Electrical approach for decontaminating a multi-metal polluted soil as influenced by electrolyte type and soil position

The remediation of heavy metals contaminated soils is increasingly a global problem with serious implications for human health. This study aimed to evaluate the in-situ remediation performance of multi element contaminated soil by the electrokinetic. To achieve this, the effects of chelating agents (water, ethylenediamine tetraacetic acid (EDTA), diethylenetriamine pentaacetic acid (DTPA)), potential gradient (0, 1, and 2 V cm − 1 ), and position of soil in electrokinetic cell on metals fractions and metals removal were investigated. The results revealed that the electric potential difference and application of EDTA or DTPA electrolyte generally enhanced heavy metals removal efficiency and for Ni and Pb the interactions effects of these factors were significantly positive. Results showed that Ni, Zn, Cd, and Pb removal efficiency is highest with DTPA, DTPA, EDTA and EDTA electrolytes, respectively. In particular, the usage of electric current remarkably shifted the soil-metal bonds from stable (residual) to a less stable (mobile and mobilisable) fraction. The optimum electric current for the removal of Zn, Cd, and Ni was 1, 1, and 2 V cm − 1 , respectively, which removed 44, 47 and 41% of the average of these heavy metals in soil, respectively. Results of present study demonstrated that removal efficiency was highly metal-dependent; and the order of metals removal was Cd > Ni > Zn > Pb.