Electrowinning of zinc from sulphate solutions in the presence of perfluoroglutaric acid

This paper deals with the effect of perfluoroglutaric acid in the presence and absence of antimony(III) on the cathodic current efficiency, energy consumption and polarisation behaviour of the cathode during electrowinning of zinc from acidic sulphate solutions. Surface morphologies and crystallographic orientations of the zinc deposits were also examined using scanning electron microscopy and X-ray diffraction analysis. Perfluoroglutaric acid was found to increase the current efficiency, decrease the energy consumption and produce better surface morphologies. Voltammetric studies revealed that perfluoroglutaric acid when present in the solution depolarised the cathode which was also reflected in the deposit morphologies showing bigger size crystal planes than the deposit obtained in its absence. Presence of antimony(III) in the solution deteriorated the deposit quality and resulted in corrugated deposits at higher concentrations.