Abstract：The potentiodynamic polarization scanning of eletrodeposited chromium electrolyte was conducted with three-electrode system using spectroscopically pure graphite electrode as working electrode. Based on the variation relationship between reducing peak current and oxidizing peak current of mass concentration of electro-active materials on graphite electrode surface, the determination method of Cr6+ and Fe2+ in eletrodeposited chromium electrolyte by linear sweep voltammetry was established. The results showed that the optimal experimental conditions were as follows: the scanning rate was 50-60 mV/s, the pH was 2.0, and the testing temperature was 20 ℃. Cr6+ was reduced at 0.43 V (vs. saturated calomel electrode, SCE). The mass concentration of Cr6+ in range of 2-14 g/L showed linearity to the reducing peak current, and the correlation coefficient of linear regression equation was R2=0.999. Fe2+ was oxidized at 0.52 V (vs. SCE). The mass concentration of Fe2+ in range of 5-15 g/L showed linearity to the oxidizing peak current,and the correlation coefficient of linear regression equation was R2=0.998. The proposed method was applied to the determination of Cr6+ and Fe2+ in actual chromium electrolyte. The relative standard deviations (RSD,n=10) were between 1.1% and 1.3%. The determination results were compared with those obtained by ammonium ferrous sulfate titration for Cr and atomic absorption spectrometry for Fe. The consistency was good.
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