applied sciences Article Eco-Structured Biosorptive Removal of Basic Fuchsin Using Pistachio Nutshells: A Definitive Screening Design—Based Approach Marwa El-Azazy * , Ahmed S. El-Shafie , Aya Ashraf and Ahmed A. Issa Department of Chemistry and Earth Sciences, College of Arts and Sciences, Qatar University, Doha 2713, Qatar; aelshafi[email protected] (A.S.E.-S.); [email protected] (A.A.); [email protected] (A.A.I.) * Correspondence: [email protected]; Tel.: +974-4403-4675; Fax: +974-4403-4651 Received: 22 October 2019; Accepted: 7 November 2019; Published: 13 November 2019 Abstract: Biosorptive removal of basic fuchsin (BF) from wastewater samples was achieved using the recycled agro-wastes of pistachio nut shells (PNS). Seven adsorbents were developed; raw shells (RPNS) and the thermally activated biomasses at six different temperatures (250–500 ◦C). Two measures were implemented to assess the performance of utilized adsorbents; %removal (%R) and adsorption capacity (qe). RPNS proved to be the best among the tested adsorbents. A smart approach, definitive-screening design (DSD) was operated to test the impact of independent variables on the adsorption capacity of RPNS. pH, adsorbent dose (AD), dye concentration (DC), and stirring time (ST), were the tested variables. Analysis of variance (ANOVA), control, and quality charts helped establishing regression model. Characterization was performed using Fourier- transform infrared (FT-IR)/Raman spectroscopies together with thermogravimetric analysis (TGA) and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX) analyses. The surface area and other textural properties were determined using the Brunauer Emmett-Teller (BET) analysis. Removal of 99.71% of BF with an adsorption capacity of 118.2 mg/g could be achieved using a factorial blend of pH 12, 100 mg/50 mL of RPNS, and 250 ppm BF for 20 min. Equilibrium studies reveal that the adsorption is physisorption with adsorption energy of 7.45 kJ/mol as indicated by Dubinin-Radushkevich (DR) and Langmuir isotherms. Moreover, adsorption follows pseudo-second-order kinetics with respect to BF and is controlled by the adsorption rate. Keywords: pistachio nutshells (PNS); definitive-screening design (DSD); basic fuchsin (BF); adsorption capacity (qe); characterization; equilibrium; kinetics 1. Introduction With the progress of human life and the escalating anthropogenic activities, pollution of water has become a crucial environmental concern. Various contaminants are intimidating the aquatic system. These contaminants include, but not limited to, drugs and pharmaceuticals, heavy metals and anions, plastics and polymers, dyes and pigments, and pesticides [1]. Industries, particularly, textiles, leather, food, and cosmetics encompass using dyes with diverse chemical structures. Consequently, the discharge of these industries is basically ‘huge’ amounts of intensively colored wastewaters. Release of such an effluent into the receiving water bodies causes a direct mutilation of water quality in terms of the aesthetic properties (color, pH, salinity, total organic carbon (TOC), suspended solids, etc.). Such a change negatively impacts the ecosystem. Just thinking about the capability to restrain the photosynthetic ability of water plants and microorganisms, shows the magnitude of the problem. This effect is worsened by the diverse structure of these dyes and their resistance to biodegradation. The negative impact does only involve the environment but also extends to human health with reported carcinogenic activity [2–5]. Appl. Sci. 2019, 9, 4855; doi:10.3390/app9224855 www.mdpi.com/journal/applsci Appl. Sci. 2019, 9, 4855 2 of 19 Appl. Sci. 2019, 9, x FOR PEER REVIEW 2 of 21 Basic fuchsin (BF), also known as Basic Violet 14, is chemically recognized as benzenamine, resistance to biodegradation. The negative impact does only involve the environment but also 4-[(4-aminophenyl)extends (4-imino-2,5-cyclohexadien-1-ylidene) to human health with reported carcinogenic activity [2–5]. methyl]-2-methyl hydrochloride, Figure1. BF is a mixture of dyesBasic (rosaniline, fuchsin (BF), also pararosaniline, known as Basic Violet new 14, fuchsine, is chemically and recognized Magenta as benzenamine, II) that is 4 commonly‐ used [(4‐aminophenyl) (4‐imino‐2,5‐cyclohexadien‐1‐ylidene) methyl]‐2‐methyl hydrochloride, Figure 1. in gram-stainingBF andis a mixture in a mixtureof dyes (rosaniline, with phenol pararosaniline, for acid-fastnew fuchsine, staining and Magenta of II) mycobacterium that is commonly (tuberculosis and leprosy) inused the procedurein gram‐staining known and in as a Ziehl-Neelsenmixture with phenol [6 ,for7]. acid Moreover,‐fast staining BF of is mycobacterium widely used in textile and (tuberculosis and leprosy) in the procedure known as Ziehl‐Neelsen [6,7]. Moreover, BF is widely leather industries.used Yet,in textile the safetyand leather data industries. sheet ofYet, BF the shows safety data that sheet the of dye BF isshows inflammable that the dye andis might cause skin and eye irritations.inflammable Moreover,and might cause the skin ingestion and eye irritations. of BF Moreover, might cause the ingestion internal of BF organs’ might cause impairment and repeated exposureinternal is usuallyorgans’ impairment associated and withrepeated nervous exposure system is usually damage associated with with nervous different system symptoms [8–10]. damage with different symptoms [8–10]. Figure 1.FigureChemical 1. Chemical structure structure of of basic basic fuchsin fuchsin (BF). (BF). Keeping in mind these toxic effects and the associated changes in the eco‐system, the Keeping ininevitability mind these for dyes’ toxic removal effects and and decolorization the associated of water changesbecomes evident. in the A eco-system,literature survey the inevitability for dyes’ removalshows and that decolorization several approaches of have water been becomesreported for evident. the removal A of literature dyes from aquatic survey bodies. shows that several However, insofar as BF removal is concerned, only a few trials were reported in the literature [10– approaches have13]. been Reported reported techniques for were the mainly removal based on of adsorption dyes from (either aquatic physisorption bodies. or chemisorption) However, insofar as BF removal is concerned,of target dyes only on an a adsorbent few trials recycled were from reported agricultural/animal in the literaturewaste products [10 [14–18].–13]. Reported techniques were mainly basedA on common adsorption feature among (either all the physisorption adopted trials is the or intimate chemisorption) attempts to develop of target the model dyes or on an adsorbent the ideal adsorbent. Such an adsorbent must have particular criteria such as availability at low‐cost recycled from agriculturaland without extensive/animal preceding waste treatment, products liability [14 for–18 regeneration,]. the possibility for application A commonon feature a large scale, among and be all green the or adopted in other words trials does is not the further intimate contaminate attempts the environment to develop or the model or produce a toxic sludge [19–24]. Activated carbons are promising adsorbents, yet, being expensive the ideal adsorbent.and with Such an inability an adsorbent to be revitalized must they have confine particular their applications criteria on the such large asscale availability [25]. Yet, at low-cost and without extensivedeveloping preceding such an adsorbent treatment, from a natural liability source for such regeneration, as recycled agricultural/animal the possibility wastes for application on ensures to a high extent the availability of these criteria. a large scale, and bePistachio green nutshells or in other (PNS) wordsare a by‐ doesproduct not of furtherpistachios; contaminateone of the most theknown environment nut trees or produce a toxic sludge [worldwide19–24]. that Activated belongs to carbonsthe cashew arefamily promising (Anacardiaceae) adsorbents, [26]. As a desert yet, plant, being pistachio expensive can and with an inability to betolerate revitalized harsh conditions they of confinetemperature their and salinity applications but not humidity. on the The tree large origin scale is mainly [25 ].Asia Yet, developing (central and western) with Iran being the top producer [26,27]. As is known, pistachio is commonly such an adsorbentused fromas a snack a natural (fresh or roasted) source as suchwell as asbeing recycled an ingredient agricultural of deserts, ice/animal‐creams, sauces, wastes pastes, ensures to a high extent the availabilityand butters. of Pistachio these criteria.shells are usually thrown away after eating the kernel with no further use and their fate is either incineration or dumping. As per the Food and Agriculture Organization (FAO) Pistachio nutshellsreports, around (PNS) 30 × are 106 atons by-product of PNS are dumped of pistachios; annually, onean issue of the that most negatively known impacts nut the trees worldwide that belongs toenvironment the cashew [28]. family (Anacardiaceae) [26]. As a desert plant, pistachio can tolerate harsh Therefore, it is quite interesting to explore PNS as an adsorbent for the remediation of conditions of temperaturewastewater from and dyes. salinitySince the objective but not of the humidity. current approach The treeis to develop origin a model is mainly adsorbent, Asia (central and western) with Iranvariables being affecting the topthe adsorption producer process [26, 27(pH,]. adsorbent As is known, dose