title: Advanced oxidation kinetics and mechanism of preservative propylparaben degradation in aqueous suspension of TiO2 and risk assessment of its degradation products.
abstract: The absolute kinetic rate constants of propylparaben (PPB) in water with different free radicals were investigated, and it was found that both hydroxyl radicals (HO(•)) and hydrated electrons could rapidly react with PPB. The advanced oxidation kinetics and mechanisms of PPB were investigated using photocatalytic process as a model technology, and the degradation was found to be a pseudo-first-order model. Oxidative species, particularly HO(•), were the most important reactive oxygen species mediating photocatalytic degradation of PPB, and PPB degradation was found to be significantly affected by pH because it was controlled by the radical reaction mechanism and was postulated to occur primarily via HO(•)-addition or H-abstraction reactions on the basis of pulse radiolysis measurements and observed reaction products. To investigate potential risk of PPB to humans and aqueous organisms, the estrogenic assays and bioassays were performed using 100 μM PPB solution degraded by photocatalysis at specific intervals. The estrogenic activity decreased as PPB was degraded, while the acute toxicity at three trophic levels first increased slowly and then decreased rapidly as the total organic carbon decreased during photocatalytic degradation.
authors: State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors: Hansun
authors: H
authors: Fang
authors: Yanpeng
authors: Y
authors: Gao
authors: Guiying
authors: G
authors: Li
authors: Jibin
authors: J
authors: An
authors: Po-Keung
authors: PK
authors: Wong
authors: Haiying
authors: H
authors: Fu
authors: Side
authors: S
authors: Yao
authors: Xiangping
authors: X
authors: Nie
authors: Taicheng
authors: T
authors: An
mesh_terms: D000818:Animals; D003621:Daphnia; D004583:Electrons; D004967:Estrogens / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D006801:Humans; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D010084:Oxidation-Reduction; D010226:Parabens / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D010782:Photolysis; D011310:Preservatives, Pharmaceutical / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D011675:Pulse Radiolysis; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity
chemical_list: D004967:Estrogens; D010226:Parabens; D011310:Preservatives, Pharmaceutical; D014874:Water Pollutants, Chemical; D014867:Water; C009495:titanium dioxide; D017665:Hydroxyl Radical; D014025:Titanium; C006068:propylparaben