Sorption of phenylthioacetates on natural soil: Application of partition-adsorption mechanism and model

Sorption of eight phenylthioacetates from water by natural soil is studied at very low to high relative concentrations (ratios of equilibrium solute concentration to solute water solubilities). The Freundlich isotherm is used to fit the experimental data, where nonlinear sorption isotherms are observed. The partition-adsorption mechanism and model is used to explain the nonlinear isotherms, which show that sorption of phenylthioacetates from water by natural soils consists of two contributions: a linear partition in SOM and a nonlinear residual adsorption on soil minerals and onto SOM because of the specific interactions between functional groups of phenylthioacetatesand OH and COOH groups of SOM Partition dominates the sorption process at moderate to high relative concentrations, and both partition and the residual adsorption dominates over partition at low relative concentration.