title: Photocatalytic oxidation of indoor toluene: process risk analysis and influence of relative humidity, photocatalysts, and VUV irradiation.
abstract: Concentrations of 13 gaseous intermediates in photocatalytic oxidation (PCO) of toluene in indoor air were determined in real-time by proton transfer reaction mass spectrometry and desorption intensities of 7 adsorbed intermediates on the surface of photocatalysts were detected by temperature-programmed desorption-mass spectrometry. Effects of relative humidity (RH), photocatalysts, and vacuum ultraviolet (VUV) irradiation on the distribution and category of the intermediates and health risk influence index (η) were investigated. RH enhances the formation rate of hydroxide radicals, leading to more intermediates with higher oxidation states in gas phase. N doping promotes the separation of photo-generated electrons and holes and enhances PCO activity accordingly. VUV irradiation results in higher mineralization rate and more intermediates with higher oxidation states and lower toxicity e.g. carboxylic acids. Health risk analysis indicates that higher RH, N doping of TiO(2), and VUV lead to "greener" intermediates and smaller η. Finally, a conceptual diagram was proposed to exhibit the scenario of η varied with extent of mineralization for various toxicities of inlet pollutants.
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China. weirong@mail.hz.zj.cn
authors.forename: Weirong
authors.initials: W
authors.lastname: Zhao
authors.forename: Jiusong
authors.initials: J
authors.lastname: Dai
authors.forename: Feifei
authors.initials: F
authors.lastname: Liu
authors.forename: Jiaze
authors.initials: J
authors.lastname: Bao
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Yanan
authors.initials: Y
authors.lastname: Yang
authors.forename: Dongye
authors.initials: D
authors.lastname: Zhao
mesh_terms: D000393:Air Pollutants / Q000737:chemistry* / Q000633:toxicity; D016902:Air Pollution, Indoor / Q000032:analysis* / Q000706:statistics & numerical data*; D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy; D006813:Humidity; D013058:Mass Spectrometry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D018570:Risk Assessment; D013696:Temperature; D014050:Toluene / Q000737:chemistry* / Q000633:toxicity; D014466:Ultraviolet Rays
chemical_list: D000393:Air Pollutants; D014050:Toluene