Determination of copper in technical zinc electrolyte with the copper ion-selective electrode

Abstract

In technical zinc electrolyte of high ionic strength (10.4 M) a copper-sensitrode (type Cu2Se/Ag2Se) is able to measure direct-potentiometrically the copper content within a working range from 200 to 0.5 mg/l. The reproducibility of the potential readings is influenced by the quality of the electrode surface of the copper-sensitrode and by the composition of the reference cell. Zinc forms a surface layer on the sensor interfering with the emf-response. This effect may be avoided by a vibrating brush cleaning the electrode surface instantaneously. A special salt bridge developed for measuring in concentrated zinc solution diminished the liquid-junction potentials essentially. The determination of copper is not affected by cadmium (100–400 mg/l), manganese (1–4 mg/l), fluoride, chloride and arsenite. Iron(III) interfered considerably. The analyzing speed is lower than 10 min.