Heavy metal ions removal from metal plating wastewater using electrocoagulation: Kinetic study and process performance

• High removal of heavy metal ions from metal plating wastewater using EC treatment.
• Pseudo first-order kinetic model describes heavy metal ions removal adequately.
• Electrocoagulation time and DC current density are the key parameters in EC process.
• Metal plating wastewater treatment by electrocoagulation is economically rewarding.

The main objective of the present study was the removal of heavy metal ions, namely Cu2+, Cr3+, Ni2+ and Zn2+, from metal plating wastewater using electrocoagulation technique. An electro-reactor was used with six carbon steel electrodes of monopolar configurations. Three of the electrodes were designated as cathodes meanwhile the other three as anodes. The results showed that the removal efficiency of heavy metal ions increases with increasing both electrocoagulation (EC) residence time and direct current (DC) density. Over 97% of heavy metal ions were removed efficiently by conducting the EC treatment at current density (CD) of 4 mA/cm2, pH of 9.56 and EC time of 45 min. These operating conditions led to specific energy consumption and specific amount of dissolved electrodes of around 6.25 kWh/m3 and 1.31 kg/m3, respectively. The process of metal plating removal using EC consumes low amount of energy, making the process economically feasible and possible to scale up. Moreover, the kinetic study demonstrated that the removal of such heavy metal ions follows pseudo first-order model with current-dependent parameters.