title: Adsorption and photocatalytic decomposition of roxarsone by TiO₂ and its mechanism.
abstract: Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) has been widely used as organic arsenic additive in animal industry. In this study, the adsorption of roxarsone on TiO₂ under dark conditions, the photocatalytic decomposition of roxarsone under UV/TiO₂, and the possible photocatalytic pathway were investigated. At the initial concentration of 5-35 mg/L, the adsorption of roxarsone fitted well with the pseudo-second-order kinetics. The isotherms analysis showed that the Langmuir model was better than the Freundlich and Dubinin–Radushkevich models for describing the adsorption process. After 7 h of photocatalytic decomposition, a complete disappearance of roxarsone was achieved. The pH value has a significant effect on both adsorption and photocatalytic decomposition of roxarsone. The results of high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) and gas chromatography-mass spectrometry (GC/MS) analyses proved the cleavage of the As-C bond during the photocatalytic decomposition process by TiO2 and the intermediates of the decomposition. Based on the results, a possible photocatalytic decomposition pathway was proposed.
authors.forename: Donglei
authors.initials: D
authors.lastname: Lu
authors.forename: Feng
authors.initials: F
authors.lastname: Ji
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Shoujun
authors.initials: S
authors.lastname: Yuan
authors.forename: Zhen-Hu
authors.initials: ZH
authors.lastname: Hu
authors.forename: Tianhu
authors.initials: T
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D010782:Photolysis; D012406:Roxarsone / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: C009495:titanium dioxide; D014025:Titanium; D012406:Roxarsone