title: [Photocatalytic Degradation of Perfluorooctanoic Acid by Pd-TiO2 Photocatalyst].
abstract: Perfluorooctanoic acid (PFOA) is a new persistent organic pollutant which has got global concern for its wide distribution, high bioaccumulation and strong biological toxicity. In present study, the photocatalytic degradation of PFOA using palladium doped TiO2 (Pd-TiO2) prepared by chemical reduction method was investigated. The photocatalysts were characterized by XRD, FESEM and UV-vis DRS and were used for PFOA degradation under 365 nm UV irradiation. The results indicated that the grain size of TiO2 was smaller while the specific surface area increased and the absorption of ultraviolet light also enhanced after using chemical reduction method, but all these changes had no influence on PFOA degradation. However, the degradation was significantly enhanced because of the deposition of Pd, the fluoride concentration of PFOA was 6.62 mg x L(-1) after 7 h irradiation which was 7.3 times higher than that of TiO2 (P25). Experiments with the addition of trapping agent and nitrogen indicated that *OH played an important role in PFOA degradation while the presence of O2 accelerated the degradation. The main intermediate products of photocatalytic degradation of PFOA were authenticated by an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry systems (UPLC-QTOF-MS). The probable photocatalytic degradation mechanism involves h+ attacking the carboxyl of PFOA and resulting in decarboxylation. The produced *CnF(2n +1) was oxidized by *OH underwent defluorinetion to form shorter-chain perfluorinated carboxylic acids. The significant enhancement of PFOA degradation can be ascribed to the palladium deposits, acting as electron traps on the Pd-TiO2 surface, which facilitated the transfer of photogenerated electrons and retarded the accumulation of electrons.
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.forename: Ze-bin
authors.initials: ZB
authors.lastname: Yu
authors.forename: Rui-han
authors.initials: RH
authors.lastname: Zhang
authors.forename: Ming-jie
authors.initials: MJ
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Kuang
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: You-hui
authors.initials: YH
authors.lastname: Zhu
mesh_terms: D002210:Caprylates / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D005466:Fluorocarbons / Q000737:chemistry*; D013058:Mass Spectrometry; D009584:Nitrogen; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D002210:Caprylates; D005466:Fluorocarbons; C009495:titanium dioxide; D010165:Palladium; C023036:perfluorooctanoic acid; D014025:Titanium; D009584:Nitrogen