| Summary: | The octanol-water partition coefficients (log Kow) of 2,4,6-trichlorophenol and pentachlorophenol were determined as functions of pH, ionic strength, and aqueous metal content. For both chlorophenols, the log Kow exhibits pH dependence in the range pKa-1 < pH < pK a+2. At lower and higher pH values, the Kow behaviour of the chlorophenols is independent of pH. Our data, in conjunction with those of Westall et al. (1985), indicate that a linear relationship exists Our data, in conjunction with those of Westall et al. (1985), indicate that a linear relationship exists between log Kow and log ionic strength of the aqueous solution for pentachlorophenol. Our results r results also suggest that aqueous metal-chlorophenol ate complexation can significantly alter the also suggest that aqueous metal-chlorophenolate complexation can significantly alter the partitioning behaviour. === We use our data to develop an empirical model of the partitioning behaviour based on speciation of the aqueous chlorophenol. The model requires knowledge of the low pH partitioning behaviour, as well as the acidity constant (pK a) of the chlorophenol of interest. Although Kow values have been measured as a function of pH and/or ionic strength for only pentachlorophenol, the input parameters for the empirical model are readily available in the literature for many chlorophenols. The model greatly expands our ability to quantify the hydrophobicity of chlorophenols, facilitating accurate estimations of the pH and ionic strength dependencies of the partitioning behaviour over a wide range of pH and ionic strength values of environmental interest.
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