【作者】 张志翔；

【导师】 陈亮；

【作者基本信息】 东华大学 ， 环境工程， 2005， 硕士

【摘要】 光催化TiO₂氧化技术作为一种高级氧化技术,对氯酚类等难降解有机物具有氧化彻底、反应快速、高效等优点,受到研究者们越来越多的重视,成为环境污染控制领域最具有发展前途的高级氧化技术之一。 以难生物降解的邻氯苯酚作为目标污染物,125W高压汞灯作为紫外光源,利用自制光催化反应器,系统地研究了光催化反应中催化剂TiO₂浓度、pH值、邻氯苯酚初始浓度等关键因素对反应的影响,确定了最佳的反应条件;对邻氯苯酚光催化降解反应过程中生成的中间产物,通过气相色谱-质谱联用方法进行了定性分析,进而探讨了邻氯苯酚光催化降解的反应机理途径;考察了悬浮相TiO₂光催化氧化邻氯苯酚的反应动力学方程。实验结果表明,在悬浮相光催化反应体系中,TiO₂浓度的最佳值为0.30g·L^-1,反应体系在pH<3时光催化活性最高,反应速率随邻氯苯酚初始浓度的升高而降低,C1取代基对邻氯苯酚的降解反应产生抑制作用,邻氯苯酚降解过程中生成的中间产物有1,2-二氯苯、苯、醌、苯邻二酚等,得出了悬浮相TiO₂光催化氧化邻氯苯酚反应的动力学方程为零级反应形式C=Kt、TOC=K′t。 采用粉体涂敷法（去离子水、无水乙醇作分散剂）、溶胶-凝胶法,以丝光沸石作为催化剂载体,在不同热处理温度300℃、400℃、500℃、600℃下制备TiO₂负载膜,通过BET比表面积、负载量、X射线衍射、扫描电子显微镜等分析手段进行了表征。研究表明,由于沸石具有较好吸附性能及独特的静电场结构,沸石负载TiO₂膜比悬浮相TiO₂光催化反应体系具有更高的催化活性,其中溶胶-凝胶法在400℃制备得到的TiO₂膜催化活性最高,不同初始浓度的邻氯苯酚溶液中的TOC降解反应动力学模型符合L-H模型,r₀=(k_L-HK_adsTOC₀)/(1+K_adsTOC₀)反应动力学更多还原

【Abstract】 Ultraviolet photocatalytic oxidation mediated by illuminated TiO₂ has received considerable attention as one of the most potential advanced oxidation technologies. It can mineralise a wide rang of organic pollutants such as chlorophenols which are difficult to remove by simple biodegradation in water completely to CO₂, H₂O with high reaction rate and high removal efficiency.Selecting 2-chlorophenol as targeted pollutant, 125W high pressure mercury vapour lamp as UV light source, the effects of TiO₂ concentration, pH value, and initial 2-chlorophenol concentration to photocatalytic reaction are studied using a selfmade photocatalytic reactor. The intermediates and mechanism of photocatalytic degradation of 2-chlorophenol are analyzed by GC-MS. The kinetics of photocatalytic degradation of reactant in slurry system are described as C=Kt TOC=K/t, which are typical of zero-order reaction. The results of experiments show that the optimum catalyst concentration is 0.30 g L^-1, the activity of photocatalysis reaches highest value when pH<3, and the relationship between reaction rate and initial 2-chlorophenol concentration is of inverse correlation. The Cl substituent restrains the photocatalytic oxidation of 2-chlorophenol. O-dichlorobenzene, benzene, （p-） benzoquinone and catechol are detected in the reaction solution by GC-MS.Thin TiO₂ films supported zeolites are prepared by Solid State Dispersion （deionized water and ethanol as dispersant respectively） and Sol-gel method under 300℃, 400℃, 500℃, 600℃. These supported catalysts are characterized by BET surface area, XRD, TiO₂ loading and SEM. For the reason that zeolite has good adsorptive capacity and particular internal structure which can form electrostaticfields in the photocatalytic degradation of 2-chlorophenol, the reaction system of TiO₂ thin film has higher photocatalytic activity than slurry TiO₂, and TiO₂ supported zeolite prepared by Sol-gel at 400℃ is the most active one among these catalysts. The form of L-H adsorption isotherm is found suitable to describe the kinetics ofreaction which can be simplified as TOCt=TOCoe^kt. Intermediatesformed during degradation can have competive adsorptive effect to 2-chlorophenol, and then the disappearance of 2-chlorophenol does not follow an apparent first-order rate. TiO₂ film falls off continually from support when it is used in solution. The phtocatalytic efficiency of TiO₂ film used repeatedly for 11 times decreases to 66.39% （reaction time = 60 min） of the first time, but still excels the of TiO₂ powder.更多还原