Desorption of pentachlorophenol from soils using mixed solvents

Desorption of pentachlorophenol (PCP) from contaminated soils in mixed solv ents of water and ethanol was investigated using desorption isotherm experi ments. The following cosolvent volume fractions of ethanol in the mixed sol vent were considered: 0, 0.3, 0.56, 0.79, 0.95, and 1.0. Three fractions of a synthetic soil (Edison soil) with approximately 1% organic matter were t he main soils used in this study in addition to K-10 montmorillonite clay a nd Ottawa sand. The effect of soil organic matter and sail surface area an desorption in mixed solvents was evaluated. Analysis of desorption data rev ealed that PCP desorption increased with PCP solubility in mixed solvent up to 0.79, 0.95, and 0.56 fraction ethanol for Edison soil, K-10 montmorillo nite, and Ottawa sand, respectively. Lower desorption of PCP from Edison so il in solvents with more than 0.79 fraction ethanol resulted from interacti ons between solvent and soil organic matter. For Edison soil, highest PCP d esorption in all mixed solvents was obtained for the soil fraction with the smallest surface area. Desorption of PCP in mixed solvents containing more than 0.79 fraction ethanol was lower for soils with organic matter than fo r other soils.