Photocatalytic Degradation of Diethyl Phthalate with Surfactant Addition

This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfon-ate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether) was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2had certain adsorption ability of DEP. TiO2could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by additives OP-10 and DBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.