The electrowinning of cadmium in the presence of zinc

The electrowinning of cadmium in the presence of zinc has been investigated. As such, the effects of initial cadmium concentration (40–160 g/L), current density (50–150 A/m2), free acid concentration (0–196 g/L), initial zinc concentration (20–120 g/L), and temperature (25–70 °C) on current efficiency (CE) and specific power consumption (SPC) in electrowinning of cadmium have been examined. Under the optimum working conditions (initial cadmium concentration 120 g/L, current density 80 A/m2, free acid concentration 98 g/L, and temperature 40 °C), CE and SPC were 98% and 1.21 kWh/kg, respectively. The presence of zinc (20–120 g/L) had no systematic effect on CE and SPC, but decreased the purity of the deposited cadmium down to 99.92%.

Research Highlights
► Increasing the initial cadmium concentration up to 120 g/L increased the CE and decreased the SPC.
► Increasing current density had an adverse effect on both CE and SPC.
► Free acid concentrations up to 98 g/L had beneficial effects on CE and SPC.
► Increasing the temperature up to 40 °C resulted in increased CE.
► The presence of zinc (20–120 g/L) had no effect on CE and SPC in the electrowinning of cadmium.