DOCSLIB.ORG

Kinetics and Mechanism of Oxygen Delignification Yun Ji

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Kinetics and Mechanism of Oxygen Delignification Yun Ji The University of Maine DigitalCommons@UMaine Electronic Theses and Dissertations Fogler Library 5-2007 Kinetics and Mechanism of Oxygen Delignification Yun Ji Follow this and additional works at: http://digitalcommons.library.umaine.edu/etd Part of the Chemical Engineering Commons, and the Organic Chemistry Commons Recommended Citation Ji, Yun, "Kinetics and Mechanism of Oxygen Delignification" (2007). Electronic Theses and Dissertations. 227. http://digitalcommons.library.umaine.edu/etd/227 This Open-Access Dissertation is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of DigitalCommons@UMaine. KINETICS AND MECHANISM OF OXYGEN DELIGNIFICATION By Yun Ji B.E. Northwest University of Light Industry, 1999 M.S. Asian Institute of Technology, 2002 A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (in Chemical Engineering) The Graduate School The University of Maine May, 2007 Advisory Committee: Adriaan R.P. Van Heiningen, Professor of Chemical Engineering, Advisor Joseph M. Genco, Professor of Chemical Engineering M. Clayton Wheeler, Professor of Chemical Engineering Barbara J. W. Cole, Professor of Chemistry Raymond C. Fort Jr., Professor of Chemistry LIBRARY RIGHTS STATEMENT In presenting this thesis in partial fulfillment of the requirements for an advanced degree at The University of Maine, I agree that the Library shall make it freely available for inspection. I further agree that permission for “fair use” copying of this thesis for scholarly purpose may be granted by Librarian. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission. Signature: Date: KINETICS AND MECHANISM OF OXYGEN DELIGNIFICATION By Yun Ji Thesis Advisor: Dr. Adriaan R.P. Van Heiningen An Abstract of the Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (in Chemical Engineering) May, 2007 Considerable research has been conducted into the kinetics and selectivity of the oxygen delignification process to overcome limitation in its use. However most studies were performed in a batch reactor whereby the hydroxide and dissolved oxygen concentrations are changing during the reaction time in an effort to simulate tower performance in pulp mills. This makes it difficult to determine the reaction order of the different reactants in the rate expressions. Also the lignin content and cellulose degradation of the pulp are only established at the end of the experiment when the sample is removed from the batch reactor. To overcome these deficiencies, we have adopted a differential reactor system used frequently for fluid-solid rate studies (so-called Berty reactor) for measurement of oxygen delignification kinetics. In this reactor, the dissolved oxygen concentration and the alkali concentration in the feed are kept constant, and the rate of lignin removal is determined from the dissolved lignin content in the outflow stream measured by UV absorption. The mass of lignin removed is verified by analyzing the pulp at several time intervals. Experiments were performed at different temperatures, oxygen pressures and caustic concentrations. The delignification rate was found to be first order in HexA-free residual lignin content. The delignification rate reaction order in caustic concentration and oxygen pressure were determined to be 0.42 and 0.44 respectively. The activation energy was found to be 53kJ/mol. The carbohydrate degradation during oxygen delignification can be described by two contributions: one due to radicals produced by phenolic delignification, and a much smaller contribution due to alkaline hydrolysis. From the first order of the reaction and the pKa of the active lignin site, a new oxygen delignification mechanism is proposed. The number 3 carbon atom in the aromatic ring with the attached methoxyl group forms the lignin active site for oxygen adsorption and subsequent electrophic reaction to form a hydroperoxide with a pKa value similar to that of the present delignification kinetics. The uniform presence of the aromatic methoxyl groups in residual lignin further support the first order in lignin kinetics. ACKNOWLWDGEMENTS I would like to acknowledge my advisor Dr. Adriaan R.P Van Heiningen for his excellent guidance and enthusiastic encouragement through this study. I am grateful to all my committee members, Dr. Adriaan R.P Van Heiningen, Dr. Joseph M. Genco, Dr. Clayton M. Wheeler, Dr. Barbara J. W. Cole and Dr. Raymond C. Fort Jr. for their valuable suggestions and guidance during the process of proposal development. I wish to express my utmost appreciation to the technical association of Finland VTT and TEKES for their financial help. I wish to thank the members of Ober Research Group for their friendship and encouragement to help me complete the study at the University of Maine. I wish to thank all the staff in the Chemical Engineering Department, especially Mr. Amos E. Cline for their warm-hearted help. I also would like to thank my parents for their sincere support and encouragement. Last but not the least, I wish to give my special thanks my husband, Xuefei Zhang, for his love and encouragement. ii TABLE OF CONTENT ACKNOWLEDGEMENTS……………………………………………………………….ii LIST OF TABLES………………………………………………………………………...x LIST OF FIGURES..……………………………………………………………………xiii LIST OF EQUATIONS…………………………………………………………………xix Chapter 1. INTRODUCTION .......................................................................................................... 1 1.1 Wood Pulping ........................................................................................................... 1 1.2 Cellulose ................................................................................................................... 3 1.3 Hemicelluloses.......................................................................................................... 4 1.4 Lignin........................................................................................................................ 7 1.5 Lignin Carbohydrates Complex (LCC) .................................................................. 11 1.6 Oxygen Delignification Process ............................................................................. 13 2. DESCRIPTION OF PROBLEM AND OBJECTIVES ................................................ 19 2.1 Description of Problem........................................................................................... 19 2.2 Objectives ............................................................................................................... 20 3. LITERATURE REVIEW ............................................................................................. 21 3.1 Introduction............................................................................................................. 21 3.1.1 Oxygen Chemistry ........................................................................................... 21 3.1.2 Lignin Chemistry ............................................................................................. 22 3.1.3 Carbohydrate Chemistry .................................................................................. 27 3.1.4 Limitations in Oxygen Delignification ............................................................ 29 3.1.5 Mass Transfer of Oxygen................................................................................. 30 iii 3.2 Kinetics of Oxygen Delignification........................................................................ 31 3.2.1 Kinetic Models of Oxygen Delignification...................................................... 32 3.2.1.1 Single Equation Model ............................................................................. 32 3.2.1.2 Two Region Model ................................................................................... 33 3.2.2 Kinetics of Carbohydrate Degradation ............................................................ 34 3.3 Interpretation of the High Rate Orders ................................................................... 35 3.4 Demand of Oxygen in Oxygen Delignification Process......................................... 36 3.5 Treatment of Experimental Data............................................................................. 37 3.5.1 Power Law Model............................................................................................ 37 3.5.2 Two Region Kinetic Model ............................................................................. 38 3.5.3 Cellulose Degradation...................................................................................... 40 3.5.3.1 Degree of Polymerization of Cellulose..................................................... 40 3.5.3.2 Number of Moles of Cellulose per Ton of Pulp ....................................... 40 3.5.3.3 Power Law Model for Cellulose Degradation .......................................... 41 3.6 Selectivity of the Oxygen Delignification Process ................................................. 42 4. EXPERIMENTAL EQUIPMENT AND PROCEDURES ........................................... 44 4.1 Testing Standards.................................................................................................... 44 4.2 Raw Materials ......................................................................................................... 44 4.3 Equipment..............................................................................................................
Load more

Recommended publications
  • Making! the E-Magazine for the Fibrous Forest Products Sector
    PAPERmaking! The e-magazine for the Fibrous Forest Products Sector Produced by: The Paper Industry Technical Association Volume 5 / Number 1 / 2019 PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 5, Number 1, 2019 CONTENTS: FEATURE ARTICLES: 1. Wastewater: Modelling control of an anaerobic reactor 2. Biobleaching: Enzyme bleaching of wood pulp 3. Novel Coatings: Using solutions of cellulose for coating purposes 4. Warehouse Design: Optimising design by using Augmented Reality technology 5. Analysis: Flow cytometry for analysis of polyelectrolyte complexes 6. Wood Panel: Explosion severity caused by wood dust 7. Agriwaste: Soda-AQ pulping of agriwaste in Sudan 8. New Ideas: 5 tips to help nurture new ideas 9. Driving: Driving in wet weather - problems caused by Spring showers 10. Women and Leadership: Importance of mentoring and sponsoring to leaders 11. Networking: 8 networking skills required by professionals 12. Time Management: 101 tips to boost everyday productivity 13. Report Writing: An introduction to report writing skills SUPPLIERS NEWS SECTION: Products & Services: Section 1 – PITA Corporate Members: ABB / ARCHROMA / JARSHIRE / VALMET Section 2 – Other Suppliers Materials Handling / Safety / Testing & Analysis / Miscellaneous DATA COMPILATION: Installations: Overview of equipment orders and installations since November 2018 Research Articles: Recent peer-reviewed articles from the technical paper press Technical Abstracts: Recent peer-reviewed articles from the general scientific press Events: Information on forthcoming national and international events and courses The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry.
    [Show full text]
  • Extended Impregnation Kraft Cooking of Softwood: Effects on Reject, Yield, Pulping Uniformity, and Physical Properties
    Extended Impregnation Kraft Cooking of Softwood: Effects on reject, yield, pulping uniformity, and physical properties Katarina Karlström Licentiate thesis Royal Institute of Technology (KTH) Department of Fibre and Polymer Technology Division of Wood Chemistry and Pulp Technology Stockholm 2009 TRITA-CHE-Report 2009:59 ISSN 1654-1081 ISBN 978-91-7415-496-2 Extended impregnation kraft cooking of softwood: Effects on reject, yield, pulping uniformity, and physical properties Katarina Karlström AKADEMISK AVHANDLING Som med tillstånd av Kungliga Tekniska Högskolan i Stockholm framlägges till offentlig granskning för avläggande av teknologie licentiatexamen fredagen den 18:e december 2009, kl. 10.00 i STFI-salen, Innventia AB, Drottning Kristinas väg 61, Stockholm. Avhandlingen försvaras på svenska. © Katarina Karlström Stockholm 2009 Department of Fibre and Polymer Technology Teknikringen 56-58 SE-100 44 Stockholm Sweden Abstract Converting wood into paper is a complex process involving many different stages, one of which is pulping. Pulping involves liberating the wood fibres from each other, which can be done either chemically or mechanically. This thesis focuses on the most common chemical pulping method, the kraft cooking process, and especially on a recently developed improvement of the impregnation phase, which is the first part of a kraft cook. Extended impregnation kraft cooking (EIC) technique is demonstrated to be an improvement of the kraft pulping process and provides a way to utilize softwood to a higher degree, at higher pulp yield. We demonstrate that it is possible to produce softwood ( Picea abies ) kraft pulp using a new cooking technique, resulting in a pulp that can be defibrated without inline refining at as high lignin content as 8% on wood, measured as kappa numbers above 90.
    [Show full text]
  • A Review on the Modeling, Control and Diagnostics of Continuous Pulp Digesters
    processes Review A Review on the Modeling, Control and Diagnostics of Continuous Pulp Digesters Moksadur Rahman * , Anders Avelin and Konstantinos Kyprianidis School of Business, Society and Engineering, Mälardalen University, Box 883, 72123 Västerås, Sweden; [email protected] (A.V.); [email protected] (K.K.) * Correspondence: [email protected]; Tel.: +46-(0)21-10-1594 Received: 12 August 2020; Accepted: 23 September 2020; Published: 1 October 2020 Abstract: Being at the heart of modern pulp mills, continuous pulp digesters have attracted much attention from the research community. In this article, a comprehensive review in the area of modeling, control and diagnostics of continuous pulp digesters is conducted. The evolution of research focus within these areas is followed and discussed. Particular effort has been devoted to identifying the state-of-the-art and the research gap in a summarized way. Finally, the current and future research directions in the areas have been analyzed and discussed. To date, digester modeling following the Purdue approach, Kappa number control using model predictive controllers and health index-based diagnostic approaches by utilizing different statistical methods have dominated the field. While the rising research interest within the field is evident, we anticipate further developments in advanced sensors and integration of these sensors for improving model prediction and controller performance; and the exploration of different AI-based approaches will be at the core of future research. Keywords: Kraft pulping; pulp digester; modeling; control; diagnostics 1. Introduction With the widespread expansion of the Internet, electronic media and paperless communication, the demand for the graphic paper (i.e., newsprint and higher-value printing and writing paper) has been declining since 2000 [1].
    [Show full text]
  • Importance of Unbleached Pulp Lignin Content
    ENVIRONMENTAL FOOTPRINT COMPARISON TOOL A tool for understanding environmental decisions related to the pulp and paper industry EFFECTS OF DECREASED RELEASE OF CHLORINATED COMPOUNDS ON ENERGY USE Importance of Unbleached Pulp Lignin Content Kappa number is a measure of the amount of lignin remaining in pulp. The higher the kappa number value, the higher the use of bleaching chemicals required to brighten the pulp. The kappa numbers of pulps leaving the digester are typically about 30 for softwoods and 20 for hardwoods in bleached kraft mills that employ conventional cooking methods. Several modifications to conventional cooking, known collectively as extended cooking (EC), have enabled kappa numbers to be further reduced in the digester in ways that minimize yield and strength losses. Kappa numbers associated with EC are about 20 for softwoods and about 14 for hardwoods. Oxygen delignification (OD) is another technology that is used extensively to lower the residual lignin content prior to the bleach plant. The technology is more selective than most extended cooking processes. Lignin reductions of approximately 50% are achievable with OD, resulting in softwood kappa number in the 14-18 range. Some mills use both extended cooking and oxygen delignification to achieve very low kappa number pulps prior to bleaching, producing pulps with kappa number values in the range of 10-12, perhaps even lower. Deterioration of pulp strength properties is the limiting obstacle for kappa number reduction prior to the bleach plant. More recent strategies have been focused away from obtaining the most delignification possible in the digester and toward optimizing the fiberline as a whole based on economic, quality, and environmental factors.
    [Show full text]
  • Effect of Different Locations on the Morphological, Chemical, Pulping and Papermaking Properties of Trema Orientalis (Nalita)
    Bioresource Technology 101 (2010) 1892–1898 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech Effect of different locations on the morphological, chemical, pulping and papermaking properties of Trema orientalis (Nalita) M. Sarwar Jahan a,b,*, Nasima Chowdhury a, Yonghao Ni b a Pulp and Paper Research Division, BCSIR Laboratories, Dr. Qudrat-E-Khuda Road, Dhaka 1205, Bangladesh b Pulp and Paper Research Centre, University of New Brunswick, Fredericton, Canada article info abstract Article history: The chemical compositions and fiber morphology of stem and branch samples from Trema orientalis at Received 24 August 2009 three different sites planted in Bangladesh were determined and their pulping, bleaching and the result- Received in revised form 1 October 2009 ing pulp properties were investigated. A large difference between the stem and branch samples was Accepted 13 October 2009 observed. The stem samples have consistently higher a-cellulose and lower lignin content, and longer Available online 14 November 2009 fibers than the branch samples in all sites. T. orientalis from the Dhaka and Rajbari region had higher a-cellulose content and longer fiber length, resulting in higher pulp yield and better papermaking prop- Keyword: erties. The T. orientalis pulp from Rajbari region also showed the best bleachability. Trema orientalis, Variation of wood Ó 2009 Elsevier Ltd. All rights reserved. properties Stem and branch Pulping and bleaching 1. Introduction sely to those of Malaysian-grown mangium and other fast-grow- ing plantation species, including the traditionally-used pulpwood The increased demand for wood and fiber and declining avail- of the Philippines.
    [Show full text]
  • Single Fiber Lignin Distributions Based on the Density Gradient Column Method
    Single Fiber Lignin Distributions Based on the Density Gradient Column Method Brian Boyer Patent Attorney 3676 Highland Avenue Redwood City, CA 94062 [email protected] Alan Rudie USDA Forest Service, Forest Products Laboratory One Gifford Pinchot Drive Madison, WI 53726 [email protected] ABSTRACT The density gradient column method was used to determine the effects of uniform and non-uniform pulping processes on variation in individual fiber lignin concentrations of the resulting pulps. A density gradient column uses solvents of different densities and a mixing process to produce a column of liquid with a smooth transition from higher density at the bottom to lower density at the top. Properly prepared pulp fibers float in the column, stabilizing at the level where the mixed solvent density equals the density of the fiber. Because lignin is the lowest density component of pulp fibers and has the largest influence on fiber density, the column effectively separates fibers by lignin concentration and allows them to be counted and the distribution of lignin concentrations determined. Ten experimental kraft pulps and three commercial pulps were evaluated. The laboratory pulps were produced from a single loblolly pine tree using 2.5-mm and 10-mm chips. All cooks used a 24% effective alkali (EA) charge on wood, 6-to-1 liquor-to-wood ratio, and 30% sulfidity. The cooking schedule was constant at 60 min rise to temperature and 240 min at temperature. The maximum cooking temperature was varied from 150°C to 170°C to provide a kappa number variation from about 60 to approximately 20.
    [Show full text]
  • Optimization of Ecf Bleaching and Refining of Kraft Pulping from Olive Tree Pruning
    PEER-REVIEWED ARTICLE bioresources.com OPTIMIZATION OF ECF BLEACHING AND REFINING OF KRAFT PULPING FROM OLIVE TREE PRUNING Ana Requejo,a,* Alejandro Rodríguez,a Jorge L. Colodette,b José L. Gomide,b and Luis Jiménez a The aim of the present work was to find an optimum kraft pulping process for olive tree pruning (OTP) in order to produce a bleachable grade pulp of Kappa number about 17. The kraft pulp produced under optimized conditions showed a viscosity of 31.5 mPa.s and good physical, mechanical, and optical properties, which are acceptable for paper grade production. The strength and optical properties were measured on pulps unrefined and refined in a PFI mill with up to 2000 revolutions before and after bleaching. The OTP pulp was bleached to 90% ISO brightness (kappa < 1); however the process demanded a long sequence of stages, OD(EP)D(EP)D, and a higher than usual total chemical dosage (24.78 kg/odt pulp). Overall, OTP is suggested as an interesting raw material for cellulosic pulp production because its properties are comparable to those of other agricultural residues currently used in the paper industry. Keywords: Kraft pulping; Olea europaea; Agricultural wastes; Refining, ECF bleaching Contact information: a: Chemical Engineering Department, Campus de Rabanales, Building Marie Curie (C-3), University of Córdoba, 14071, Córdoba, Spain; b: Laboratory of pulp and paper, Department of Forest Engineering, Federal University of Viçosa, Campus UFV, 36570, MG, Brazil. * Corresponding author: [email protected] INTRODUCTION Pulp production in Europe amounts to 36.9 million tons per year, which represents 21.6% of the world’s production; the production of paper and cardboard accounts for 25.3% of the total with 88.7 million tons.
    [Show full text]
  • Pulp and Papermaking Properties of Bamboo Species Melocanna Baccifera
    CELLULOSE CHEMISTRY AND TECHNOLOGY PULP AND PAPERMAKING PROPERTIES OF BAMBOO SPECIES MELOCANNA BACCIFERA SANDEEP KUMAR TRIPATHI, OM PRAKASH MISHRA, NISHI KANT BHARDWAJ and RAGHAVAN VARADHAN Avantha Centre for Industrial Research and Development, BILT Paper Mill Campus, Yamuna Nagar, Haryana, India ✉Corresponding author: S. Kumar Tripathi, [email protected] Received August, 17, 2016 Pulp and paper making properties of bamboo species Melocanna baccifera were studied with a focus on the physical properties and chemical composition of bamboo chips, on pulping behavior, bleaching response, fiber morphology, refining behavior and strength properties of the bleached pulp. Melocanna baccifera species was found to have 52.8% cellulose, 21.1% hemicelluloses and 25.2% lignin, i.e. similar to hardwood. The produced pulp could be bleached to 89 ± 1% ISO brightness. The bleached pulp refined to 25 °SR had 54.6 Nm/g tensile index, 10.7 mN.m 2/g tear index, 4.95 kN.m 2/g burst index and 328 double folds. Also, the bleached pulp had an average fiber length of 1.68 mm, which is higher than that of hardwood pulp (0.88-1.1 mm), but lower than that of softwood pulp (2.2-3.5 mm). Meanwhile, the pulp had an average fiber width of 17.1 µm, which is similar to that of hardwood fiber (16-20 µm), but lower than that of softwood fiber (28-35 µm). Keywords : bamboo, bleaching, extractives, papermaking properties, pulping INTRODUCTION dimensions has been reported among the species, Bamboo is one of the most versatile plants in but no significant differences in the chemical the world.
    [Show full text]
  • United States Patent (19) 11 Patent Number: 5,953,111 Millar Et Al
    USOO5953111A United States Patent (19) 11 Patent Number: 5,953,111 Millar et al. (45) Date of Patent: *Sep. 14, 1999 54 CONTINUOUS IN-LINE KAPPA 57 ABSTRACT MEASUREMENT SYSTEM A System for the continual, real-time, in-situ generation of a 75 Inventors: Ord D. Millar, Pierrefonds, Canada; Kappa number used by a process control System to control Richard J. Van Fleet, Cave Creek, the delignification of papermaking pulps that includes inject Ariz. ing broad-spectrum light energy from a light energy Source into the pulp and collecting the resultant reflected light 73 Assignee: Honeywell Inc., Minneapolis, Minn. energy from a near-and a far-light collector. The reflected light energy collected by the light collectorS is analyzed by c: - - - asSociated near- and far-light analyzers that generate analog * Notice: This patent is Subject to a terminal dis output signals representing the intensity of Selected wave claimer. lengths of light energy received by the light collectors. An included feedback arrangement conducts the light energy emitted by the light Source to a location proximate the point 21 Appl. No.: 08/989,720 of injection and then to an associated light analyzer that 22 Filed: Dec. 11, 1997 generates analog output signals representing the intensity of the light energy emitted by the light Source in Selected (51) Int. Cl. ............................................... G01N 21/64 wavelengths. The output Signals from the near-, far- and 52 U.S. Cl. ............................................... 356/73; 356/425 feedback-light analyzers are transmitted to a measurement processing System that converts the analog signals to digital 58 Field of Search ................................. 356/73, 42,318 Signals and passes the Signals to a measurement computer.
    [Show full text]
  • Using Oxygen and Peroxide to Bleach Kraft Pulps
    Using Oxygen and Peroxide to Bleach Kraft Pulps B. VAN LIEROP, N. LIEBERGOTT and M.G. FAUBERT An oxygen-clielation-pero~ide(OQe 15, and removal of transition metal ions from stage to obtain the maximum brightness gain EopQP or QEopP) sequence brightened a the pulp before the peroxide stage. A low from OQP and QEopP sequences. kraft pulp to an IS0 brightness of 70%, kappa pulp is achieved without difficulty in provided that the kappa number of the pulp mills equipped with an oxygen delignifica- entering the peroxide stage was below 17. tion stage. The next chlorination tower and EXPERIMENTAL When the kappa number before P was as low washer can be adapted for a chelation (Q) Various commercially prepared soft- as IO, the brightness afrer QP increased stage [l] or for pulp acidification (A) [6] to wood and hardwood kraft pulps were either linearly to about 79%. High temperatures remove metal ions. The peroxide treatment oxygen-delignified in the mill, or in a spe- (90°C) and long retention times (4 h) in the can be done in the extraction stage or even cially designed laboratoq mixer described P stage increased the brightness of the pulp in the chlorine dioxide towers, provided that elsewhere [8]. The treatments listed in Table provided that the pulp wasfirst chelated and the metallurgy is compatible. This combina- I reduced the kappa numbers by approxi- that residual peroxide remained in the tion of stages is designated OQP, and one mately 30% (Eop) and 45% (0). bleach liquor: The correct combination of version of the process has been named the A chelation treatment with DTPA or H202, NaOH, and DTPA in the "Lignox" process by Eka-Nobel [l].
    [Show full text]
  • TAPPI Standards: Regulations and Style Guidelines
    TAPPI Standards: Regulations and Style Guidelines REVISED January 2018 1 Preface This manual contains the TAPPI regulations and style guidelines for TAPPI Standards. The regulations and guidelines are developed and approved by the Quality and Standards Management Committee with the advice and consent of the TAPPI Board of Directors. NOTE: Throughout this manual, “Standards” used alone as a noun refers to ALL categories of Standards. For specific types, the word “Standard” is used as an adjective, e.g., “Standard Test Method,” “Standard Specification,” “Standard Glossary,” or “Standard Guideline.” If you are a Working Group Chairman preparing a Standard or reviewing an existing Standard, you will find the following important information in this manual: • How to write a Standard Test Method using proper terminology and format (Section 7) • How to write TAPPI Standard Specifications, Glossaries, and Guidelines using proper terminology and format (Section 8) • What requirements exist for precision statements in Official and Provisional Test Methods (Sections 4.1.1.1, 4.1.1.2, 6.4.5, 7.4.17). • Use of a checklist to make sure that all required sections have been included in a Standard draft (Appendix 4). • How Working Group Chairman, Working Groups, and Standard-Specific Interest Groups fit into the process of preparing a Standard (Section 6.3, 6.4.1, 6.4.2, 6.4.3, 6.4.4, 6.4.6, 6.4.7). • How the balloting process works (Sections 6.4.6, 6.4.7, 6.4.8, 6.4.9) • How to resolve comments and negative votes (Sections 9.5, 9.6, 9.7) NOTE: This document covers only the regulations for TAPPI Standards, which may include Test Methods or other types of Standards as defined in these regulations.
    [Show full text]
  • Production of Dissolving Grade Pulp from Alfa
    PEER-REVIEWED ARTICLE bioresources.com PRODUCTION OF DISSOLVING GRADE PULP FROM ALFA * Baya Bouiri and Moussa Amrani Alfa, also known as Stipa tenacissimaI or “halfa”, is grown in North Africa and south Spain. Due to its short fiber length, paper made from alfa pulp retains bulk and takes block letters well. In this study alfa was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositions were pulped by a conventional kraft process. One sample was taken from the original alfa material and another from alfa that had been pretreated by diluted acid. The pulp produced from the pretreated alfa was bleached by the elemental-chlorine-free sequences DEPD and DEDP. The yield, Kappa number, brightness, and α- cellulose content of bleached and unbleached pulps were evaluated. The results showed that during the chemical pulping process, treated alfa cooked more easily than the original alfa. The treated alfa pulp also showed very good bleaching, reaching a brightness level of 94.8% ISO with a yield of 93.6% at an α-cellulose content 96.8(%) with a DEDP bleaching sequence, compared to 83.2% ISO brightness level, 92.8% yield, and 95.1% α-cellulose content for bleached pulp with a DEPD bleaching sequence. Therefore, this alfa material could be considered as a worthwhile choice for cellulosic fiber supply. Keywords: Alfa; Kraft; Dissolving grade Pulp; Bleaching; Chlorine dioxide; Prehydrolysis Contact information: Laboratory of composite, materials and environment, M’Hamed Bouguerra University, 35000 Boumerdes, Algeria *Corresponding author: [email protected] INTRODUCTION The paper consumption in the world has increased by 50% during the last decade, and the quantitative growth of paper production has been accompanied by a demand for new grades and by technological developments in response to ecological challenges (Lopez et al.
    [Show full text]