%0 Journal Article
%T Development and Evaluation of Environmentally Benign Aqueous Two Phase Systems for the Recovery of Proteins from Tannery Waste Water
%A Selvaraj Raja
%A Vytla Ramachandra Murty
%J ISRN Chemical Engineering
%D 2012
%R 10.5402/2012/290471
%X Aqueous two phase systems (ATPSs) containing high molecular weight polyethylene glycol, PEG (10000), and completely biodegradable citrate salts (sodium citrate, potassium citrate, and ammonium citrate) with water were developed to recover the waste water proteins from a model tannery waste water system. The variations in the phase diagram were explained on the basis of ionic radius of cations, Gibbs free energy of hydration ( ) of cations, and effective excluded volume (EEV) of salts. The salting-out capability of the cations followed the sequence: Sodium citrate > Potassium citrate > Ammonium citrate. Setschenow-type equations were used to correlate tie-line compositions. During partitioning studies, recovery of tannery waste water proteins in PEG 10000 + Sodium citrate ATPS was found superior to other systems. It was possible to recover 95.86% of proteins from tannery waste water in the bottom phase with PEG 10000 30% (w/w) + Sodium citrate 13% (w/w) at 30ˇăC. The partition coefficients were correlated with the salt compositions by a quadratic equation and the coefficients were calculated. 1. Introduction Leather industry is one of the prominent industries in Indian economy which potentially provides employment, growth, and export. Up to date, approximately 2000 tanneries are present in India [1] and the waste water generated from them is enormous. During leather processing the skin and hides have to undergo series of processes such as soaking, liming, dehairing, bating, and degreasing. When the skin is subjected to liming process, the collagen structure will be swollen and the fiber bundles are opened up. This step enables the removal of interfibrillary soluble proteins and other biomolecules [2]. The presence of these proteins in the tannery waste water (TWW) effluents increases the biological oxygen demand and chemical oxygen demand and leads to pollution. Currently research is focused on the recovery of valuables from waste effluent generated by the industries. Instead of merely letting off these effluents, the biomolecules present in them can be recovered, since these biomolecules find applications in food and pharmaceutical industries [3]. Thus in this context, a separation method, aqueous two phase system (ATPS) is employed to recover the soluble proteins present in the TWW. ATPS is based on liquid-liquid extraction principle and can be formulated by mixing two chemically differing hydrophilic polymers or one hydrophilic polymer and one salt with water above certain concentrations [4]. It has been proved that a salt-based ATPS is an efficient
%U http://www.hindawi.com/journals/isrn.chemical.engineering/2012/290471/