Electrochemical reduction of As(III) in acid media

Abstract

Measurements of the cathode potentials of different electrode materials in the galvanostatic electrolysis of As2O3 solutions in sulfuric acid indicate that the Pb cathode ensures the most stable negative potential, favorable for AsH3 formation. Preparative electrolyses confirm stability of the arsine yield in a series of experiments. The current efficiency for arsine on the Pb cathode is 60–70%. The byproduct of this process is As0, with a current efficiency of about 2%. We have designed and tested an electrolyzer with improved hydrodynamics, which makes it possible to avoid the formation of dead zones and to prevent the cathode chamber from being clogged.