Electrochemical removal of cadmium from simulated wastewater using a smooth rotating cylinder electrode

Abstract

Rate of mass transfer to a smooth stainless-steel rotating cylinder electrode was found by measuring the limiting current for the cathodic reduction of Cd²⁺ in 0.5 M sodium sulfate supporting electrolyte in hydrodynamic voltammetry mode. The studied parameters were electrolyte pH (4, 5, 6, and 7), initial Cd²⁺ concentrations (50, 100, 200, 300, and 400 ppm), and rotation rates (100, 150, 200, and 250 rpm). Reduction potential for mass transfer control conditions was found to be –0.13 V. Diffusion coefficient was determined and correlated with the bulk concentration of Cd²⁺ in sodium sulfate solution. The experimental data were well fitted by an empirical dimensionless correlation among the Sherwood number, Reynolds number, and Schmidt number.

Keywords:

• Hydrodynamic voltammetry
• Cadmium
• Electrodeposition
• Rotating cylinder electrode