The effect of aromatic and aliphatic amines on copper electrowinning from acidic sulphate electrolyte

Copper electrodeposition in the presence of various types of aromatic and aliphatic amines was studied. The effects of operating variables including organic additives concentrations and temperature on the limiting current were investigated by the potentio-dynamic polarization technique. The effects of amines on the surface tensions of the solutions were measured; the results showed that amines reduce solution surface tension. The adsorption of all inhibitors on copper cathode was found to obey Temkin. Flory-Huggin and kinetic adsorption isotherm. The calculated free energy of adsorption (Delta G(ads.)) of inhibitor on copper surface indicated that the adsorption reactions were spontaneous (Delta G(ads.)<0). The thermodynamic activation parameters (E-a, Delta H*, Delta S* and Delta G*) were estimated and discussed. It was found that activation energy values for copper electrodeposition in the inhibited solutions were higher than that for the uninhibited solution. The high inhibitor efficiency was discussed in terms of the strong adsorption of inhibitor molecules on the copper surface. (C) 2010 Elsevier B.V. All rights reserved.