Effect of organic solvent on sorption of aromatic solutes onto soils

Hydrophobic aromatic solutes generally display a semi-logarithmic increase in solubility with increasing volume fraction of solvent in solvent/water mixtures. This results in a semi-logarithmic decrease in the tendency for these solutes to sorb onto soil. A semi-empirical model is developed in this investigation which supports these findings. However, the increase in solute solubility does not result in a directly proportional decrease in the sorption coefficient. This is believed to be a result of the solvent swelling the soil organic carbon material and thereby increasing the accessibility of the solute to this material. The effect of solvent on the increase in solute solubility and the decrease in soil sorption is much more pronounced for the more hydrophobic solutes.