Stabilized Protein Waste as a Source for Removal of Color from Wastewaters Nishter Nishad Fathima, Rathinam Aravindhan, Jonnalagadda Raghava Rao, Balachandran Unni Nair Chemical Lab, Central Leather Research Institute, Council for Scientific and Industrial Research, Adyar, Chennai 20, India Received 21 April 2009; accepted 25 May 2010 DOI 10.1002/app.32884 Published online 29 November 2010 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Seeking solution to pollution problems is a prime concern of many researchers today. The waste from one industry can be judiciously used to treat another waste. This concept has been used in this study, wherein, the fleshing, a solid waste (biopolymer) emanating from leather industry has been used as an adsorbent for re- moval of dyes from wastewater. Fleshing has been cross- linked with glutaraldehyde to stabilize it against degradation. The various parameters like effect of pH, role of salt concentration, adsorbent dosage, and initial concen- tration of dye have been standardized. About 90% dye re- moval has been achieved by treating 100 mg/L dye solution with 12 g/L of glutaraldehyde-crosslinked flesh- ing. The dye removal has been found to follow Langmuir type of adsorption isotherm. The optimized parameters of batch adsorption studies have been applied to treat sec- tional wastewater from a commercial tannery. The study also explores the possibility of reusing the dye loaded fleshing as a reductant in the manufacture of a tanning salt, which is used in leather industry for tanning of leath- ers. Thus, a holistic solution to both solid and liquid waste has been presented in this work. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1397–1402, 2011 Key words: dyes; tannery fleshing; isotherms; adsorption; solid waste; water pollution INTRODUCTION Leather is one of the oldest commodities in today’s world market. Leather manufacturing is a by-prod- uct industry, which existed from the day man hunted animals and will exist until man consumes animal as food. Nevertheless, it also exists as an in- dependent industry because of the unique properties of the leather itself. This industry is also synony- mous with pollution. Every step in leather process- ing generates waste either in solid or liquid form. Fleshing, which is integral part of a hide/skin, is removed during leather processing as it is an unwanted material in the final leather. For every ton of leather processed, about 100–150 kg of fleshing is generated. 1 This shows the quantum of fleshing waste generated by tanneries. This also depicts the enormity of the solid waste disposal problem, which arises because of this fleshing. The presently followed disposal techniques are not economical. For instance, the widely followed disposal method for fleshing is glue manufacture. 2 This method is highly noneconomical in terms of ini- tial capital costs and maintenance costs. Hence, the need of the hour is to develop cost effective disposal methodologies for fleshing emanating from tanneries. On the other hand, there is another problem, which is grabbing the attention of environmentalists worldwide, namely dyes. This pertains not only to leather industry but also to many other industries such as textiles, paper etc. Dyes not only color the wastewater but also cause various health hazards. 3 Although various dye removal techniques are avail- able, adsorption scores over many owing to its effi- ciency. 4–6 The uptake of the diazo dye Acid Blue 113 by hydrotalcite and calcined hydrotalcite, fly ash was studied recently. 7,8 Activated carbon is the most widely used adsorbent; however, there are draw- backs like high initial cost and regeneration cost associated with it. Hence, there is a look out for low- cost adsorbent for dye removal. A number of low- cost adsorbents from steel and fertilizer industries wastes have been prepared and investigated for the removal of anionic dyes such as ethyl orange, meta- nil yellow, and acid blue 113 from aqueous solu- tions. 9 Use of seaweeds and calcium alginate beads for dye removal has been studied recently. 10,11 Tan- nery fleshing contains proteins like collagen, elastin, reticulin, and fats. 12 This leads to the presence of Correspondence to: J. R. Rao (rao_clri@yahoo.com or clrichem@mailcity.com). Contract grant sponsor: Council of Scientific and Industrial Research, Govt. of India, New Delhi. Journal of Applied Polymer Science, Vol. 120, 1397–1402 (2011) V C 2010 Wiley Periodicals, Inc.