Simultaneous removal of Cd2+ and Zn2+ from aqueous solution using an upflow Al-electrocoagulation reactor: optimization by response surface methodology.

Abstract

The presence of heavy metals in the environment has increased, and cadmium (Cd) and zinc (Zn) are considered to be among the most dangerous. An upflow Al-electrocoagulation reactor was used to remove Cd2+ and Zn2+ ions from aqueous media. The system consisted of perforated aluminum circular electrodes for fluid distribution with elimination of external agitation. The effect of different parameters, i.e. current intensity, electrolysis time, concentration of Cd2+ and Zn2+ ions and electrolytic support dose were optimized by response surface methodology. The results indicated that increasing the current intensity and the electrolysis time had a positive effect on the elimination efficiency of the pollutant ions. Likewise, increasing the dose of electrolytic support and decreasing the concentration of the pollutants improved the efficiency of the system. The optimal results were: current intensity of 0.4 A, electrolysis time of 40 min, ion concentration of 44.6 mg·L-1 and electrolytic support dose of 0.56 mg·L-1, with the maximum elimination percentages of 96 ± 3.8% and 96 ± 2.7% for Cd2+ and Zn2+, respectively. This study showed that the electrocoagulation process in an upflow electrocoagulation reactor could be successfully applied to remove pollutants from water.