Multivariable study of phenanthrene adsorption in soil-water systems

Abstract

Batch adsorption tests and different statistical tools of data analysis were used to evaluate the overall effect of soil characteristics and liquid phase composition on phenanthrene adsorption extent in complex soil-water systems. Both linear and Freundlich isotherm models were capable of adequately describing the equilibrium data under extremely valying conditions of soil type, environmental conditions (pH, temperature) and amendments (surfactant, oil, etc.). Consistent with existing mechanistic models, the multivariate approach also identified the organic carbon content (foc) of soil as the keyparameter of phenanthrene adsorption constant (kd) in  nonamended systems (koc was of 17,700 ml/g). From studying the effect of the amendments, two interactions (surfactant-pH and surfactant-oil) and two main effects (surfactant and oil) have been detected. An empirical linear model of K, as a function of foc, pH, oil content of soil and surfactant dose was developed for the range of conditions studied. The proposed model and modelling approach can be adapted to other types of contaminants or variables for specific natural and engineered systems.