Electrochemical oxidation of arsenopyrite in chloride solutions

Cyclic voltammetry, potential step, and AC impedance techniques were applied to study the electrochemical reaction of arsenopyrite in chloride solutions. The relationship between anodic current density and time in potential step measurements indicates that the oxidation of arsenopyrite is irreversible. The results of the constant potential coulometry show that the stoichiometric factor of electron involves in the overall reaction is 14. It is proposed that the dissolution of arsenopyrite is retarded by the coverage of sulfur produced in the reaction as an intermediate product. The measured results of AC impedance strongly support this proposition. The proposed reaction mechanism also explains satisfactorily the charging current density and slopes of polarization plot measured in potential step measurements.