Abstract

ORTIZ, JUAN; BARBATO, SALVADOR  and  GAUTIER, JUAN LUIS. REDUCCION DEL OXIGENO SOBRE CALCOSITA, PIRITA Y GALENA EN MEDIO ALCALINO. Bol. Soc. Chil. Quím. [online]. 2000, vol.45, n.3, pp.441-448. ISSN 0366-1644.  http://dx.doi.org/10.4067/S0366-16442000000300015.

The oxygen reduction reaction (ORR) was studied on chalcosite, pyrite and galene by cyclic voltammetry and stationary potential measurements using a double channel electrode flow cell (DCEFC) at pH = 14. The electrode surface was characterized using thermodynamic and voltammetric data. Stationary voltammetry results show that molecular oxygen is reduced to peroxide ions, HO₂^-, in all cases. At experimental pH, the O₂ reduction occurs on chalcosite surface containing Cu₂S film and on pyrite surface supporting a Fe(OH)₃ film. In the case of galene, the formation of elemental S on generator electrode (due to surface chemical oxidation) and collector electrode of the flow cell (due to oxidation of the generated sulphide ions) hinder the electroreduction of oxygen, impeding the determination of the kinetic parameters, k₁ (direct way) and k₂ (indirect way). From the k₁/k₂ ratio, chalcosite appears to be the best catalyst for ORR. In fact, this mineral produces less HO₂^- ions than galene and the oxidation of flotation collectors is reduced.

Keywords : oxygen reduction; chalcosite; pyrite; galene; double channel flow cell.