Removal of DDT residues from soil by leaching with surfactants

Abstract

Abstract Aqueous solutions of surfactants were used in experiments which attempted to leach DDT residues from small columns of contaminated soil. The DDT had been applied to the soil between 1951 and 1965, and had persisted since then. The DDT concentrations were highest (8.5 mg/kg) in the light fraction which contained 15.8% carbon, and the DDT was probably associated with the soil organic matter. Since the soil contained 41% silt, and a large part of the organic matter was present in the silt fraction, most residues were held in this fraction. Solutions of, the surfactants Triton X‐100 and polypropylene glycolethoxylate (PPG) removed 25–45% of the DDT residues. These surfactants contain both nonpolar chains which can interact with the DDT residues, and polar ethoxy chains which interact with water. As a result of these interactions, DDT residues were solubilised and desorbed from the soil. The amount of DDT residues removed by leaching with PPG increased as the concentration of the PPG increased from 1%...