Generalized models for prediction of pentachlorophenol adsorption by natural soils

Pentachlorophenol (PCP) is an ionogenic substance for which soil adsorption is a function of soil characteristics, solution composition, and pH. Generalized sorption models are developed to predict the sorption of PCP by natural soils. The proposed models use easily measured system variables as predictors, to capture the effects of soil, solution, and solute properties on the overall sorption process. Although these empirical models do not provide a mechanistic explanation of the process, they clearly demonstrate and quantify the correlation between the process variables and can be adapted to modeling of subsurface transport of PCP and to the design of soil remediation technologies, such as soil washing and bioremediation. Soil properties, such as cation-exchange capacity, particle size distribution, and organic carbon content, and soil-solution properties, such as soil-to-solution ratio and pH, and the aqueous solubility of PCP were found to be good predictors of the partitioning of this compound between the solid and the aqueous phases. The methodology developed here can be used to derive generalized nonlinear or log-linear models for other ionogenic substances for which the organic carbon-normalized partition coefficient does not adequately describe sorption by natural soils.