Single and Binary Competitive Sorption of Phenanthrene and Pyrene in Natural and Synthetic Sorbents

초록

Sorption of phenanthrene (PHE) and pyrene (PYR) in several sorbents, i.e., natural soil, BionSoil®, Pahokee peat,vermicompost and Devonian Ohio Shale and a surfactant (hexadecyltrimethyl ammonium chloride)-modifiedmontmorillonite (HDTMA-M) were investigated. Pyrene exhibited higher sorption tendency than phenanthrene, aspredicted by its higher octanol to water partition coefficient (Kow). Several sorption models: linear, Freundlich, solubilitynormalizedFreundlich model, and Polanyi-Manes model (PMM) were used to analyze sorption isotherms. Linearisotherms were observed for natural soil, BionSoil®, Pahokee peat, vermicompost, while nonlinear Freundlich isothermsfitted for Ohio shale and HDTMA-M. The relationship between sorption model parameters, organic carbon content ( foc),and elemental C/N ratio was studied. In the binary competitive sorption of phenanthrene and pyrene in natural soil,competition between the solutes caused reduction in the sorption of each solute compared with that in the single-solutesystem. The ideal adsorbed solution theory (IAST) coupled with the single-solute Freundlich model was not successful indescribing the binary competitive sorption equilibria. This was due to the inherent nature of linear sorption ofphenanthrene and pyrene in natural soil. The result indicates that the applicability of IAST for the prediction of binarycompetitive sorption is limited when the sorption isotherms are inherently linear.

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