Determination of zinc and acid in zinc plant electrolyte by discontinuous flow analysis

Abstract

The method of discontinuous flow analysis was applied to the determination of zinc and sulfuric acid in zinc plant electrolyte by titration with ethylenediaminetetraacetic acid and sodium tetraborate, respectively. Zinc was determined potentiometrically by using a polymer membrane-based zinc sensor and spectrophotometrically by using Alizarin Complexone as indicator, the acid was determined spectrophotometrically by using Bromocresol Green as indicator. It was necessary to carry out the titration of zinc at pH 4.3 to minimize any interference from Mn²⁺ and Mg²⁺ that were present in the samples. The results agreed well with those obtained by atomic absorption spectrometry and manual titrations. The use of sodium hydroxide as a titrant for the acid determination led to an error because of the precipitation of zinc hydroxide. This was partly corrected for by adding zinc and managanese to the acid standards and was overcome by using sodium tetraborate as titrant.