Zinc electrowinning from acidic sulphate solutions. Part III: Effects of quaternary ammonium bromides

The effects of the organic additives cetyltrimethylammonium bromide (CTABr) and tetrabutyl ammonium bromide (TBABr) on the electrowinning of zinc from acidic sulphate solutions were studied in the presence and absence of trac e amounts of antimony(iii). The results indicated that CTABr has similar pr operties to the commonly used industrial additive glue with respect to curr ent efficiency, power consumption, polarization behaviour, and the crystall ographic orientation and surface morphology of the zinc deposits. TBABr was generally less useful with respect to all these properties. Voltammetric s tudies indicate that polarisation for zinc electrodeposition decreased in t he order CTABr > glue > TBABr. The nature of the electrode reactions were i nvestigated through measurements of exchange current densities, Tafel slope s and transfer coefficients.