Photocatalytic degradation of phenanthrene in nonionic-anionic surfactant using titania catalysts

Photocatalytic degradation of phenanthrene by titania in nonionic-anionic surfactant micelles was investigated as a promising strategy for soil/sediment/groundwater remediation after using nonionic-anionic surfactant as solubilizing agents for removal of contaminants from soils/sediment/groundwater. All photocatalytic experiments were conducted using a 365 nm mercury monochromatic ultraviolet lamp in a photocatalytic reactor. Addition of 1 g/L titania is suitable to this photocatalytic degradation rate and efficiency of phenanthrene atthe ratio of Triton X-100 (TX100) to sodium dodecyl sulfate (SDS) 1 : 2. Both the decrease in the critical micelle concentration (CMC) of mixed surfactant and the more negative free energy to easily sorb the contaminant on the surface of titaniawould lead to the gradual increase in the degradation efficiency of phenanthrene. Pseudo-second-order kinetics was observed for the photocatalytic degradation of phenanthrene. Acidic solution environment (pH< PZCTiO2) was beneficial to the photocatalytic degradation of phenanthrene. Based on the GC/MS analysis of the intermediates, the possible pathways of the photocatalytic degradation of phenanthrene and TX100 were proposed.   Key words: Photocatalytic degradation, nonionic-anionic surfactant, phenanthrene, soil remediation.