Table of Contents
ISRN Chemical Engineering
Volume 2012, Article ID 290471, 9 pages
Research Article

Development and Evaluation of Environmentally Benign Aqueous Two Phase Systems for the Recovery of Proteins from Tannery Waste Water

Department of Biotechnology, Manipal Institute of Technology, Karnataka Manipal 576104, India

Received 29 September 2012; Accepted 11 November 2012

Academic Editors: P. V. Bonnesen and G. D’Errico

Copyright © 2012 Selvaraj Raja and Vytla Ramachandra Murty. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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 30°C. The partition coefficients were correlated with the salt compositions by a quadratic equation and the coefficients were calculated.