Adsorption of Polycyclic Aromatic Hydrocarbons(PAHs)in Sand Soils

Adsorption of PAHs in sand soils was studied in this investigation.The results showed that two-phase model can be used to describe the sorption dynamic of PAHs in the soils. The first phase was linear sorption and the sorption velocity was rapid, while the adsorption speed of PAHs in the soils may be described by sorption coefficient. The second phase was simulated by power equation and power exponent indicated the sorption speed. The sorption of PAHs was not only affected by soil properties (e.g. TOC content), but also affected by physical and chemical structures (e.g. octane-water partition coefficient, molecularconnectivity index, molecular length, solubility) of the individual PAHs. logKoc value of PAHs calculated by isotherm sorption experiment was proportion to octane-water partition coefficient and molecular connectivity index, while inverse proportion to solubility of PAHs. The capacities of PAHs sorption increased with the increase of octane-water partition coefficient and molecular connectivity index, while decreased with the increase of solubility of PAHs. However, there was no a marked relativity between logKoc values of PAHs and their molecular length. The soil samples with higher TOC contents had stronger sorption capability, and PAHs with biger ring had higher sorption amount and speed in soil compared to low ring PAHs. It has been also discovered that the sorption characters canbe depicted by soil/water partition coefficient.