Simultaneous Determination of Copper(Ⅱ), Cobalt(Ⅱ) and Nickel(Ⅱ) in Zinc Electrolyte by Differential Pulse Adsorptive Stripping Voltammetry

In an NH3 (aq.) NH4Cl buffer solution of pH 8.8 containing Na2SO3, adsorptive complex waves of dimethylglyoxime-zincon system with Cu(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) were observed. Based on this fact, a method of differential pulse adsorptive stripping voltammetry for the determination of Cu(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) in zinc plant electrolyte was proposed. It was found that the peak potential of Cu(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) complexes were obtained at -0.65, -0.92 and -1.06 V, respectively. Linear relationships between values of peak current and concentration were found in the range of 6.02×10-5-1.00×10-3g·L-1 for Cu(Ⅱ), 6.01×10-6-1.20×10-3g·L-1 for Co(Ⅱ), and 8.04×10-6-4.03×10-4g·L-1 for Ni(Ⅱ). Values of detection limits of Cu(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) found were 9.41×10-7, 1.14×10-5 and 5.48×10-6g·L-1 respectively.