Copper (II) removal in a column reactor using electrocoagulation: Parametric optimization by response surface methodology using central composite design

In the present work, electrocoagulation was applied for copper removal from aqueous solution employing iron electrodes in a cylindrical reactor. A four-factorial central composite design (CCD) based on response surface methodology (RSM) was applied to study the effect of various process parameters on removal efficiency and energy consumption as the responses. On optimization, maximum removal efficiency up to 95% was attained with energy consumption as 0.903 W-hour per gram removal of Cu (II) at applied current 0.26 A, initial copper concentration of 27.8 ppm, application time of 5.4 min and pH 7. The interaction between the process variables was evaluated by using the obtained 3-D plots. The models generated were validated by analysis of variance (ANOVA). Studies carried on Cu (II) removal rate showed adsorption suited pseudo-Ist order kinetics best. Overall, the electrocoagulation process proved efficient, low cost and a promising alternative to conventional treatment procedures in removing Cu (II). Practitioner points: Adsorption over hydroxide/polyhydroxide complexes of Fe assisted in enhanced removal of Cu (II) by EC. Higher concentrations treated at lower current but longer duration reduces energy. pH was found to be the deterministic factor for coagulation. CCD-based optimization reduced energy consumption substantially.