Studies Relating to Removal of Arsenate by Electrochemical Coagulation: Optimization, Kinetics, Coagulant Characterization

The present investigation aims to remove arsenate [As(V)] by electrochemical coagulation using mild steel as anode and cathode. The results showed that the optimum removal efficiency of 98.6% was achieved at a current density of 0.2Adm-2, at a pH of 7.0. The effect of current density, solution pH, temperature, co-existing ions, adsorption isotherm, and kinetics has been studied. Kinetics reveals that the removal of arsenate by electrochemical coagulation is very rapid in the first 15min and remains almost constant with the progress of reaction. The adsorption kinetics obeys the second-order rate expression. An equilibrium isotherm was measured experimentally and the results were analyzed by Langmuir, Freundlich, Dubinin- Redushkevich, and Frumkin using the linearized correlation co-efficient. The characteristics parameters for each isotherm were determined. The Langmuir adsorption isotherm was found to fit the equilibrium data for arsenate adsorption. Temperature studies showed that the adsorption was endothermic and spontaneous in nature.