Performance Evaluation and Optimization of Electrocoagulation for Cadmium Removal from Wastewater

Abstract

This study investigates the optimization of cadmium (Cd) removal from wastewater using the electrocoagulation (EC) process coupled with Response Surface Methodology (RSM). Synthetic wastewater containing 100 mg/L of Cd²⁺ was treated in a laboratory-scale reactor using aluminum and iron electrodes. Key operational parameters such as pH (4-10), current density (30-90 A/m²) and reaction time (20-60 min) were studied to investigate their influence on cadmium removal efficiency by Box-Behnken design. Cd removal efficiency ranged from 85.8-99.2% with better efficiency at neutral to slightly alkaline conditions. Statistical analysis indicated that pH was the most significant factor affecting removal efficiency followed by reaction time and current density had a minor effect. The quadratic model developed was found to be highly significant (p < 0.0001) with high coefficient of determination (R² = 0.992) and non-significant lack-of-fit confirming its reliability. The optimum conditions were found to be pH 8.8, current density 68.5 A/m² and reaction time 40.5 min which predicted a removal efficiency of 99.49%. Experimental validation showed removal efficiency of 97.64% with only 1.85% deviation. The results obtained suggest that EC combined with RSM is an effective and promising method for the cadmium removal from wastewater.