SORPTION KINETICS OF PAHS IN METHANOL-WATER SYSTEMS

The objectives of this study were to evaluate the relationships betwee n the equilibrium sorption constant (K-p), the first-order desorption rate coefficient (k(2)), and the volumetric fraction of water miscible solvent (f(c)); and to utilize SPARC-calculated (SPARC Performs Autom atic Reasoning in Chemistry) solubility and partitioning parameters wi th empirical measurements for a priori prediction of solute sorption k inetics in aqueous and mixed solvent systems. Soil column miscible dis placement experiments were performed using naphthalene, phenanthrene, anthracene, pyrene and benzo(a)pyrene over an f(c) range from 0.0 to 0 .8. Data from the miscible displacement studies were analyzed using a two-domain first-order mass transfer model to obtain K-p and k(2). Res ults corroborated and extended the range of the validity of the log-lo g linear relationship between k(2) and K-p and log-linear relationship between k(2) and f(c) for mixed solvent systems. In addition, the slo pe of the log k(2)-log K-p relationship was found to be relatively sol ute independent. Predicted values of k(2) in aqueous systems agreed we ll with experimentally measured values, thus, indicating the general a pplicability of the predictive approaches for predicting the sorption kinetics of hydrophobic organic compounds. (C) 1998 Elsevier Science B .V. All rights reserved.