Optimization Through Box-Behnken Design for Cr(VI) Degradation from Real Tannery Wastewater Using Graphite Electrode by Electrocoagulation

Abstract

The mitigation of tannery effluents is a rising issue owing to the complex mixture of contaminants and hazardous chemicals, mostly chromium. The disposal of tannery effluent into the various water sources such as ponds, lakes, rivers, etc., affects the ecosystem and aquatic lives. The current work scrutinizes the performance of EC unit for Cr(VI) degradation from real tannery effluent. The chromium removal efficiency was evaluated using an iron and graphite electrode in parallel arrangement (MP-P). The iron anode was employed to generate metal coagulant species whereas, graphite served as the cathode. Furthermore, based upon factors mainly pH, current density (CD), electrolysis duration and initial pollutant concentration, the process was statistically optimized using BBD-based response surface methodology (RSM). Optimization of all the four independent variables was determined to be pH = 5.27, CD = 6.26 mA/cm2, electrolysis time = 26.7 minutes and initial concentration = 133.62 mg/L respectively based on which maximum chromium removal efficiency of 89.12% was obtained. Residual, response, probability, 3D surfaces, and contour plots were determined using analysis of variance (ANOVA).