Prediction of octanol-water partition coefficients for alkyl-PAHs based on the solvation free energy

Abstract

Octanol-water partition coefficients (KOW ) are of great importance in assessing the environmental fate and risk of hydrophobic organic pollutants including alkyl-polycyclic aromatic hydrocarbons (alkyl-PAHs). Due to the time-consuming and laborious of experimental determination of KOW , it is desirable to develop a rapid and accurate prediction model for the KOW of alkyl-PAHs. In this study, a prediction model for log KOW of alkyl-PAHs was developed according to the thermodynamic relationship between KOW and the solvation free energy from n-octanol phase to aqueous phase (ΔGOW ). ΔGOW values of alkyl-PAHs were calculated by the SMD model. The effect of dimer formation on the partition behaviour and partition coefficient was explored. After taking the effect of dimer formation into account, the goodness-of-fit, predictive ability, and robustness of the prediction model was significantly improved. The developed model in this study had the superiorities of universal application domain, low dependence on the experimental values and clear model mechanism.