title: Significant changes in the photo-reactivity of TiO2in the presence of a capped natural dissolved organic matter layer.
abstract: Natural dissolved organic matter (NDOM) in surface waters has a high sorption affinity for TiO2during long contact. An attached NDOM layer can act as a conduction band electron and/or valance band hole acceptor, and NDOM can also decrease the concentration of hydroxyl radicals (OH) in the bulk phase. Therefore, the degradation kinetics and mechanism for degradation of acetaminophen on NDOM capped TiO2(NDOM-TiO2) are significantly different from those on raw TiO2. Quantum calculation results suggest that hydroxylation to the ortho position in relation to the acetamide group is more favorable. Although OH induced hydroxylation is the predominant pathway for degradation of acetaminophen on TiO2, one-electron oxidation of acetaminophen by a valance band hole, excited triplet NDOM or NDOM radical cation is the major degradation pathway on NDOM-TiO2. This study is the first to detect and confirm APAP oligomers as intermediates during the degradation of acetaminophen by TiO2photocatalysis, especially when using NDOM-TiO2as a catalyst. The results suggest the reactivity of TiO2could change significantly after long exposure to natural water, which need to be concerned about for removal of micropollutants in surface water by TiO2photocatalysis.
authors.affiliation: State Key Laboratory of Water Resources and Hydropower Engineering Science, School of Water Resources and Hydropower, Wuhan University, Wuhan, 430072, PR China.
authors.forename: Hong
authors.initials: H
authors.lastname: Peng
authors.affiliation: School of Resources and Environmental Science, Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan, 430079, PR China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Resources and Environmental Science, Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan, 430079, PR China.
authors.forename: Lu
authors.initials: L
authors.lastname: Mao
authors.affiliation: School of Resources and Environmental Science, Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan, 430079, PR China. Electronic address: xuzhangwhu@gmail.com.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
mesh_terms: D002384:Catalysis; D017665:Hydroxyl Radical; D010084:Oxidation-Reduction; D014025:Titanium; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D017665:Hydroxyl Radical; D014025:Titanium
keywords: Acetaminophen; Hydroxylation; NDOM; Oligomer; TiO(2)