INFLUENCE OF SOLVENT AND SORBENT CHARACTERISTICS ON DISTRIBUTION OF PENTACHLOROPHENOL IN OCTANOL-WATER AND SOIL-WATER SYSTEMS

Sorbent and solvent characteristics influencing sorption of pentachlorophenol (PCP) were investigated. Analysis of aqueous sorption data for several sorbents over a broad pH range suggested hydrophobic sorption of neutral PCP predominates at pH < 7. At pH > 7, sorption of the pentachlorophenolate anion (PCP−) and the formation and sorption of neutral ion pairs [e.g., metal cation (M+) + (PCP−) = MPCP0] was considered. The observed sorption data were described over the entire pH range with knowledge of pH, soil organic carbon content, and PCP's pKa. Increased sorption of PCP− was observed with increasing ionic strength for batch sorption studies conducted in aqueous CaCl2 solutions. Octanol-water partition coefficients measured in various electrolyte solutions suggested that formation of MPCP0 and the partitioning of PCP− are influenced by the cationic species. Batch sorption studies conducted in methanol-water solutions suggest the predominance of solute-solvent interactions in the sorption of both the neutral and ionized forms of PCP; sorption decreased in a log-linear manner with increasing methanol fractions. © 1990, American Chemical Society. All rights reserved.