Modeling and optimizing by the response surface methodology of the Pb(II)-removing effectiveness from a soil by electrokinetic remediation

ABSTRACT Herein, we report the optimization of Pb(II) ions removal from soil by electrokinetic remediation, using the response surface methodology (RSM) based on central composite design (CCD) describing individual and interactive effects of three chosen variables: the current intensity (I), electrolyte concentration (C) and remediation time (t). Sulfuric acid was selected as the electrolyte medium. The physicochemical properties of the soil were well characterized. The electrokinetic remediation (EKR) experiments were performed in galvanostatic mode, at constant current intensity. The lead Pb(II) content was measured using the atomic absorption spectrophotometer (AAS). Designing and modeling of the experimental runs were done using the Design Expert software. The results establish that the quadratic polynomial model matches the experimental data between the removal efficiency (η %) and the influencing factors. The obtained p-values (<0.05) through ANOVA analysis reveal a significant term, suggesting that the model was satisfactory. The significance of influencing factors increases is in that order: I < C (H2SO4) < t; increasing the remediation time translates into higher removal efficiencies. The statistical optimization strategy used in this study was successful in attaining the maximal lead removal of 86.79% using current intensity of 0.05 A, H2SO4 concentration of 0.05 M, and remediation time of 24 h 38 min. Ultimately, besides the great potential of the electrokinetic remediation for efficient removal of Pb(II) species, the RSM-based CCD is a promising and valuable tool for modeling and optimizing their elimination from contaminated soils.