On-line detection of Cu (II) in bioleaching system by anodic stripping differential pulse voltammetry

On-line Cu (II) ion concentration detection in bioleaching system was achieved by anodic stripping differential pulse voltammetry (ASDPV). Good linearity between Cu (II) concentration and oxidation peak current was obtained when Cu (II) existed in 0K media in the concentration range of 1 μmol/L (64 μg/L) to 1 mmol/L (64 mg/L). Moreover, when 0.2 mol/L KCl was added into this media, the linear detection range could be extended from 1 mmol/L to 100 mmol/L (6.4 g/L). The reduction of Cu (II) to metallic copper was shown to proceed as two successive single-electron transfer reactions involving an intermediate chemical step where the cuprous ion (Cu+) was complexed by chloride to form the dichlorocuprous anion (CuCl−). In addition, interference effect was also investigated when Fe3+ existed in the media, which was the common situation in the copper bioleaching system. The results showed no interference effect once the concentration of Fe3+ was less than 100 mmol/L (5.6 g/L).