Contribution of various molecular forces to sorption of nonionic organic compounds on natural soils

Abstract

In this paper, the solvatochromic method was extended to deal with the sorption coefficients (KOM) of different class nonionic organic (both polar and nonpolar) compounds. A united model equation for KOM was obtained, which provided a quantitative description for the contribution of various molecular forces, such as dispersion (London forces), polar interaction, and H‐bonding, to the sorption of nonionic compounds by natural soil from aqueous solution. It was clearly demonstrated from this study that polar interactions and H‐bonding played an important role in the sorption of nonionic polar organic compounds. Finally, we dealt with the deviation between KOM and KOW for polar and nonpolar compounds and provided a quantitative explanation, which gave a strong evidence that octanol is not a good general model for soil organic matter (SOM) because of the higher polarity of SOM relative to octanol, the significant contribution to this deviation are mainly due to the higher cohensive energy and stronger hydroge...