Use of Organic Solvents to Extract Organochlorine Pesticides (OCPs) from Aged Contaminated Soils

Problems associated with organochlorine pesticide (OCP)-contaminated sites in China have received wide attention. To solve such problems, innovative ex-situ methods of site remediation are urgently needed. We investigated the feasibility of the extraction method with different organic solvents, ethanol, 1-propanol, and three fractions of petroleum ether, using a soil collected from Wujiang (WJ), China, a region with long-term contamination of dichlorodiphenyltrichloroethanes (DDTs). We evaluated different influential factors, including organic solvent concentration, washing time, mixing speed, solution-to-soil ratio, and washing temperature, on the removal of DDTs from the WJ soil. A set of relatively better parameters were selected for extraction with 100 mL L−1 petroleum ether (60–90 °C): washing time of 180 min, mixing speed of 100 r min−1, solution-to-soil ratio of 10:1, and washing temperature of 50 °C. These selected parameters were also applied on three other seriously OCP-polluted soils. Results demonstrated their broad-spectrum effectiveness and excellent OCP extraction performance on the contaminated soils with different characteristics.