Preparation of porous ceramics immobilized TiO2 thin film and formaldehyde photocatalytic kinetics
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摘要: 以四氯化钛为初始反应物,采用水解沉淀法合成纳米TiO2薄膜。结合XRD、TEM以及FTIR等手段对TiO2/硅藻土基多孔陶瓷复合材料的晶体结构和形貌进行了表征;以复合材料为空气净化器芯体,甲醛为降解对象,对光催化降解动力学进行了探讨。结果表明:纳米TiO2经600℃煅烧后为锐钛矿型,平均粒径约10.6nm,纳米TiO2薄膜牢固包覆于载体表面(膜厚300~450nm)。包覆层与TiO2薄膜之间的界面上形成了Si-O-Ti键。甲醛初始浓度为1.302mg/m3,紫外光照240min,甲醛去除率达到94.6%。动力学研究表明:可用Langmuir-Hinshelwood动力学方程来描述甲醛光催化降解反应,该气相光催化一级反应时的反应速度常数为0.576mg/(m3·min),吸附系数为0.048m3/mg。并建立了甲醛的气相光催化动力学方程。Abstract: Using the titanium tetrachloride as raw material, nano-TiO2 compound membrane was synthesized by the hydrolysis precipitation method. The crystal structure, morphology of TiO2/diatomite-based porous ceramics were characterized by XRD, TEM, FTIR and so on. Composite as the air filter core body, the photocatalytic kinetics of materials was investigated by the degradation for formaldehyde. The results indicate that nano-TiO2 calcined at 600℃ is anatase, and the average grain size of TiO2 is 10.6 nm. Nano-TiO2 thin film is loaded strongly on the carrier surface, and the thickness is 300-450 nm. The Si-O-Ti bonds between the interface of the coating layer and the surface of nano-TiO2 particle are formed. The elimination ratio of the composites for formaldehyde with the concentration 1.302 mg/m3 reaches 94.6% in 240 min under an ultraviolet lamp irradiation. Kinetics study showed that the kinetics of formaldehyde degradation inaction can be described by Langmuir-Hinshelwood model. The rate constant of the gas phase photocatalytic first order reaction and adsorption coefficient are 0.576 mg/(m3·min) and 0.048 m3/mg respectively. The kinetic equations of photocatalysis are established.
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