Electrochemical study of the dissolution of enargite (Cu3AsS4) in contact with activated carbon

The effect of activated carbon on the electrochemical dissolution of enargite was studied in solutions of different acid and ferric sulphate concentration. The dissolution of enargite was studied by OCP measurement, EIS and Mott-Schottky techniques and the results were interpreted in terms of mixed-potential theory. Activated carbon increased the dissolution current density of enargite by more than two orders of magnitude in iron-free solutions and by factors of about 30 in iron-containing solutions. It was shown that the catalytic effect of carbon on the dissolution of enargite is more complex than simply acting as an extended surface area for the reduction of O2 or Fe3+ but may also be a consequence of changes in the semiconducting properties of the enargite.