Selective sorption of PAHs from TX100 solution by resin SP850: effects of TX100 concentrations and PAHs solubility.

Abstract

Recycling of washing effluent by selective sorption using resins is a feasible method to lower the operation costs of surfactant enhanced remediation (SER). In this study, correlations capable of predicting the selective sorption removal of polycyclic aromatic hydrocarbons (PAHs) by resin SP850 from TX100 solution to recycle washing effluent in SER were developed. A negative relationship of sorption coefficients (log Kf) of PAHs by resin SP850 with TX100 initial concentrations (log C0,TX100) and water solubilities (log Sw) of PAHs was observed, which indicated that solubility enhancement of PAHs in TX100 micelles was responsible for the decreasing of the selective sorption. Freundlich exponential coefficients (1/n) of PAHs were relatively constant (0.775 ± 0.012), suggesting that the sorption of PAHs by SP850 in the presence of surfactant is a surface adsorption process. The modified selectivity parameter (S*), having a relationship with log C0,TX100 and PAHs log Sw as well, could be employed to evaluate the efficiency of the selective sorption process and select the optimal TX100 concentration in washing effluents. For example, at the given SP850 dose of 1.0 g L−1, the optimal TX100 concentrations (CopTX100) for naphthalene, acenaphthene, phenanthrene, pyrene, anthracene and benzanthracene were about 4200, 7100, 8000, 10 000, 18 000 and 19 500 mg L−1, respectively, having a negative relationship with their log Sw. Moreover, the CopTX100 was independent of the solid-to-solution ratio of SP850 and TX100 solution containing PAHs. These correlations would be helpful for the application of SER in contaminated soils by giving a method to quantitatively predict the selective sorption behaviors of PAHs by SP850 from TX100 solution, especially for the CopTX100, using the Sw of organic compounds and surfactant concentrations.