Characterization of natural enargite/aqueous solution systems by electrochemical techniques

CORDOVA, R; Gómez H.; Schrebler, R; Real S.G.; Vilche J.R.

Keywords: copper, precipitation, oxidation, enargite, spectroscopy, solutions, polarization, electrodes, ph, passivation, effects, (chemical), Electrochemical, Anodic

Abstract

The electrochemical behavior of natural enargite electrodes in stirred and quiescent aqueous solutions covering a wide pH range was investigated using ac and dc electrochemical techniques. It is proposed that in the first stage of enargite oxidation the release of copper ions takes place and a copper-depleted passivating film is formed on the electrode surface. At more positive potential the film becomes oxidized but depending on solution pH, a secondary passivation can be attained due to the precipitation of cupric arsenate. The electroreduction of enargite or a possible oxidized film formed during the preliminary treatment of the mineral surface initially releases S(II-) species and generates a surface film containing As 2S 2 and Cu 2S. At more negative potentials the electroreduction of As 2S 2 to metallic As predominates. A dynamic system analysis carried out at pH 9.2 using electrochemical impedance spectroscopy gave additional information about the processes occurring on the enargite surface under anodic polarization.

Más información

Título de la Revista: JOURNAL OF THE ELECTROCHEMICAL SOCIETY
Volumen: 144
Número: 8
Editorial: ELECTROCHEMICAL SOC INC
Fecha de publicación: 1997
Página de inicio: 2628
Página final: 2636
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-0031209162&partnerID=q2rCbXpz