Optimization studies on aqueous two-phase extraction of hexavalent chromium from contaminated aqueous solutions

Abstract

Chromium has wide applications in industry and its resources are limited. The total chromium discharge to the environment needs to be monitoredand regulated. The extraction of chromium to PEG offers its reuse in pure form. The present study focuses on the optimization of hexavalent chromium extraction to PEG 1500 using ammonium salt. The effect of independent parameters as to the initial salt solution pH and initial salt phase metal concentration on the extraction efficiency has been studied experimentally. Second-order polynomial models have been used to fit the dependent variables in the experimental range of parameters.Central composite rotatable design in Minitabstatistical software version 16is used as the optimization tool. The maximum efficiency that is achieved through the optimization studies is 29.8%at an initialsalt solution pH of 6.5 and initial metal concentration 24.4 ppm. The corresponding distribution coefficient at the optimum conditionshas been found to be 1.14. The results of the optimization studies have been validated by conducting experiments at the optimum conditions.