Effect of thiourea on the copper cathode polarization behavior in acidic copper sulfate at 65 °C

Abstract

The effects of different concentrations of thiourea (TU) on the copper cathode polarization behavior in an acidic copper sulfate solution was investigated at 65 °C using potentiodynamic and galvanostatic methods. The results showed that there was a transition current density for each concentration of the fresh TU, below which the TU exhibited a polarizing effect and above which the TU manifested a depolarizing effect on the copper cathode. The depolarizing effect increased with cathodic overpotential. The transition current density increased with TU concentration and decreased with time. Lowering of the electrolyte temperature resulted in diminution of the transition current density considerably. In the modern copper electrorefining conditions (65 °C, 150 to 350 A/m2, and using approximately 1 to 4 mg/dm3 of TU), TU produces only a polarizing effect on the copper cathode.