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 trace amounts of antimony(iii). The results indicated that CTABr has similar properties to the commonly used industrial additive glue with respect to current efficiency, power consumption, polarization behaviour, and the crystallographic orientation and surface morphology of the zinc deposits. TBABr was generally less useful with respect to all these properties. Voltammetric studies indicate that polarisation for zinc electrodeposition decreased in the order CTABr > glue > TBABr. The nature of the electrode reactions were investigated through measurements of exchange current densities, Tafel slopes and transfer coefficients.