Electroreduction of As(III) in acid environment

The main reduction products of aqueous sulfuric acid solutions of As(III) a re arsine and elemental arsenic, whose yields are substantially dependent o n the electrolysis conditions. At a current density of 500 A m(-2) and an A s(III) concentration of 0.25 M, the following current efficiencies (CE) for arsenic and arsine are obtained: Cd, 28.2 and 26.2; Pb, 29.3 and 22.9; Ti, 16.1 and 22.4; steel 3, 21.0 and 21.0; Cu, 20.3 and 19.9; and stainless. s teel, 24.9 and 16.9. For arsine, CE on a Pb cathode is virtually temperatur e-independent at 15-80 degreesC. Multiple use of the same Pb cathode barely impacts its activity. The arsine CE considerably increases at 2500-3000 A m(-2) and reaches 75-78% and 50-53% on Ph and Cd, respectively.