Studies on the Oxidation of As(III) to As(V) by In-Situ-Generated Hypochlorite

The objective of this study is to oxidize arsenite, which is denoted as As(III), into arsenate, which is denoted as As(V), with an in-situgenerated hypochlorite, using metal-oxide-coated titanium and stainless steel as the insoluble anode and cathode, respectively. The cells were operated at different pH values (pH 3-8), temperatures (300-333 K), concentrations of chloride (50-500 mg/L), and current densities (0.02-0.22 mA/dm^2). The oxidation of As(III) (3 mg/L) to As(V) with in-situ-generated hypochlorite proceeds efficiently (by achieving a oxidation efficiency of 100%) when 125 mg/L of chloride (pH 7.00) is electrolyzed at a current density of 0.04 mA/dm^2 and a temperature of 300 K. It is proven that oxidation by electrolytically formed hypochlorite is a more convenient method/process than dosing the solution with other oxidants.