Enhancement of the electrokinetic removal of heavy metals, cations, anions, and other elements from soil by integrating PCPSS and a chelating agent

Background: Recently, we have developed a new soil electrokinetic remediation (SEKR) process, hereinafter referred to as the perforated cathode pipe SEKR system (PCPSS), to achieve remediation intensification. Some obstacles, such as the low removal of some heavy metals, particularly Ni, limited our previous PCPCS.& nbsp;Methods: We aim to improve the removal efficiency of the PCPSS by adding a chelating agent (i.e., ethylene-diaminetetraacetic acid (EDTA)). Given the unsatisfactory remediation results obtained in our previous stud-ies, the Taguchi approach (L9OA) was exploited in this work as an experimental design to determine the optimal level of factors that could enhance Ni removal.& nbsp;Significantfindings: Results showed that an electric potential of 3 V, addition of 0.5 mol of EDTA, and an initial Ni concentration in the range of 10-20 mg kg(-1) could optimize Ni removal. Confirmation experiments con-ducted on natural contaminated soil showed the following order of removal of heavy metals and other ele-ments: Al (70%) > Co (69%) > Fe (63.5%) > Cu (55%) > Mn (52.8%) > Zn (43.17%) > Cr (41.41%) > Ni (22.26%). Among the studied soil cations, Mg showed the best removal rate, Ba showed moderate removal rate, and Ca showed the lowest removal rate. Notably, the removal rate of V was much higher than that of born (B). (C)& nbsp;2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

This study aims to improve the removal efficiency of the soil electrokinetic remediation system by adding a chelating agent (EDTA) and optimizing the key factors. The results showed that an electric potential of 3V, addition of 0.5 mol of EDTA, and an initial Ni concentration of 10-20 mg kg(-1) could optimize Ni removal. The study also revealed the order of heavy metal removal in contaminated soil, with Al having the highest removal rate and Ni having the lowest.