Enhanced washing for Cr(VI) removal from contaminated soil using EDTA and microwave radiation

Soils contaminated with Cr are commonly found. This study investigated Cr(VI) removal from contaminated soil using ethylenediaminetetraacetic acid (EDTA) and microwave-enhanced washing. The effects of microwave radiation time and power on Cr(VI) removal were also investigated. Results showed that the removal percentages of Cr(VI) with 0.01 and 0.05 mol/L EDTA were 61 and 85 %, respectively. These values increased by 21 and 30 % under microwave radiation (900 W, 5 min) compared with those without microwave treatment. The final Cr content in contaminated soil was 453.25 mg/kg, which was below the Class B limit (610 mg/kg) for soil quality in China for an exhibition area. In addition, the processing time to achieve the same removal efficiency was greatly reduced from 8 h to 5 min. Microwave-assisted EDTA washing can be a promising remediation method for Cr(VI)-contaminated sites.