Treatment of electroplating rinsewater by hybrid ion exchange and electrochemical techniques

Abstract

Pollution of water bodies is gradually increasing due to industrial proliferations. Heavy metals such as lead, copper, cadmium, zinc and nickel are among the most common pollutants found in effluents discharged from industries like electroplating, mining operations, and battery manufacturing. In this research, the removal of Cu(II), Ni(II) and Zn(II) ions from synthetic electroplating rinse water (SEPRW) using Ceralite IR 120 (UMR) resin was studied. Effect of various experimental parameters such as pH, contact time, dosage, presence of chelating agent EDTA and co-ions were optimized with the help of batch experiments. The data obtained in batch experiments were fitted with Langmuir and Freundlich isotherm models and the constants were evaluated. Maximum adsorption capacity Qmax obtained for unmodified resin (UMR) was found to be in the order: Cu(II)-164.3 mg g-1 gtNi(II)-108.6 mg g-1 gt Zn(II)-105.1 mg g-1. The results obtained for voltage current characteristics of EIX system with different inter electrode distance such as 0.5, 0.6 and 0.7dm showed that the electric current flows inside the stack cell increased with decrease in inter electrode distance. Thus the optimum electrode distance was fixed at 0.5dm. In similar manner other geometrical parameters were varied and the E I behavior was noted. The optimized conditions for better current flow across the EIX stack thus obtained were 10g resin loading, Ti/RuO2 anode and Nafion 117 membrane. Breakpoint comparative analysis with ion exchange process alone showed that IX process (with 10g PMR) has an efficiency to discharge 4.5L of treated IEPRW whereas the EIX (with 10g of PMR) discharged 19.5L of treated IEPRW. This increase of breakpoint was obtained due hybridization of ion exchange and electrodialysis. newline newline newline