Electrokinetic remediation of soil containing Cr(VI) by photovoltaic solar panels and a DC-DC converter

Abstract

BACKGROUND: In China, soil pollution is becoming more and more serious with the national economy rapidly developing. How to remedy soil containing heavy metals in an effective and low cost way is increasingly becoming an urgent problem. Utilization of renewable photovoltaic energy in the environmental protection field brings forward a solution. RESULTS: Cr(VI) removal from soil using an electrokinetic remediation process powered by photovoltaic solar modules and a DC-DC converter was studied. The results show that under solar irradiation intensity of 650±20Wm-2 and 9V output voltage of the converter, Cr(VI) removal efficiency of an iron electrode can increase to 99.8% in 30min. For output voltage in the range 3-11.5V, voltage has a significant effect on Cr(VI) removal efficiency. When initial Cr(VI) concentration is increased from 200mgkg-1 to 450mgkg-1, Cr(VI) removal efficiency and removal rate decrease. Total Cr concentrations and XRD analysis show that chromium in soil is accumulated near the anodic zone after electrokinetic remediation. For the highest voltage of 11.5V, although sunlight utilization efficiency is the highest, electric energy consumption is the largest, and EPV and EPM are 249.4 kWh kg-1 and 156.1 kWh m-3, respectively. CONCLUSION: The process used for removal of Cr(VI) from soil is feasible.