Green extraction of Cu (II) in PEG-zinc sulfate aqueous two phase system using response surface methodology

Abstract

The present study investigated the partition and extraction conduct of Cu (II) in Aqueous Two-Phase Systems (ATPS) of Poly (Ethylene Glycol) (PEG)–zinc sulfate in the presence of ammonium thiocyanate as an extractor. The polymer weight percent in the feed (20, 25, and 30%), salt weight percent in the feed (15, 23, and 31%), polymer molecular weight (2000, 4000, and 6000 g.mol-1), and the pH (2.5, 3.6, and 4.7) are the determiners of the partition coefficient of Cu (II) in the target system. The Central Composite Design (CCD) was taken into account to investigate the impacts of various parameters on the partition coefficient of Cu (II) by a quadratic model. High F-value (50.58), very low P-value (<0.0001), non-significant lack of fit, the determination coefficient (R2 = 0.9793) demonstrate an excellent correlation between experimental and predicted values of the response. The model results indicated that the pH and weight percent of the salt in the feed had major and minor effects on the copper ion partition coefficient, respectively. The pH of ATPS can alter the Cu (II) partition coefficient through the variation of the copper ion net charge. The weight percent of polymer in the feed decreased the partition coefficients. Moreover, by increasing the polymer molecular weight, the partition coefficient of Cu (II) was increased. The highest value for the productivity of Cu ions extraction was found to be 93.3% with regard to the excellent separation factors (pH = 4.7, PEG molecular weight = 6000, PEG concentration = 20 and salt concentration = 15)