title: TiO2 photocatalytic degradation and transformation of oxazaphosphorine drugs in an aqueous environment.
abstract: This study investigated the TiO2 photocatalytic degradation and transformation of the oxazaphosphorines ifosfamide (IFO), cyclophosphamide (CP) and trofosfamide (TRO). Under the optimum conditions of TiO2=100mg/L, IFO=100μg/L and solution pH=5.5, IFO was completely removed within 10min (k=0.433min(-1)). The results indicated that OHfree radicals generated by valence holes in the bulk solution were the predominant species for the degradation of IFO. At higher initial concentrations of oxazaphosphorines (20mg/L), >50% of TOC remained after 6h of reaction time, indicating that parent compounds were transformed to byproducts, which exhibit higher Microtox acute toxicities; chlorinated byproducts were likely the source of toxicity. Photocatalytic degradation pathways of the three oxazaphosphorines were proposed. IFO, CP and TRO follow very similar pathways and bond-breaking processes: ketonization and breaking of the CCl bond, the PN bond and the CN bond (N-dechloroethylation). Chloride (Cl(-)) release is likely the first and primary step in the decomposition process. Several of the identified byproducts were also metabolites, which implies that photocatalytic oxidation proceeds through pathways that are similar to metabolic pathways.
authors: Graduate Institute of Environmental Engineering, National Taiwan University, 71-Chou-shan Road, Taipei 106, Taiwan, ROC.
authors: Webber Wei-Po
authors: WW
authors: Lai
authors: Graduate Institute of Environmental Engineering, National Taiwan University, 71-Chou-shan Road, Taipei 106, Taiwan, ROC.
authors: Hank Hui-Hsiang
authors: HH
authors: Lin
authors: Graduate Institute of Environmental Engineering, National Taiwan University, 71-Chou-shan Road, Taipei 106, Taiwan, ROC. Electronic address: yuchenlin@ntu.edu.tw.
authors: Angela Yu-Chen
authors: AY
authors: Lin
mesh_terms: D003520:Cyclophosphamide / Q000737:chemistry* / Q000528:radiation effects / Q000633:toxicity; D007700:Kinetics; D010084:Oxidation-Reduction; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*; D018675:Toxicity Tests; D014466:Ultraviolet Rays; D014733:Vibrio; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects / Q000633:toxicity
chemical_list: D003520:Cyclophosphamide; D014025:Titanium; D062065:Wastewater; D014874:Water Pollutants, Chemical; C009495:titanium dioxide
keywords: Oxazaphosphorine drugs; Photocatalytic degradation; Titanium dioxide; Toxicity