Studies on the Al–Zn–In-alloy as anode material for the removal of chromium from drinking water in electrocoagulation process

The present study provides the removal of chromium from water by an electrocoagulation process. The various operating parameters like effect of anode materials, effect of pH, concentration of chromium, current density and temperature have been studied. The effect of co-existing anions such as carbonate, boron, silicate and fluoride was studied on the removal efficiency of chromium. The results showed that the optimum removal efficiency of 98.2% was achieved using aluminum alloy anode at a current density of 0.2 A dm− 2, at a pH of 7.0. First and second-order rate equations were applied to study the adsorption kinetics. The adsorption process follows first order kinetics model with good correlation. The Langmuir, Freundlich, D–R and Frumkin adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The experimental adsorption data were fitted to the Langmuir adsorption model. Temperature studies showed that the adsorption was endothermic and spontaneous in nature.

Research highlights
► Very high removal efficiency of chromium was achieved by electrocoagulation.
► Aluminum alloy anode prevents residual aluminum in treated water.
► Compact treatment facility and complete automation.
► The adsorption model fits Langmuir and follow first order kinetics.
► The process is endothermic and spontaneous.