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研究报告

Photocatalytic degradation of toluene by nitrogen-doped titanium dioxide composite film

摘要：采用溶胶-凝胶法以聚丙烯（PP）中空纤维膜为载体制备了N-TiO₂/PP复合催化膜，并考察了其催化降解甲苯有机废气的性能.结果发现，紫外光催化的甲苯降解率可达84%，去除负荷为89.8 g·m^-3·h^-1，自然光催化的甲苯降解率可达63.9%，去除负荷为69.25 g·m^-3·h^-1.同时，采用紫外-可见光谱（UV-Vis）、X-射线光电子能谱（XPS）和傅里叶变换红外光谱（FT-IR）表征了N-TiO₂/PP复合催化膜，并采用GC-MS分析甲苯降解过程的中间产物并推测甲苯反应过程机理.采用GC-MS分析出口气样的研究结果表明，苯（C₆H₆）、苯甲醛（C₇H₆O）、苯乙酸（C₈H₈O₂）、丙烯醛（C₃H₄O）、甲酸甲酯（C₂H₄O₂）为甲苯光催化降解的中间产物.N-TiO₂/PP复合催化膜降解甲苯的机制为甲苯气体通过中空纤维膜传质到N-TiO₂/PP复合催化膜，光催化产生羟基自由基，甲苯气体被羟基自由基氧化成中间产物，并继续降解为最终产物二氧化碳和水.

Abstract：The N-doped titanium dioxide was prepared by the sol-gel method, which was then loaded on Polypropylene (PP) hollow fiber membranes to prepare N-TiO₂/PP composite members. The photocatalytic degradation of toluene over N-TiO₂/PP was tested with the use of UV irradiation and visible light. Removal efficiency of toluene by UV irradiation was up to 84% and the maximum elimination capacity reached 89.8 g·m^-3·h^-1. The removal efficiency of toluene by visible light was up to 63.9% and the maximum elimination capacity reached 69.25 g·m^-3·h^-1. UV-Vis spectra, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrometer (FT-IR) were used to characterize the prepared N-TiO₂/PP. GC-MS was used to detect outlet gases. The gas-phase photodegradation intermediate organic products identified by gas chromatography/mass spectrometry (GC-MS) were benzene (C₆H₆), benzaldehyde (C₇H₆O), phenylacetic acid (C₈H₈O₂), acrolein (C₃H₄O), and methyl formate (C₂H₄O₂). Toluene diffused from the gas-phase to the surface of the N-TiO₂/PP membranes, and then was oxidized into CO₂ and H₂O by the strong oxidant hydroxyl radicals.

Key words：N-TiO₂/PP composite film photocatalytic oxidation(PCO) volatile organic compounds (VOCs) toluene