Abstract
Evaluation of different solid electrode systems for detection of zinc, lead, cobalt and nickel in process water from metallurgical nickel industry with use of differential pulse stripping voltammetry has been performed. Zinc was detected by differential pulse anodic stripping voltammetry (DPASV) on a dental amalgam electrode as inter metallic Ni-Zn compound after dilution in ammonium buffer solution. The inter metallic compound was observed at -375 mV, and a linear response was found in the range from 0,2 to 1,2 mg/L (r2 = 0.98) for 60 s deposition time. Simultaneously detection of nickel and cobalt in the low g/L range was successfully performed by use of adsorptive cathodic stripping voltammetry (AdCSV) of dimethylglyoxime complexes on a silver-bismuth alloy electrode, and a good correlation was found between voltammetric and corresponding AAS analyses (r2 = 0,999 for nickel and 0,965 for cobalt). Analyses of lead in the g/L range in nickel-plating process solution was performed by DPASV. A system using a silver-working electrode together with a glassy carbon counter electrode in samples diluted 1:3 with distilled water and acidified with H2SO4 to pH 2, was found to give good sensitivity and stability. A commercial automatic at-line system was tested, and the results were found to be in good agreement with parallel check measurements. The stability of the electrode systems was found to be from one to several days without any maintenance needed.