported. Acute toxicity of these bleach activators was measured using Daphnia sp.

Immobilization Test. Young daphnia, aged less than 24 hours at the start of the test, were exposed to the test substance at a range of concentrations for a period of 48 hours.

Immobilization was recorded at 48 hours and compared with control values. The results were analyzed in order to calculate the EC50 at 48h. EC50 is the concentration estimated to immobilize 50% of the daphnia within a stated exposure period. Immobilization is defined as:

Those animals that are not able to swim within 15 seconds, after gentle agitation of the test vessel are considered to be immobilized (even if they can still move their antennae) [186].

Chronic toxicity of two selected bleach activators was measured using Freshwater Alga

Growth Inhibition Test. This test is used to determine the effects of a substance on the growth of freshwater algae. The algae will be exposed to the test substance in the batch cultures in 72 hours. Growth and growth inhibition are quantified from measurements of the algal biomass as a function of time. Algal biomass is defined as the cell counts per volume. The test endpoint is inhibition of growth, expressed as the logarithmic increase in biomass (average specific growth rate) during the exposure period. From the average specific growth rates recorded in a series of test solutions, the concentration bringing about a specified 50 % inhibition of growth rate is determined and expressed as the ErC50 [244].

Apart from acute and chronic toxicity, one of the most carefully studied features of any compound newly introduced into common use should be its mutagenicity. The mutagenic chemicals can induce serious diseases, including cancer, due to their genotoxic activities [180-

185]. There several bioassays, in vivo and in vitro that can be used to verify the mutagenic

effect of chemicals and among the in vitro ones, the Salmonella/microsome assay have been the most used [240]. The Salmonella/microsome assay, also known as the Ames test, uses a bacteria, Salmonella typhimurium that was previously mutated and is not able to growth in histidine free media. Only if a mutation occurs, the histidine production capacity will be restored. There are several protocols that can be applied and in this project we decided for the microsuspension version of the assay because limited amount of the chemicals of interest were available [241]. There also several strains with different characteristics but the most used ones are TA100 and TA98 because they are more sensitive to the majority of the environmental chemicals. To enhance the ability of the assay to detect mutagenic compounds, an exogenous metabolic system is added to the mixture along with the bacteria that will mimic the reaction of the chemical with enzymes present in the organisms that are responsible for detoxification of xenobiotics. Sometimes when this reaction occur then the compound becomes active and interacts with DNA. An example is the benzo[a]pyrene that only reacts with DNA after metabolization with those enzymes. The system that provides this metabolic reaction is called

S9 and it is known as S9 mixture. Therefore the assay is always done in the presence and in the absence of S9 mixture.

3.2 Experimental

3.2.1 Chemicals and media

Ten substances tests were sent to Technology laboratory (UNICAMP/Brazil) and their structure are showed below.

The structure of bleach activators:

O O

N N TBCC: TBBC:

O O O O

N N N N PBCC: PBBC:

O O O O

N N N N N N DOBCC: DOBBC:

O O O O O O NH2 NH2 N N N N NABCC: NABBC:

O O O O

N N N N 3-PBCC: 3-PBBC:

The water solubility informed was 8 g/L. The stock solutions were prepared in culture media and diluted in different concentrations at water solubility limit. The solubility was

visually determined in the culture media and some substances, such as NABCC, TBBC and

NABBC had to be sonicated (Cole-Parmer Ultrasonic cleaner, 50-60Hz) by 5 min at 25 °C ±

2 °C to improve the dissolution.

3.2.2 Daphnia sp. Immobilization Test

3.2.2.1 Culture of aquatic organisms

The organisms used in the test were Daphnia similis from Faculty of Technology laboratory (UNICAMP/Brazil). The daphnia culture was maintained in control media at 20 °C

± 2 °C, pH in the range of 6 to 9, hardness between 40 to 48 mg/L as CaCO3, with a light intensity of 1000 lux under photoperiod, 16:8 light/dark [186]. The daphnia were fed daily with the green algae Raphidocelis subcapitata (106 cell/org).

3.2.2.2 Experiment design

The experiment was performed using three replicates of each concentration. Nine concentrations and a control were employed. In each replicate five neonates organisms, 6-24h old, were exposure to the substance in plastic tubes (10mL) for 48h at 20 °C ± 2 °C, with a light intensity of 1000 lux under photoperiod (16:8 light/dark), without feed. After 48h hour exposure, the number of immobilized organisms were counted. The tests were considering valid if the immobilization rate was less than 10% in the negative control group [186]. The sensitivity test was performed with NaCl P.A. at EC50 2.6 g/L. The results were statistically analyzed by ToxCalcMix model [187] and the effective concentration (EC50) expressed in mg/L.

3.2.3 Algae Toxicity assay

3.2.3.1 Culture of aquatic organisms

The inoculum was composed of algae cells harvested from a liquid stock algal culture that is 3 days old and was in a logarithmic phase of growth. The initial cell density was

10000 ± 1000 cells/mL for all replicates. The test was performed under static conditions for

72 hours without media renewal, at 24 ± 2 °C under continuous fluorescent light (4000 ± 400 lux).

3.2.3.2 Experiment design

Two cationic bleach activators, TBBC and 3-PBBC, were used to assess the chronic toxicity. Chemical stock solutions were prepared in DMSO ultrasonicated (Cole-Parmer

Ultrasonic cleaner, 50-60 Hz) by 5 min at 25 °C ± 2 °C. Test solutions and negative control

(deionized water) were prepared in sterilized oligo medium [242]. The range concentration of

TBBC was 0.01 to 10 mg/L and the chemical 3-PBBC was 10 to 400 mg/L. The experiment was performed with three replicates per each concentration. The concentration of DMSO in the test was less than 0.01%. A DMSO control at maximum concentration used in the test was performed at the same time to the chemicals. The number of cells was evaluated by counting with a Neubauer chamber. The endpoint measured was the inhibition of algal biomass in comparison to the negative control and expressed in inhibition concentration (IC50) in mg/L.

Data were statistically analysed by ICp [243] and the inhibition concentration (IC50) was expressed in mg/L.

3.2.4 The Salmonella/microsome assay

3.2.4.1 Sample preparation

Two chemical substances (TBBC, 3-PBBC) were selected for analysis in the

Salmonella/microsome assay. They were dissolved in dimethylsulfoxide (DMSO) at the solubility limit just before testing. The maximum doses tested were 0.5 mg/plate.

3.2.4.2 Experiment design

The Salmonella/microsome microsuspension assay was performed in dose response experiments with TA100 with and without S9. And it was performed with positive and negative controls to ensure the responsiveness of the strain and efficacy of a metabolic activation system. As a negative control, DMSO was used as the solvent. The negative control is needed to establish the number of spontaneous revertants and was tested with five replicates. As positive controls were used for both strains, 4-nitroquinoline-1-oxide (4NQO) at 0.125 μg/plate without S9 and 2- aminoanthracene (2AA) at 0.625 μg/plate with S9. Each dose was tested in duplicates and positive controls in triplicates. Experiments were performed with overnight cultures (around 109 cells/mL) 5-fold concentrated by centrifugation (10,000 g at 4 ºC for 10 min) and re-suspended into 0.015 M sodium phosphate buffer. Volume of 50 μL of cell suspension, 50 μL of 0.015 M sodium phosphate buffer or S9 mix, and 5 μL of the sample were incubated at 37 ºC for 90 min without shaking. To the mixture, 2 mL of molten agar was added and poured onto a minimal agar plate. Colonies were counted after 66 h of incubation at 37 ºC by counter automatic. Toxicity was also carefully evaluated observing the background of the agar plates. Metabolic activation was provided by Aroclor 1254- induced Sprague

Dawley rat liver S9 mix (MolTox, Boone, NC) prepared at 4 % v/v and the required co-factors.

3.2.4.3 Data evaluation and potencies

An ANOVA was followed by a linear regression using the using the Salanal program

(Bernstein model, p<0.05) [245]. Potency were expressed number of revertants per mg of the tested chemical.

3.3 Results

3.3.1 Daphnia sp. Immobilization Test

The preliminary tests were performed to discover the range of toxicity. The preliminary acute toxicity results are shown in the Table 3.1 and summarized in Figure 3.1. TBCC is less toxic than TBBC to daphnia. All of the new bleach activators have less toxicity than TBBC.

The confidence interval of toxicity of NABCC, PBBC and NABBC is not available. Because the results of these bleach activators did not fit well to the ToxCalcMix model. DOBBC and

3-PBBC have significant low toxicity among all of the bleach activators. 3-PBBC is 86 times less toxic than TBBC in acute toxicity test. The globally harmonized system (GHS) criteria for classification of a substance in acute categories is listed in Table 3.2. According to this classification, PBCC and TBBC are in Acute I category. TBCC and other seven newly synthesized cationic bleach activators are in Acute III category.

Table 3.1. EC50 values of each substance tested in D. similis acute toxicity test. Substance EC50 (mg/L) 95% CI

TBBC 1.5 ±0.14

PBCC 4 ±2

NABCC 18** -

PBBC 21* -

DOBCC 34 ±10

TBCC 35 ±8

3-PBCC 39 ±6

NABBC 64*** -

DOBBC 114 ±20

3-PBBC 129 ±8.4

EC50 – effective concentration that caused 50% of mortality in 48h

CI – confidence interval

*10 mg/L 0%, 50 mg/L 100%

** 16mg/L (4/15) 40mg/L 100%

*** 60 mg/L (1/15); 80 mg/L 100%

140

120

100

) 80

1 -

EC50 (mg/L EC50 40

0 TBBC PBCC NABCC PBBC DOBCC TBCC 3-PBCC NABBC DOBBC 3-PBBC -20

Figure 3.1. EC50, 48h in mg/L-1 of each substance tested in D. similis acute toxicity test and the respective confidence interval of 95%.

Table 3.2. The GHS criteria for classification of a substance in acute categories

Category Acute toxicity (48 hr EC50) Acute I ≤1 mg/L Acute II 1-10 mg/L Acute III 10-100 mg/L

3.3.2 Algae Toxicity assay

The results of chronic toxicity of TBBC and 3-PBBC to freshwater algae

Raphidocelis subcapitata are shown in Table 3.3. The 3-PBBC and TBBC both were toxic in the algae inhibition test but 3-PBBC is 18 times less toxic than TBBC. The globally harmonized system (GHS) criteria for classification of a substance in chronic categories is listed in Table 3.4. According to this classification, TBBC is in Chronic II category. 3-PBBC is in Chronic III category.

Table 3.3. Algae toxicity test.results expressed in inhibition concentration 50%, 72h (IC50) for the selected chemicals IC50 95% Confidence Interval Chemicals (mg/L) (mg/L) TBBC 5.4 4.7 – 6.6

3-PBBC 93.2 84.1 – 104.1

Table 3.4. The GHS criteria for classification of a substance in chronic categories

Category Chronic toxicity (72 hr ErC50) Chronic I ≤1 mg/L Chronic II 1-10 mg/L Chronic III 10-100 mg/L

3.3.3 The Salmonella/microsome assay

The results of the experiments with different concentrations of TBBC and 3-PBBC are summarized in Table 3.5 and 3.6. With 0.5 mg/plate, the revertant numbers declined in TBBC due to the acute toxicity. Both compounds showed mutagenic activity without metabolic activation (S9). The bacteria potency revertant number per 1 mg of TBBC without S9 in the plate is 3300. The bacteria potency revertant number per 1 mg of 3-PBBC without S9 in the plate is 300. Only TBBC showed mutagenic activity with TA100 with S9. The bacteria potency revertant number per 1 mg of TBBC with S9 in the plate is 3400. The bacteria potency revertant number per 1 mg of 3-PBBC with S9 in the plate is negative, which means the 3-PBBC will not have mutagenicity in the presence of S9. 3-PBBC was ~10 times less mutagenic than TBBC without S9 and in the presence of S9.

Table 3.5. Mutagenicity for TBBC compound in the Salmonella/microsome microsuspension assay with TA100 without and with S9. Doses Mean of Number of Revertants/plate and Standard Deviation (SD) TA100 mg/plate -S9 +S9 Mean SD Mean SD Negative control 158 11 149 21 0.005 128 3.54 175 12.02 0.01 155 4.24 184 24.75 0.05 342 18.38* 329 23.33* 0.1 474 12.02* 480 30.41* 0.5 165 43.13 129 44.55 Positive controla 3765 205.1 3797 148.4 Potency Revertants/mg 3300 3400 * significant at 1% aPositive controls were 4-nitroquinoline-1-oxide (4NQO) at 0.125 μg/plate without metabolic activation mixture (-S9) and 2- aminoanthracene (2AA) at 0.625 μg/plate with metabolic activaton mixture (+S9).

Table 3.6. Mutagenicity for 3-PBBC compound in the Salmonella/microsome microsuspension assay with TA100 without and with S9. Doses Mean of Number of Revertants/plate and Standard Deviation (SD) TA100 mg/plate -S9 +S9 Mean SD Mean SD Negative control 158 11 149 21 0.005 144 31.82 167 16.97 0.01 138 0.71 180 16.26 0.05 152 28.28 165 7.78 0.1 171 19.80 166 31.11 0.5 298 25.46* 201 34.65 Positive controla 3765 205.1 3797 148.4 Potency Revertants/mg 300 Negative response * significant at 1% aPositive controls were 4-nitroquinoline-1-oxide (4NQO) at 0.125 μg/plate without metabolic activation mixture (-S9) and 2- aminoanthracene (2AA) at 0.625 μg/plate with metabolic activaton mixture (+S9).

3.4 Conclusion

Based on these results, using less toxic amino groups to replace the cationic group of

TBCC and TBBC can obtain less toxic cationic bleach activators. 3-PBCC and 3-PBBC have the similar bleaching performance under neutral pH and low temperature as the bench mark products, TBCC and TBBC. While these two new bleach activators have low toxicity than the bench mark products. 3-PBBC compound is 86 times less toxic in Daphnia sp. Immobilization

Test, 18 times less toxic in Algae Toxicity assay and 10 times less mutagenic in the

Salmonella/microsome microsuspension assay in comparison with the TBBC. It would be necessary to do the mutagenic testing with TA98 in the future to complement the analysis.

Chapter 4 A comparative life cycle assessment for bleaching process of cotton.

4.1 Introduction

As one of the most important textile materials, cotton has been dominant for centuries due to its comfort, relatively low cost, good dyeability and color fastness properties. To produce commercially acceptable cotton products that satisfy consumers aesthetically and functionally, wet processing of cotton, including preparation, dyeing and finishing, is an essential part of producing cotton fabrics. However, current wet processing of cotton is problematic from an environmental point of view due to the extensive use of water and energy as well as the high content of chemicals in effluents [188].

Bleaching is one of the critical processes in wet processing of cotton. In the textile industry, conventional bleaching of cotton using hydrogen peroxide requires a high temperature (95-105 ˚C) and alkali conditions (pH ~11.5), which not only consume high levels of energy but also damage cotton fibers [20]. Also, significant quantities of water are required for washing the residual alkali and non-decomposed hydrogen peroxide after bleaching [189].

Thus, modified new bleaching using bleach activators are increasingly being considered in the textile industry to reduce energy consumption, processing time, fiber damage, and cotton weight loss [20, 23,24]. In previous research, some LCA studies have been done on the textiles wet processing industry [190-194], but there is no analysis to compare the environmental impact of modified new bleaching using bleach activators with the conventional method.

Since one of the major reasons for pursuing modified new wet processing is to reduce environmental impact, it is important to determine whether these new processes are environmentally beneficial. In this chapter, the relative environmental performance of modified new bleaching process is analyzed and compared with the conventional bleaching

method using life cycle assessment (LCA). First, based on data from industry, pre-published research, lab-scale experiments and the Ecoinvent database [195], the life-cycle-inventory

(LCI) for both modified new and conventional bleaching process was developed and modeled in openLCA. With the help of openLCA, seven impact categories from TRACI [196], USETox

[197] and IPCC 2007 [198] were selected to evaluate the impact based on the results of the

LCI. Finally, the environmental impacts of the two wet processing methods, the limitations of our study, and potential improvements for future work were compared and discussed. The outcomes of this study can provide important decision support to both researchers in this field and manufacturers in the textile industry.

4.2 Methods

4.2.1 Goal and scope

The goal of this study is to compare the environmental impacts of modified new bleach processing using a bleach activator with conventional bleach processing. The target audiences are textile garment manufacturers and eco-conscious consumers. This comparative LCA will support decisions related to the development of textile wet processing for high efficiency and low environmental impacts.

4.2.1.1 Functional unit

To ensure the validity of the comparison, the functional unit of this study was defined as 1000 kg of cotton fabrics bleached for dyeing in US.

4.2.1.2 System boundaries

The study mainly focused on the bleaching process in cotton wet processing. The system maps (Figure 4.1 and 4.2) show processes and flows included in the system boundaries of both conventional and modified new bleaching systems. Other wet processing of cotton fabrics that were not influenced by replacing conventional bleaching with modified new method are not included in the system boundaries. However, different amounts of greige cotton fabrics were consumed in the two bleaching processes due to different cotton weight losses caused by bleaching. Thus, the environmental impacts associated with growing and producing a given weight of greige cotton fabrics was analyzed and included in the bleaching stage. In both scenarios, transportation of cotton fabrics, chemicals, and water were excluded and no co-product was modeled. Data regarding the production process, chemicals, energy and impact assessment methods involved are mainly from the textile industry in the United States.

Inputs: Greige fabric, chemical, water, steam, electricity.

Wastewater Conventional bleaching process

Wastewater Treatment

Rinsing & Neutralizing process Wastewater

Outputs: Bleached fabric

Inputs: Greige fabric, chemical, water, steam, electricity.

Wastewater Modified new bleaching process Wastewater treatment

Outputs: Bleached fabric

4.2.2 Data collection and LCI analysis

Three types of data are included in this research. First, for conventional wet processing, data regarding the production process, including procedures and chemical consumptions, were obtained from a cooperating textile enterprise. Based on the wet processing procedures and formulas, the consumption of water and other chemicals were estimated as well as the amount of wastewater produced and the chemicals left in the effluent.

Second, data from on-going research and previously published literature were used to determine the procedures and chemical use associated with the modified new bleaching process and the cotton weight losses during processing [20,25, 199]. After the bleaching

procedure was determined, consumption of electricity and steam in both scenarios were estimated by referring to published LCA studies on textiles wet processing industry [192-194].

Background processes and product flows were modeled in openLCA using Ecoinvent v2.2 [200]. Data sets in Ecoinvent were verified and updated as necessary by comparing with published research. For example, data regarding the production of greige cotton fabrics, especially electricity consumption of weaving and spinning, are modified based on existing literature [193,194] since data provided in Ecoinvent is out of date. However, for some chemicals used in the bleaching, no background processes and information can be found in

Ecoinvent. Thus, by referring to the literature and chemical production information [201], intermediates and more common chemical structures, such as trimethylamine and toluene, were selected as proxies for the unfound chemicals within the process models. The wastewater treatment process was the “treatment, sewage, to wastewater treatment, class 3” process provided in Ecoinvent. The wastewater was purified in a medium size municipal wastewater treatment plant with an average capacity size of 24900 per-captia-equivalents PCE. This process is similar to textile wastewater treatment plant according to previous research [202].

The electricity consumption and other inputs of wastewater treatment are only related to the volume of wastewater treated while waste content and other factors were not considered.

4.2.3 Impact assessment

Seven impact categories were considered, including: Global Warming Potential

(GWP), Ozone Depletion Potential (ODP), Acidification Potential (AP), Eutrophication

Potential (EP), Ecotoxicity Potential (ETP) Human Health-Carcinogenics (HH-C), and Human

Health-Non-Carcinogenics (HH-NC). The reason for considering ODP is that a large amount of chemicals are used in these two wet processing and they may have the potential to degrade stratospheric ozone. Also, EP, ETP and HH were included because in wet processing of cotton, large amounts of wastewater are produced and the chemicals as well as dyes left in wastewater might be toxic and may cause eutrophication of water-based ecosystems. As the major impact categories, GWP and AP are also considered since there is high electricity consumption associated with cotton processing.

The USETox impact assessment methodology was used for quantifying the ecotoxicity potential and human health impacts (carcinogenic and non-carcinogenic). For other impact categories, the Tool for the Reduction and Assessment of Chemical and Other Environmental

Impacts (TRACI) was used while the out-of-date impact factors for GWP in TRACI were updated based on IPCC (2007). Based on the fact that this comparative LCA investigates environmental impacts of the US textile industry, TRACI was used since it is the only methodology tailored specifically to US conditions [203]. Midpoint impacts (Table 4.1) were utilized, which are considered impact scores with less uncertainty compared with endpoint impacts (SAIC 2006). For all included environmental impact categories, 95 % of the overall impacts are included.

Table 4.1. Impact categories used in impact assessment Impact category Units Description Converts inventory amounts to CO Global Warming Kg CO 2 2 equivalents Converts inventory amounts to CTU Ecotoxicity CTU* equivalents Converts inventory amounts to CTU Human Health-Carcinogenics CTU equivalents Converts inventory amounts to CTU Human Health-Non-Carcinogenics CTU equivalents Converts inventory amounts to CFC-11 Ozone Depletion CFC-11 equivalents Converts inventory amounts to Eutrophication Kg N nitrogen equivalents Converts inventory amounts to moles Acidification Mole of H+ of H+ equivalents *CTU comparative toxicity units

4.2.3.1 Normalization and weighting

Normalization was used to assist in the interpretation of the LCIA results. To identify the key impact categories for this assessment, the impact results were normalized to person equivalents based on normalization factors from TRACI [203] and the normalization reference for USETox for North America [204]. Normalization factors for impact categories analyzed are listed in Table 4.2.

Table 4.2. Normalization factors for all impact categories analyzed Total normalized value Normalized unit per Impact category per capita capita 4 Global Warming 2.45×10 CO2 equiv/yr/capita Ecotoxicity 1.47×104 CTU equiv/yr/capita Human Health-Carcinogenics 1.02×10-4 CTU equiv/yr/capita Human Health-Non-Carcinogenics 4.54×10-4 CTU equiv/yr/capita Ozone Depletion 3.11×10-1 CFC-11 equiv/yr/capita Eutrophication 1.80×101 N equiv/yr/capita Acidification 7.44×103 H+ equiv/yr/capita

4.3 Results and Discussion

4.3.1 Inventory analysis

The product flows for the manufacture of bleached cotton fabric through conventional and modified new bleaching process is shown in Table 4.3. Results indicate that the modified new bleaching process consumed less electricity, steam and water than the conventional bleaching process. The major reason is that bleach activators were used in the modified bleaching process, which enables effective bleaching under low temperature and neutral pH.

It not only saves energy, but also saves water for neutralizing and rinsing after bleaching.

Additionally, more greige fabrics were consumed in conventional bleaching since, based on estimation from cooperative plant and lab experiments, the fabric weight loss in conventional bleaching is 7.5% while weight loss in modified new bleaching is only 4%. Another major difference in product flows of the two scenarios relates to chemical consumption. In modified new processing, large amounts of bleach activators was used. Also, the volume of wastewater to be treated is proportional to the water consumption in the wet processing stages.

Table 4.3. Product flows for manufacture of dyed cotton fabric products through conventional and bleaching process Quantity per producing 1000 kg Input Unit products Conventional Modified new Electricity MJ 1370 644 Tap water Kg 98710 16451 Steam Kg 4272 1425 Cotton fabric Consumed Kg 1176.47 1052.63 Sodium Hydroxide 50% Kg 50 0 Hydrogen peroxide 50% Kg 15 30 Bleach Activator Kg 0 50 Acetic Acid Kg 6 0 Sodium Carbonate Kg 0 15

4.3.2 Life cycle impact assessment

Based on the results of life cycle inventory, life cycle impacts of both conventional and modified new cotton wet processing were calculated. The data presented is for producing 1000 kg dyed cotton product, which is the functional unit. Also, process contributions were analyzed to identify the key up stream processes. Normalization and weighting were applied to help compare the impacts across categories.

4.3.2.1 Comparative analysis

The LCIA results for both conventional and modified new wet processing of all the impact categories are listed in Table 4.4. For all of the impact categories conventional bleaching process contributed higher impacts than the modified new bleaching process did.

Table 4.4. Comparative LCIA results associated with conventional and modified new bleaching process Usage for 1000 Kg cotton fabric Impact Category Unit bleaching Conventional Modified new Global Warming Potential Kg CO2 2924.74 1571.37 Ecotoxicity Potential CTU 2002 1061.2 Human Health-Carcinogenics CTU 1.44×10-4 8.33×10-5 Human Health-Non- CTU 1.58×10-4 7.93×10-5 Carcinogenics Ozone Depletion Potential CFC-11 1.93×10-4 1.21×10-4 Eutrophication Potential Kg N 6.07 2.24 Acidification Potential Mole of H+ 804.5 459.5

4.3.2.2 Contribution analysis

Processes contributions to each impact category for both conventional and modified new bleaching process are shown in Figure 4.3.

Figure 4.3(a-g). Results of contribution analysis for conventional and modified new cotton wet processing

GWP 3500 ETP 2500 3000

2 2500 2000 2000 Kg Kg CO 1500

1500 CTU 1000 1000 500 500 0 0 Conventional Modified New Conventional 3-b Modified New

3-a

HH-C HH-NC 0.00020 0.00020

0.00015 0.00015 CTU CTU 0.00010 0.00010

0.00005 0.00005

0.00000 0.00000 Conventional Modified New Conventional Modified New 3-c 3-d

ODP EP 0.00025 8

0.0002

11 6 - 0.00015

4 Kg Kg N Kg Kg CFC 0.0001

0.00005 2

0 0 Conventional Modified New Conventional Modified New 3-e 3-f

AP 1000

800 Wastewater treatment + 600 Rinsing and Neutralizing Bleaching

400 Molesof H

200

0 Conventional Modified New

3-g

Figure 4.3 shows that, compared with conventional bleaching process, the lower environmental impacts of modified new method are mainly caused by reductions in the bleaching process. The modified new bleaching process leads to less emissions because it consumes much less steam and electricity and also has much less cotton weight loss. In both bleaching processes, the weight loss of cotton fabrics is the major upstream contribution to the impacts since producing cotton fabrics – from cotton growing to fabric production – consumes large amounts of energy. Since the weight loss of cotton in both the conventional and modified new processes might be vary based on the specific industrial processing conditions, sensitivity analysis on cotton weight loss is necessary.

Wastewater treatment in conventional bleaching process contributes significant level of eutrophication potential to the environment. It is because that conventional bleaching process requires large amount of water to resin and neutralize the fabric after bleaching. High volume of wastewater will be generated.

4.3.2.3 Normalization

Based on normalization factors provided in Table 4.2, impacts of all categories were normalized and results are presented in Figure 4.4.

0.1081 Acidification 0.0618

0.3372 Eutrophication 0.1244

0.0006 Ozone Depletion 0.0004

0.3480 Non-Carcinogenics 0.1747

1.4118 Carcinogenics 0.8167

0.1362 Ecotoxicity 0.0722

0.1194 Global Warming 0.0641

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Person Equivelent

Conventional Innovative

Figure 4.4. Normalized impacts of all categories for conventional and modified new bleaching process

The human health- carcinogenic potential is the most important impact category in this assessment. And the modified new bleaching process provides 42% less than conventional bleaching process in HH-C.

4.3.3 Sensitivity and uncertainty analysis

The fabric weight loss associated with modified new bleaching was measured after a

Lab-scale experiment. The weight loss percentage might be changed when applying this method to industrial level bleaching jet machines. If the fabric weight loss of both bleaching processes is similar, the advantage of modified new wet processing on reducing environmental impacts might not be as significant as we assume here.

The cotton fabric weight loss is 5-10% for conventional bleaching and 3-5% for modified new bleaching, which represent reasonable ranges for cotton weight loss based on current lab work. Figure 4.5 shows the nomalized potential of conventional and modified new bleaching process with the same weight loss percentages (5%). Results indicate that modified new bleaching process still has less environmental impact than conventional bleaching process.

But the difference is reduced in most of the impact categories.

0.4866 Acidification 0.3088

1.4853 Eutrophication 0.6222

0.0028 Ozone Depletion 0.0019

2.5865 Non-Carcinogenics 1.9214

10.2548 Carcinogenics 8.9833

0.9545 Ecotoxicity 0.7941

1.1253 Global Warming 1.0262

0 2 4 6 8 10 12 Person Equivelent

Conventional Innovative

Figure 4.5. Normalized impacts of conventional and modified new wet processing with the same assumed weight loss (5%) during bleaching

4.4 Discussion

Since upstream processes and impact factors of bleach activator used in bleaching process is unavailable in the Ecoinvent database and broader literature, it was replaced by more common chemicals and intermediates, which were used to synthesize the bleach activator. The substitutions in chemicals may cause uncertainties for impact analysis since the real toxicity and other impacts of chemicals were modeled using substitutes. Due to the importance of HH-

NC in this project, it is necessary to re-do the analysis after obtaining more accurate data for the bleach activator.

4.5 Conclusions

In general, modified new bleaching process has lower environmental impacts than conventional method. It consumes less electricity, steam, water, and process time by modifying the conventional bleaching process. The differences of fabric weight loss between conventional and modified new wet processing dominate the main differences of the most environmental impacts. Sensitivity analysis indicates that if the two systems have the same fabric weight loss after bleaching, modified new bleaching process still has less impact to environment, but the difference between conventional and modified new process is reduced.

Further work to obtain specific data associated with chemicals used in the modified new wet processing would increase the accuracy of future LCA studies.

Chapter 5 Decolorization of colored PET using Fenton’s reagent in solvent/water

solution

5.1 Introduction

Oil, as an un-renewable natural energy resource, is very important to humans. Since the oil is limited, the efficiency of oil products usage is developed in many fields. Polyethylene terephthalate (PET) is made from by-product of oil. Because of its ultimate physical and chemical properties, it is widely used in daily life, such as plastic beverage bottle, fibers, thin film and mechanical components [206]. A report by Global Industry Analysts estimated the global consumption of polyester at about 40 million tons per year, which represents nearly

1270 kg every second [207]. The recycling of plastic bottles made from PET has been developed and used since 1977 [208]. However, most of the PET textiles are usually dumped.

In 2013, Municipal Solid Waste (MSW)—more commonly known as trash or garbage is 254 million tons. And textiles is about 12.4 million tons. 85% of all textile waste goes to landfills

[209]. The production of polyester fibers accounts for about 40-45% of total global annual fiber production. So it is about 4.2 to 4.7 million tons of PET textile waste goes to landfills every year. Since polyester is hard to be decomposed in natural environment, a simple landfill will cause environmental issues. PET textile recycling become a suitable process to reduce its environmental impacts. However the dyes remaining in the fibers makes the recycling process much complicated compared to PET bottle recycling. There are two main problems of PET fabric recycling. During the recycling stage, the dye will be the initiate specie, which can break the molecular chain of PET and decrease the degree of polymerization of PET. Then recycled

PET will not have proper strength for apparel manufacturing [210]. And PET fiber containing different dyes will not be a uniform substrate for dyeing and it is hard to get target color. If the

color is not removed, it will require expensive manual sorting of different color fiber and obscure different color with additional dyes.

Disperse dye is the main type of dyes used for PET coloring. It can penetrate into the

PET fiber during high temperature dyeing procedure. And after the dyeing process, dye will be “locked” in the PET fiber. There is no research about PET fiber or fabric color removing specifically but the only related research is PET beverage bottle color removing. Previous work carried out in this field demonstrate the use of chemical processing steps using highly toxic and expensive reagents, such as 1,1,1,3,3,3-hexafluoroisopropanol solution containing silica gel as absorbent, or extraction of colorants from polymer in hot dichloromethane [211,212].

The latest method is developed by using aqueous solution of hydrogen peroxide for oxidative decolorization of green and blue colored PET beverage bottles [213]. But this method requires high volume of H2O2 which will cause explosive pressure during decolorization. And the process requires 2 to 15 hours depending on the severity of the bleaching conditions and the specifics of the chromophore used in the PET bottles.

The decolorization of dyes in wastewater has been developed since 1970’s [214]. There are two types of decolorization approaches: physical absorption [215-217] and chemical decomposition [218-221]. Adsorption methods can remove the color by simply adsorbing dyes from water and then change or destroy the dye chromophore [222]. However it cannot remove the residual dye completely, so the treated wastewater may still pose environmental problems.

Chemical decomposition approach would break down the dye into small pieces of organic segments, which could reduce the toxicity and chemical oxygen demand [223,224]. Dye solution containing disperse dye can be decolorized by Fenton oxidation processes and the decolorization efficiency is more than 90% in two hours [225-227]. Fenton’s reagent is a

2+ Fe /H2O2 solution which can produce hydroxyl radical (OH•) [318]. OH• is the second highest powerful oxidant after fluorine [229]. It can react with most of the organic compounds and make new oxidized intermediates with lower molecular weight or CO2 and water [230].

In this research, a process for PET fiber decolorization via Fenton’s reagent was demonstrated. A 24 full factorial design of experiment was used to determine the key factors

(FeSO4 and H2O2 concentration, solvent ratio, temperature) associated with this new application of Fenton’s reagent. The initial level of each factor was chosen based on previous work [231-234]. Color strength theory was used to evaluate the decolorization efficiency.

Seven disperse dyes: two azo dyes (Disperse Orange 30 and Disperse Blue 79), two nitro dyes

(Disperse Yellow 42 and Disperse Yellow 86), two anthraquinones dyes (Disperse Blue 56 and Disperse Red 60), one quinoline dye (Disperse Yellow 54), and one basic dye (Basic

Yellow 28) were used to establish the versatility of the method employed. The structures of dyes used in this study are showed in Figure 5.1.

To ensure that the decolorization process did not adversely affect fiber strength, the degree of polymerization (DP) was measured after decolorization and compared to that of the

DP of original fabric.

Figure 5.1. Structures of dyes used in PET decolorization studies

5.2 Experimental

5.2.1 Materials

Knitted cationic dyeable PET white sportswear fabric was provided by Nike, Inc. Basic

Yellow 28 and Disperse Orange 30, Blue 79 and Red 60 were purchased from Huntsman®.

Disperse Yellow 42, Yellow 86 and Blue 56 were purchased from M. Dohmen® USA

(Greenville, SC). Ferrous sulfate, hydrogen peroxide, sulfuric acid and acetone were purchased from Fisher Scientific® (Pittsburgh, PA).

5.2.2 PET fabric dyeing

Cationic dyeable PET fabric was dyed at a 0.75% shade depth (based on the weight of the fabric; owf) using Basic Yellow 28 and seven disperse dyes, using an Ahiba® Nuance

Infrared laboratory dyeing machine (Datacolor® International, USA) at a liquor to goods ratio

(bath weight/fabric weight) of 15:1. A conventional dyeing procedure (Fig.2; 6 g/L Na2SO4, pH=4.5, adjusted by 20% acetic acid) was used. After dyeing, the dyed samples were rinsed and washed with 2 g/l of non-ionic detergent at 70 ˚C for 10 min then air dried.

Figure 5.2. Schematic of the dyeing procedure employed for cationic dyeable PET.

5.2.3 Decolorization experiments

All decolorization experiments were performed using an Ahiba® Nuance Infrared laboratory dyeing machine (Datacolor® International, USA) at a liquor-to-goods ratio of 10:1.

The process is showed in Figure 5.3. Dyed PET fabric (5 g) was added to the stainless steel beaker containing the target amount of amount of FeSO4 and acetone/water medium. The bath pH value was adjusted to 3 using 20% sulfuric acid, to degrade organic matter generated by

2+ Fenton’s reagent (Kochany and Lipczynska-Kochany, 2009). Also, Fe and H2O2 are more stable at lower pH (Meric et al. 2004). In stage I (extraction), the bath was heated to 60 ˚C at

4 ˚C/min and was held for 15 min. Then the target amount of H2O2 was added to the bath. In stage II (decolorization), the bath was heated up to target temperature at 4 ˚C/min. After 15 min, the beaker was cooled to 60 ˚C at 4 ˚C/min and decolorized PET fabric was washed with water until the rinse water had neutral pH and then air-dried.

Figure 5.3. PET fabric decolorization procedure used in this study.

5.2.4 Full factorial design of experiments

The 24 experimental design and statistical analysis were performed using JMP 11.0 software (SAS Inc, USA). Table 5.1 shows the factors and levels employed. Cationic dyeable

PET fabric dyed using Basic Yellow 28 was used.

Table 5.1. Factor levels used in DOEs Factor Low Level (-1) High Level (+1) Medium Water Water: acetone=1:1 Temperature 70 ˚C 120 ˚C FeSO4 5 mM 10 mM H2O2 150 mM 300 mM

5.2.5 Effect of FeSO4, H2O2 and solvent ratio

The effects of FeSO4, H2O2 and water: acetone ratio were investigated using levels listed in Table 5.2. In this series of experiments, the cationic dye-able PET fabric colored by basic yellow 28 was used.

Table 5.2. FeSO4, H2O2 and water: acetone levels used [FeSO4](mM) [H2O2](mM) Water: acetone 0.09 150 No acetone 0.18 300 4 : 1 0.36 600 2 : 1 0.72 800 1 : 1 1.44 1000 1 : 2 3.25 1200 1 : 4 5 10

5.2.6 Decolorization efficiency on different dyes

The decolorization efficiency of the optimized method on different dyes was studied, using the combinations listed in Table 5.3. In this series of experiments cationic dyeable PET fabrics dyed with 7 disperse dyes were used.

Table 5.3. Recipes used to decolorize PET fabric containing 7 disperse dyes. Temperature [FeSO ] [H O ] No. 4 2 2 water: acetone (˚C) (mM) (mM) 1 120 1.8 1235 1:1 2 120 0.18 1235 1:1 * 3 120 0.72 1235 1:1 *: only used in disperse yellow 54 fabric decolorization

5.2.7 UV-Vis measurements

Bath solution samples were collected after stage I (extraction) and stage II of the fabric decolorization process (Fig 5.3) and absorption spectra were recorded using a Varian

Cary 300 UV-visible spectrophotometer.

5.2.8 Reflectance and color strength

The reflectance of PET fabric was measured before and after decolorization using a

Datacolor® Spectraflash SF650X (Datacolor® International, USA). A four-layer fabric sample was measured four times by rotating the sample at 90 degrees between each measurement. The average value was recorded and the reflectance data were converted to

K/S values using Color icontrol® software (X-Rite, USA).

K/S values were determined using the Kubelka-Munk equation (1), where R = 1.0 at

100% reflectance. The higher the K/S values the deeper the fabric color at a given wavelength.

(1−푅)2 K/S= (1) 2푅

L*, a*, b*, C* and h˚ values of the fabric were obtained using a Datacolor Spectraflash

SF650X. The values L*, a*, b*, C* and h˚ are the variables in the CIELAB color space

(McLaren, 1983). The higher the L* value the lighter the fabric color and the lower the L* value the darker the fabric color. A more positive a* value indicates a redder fabric color while a more negative a* value indicates a greener color. More positive b* value indicates a more yellow color and more negative b* value indicates a bluer color. The calculated fabric images

were generated from their L*, a* and b* values using Adobe® Photoshop CS 6.0 (Adobe®

System).

5.2.9 Analysis of bath residuals

Insoluble residuals in the solvent medium after Fenton’s treatment were characterized using an FEI Titan 80-300 transmission electron microscope (TEM) and energy-dispersive X- ray spectroscopy (EDS). X-ray photo-electron spectroscopy (XPS) measurements were performed on SPECS XPS using Al Kα radiation.

5.2.10 Intrinsic viscosity

Intrinsic viscosity (IV) measurements were made by dissolving 0.2 g of the PET fabric in 20 mL of O-chlorophenol at 75 ˚C over 40 min. The solutions were cooled and placed in an

Ubbelhode viscometer in a constant temperature bath at 25 ˚C for 30 min prior to the measurement of the drop time. The average drop time for five measurements was recorded and was compared to that of pure O-chlorophenol, to determine the relative viscosity (RV). RV was converted to IV using the ISO certificated equation: IV = [(RV - 1) × 0.6907] + 0.0631

[235].

5.3 Results and discussion

5.3.1 Full factorial design of experiments (FFD)

Basic Yellow 28 (0.75% owf) dyed cationic dyeable PET fabric was used in this component of the study. Results of this 16-set trial, along with the associated factors are listed in Table 5.4, where it can be seen from K/S values that water/acetone mixture as the medium gave higher color removal than water alone (cf. trials 1 vs. 5, 7 vs. 6, and 14 vs. 15). Also seen

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in the Table 4 results is greater color removal was achieved at 120o C than at 70o C, presumably due to better fiber swelling making dye more accessible.

Table 5.4. Conditions and testing results of the FFD with actual levels of factors for decolorizing Basic Yellow 28 (0.75 owf) on cationic dyeable PET Factors Temperature FeSO H O Solution 4 2 2 K/S values Trial No. (˚C) (mM) (mM) 1 Water/acetone* 70 10 150 2.624 2 Water/acetone* 70 10 300 2.964 3 Water 70 5 150 6.552 4 Water 70 10 300 7.49 5 Water 70 10 150 5.767 6 Water 70 5 300 6.048 7 Water/acetone* 70 5 300 3.085 8 Water/acetone* 70 5 150 3.034 9 Water 120 5 150 6.632 10 Water/acetone* 120 5 300 1.965 11 Water 120 5 300 7.77 12 Water/acetone* 120 5 150 1.978 13 Water 120 10 150 10.49 14 Water/acetone* 120 10 300 1.802 15 Water 120 10 300 10.463 16 Water/acetone* 120 10 150 2.801 *: Water: acetone = 1:1

The data was analyzed using stepwise regression, a semi-automated process built into

JMP, which can add or remove factors based on t-statistics of their estimated coefficients. After running the stepwise regression by setting the stopping rule list at P-value to enter = 0.05 and

P-value to leave = 0.1, the mixed stepwise procedure removed H2O2 levels as a key factor because its effect on decolorization is not significant. On the other hand, reaction medium and temperature were maintained as important factors. The experimental data were sufficient to fit a least squares (LS) model. Figure 5.4 shows the actual versus predicted plot of K/S values arising from this model. The black dots represent the actual K/S value at certain wavelength and the red line is the LS model regression line. The red dashed lines represent the confidence

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interval. The blue dashed line stands for the mean of the K/S leverage residuals. The size of the random noise as measured by the root mean square error (RMSE) was only 0.9756%, which indicated that the model has good predictive capability. The analysis of variance (ANOVA) for the full factorial LS model is summarized in Table 5.5. The p-value is 0.0114 and it means there is at least one significant effect in the model.

Figure 5.4. Actual Vs. predicted plot of K/S values for decolorizing Basic Yellow 28 dyed cationic dyeable PET

Table 5.5 ANOVA summary for the full factorial LS model Source df Sum of squares Mean square F ratio Prob > f Model 4 120.74244 30.1856 31.7161 Error 11 10.46917 0.9517 C. Total 15 131.21162 2.55058 <.0001* Lack of fit 3 7.651730 0.35218 7.2422 Pure error 8 2.817445 Total error 11 10.469174 0.0114*

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Table 5.6 contains the model coefficients and their standard errors. The medium type and interactions between medium type and temperature are highly significant (p-value < 0.05).

An equation can be used to predict the K/S value and it was shown below:

K/S = 5.09-2.56X1+0.396X2+0.46X3-0.79X1X2 where X1= Medium type level (-1 and 1); X2= Temperature level (-1 and 1); X3= [FeSO4] level

(-1 and 1).

Table 5.6 Parameter estimates (Adjusted R2 = 0.8912). Term Estimate Std Error t Ratio Prob>|t| Intercept 5.0915625 0.243893 20.88 <.0001* Medium -2.559938 0.243893 -10.50 <.0001* Temperature 0.3960625 0.243893 1.62 0.1327 FeSO4 0.4585625 0.243893 1.88 0.0868 Medium*Temperature -0.791188 0.243893 -3.24 0.0078*

At constant decolorization temperature and Fenton’s reagent level, water/acetone mixed solution can provide better decolorization than water only solution. Acetone helped to extract the dye into the aquatic environment from the solid environment, which let the hydroxyl radicals be able to decompose the dye structure more efficiently. The coefficient estimate of the interaction between solution type and temperature is negative. For the sets of experiments conducted under water only solution, the decolorization performance decreased with the increasing of temperature. While the fabric treated under water/acetone mixed solution had less colorant left at higher temperature. The model indicated that decolorization performance did not improve significantly by varying [FeSO4] level. In both solvent types, the decolorization performance was worse when the higher amount of FeSO4 was used. After the decolorization stage, even though the dye was decolorized by the hydroxyl radical, the excess of Fe and its derivatives produced a brown stain on the fabric.

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5.3.2 Effects of FeSO4, H2O2 and solvent ratio

In order to optimize the decolorization procedure, FeSO4, H2O2 and water: acetone ratios were used at various levels. Figure 5.5 shows the Σ K/S (400-750nm) values for Basic

Yellow 28 dyed cationic dyeable PET fabric treated using various amounts of FeSO4 and 1200 mM H2O2 at 120 ˚C in water/acetone (1:1) medium. When the FeSO4 level was below 1.44 mM, the dyed fabric was decolorized, with 0.18 mM FeSO4 providing the best decolorization performance. When the amount of FeSO4 exceeded 1.44 mM, the ∑ K/S of the treated fabric was significantly higher, reaching a maximum at 5.0 mM. This was due to the brown stain fabric surface after high [FeSO4] treatment. Figure 5.6 shows the Σ K/S (400-750nm) of cationic dyeable PET fabric decolorized by various H2O2 levels and 0.18 mM FeSO4 at 120 ˚C in water/acetone (1:1) medium. Increasing [H2O2] from 150 mM to 900 mM gave only a slight increase in fabric color loss, while [H2O2] = 1200 mM gave nearly complete decolorization.

Figure 5.7 shows the Σ K/S (400-750nm) of cationic dyeable PET fabric treated using 0.18 mM FeSO4 and 1200 mM H2O2 at 120 ˚C in various ratios of water: acetone. Adding acetone to water enhanced decolorization performance, with water: acetone = 1:1 providing nearly complete decolorization.

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15 ∑ K/S ∑

0 0.09 mM 0.18 mM 0.36 mM 0.72 mM 1.44 mM 3.25 mM 5 mM 10 mM

Figure 5.5. Σ K/S (400-750nm) for Basic Yellow 28 dyed cationic PET fabric treated with Fenton’s reagent contaning various [FeSO4].

8 ∑ K/S ∑ 6

0 150 mM 300 mM 600 mM 900 mM 1200 mM

Figure 5.6. Σ K/S (400-750nm) for Basic Yellow 28 dyed cationic PET fabric treated with Fenton’s reagent contaning various [H2O2].

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15 ∑ K/S ∑

0 No Acetone 4 : 1 2: 1 1 : 1 1 : 2 1 : 4

Figure 5.7. Σ K/S (400-750nm) for Basic Yellow 28 dyed cationic PET fabric treated with Fenton’s reagent in various water:acetone ratios.

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The above results suggest that optimum conditions for decolorizing cationic dyeable fabric containing Basic Yellow 28 are: 120 ˚C, [FeSO4] = 0.18mM, [H2O2] = 1235mM, and water : acetone = 1:1. The images of original fabric dyed using Basic Yellow 28 and decolorized fabric using optimum conditions are showed in Figure 5.8 and the corresponding reflectance values are listed in Table 5.7. The result shows that fabric containing Basic Yellow

28 can be decolorized completely using Fenton’s treatment, as demonstrated through the very high L* value of 97.48. K/S spectra of fabrics containing basic yellow 28 before/after Fenton’s treatment are shown in Figure 5.9. These results indicate that basic yellow 28 can be decolorized using Fenton’s reagent.

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Table 5.7 The color coordinates of the original dyed fabric and fabric after decolorization. S.No Sample ID L* a* b* C* h° 1 Basic yellow 28 original 85.77 14.89 64.54 66.23 77 2 Basic yellow 28 low FeSO4 97.48 -0.25 6.78 6.79 92.12 3 Disperse Orange 30 original 57.29 37.51 49.92 62.44 53.08 4 Disperse Orange 30 high FeSO4 84.35 5.92 21.82 22.61 74.81 5 Disperse Orange 30 low FeSO4 73.57 25.54 39.13 46.73 56.87 6 Disperse Blue 79 original 36.7 -2.34 -22.11 22.24 263.97 7 Disperse Blue 79 high FeSO4 85.81 4.56 14.87 15.55 72.94 8 Disperse Blue 79 low FeSO4 98.12 -2.8 9.33 9.74 106.7 9 Disperse Yellow 42 original 88.91 1.46 64.09 64.1 88.69 10 Disperse Yellow 42 high FeSO4 88.06 1.08 25.35 25.37 87.56 11 Disperse Yellow 42 low FeSO4 94.2 -2.5 48.82 48.89 92.93 12 Disperse Yellow 86 original 82.62 14.75 55.77 57.69 75.18 13 Disperse Yellow 86 high FeSO4 84.3 7.45 21.3 22.57 70.73 14 Disperse Yellow 86 low FeSO4 96.46 -2.35 18.18 18.33 97.38 15 Disperse Blue 56 original 41.6 0.02 -40.51 40.51 270.03 16 Disperse Blue 56 high FeSO4 85.66 4.41 15.26 15.89 73.88 17 Disperse Blue 56 low FeSO4 89.02 -1.83 -10.78 10.93 260.35 18 Disperse Red 60 original 52.84 64.63 0.33 64.63 0.29 19 Disperse Red 60 high FeSO4 85.52 5.68 19.15 19.98 73.48 20 Disperse Red 60 low FeSO4 97.85 -1.27 2.99 3.25 112.95 21 Disperse Yellow 54 original 85.5 3.89 88.39 88.48 87.48 22 Disperse Yellow 54 high FeSO4 84.25 6.25 23.55 21.23 76.36 23 Disperse Yellow 54 FeSO4* 96.58 -2.72 13.8 14.07 101.13 Note: low FeSO4 = 0.18 mM; high FeSO4 = 1.8 mM; FeSO4*= 0.72 mM

Figure 5.8. Calculated fabric samples containing Basic Yellow 28 before and after Fenton’s treatment.

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BASIC YELLOW 28 3.5 3 2.5 2

1.5 K/S VALUE K/S 1 0.5 0 360 410 460 510 560 610 660 710 760 Wavelength, nm

Basic yellow 28, original Basic yellow 28, low FeSO4

Figure 5.9. Σ K/S values of fabrics colored by basic yellow 28 before and after decolorization using Fenton’s reagent under different conditions.

5.3.3 Decolorization efficiency on different dyes

This component of the study involved a determination of the scope of disperse dyes that could be decolorized using the optimized Fenton’s method. Images of the original dyed

PET fabrics Disperse Orange 30, Disperse Blue 79, Disperse Yellow 42, Disperse Yellow 86,

Disperse Yellow 54, Disperse Blue 56 and Disperse Red 60) and the corresponding treated

* * * PET fabrics at two levels of [FeSO4] are shown in Figure 5.10 and their L , a and b values are listed in Table 7. The associated K/S spectra are showed in Figure 5.11. The L* value of fabrics containing one of the quinoline (Yellow 54), azo (Disperse Blue 79), and anthraquinone

Disperse Red 60 dyes are significantly above 90 and their a* and b* values are close to center point after Fenton’s treatment. Unlike the other cases, fabrics containing the azo dye Disperse

* Orange 30 was decolorized better at high [FeSO4], based on the higher L value, perhaps due to secondary color (e.g. an oxidation type dye) formation that is partly degraded in the presence of excess Fe(II). The resulting UV-Vis and K/S spectra indicate that the fabric still has a

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residual orange color after Fenton’s treatment. Fabrics containing the two nitro dyes (Disperse

Yellow 42 and Disperse Yellow 86) have high L* values (>94) but their b* values are not as close to center point as Yellow 54, Red 60 and Blue 79. Fabrics containing these two dyes have a residual yellow color, indicating the relative resistance of the nitro chromogen to complete decolorization. Although the quinoline dye (Disperse Yellow 54) can be decolorized completely, an increase in [FeSO4] from 0.18mM to 0.72mM gave the best results. The higher

[FeSO4] seems to be below the Fe dosage that contributes to a brown color at the end of the treatment.

Figure 5.10. Fabric samples containing disperse dyes before and after Fenton’s treatment at high and low Fe(II) levels.

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K/S spectra of fabrics containing different dyes before/after Fenton’s treatment are shown in Fig 5.11. These results indicate that all of the dye classes investigated in this research can be appreciably decolorized using Fenton’s reagent.

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Figure 5.11. Σ K/S values of fabrics before and after decolorization using Fenton’s reagent at different Fe(II) levels (0.10 and 1.8 mM).

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ORANGE 30 BLUE 79 10 10

8 8

6 6

4 4

K/S VALUE K/S K/S VALUE K/S 2 2

0 0 360 410 460 510 560 610 660 710 760 360 410 460 510 560 610 660 710 760

Orange 30, original Orange 30. high FeSO4 Blue 79, original Blue 79, high FeSO4 Orange 30, low FeSO4 Blue 79, low FeSO4

YELLOW 42 YELLOW 86 3.5 3.5 3 3 2.5 2.5 2 2

1.5 1.5 K/S VALUE K/S 1 VALUE K/S 1 0.5 0.5 0 0 360 410 460 510 560 610 660 710 760 360 410 460 510 560 610 660 710 760

Yellow 42, original Yellow 42, high FeSO4 Yellow 86, original Yellow 86, high FeSO4 Yellow 42, low FeSO4 Yellow 86, low FeSO4

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BLUE 56 RED 60 12 8 7 10 6 8 5

6 4 K/S VALUE K/S K/SVALUE 3 4 2 2 1 0 0 360 410 460 510 560 610 660 710 760 360 410 460 510 560 610 660 710 760

Blue 56, original Blue 56, high FeSO4 Red 60, original Red 60, high FeSO4 Blue 56, low FeSO4 Red 60, low FeSO4

YELLOW 54 20

K/S VALUE K/S 5

0 360 410 460 510 560 610 660 710 760

Yellow 54, Original Yellow 54, 0.72 mM FeSO4 Yellow 54, low FeSO4

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The absorption spectra of solutions collected at the end of stage I (extraction) and stage

II (decolorization) of the decolorization process are shown in Figure 5.12. The UV-Visible spectra of Disperse Blue 79, Blue 56 and Red 60 show that the λmax of these spectra were shifted out of the visible light wavelength range. It suggests that these dyes extracted into the solution after stage I could be decoloried after stage II process and the fabric decolorization occurred due to Fenton’s reagent decolorization ability but not the medium extraction.While the UV-Vis spectrum of Disperse Orange 30, Yellow 42 and Yellow 86 show that the λmax did not change after stage II.

And the absorbance of the solution colleceted after stage II was higher than the absorbance of solution collecelted after stage I. It indicates these three dyes can not be decolorized using the optimum method. And the fabric color removing is mainly due to the medium extraction.

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Figure 5.12. UV-Vis spectrums of solution collected at the end of stage I (extraction) and stage II (decolorization) in decolorization process

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Orange 30 6

3 Absorbance 2

0 360 410 460 510 560 610 660 710 760 Wavelength, nm

After extraction After decolorization

Blue 79 4

3.5

2.5

Absorbance 1.5

0.5

0 360 410 460 510 560 610 660 710 760 Wavelength, nm

After extraction After decolorization

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Yellow 42 4.5

3.5

2.5

2 Absorbance 1.5

0.5

0 360 410 460 510 560 610 660 710 760 Wavelength, nm

After extraction after decolorization

yellow 86 4

3.5

2.5

Absorbance 1.5

0.5

0 360 410 460 510 560 610 660 710 760 Wavelength, nm

After extraction after decolorization

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Red 60 2

1.8

1.6

1.4

1.2

0.8 Absorbance 0.6

0.4

0.2

0 360 410 460 510 560 610 660 710 760 Wavelength, nm

After extraction after decolorization

Blue 56 1.2

0.8

0.6 Absorbance 0.4

0.2

0 360 410 460 510 560 610 660 710 760 Wavelength, nm

after extraction after decolorization

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5.3.4 TEM, EDS and XPS analysis

Photographs “A” and “B” in Figure 5.13 are TEM images of insoluble matter. Most of this substance constitutes solid with attached fibrils. Photographs C and D are images of the solid compounds at higher amplification. EDS analysis of this substance was conducted and the results are showed in Figure 5.13 (E). The elemental weight and atom percentage of solid precipitate in Figure 5.13 (C) is showed in Table 5.8. The amount of carbon is not included in the table due to the large quantity. After excluding carbon, the iron in the precipitate is only

9.3% at weight percentage and 3.1% at atonic percentage. The results suggest that the precipitate does not contain large amount of iron and it is mainly consist of fibril and organic particles.

Table 5.8 EDS analysis of compound attached on fibril precipitate. Element [Weight %] [Atomic %] Iron 9.30 3.10 Oxygen 76.60 89.12 Sulfur 5.49 3.19 Chlorine 1.21 0.63 Potassium 3.89 1.85 Phosphorus 3.50 2.11

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Figure 5.13. (A-D) TEM images of insolubles produced during Fenton’s decolorization, at normal (A&B) and high (C&D) magnification; EDS image (E) of solid precipitate in image (C).

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Figure 5.14 shows the XPS survey of original uncolored white PET fabric and fabric colored by Disperse Red 60 then decolorized using recipe 1 in Table 5.3. The result shows that there is no target signal at binding energy 700-730 eV- the Fe signal area. This suggests that the iron left on the fabric after high [FeSO4] decolorization is less than 0.1 % of fabric weight, which is out of the detection limitation of XPS instrument.

Figure 5.14. XPS survey of original PET fabric (left) and decolorized PET fabric (right) by using Fenton’s reagent method.

5.3.5 Polymer degradation

Figure 5.15 shows the intrinsic average molecular weight of PET fabric dyed by

Disperse Blue 56 and the same fabrics after decolorization using optimum method. The molecular weight difference after decolorization is 1.1%. It suggests that the polymer degradation after decolorization is not significant.

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20000

19500 19425 19203 19218

19000 MW

18500

18000 Original Decolorized sample 1 Decolorized sample 2

Figure 5.15. Intrinsic average molecular weight of PET fabric dyed by Disperse Blue 56 and decolorized using optimum method

5.4 Conclusion

The Fenton’s reagent can be used to decolorize PET fabric colored Basic Yellow 28.

And the results of full factorial experiments indicated acetone was the most important factor to provide efficient decolorization. A high temperature can improve the decolorization performance but high amount of FeSO4 could cause brown stain left on fabric after decolorization. The optimum conditions are: [FeSO4] = 0.18 mM, [H2O2] = 1235 mM, water: acetone = 1:1, Temperature = 120 ˚C, Time = 15 min, liquor ratio = 10:1.

PET fabric colored by typical commercial disperse dyes, including azo (Disperse Blue

79), anthraquinone (Disperse Blue 56 & Disperse Red 60) and quinolone (Disperse Yellow 54) can be decolorized using the optimum conditions. The dyes were removed from fabric due to

Fenton’s reagent decolorization not water/acetone medium extraction. While the color removing of fabric dyed by Disperse Orange 30, Disperse Yellow 42 and Disperse Yellow 86

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is because of the solvent extraction and Fenton’s reagent cannot used to decolorize these three dyes.

The precipitate in the bath after decolorization contains little amount of iron and most of the contents are fabrils and organic particles. The amount of iron remaining on fabric after decolorization is less than 0.1 %. A complete decolorization using the optimum method will not cause significant polymer degradation.

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Chapter 6 A life-cycle assessment case study of post-consumer PET fabric-to-fiber

recycling

6.1 Introduction

The production of polyester fibers accounts for about 40-45% of total global annual fiber production. About 65-70 percent of global polyester production is used for textiles. The majority of the remaining 25-30 percent is used in the manufacture of PET beverage bottles.

PET Bottles and Jars recycling rates in 2013 is 31.3%. In 2013, Municipal Solid Waste

(MSW)—more commonly known as trash or garbage is 254 million tons per year. And textiles account for 6 percent of it, which is 15.24 million tons. 85% of all textile waste goes to landfills and according to the EPA, a 68 lbs. per person heads to the landfill each year [209]. By developing the method which can be used to remove the dye in the used PET garments, it is possible to recycle used PET garments for PET fiber production. The purpose of this study is to compare the environmental impacts of fiber production using post-consumer PET fabric with virgin PET fiber production.

In this study, the analysis will follow the “cut-off” principle [236]. “Cut-off” principle distinguishes the virgin product and the recycled product as separate system. The after-use waste from the virgin product life cycle will be the feedstock in the recycled product life cycle.

And its environmental impacts will not be included in the second life cycle.

The data of decolorization process was estimated by scaling up the chemicals, water, and energy consumption data obtained from lab experiments. Two PET recycling methods, semi- mechanical recycling and back-to-monomer recycling, are used in this study. This post- consumer PET fabric to fiber system is proposed only and the fabric collection, transportation

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and PET fabric recycling process were assumed based on the processes used in PET bottle recycling.

6.2 Methodology

6.2.1 Goal, functional unit and system boundary

6.2.1.1 Goal and functional unit

The goal of this LCA is to assess the environmental impacts of recycled PET fiber production using decolorized post-consumer PET fabric compared to virgin PET fiber production. The functional unit is defined as “one metric ton of PET fiber”. Semi-mechanical and chemical recycling methods were used to recycle decolorized PET garment. The quality of recycled polymer using these two methods is identical with virgin polymer. Table 6.1 shows the product systems in this study.

Table 6.1. Product systems in this study, comparing type of fiber, property and application PET garments Virgin PET Recycling case 1 Recycling case 2 References Technology Semi-Mechanical Chemical Single-use Virgin PET Technology level Large scale Small scale Large scale production Type of fiber studied Filament Filament Filament Application Footwear Apparel Apparel

6.2.1.2 System boundary

The scope of this LCA is cradle to gate. For virgin products, raw material and fuels extraction and transportation were included. And the PET polymer production, pellet production and fiber production were studied as well. While the textile garment production

(fabric production, dyeing & finishing and production of end product), the use phase and the post-consumer waste management were excluded.

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For open-loop recycling, Figure 6.1 illustrates the concept of the “cut-off” approach.

The used PET textile products are considered to be waste and it does not take any environmental burden in life cycle I. These used PET textile products then became the feedstock in life cycle II and the “cradle” of life cycle II is defined as the collection and transportation of used PET textile products.

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Figure 6.1. Cradle-to-factory gate system boundary of recycling PET fibers from waste PET fabric, splitting the fiber life and the second life based on the “Cut-off” approach

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6.2.2 General data and assumptions

The LCI data of amorphous PET polymer production is from ecoinvent v2.2 database.

For the data used in recycling PET garments into fiber, the data of post-consumer PET fabric collection and transportation was assumed based on the data of collection and transportation for PET bottle recycling in published paper [236-238]. The energy and material used in PET fabric decolorization was calculated by scaling up the data of PET decolorization processing in lab trial. The data of semi-mechanical and chemical recycling processes was from previous published paper. The data of pellet and fiber production was from previous published paper.

The data of heat and power generation, chemical production and transportation were obtained from ecoinvent v2.2 database. Table 6.2 summarize the data and assumptions used in this study.

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Table 6.2. Data and assumptions in this study Data Sources Grid electricity Ecoinvent v2.2 Production of steam, natural gas, fuel oil and diesel Ecoinvent v2.2 Production of chemicals Ecoinvent v2.2 Virgin polymer production Ecoinvent v2.2 PET fabric collection Assumed from literature [236] Pellet and fiber production Published literature [237] Energy and materials use of PET recycling Published literature [236, 238] Energy and materials use of PET decolorization Assumed by scaling up energy and materials used in lab experiments

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6.2.3 Environmental impact assessment

In life-cycle assessment, all raw material requirements and emissions released from the product system to the environment in life-cycle inventory were converted into environmental impact categories. These results represent the effects of product systems on environment. In this study, the environmental indicators are: global warming potential (GWP), ozone depletion, acidification, eutrophication and photochemical oxidation from Tool for the Reduction and

Assessment of Chemical and other Environmental Impacts (TRACI), and ecotoxicity, human health impacts (carcinogenic and non-carcinogenic) from USEtox. Midpoint impacts (Table

6.3) were utilized, which are considered impact scores with less uncertainty compared with endpoint impacts (SAIC 2006).

Table 6.3. Impact categories used in impact assessment Impact category Units Description

Global Warming Kg CO2 Converts inventory amounts to CO2 equivalents Ozone Depletion CFC-11* Converts inventory amounts to CFC-11 equivalents Eutrophication Kg N Converts inventory amounts to nitrogen equivalents + + Converts inventory amounts to moles of H Acidification Mole of H equivalents Photochemical oxidation Kg NOx Converts inventory amounts to NOx equivalents Ecotoxicity CTU* Converts inventory amounts to CTU equivalents Human Health- CTU Converts inventory amounts to CTU equivalents Carcinogenics Human Health-Non- CTU Converts inventory amounts to CTU equivalents Carcinogenics *CTU: comparative toxicity units; CFC-11: Trichlorofluoromethane

6.2.4 Normalization and weighting

Normalization was used to assist in the interpretation of the LCIA results by adjusting the characterization result to common unit. The basic calculation of normalization results is of the following:

Ni = Si/Ai

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where i = impact category, N = the normalized results, S = product system results prior to normalization, and A = normalization factor of the reference area.

To identify the key impact categories for this assessment, the impact results were normalized to person equivalents based on normalization factors from TRACI and the normalization reference for USETox for North America. Normalization factors for impact categories analyzed are listed in Table 6.4.

Table 6.4. Normalization factors for all impact categories analyzed Total normalized value Impact category Normalized unit per capita per capita 4 Global Warming 2.45×10 CO2 equiv/yr/capita Ozone Depletion 3.11×10-1 CFC-11 equiv/yr/capita Eutrophication 1.80×101 N equiv/yr/capita Acidification 7.44×103 H+ equiv/yr/capita 2 Photochemical oxidation 1.21×10 NOx equive/yr/capita Ecotoxicity 1.47×104 CTU equiv/yr/capita Human Health-Carcinogenics 1.02×10-4 CTU equiv/yr/capita Human Health-Non- 4.54×10-4 CTU equiv/yr/capita Carcinogenics

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6.3 Recycling PET garments into fiber

6.3.1 Collection of used PET fabric

PET clothes collection methods are listed below:

a. Mandatory extended producer responsibility, in France since 2006 and planned to be

implemented in Canada by 2017.

b. Container collection, provide by charity organizations, commonly used

c. Container collection, provide by recycling company, in central Finland

d. Second hand shop in-store collection, charities and commercial, most of the charity

organizations in Nordic countries with shops offer this service

e. Collection of own brand polyester products in stores for chemical recycling,

Patagonia, Houdini, Haglofs and other high end brands.

f. Private collections,

The assumption in this project is using the used PET bottle collection system to collect used PET clothes. And the major environmental burdens from the collection step are related to the fuel consumption and air emissions from the transportation of used PET clothes. The average transport distance of used PET bottles by truck is 200 km in previous research [239].

In this study, the PET clothes transportation distance was assumed as the same.

6.3.2 PET fabric decolorization

Figure 6.2 shows that flow sheet of the post-consumer PET fabric decolorization process. The post-consumer PET fabric will be chopped into small pieces of fabric. Then the fabric was decolorized using Fenton’s reagent decolorization method. After decolorization, the fabric will be rinsed until the pH to neutral and dried. Finally, the dried PET fabric will be transported to a pellet plant or a fiber plant.

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PET Textiles

Chopping

Decolorization

Rinsing

Drying

Pellet plant

Figure 6.2. The PET fabric decolorization process

6.3.3 PET recycling

6.3.3.1 Semi-mechanical recycling

Mechanical recycling is the physical conversion of fabric into fiber or other products by melt-extrusion. Since the quality of fiber produced by mechanical recycling cannot meet the requirement for PET garment manufacturing, semi-mechanical recycling is used in this project. In semi-mechanical recycling, the fabric will be first extruded into pellets and then converted into fiber and other products. A small amount of ethylene glycol is added to meet the final requirements.

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6.3.3.2 Chemical recycling

In chemical recycling, depolymerization technique are used to break down PET polymer into monomers. The quality of PET recycled by chemical recycling is competitive to virgin PET. The disadvantage of chemical recycling is the high cost. So a large scale is usually required to make it economically feasible. In this study, the PET is depolymerized with methnol to DMT and EG in the presence of catalysts under a pressure of 2-4 MPA and temperature of 180-280 ˚C [246] (Paszun and Spychaj, 1997). After repolymerization, the recycled polymer is then converted into fiber via spinning and finishing processes.

6.4 Life-cycle assessment results

6.4.1 Comparative analysis

Table 6.6 shows the cradle-to-gate LCA results for 1000 kg of PET fiber production using virgin and post-consumer PET fabric through two recycling processes (chemical & semi- mechanical). Compared to the impacts of fiber production using virgin PET, using post- consume PET fabric for fiber production is 5.45% (chemical) and 19.26% (semi-mechanical) lower in photochemical oxidation; 10.69% (chemical) and 12.79% (semi-mechanical) lower in acidification; 40% (chemical) and 44.61% (semi-mechanical) lower in eutrophication;

13.86% (chemical) and 29.05% (semi-mechanical) lower in global warming; 25.75%

(chemical) and 36.53% (semi-mechanical) lower in human toxicity- non-carcinogenic; 8.59%

(chemical) and 13.64% (semi-mechanical) lower in human toxicity-carcinogenic; 15.41%

(chemical) and 22.10% (semi-mechanical) lower in ecotoxicity.

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Table 6.6. LCA results for 1000 kg of PET fiber production using virgin and used PET fabric Impact category Virgin PET Chemical Semi- Reference unit Mechanical photochemical oxidation 6.23 5.89 4.92 kg NOx-Eq acidification 765.49 683.65 653.11 moles of H+-Eq eutrophication 0.65 0.39 0.36 kg N ozone depletion 1.93E-04 2.34E-04 1.80E-04 kg CFC-11-Eq global warming 3790 3264.72 2629.25 kg CO2-Eq human toxicity - non-carcinogenic 1.67E-04 1.24E-04 1.00E-04 CTU human toxicity - carcinogenic 1.98E-04 1.81E-04 1.70E-04 CTU ecotoxicity 1878.31 1595.78 1423.08 CTU

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Figure 6.3 shows the normalized LCA results using normalization factors in Table 6.4.

Compared to fiber production using virgin PET, the fiber produced using recycled PET fabric cause lower environmental impacts in most of the categories except for ozone depletion. The ozone depletion potential of PET fiber production using post-consumer PET fabric via chemical recycling process is the highest in all of the three PET production systems. The human toxicity- carcinogenic is the highest impact in all three systems and the detail will be discussed in section 6.4.2.

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1.28E-01 ecotoxicity 1.09E-01 9.68E-02

1.94E+00 carcinogenic 1.78E+00 1.67E+00

3.67E-01 non-carcinogenic 2.73E-01 2.20E-01

1.55E-01 global warming 1.33E-01 1.07E-01

6.21E-04 ozone depletion 7.53E-04 5.79E-04

3.61E-02 eutrophication 2.17E-02 1.98E-02

1.03E-01 acidification 9.19E-02 8.78E-02

5.15E-02 photochemical oxidation 4.87E-02 4.07E-02

0 0.5 1 1.5 2 2.5 Person Equivelent

Virgin PET Via Chemical recycling Via Semi-Mechanical recycling

Figure 6.3. The normalized environmental impacts of three PET fiber production systems

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6.4.2 Contribution analysis

A contribution analysis was conducted to discuss the contributions of processes to the impact categories. The results are shown in Figure 6.4. For the fiber production using virgin

PET, the amorphous PET production process contributes the most in all of the impact categories and it is due to the raw material extraction and producing from oil. Because of the

“cut-off” principle, this part of environment impact is excluded in the life-cycle of PET fiber production using post-consume PET fabric. Compared to other processes in both fiber production systems using post-consume fabric, the impacts of collection and transportation in all of the impact categories are negligible. For photochemical oxidation, acidification and eutrophication, there is no significant differences between two recycling systems. For ozone depletion, global warming, human toxicity carcinogenic & non-carcinogenic and ecotoxicity, the method of recycling process is the reason to make the emissions released by these two systems different. The ethylene glycol and methanol used in chemical recycling process, the energy and materials used to produce these chemicals contribute the most in these impacts categories. For both recycling systems, the PET decolorization process is another main contribution process in all of the impact categories. In decolorization process, high temperature is required to provide a successful decolorization and it consumes large quantity of energy.

The heat and electricity provided by burning natural gas and fuel will release high level of emissions to the environment. Hydrogen peroxide is used in PET decolorization process. The energy used for hydrogen peroxide production contributes 5%-11% to impact categories. The total amount of emissions released by decolorization and recycling processes is less than that released by amorphous PET production in most of impact categories except for ozone depletion.

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Figure 6.4. Results of contribution analysis for PET fiber production using virgin PET and used PET fabric through chemical & semi-mechanical recycling

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photochemical oxidation 7

x 4

Kg NO Kg 3

0 Virgin Chemical Semi-Mechanical

acidification 900 800 700

600 + 500 400 Mole Mole H of 300 200 100 0 Virgin Chemical Semi-Mechanical

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eutrophication 0.7

0.6

0.5

0.4

Kg N Kg 0.3

0.2

0.1

0 Virgin Chemical Semi-Mechanical

ozone depletion 2.50E-04

2.00E-04

1.50E-04

11 -

CFC 1.00E-04

5.00E-05

0.00E+00 Virgin Chemical Semi-Mechanical

global warming 4000 3500 3000

2 2500 2000

Kg CO Kg 1500 1000 500 0 Virgin Chemical Semi-Mechanical

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human toxicitiy- non-carcinogenic 0.00018 0.00016 0.00014 0.00012 0.0001

CTU 0.00008 0.00006 0.00004 0.00002 0 Virgin Chemical Semi-Mechanical

human toxicitiy-carcinogenic 0.00025

0.0002

0.00015 CTU 0.0001

0.00005

0 Virgin Chemical Semi-Mechanical

ecotoxicity 2500 Spinning process 2000 Rrecycling process

1500 PET decolorization

CTU Fabric collection 1000 Pellet production

500 Amorphous PET produciton

0 Virgin Chemical Semi-Mechanical

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6.5 Discussion

In this study, the fabric recycling process is only a proposal but not used in reality. The two recycling processes in fiber production using post-consume fabric after decolorization are assumed from public literature of PET bottle recycling process. The differences between bottle and fabric recycling process will cause uncertainty in the analysis. The collection and sorting process for PET fabric recycling is more complicate than PET bottle recycling and it is not well developed yet. The fabric decolorization process is only conducted under lab scale experiments. The electricity usage of the decolorization process is assumed using data from bleaching process in textile industry and the heat usage is calculated based on the lab data. In the decolorization process, hydrogen peroxide was used to decolorize fabric under high temperature. Through the contribution analysis, the impacts of energy and raw material used for hydrogen peroxide production to environment contribute around 25% in decolorization process. In order to reduce the impacts of decolorization process, a more efficient and environmental responsible method should be used to produce hydrogen peroxide, such as using solar energy. Also, the optimization of decolorization process is necessary to reduce the energy and chemical use.

6.6 Conclusion

In this study, the environmental impacts of PET fiber production using post-consumer

PET fabric was compared to virgin PET production. The post-consumer PET fabric was firstly decolorized using Fenton’s reagent in water-acetone medium. Two recycling methods: semi- mechanical and chemical processes were used to recycle the decolorized PET fabric. This PET fabric to fiber production is a proposed process. So the data of fabric collection and recycling process is assumed from PET bottle to fiber production. The purpose of this study is to evaluate

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the feasibility of post-consumer PET fabric to fiber production. The results showed for most of the impact categories (photochemical oxidation, acidification, eutrophication, global warming, human toxicity: carcinogenic & non-carcinogenic and ecotoxicity), using post- consumer PET fabric to produce fiber will release 5.45% to 44.61% less impacts to the environment compared to virgin PET production. Only emissions, which cause ozone depletion, released by recycled fiber production through chemical recycling process are more than emissions released by virgin PET production. After normalization and weighting, this impact is negligible. In order to reduce the environmental impacts of the post-consumer PET fabric to fiber production, the optimizations of PET fabric decolorization process, recycling process and chemical production are necessary. A decolorization process using less chemical and at lower temperature should be developed in the future. A more environmental friendly process for hydrogen peroxide production should be used.

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Chapter 7 Conclusions and Recommendations for Future Research

The toxicity of 8 newly invented cationic bleach activators and two bench mark cationic bleach activators: TBBC and TBCC were measured. All of the new cationic bleach activators have less acute toxicity to daphnia compared to TBBC. And 3-PBBC and 3-PBCC have same ability as TBBC and TBCC in effective bleaching under low temperature and neutral pH, but both of the new invented bleach activators have much less toxicity than these two bench mark products. 3-PBBC compound is 86 times less toxic in Daphnia sp. Immobilization Test, 18 times less toxic in Algae Toxicity assay and 10 times less mutagenic in the

Salmonella/microsome microsuspension assay in comparison with the TBBC. The results confirmed that it is possible to reduce the toxicity of cationic bleach activators by replacing its cationic group using less toxic ammines. It would be necessary to do the mutagenic testing with TA98 in the future to complement the analysis.

The modified new bleaching process has lower environmental impacts than conventional method. It consumes less electricity, steam, water, and process time by modifying the conventional bleaching process. The differences of fabric weight loss between conventional and modified new bleaching process dominate the main differences of the most environmental impacts. Sensitivity analysis indicates that even if the two systems have the same fabric weight loss after bleaching, modified new bleaching process still has less impact to environment, but the difference between conventional and modified new process is reduced.

Further work to obtain specific data associated with chemicals used in the modified new wet processing would increase the accuracy of future LCA studies.

The Fenton’s reagent can be used to decolorize PET fabric colored basic yellow 28.

And the results of full factorial experiments indicated acetone was the most important factor

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to provide efficient decolorization. The optimum conditions are: [FeSO4] = 0.18 mM, [H2O2]

= 1235 mM, water: acetone = 1:1, Temperature = 120 ˚C, Time = 15 min, liquor ratio = 10:1.

PET fabric colored by typical commercial disperse dyes, including azo (Disperse Blue 79), anthraquinone (Disperse Blue 56 & Disperse Red 60) and quinolone (Disperse Yellow 54) can be decolorized using the optimum conditions. Fenton's reagent was less effective for decolorizing PET dyed with azo dye Disperse Orange 30 and nitro dyes Disperse Yellow 42 and Yellow 86. The precipitate in the bath after decolorization contains little amount of iron and most of the contents are fabrils and organic particles. The amount of iron remaining on fabric after decolorization is less than 0.1 %. A complete decolorization using the optimum method will not cause significant polymer degradation. A further study of chemical residuals in solution after decolorization, such as identification of contents and their toxicity to aquatic organism, is necessary.

The environmental impacts of PET fiber production using post-consumer PET fabric was compared to virgin PET production. The results showed for most of the impact categories

(photochemical oxidation, acidification, eutrophication, global warming, human toxicity: carcinogenic & non-carcinogenic and ecotoxicity), using post-consumer PET fabric to produce fiber will release 5.45% to 44.61% less impacts to the environment compared to virgin PET production. The ozone depletion emissions of PET fiber production using post-consumer fabric is higher than virgin PET fiber production. The optimizations of PET fabric decolorization process, recycling process and chemical production are necessary to reduce the environmental impacts of the post-consumer PET fabric to fiber production. A decolorization process using less chemical and at lower temperature should be developed in the future. A more environmental friendly process for hydrogen peroxide production should be used.

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