【作者】 李迪；

【导师】 周保学；

【作者基本信息】 上海交通大学 ， 环境科学， 2012， 硕士

【摘要】 TiO₂纳米管阵列（Titania nanotube array, TNA）电极材料具有高效的光电催化降解有机物性能。本文利用薄层反应器中发生的耗竭氧化反应,研究了采用阳极氧化技术制备的TNA电极的光电催化降解不同类型有机污染物的反应特性和反应机制,探讨提高有机物光电催化降解的有效途径。论文首先以易降解的葡萄糖和难降解的丁二酸、邻苯二甲酸作为模型化合物,考查了有机物在TNA光电催化薄层反应器中的光电流-反应时间（I-t）变化特征,表明I-t曲线的变化特征能够瞬时反映有机物在TNA电极表面的反应速率变化。同时还考查了反应器体积等参数的变化对于有机物光电催化反应性能的影响,表明随着反应器液层厚度的增加,有机物耗竭氧化反应时间相应增加。利用有机物可以在薄层反应器中发生耗竭氧化反应的特点,论文选择具有不同电极吸附特性的有机物—弱吸附型的葡萄糖和强吸附型的邻苯二甲酸作为研究对象,研究了两种有机物在TNA电极表面不同的光电催化反应性能和反应机制。对于弱吸附型的葡萄糖,由于其在TNA电极表面吸附能力弱,从溶液本体被吸附至电极表面较慢,致使葡萄糖在高浓度时,其光电催化反应速率出现瞬时升高然后迅速下降,再呈现缓慢下降的变化趋势。对于强吸附型的邻苯二甲酸,其吸附性强且难降解,电极表面总是存在着大量的邻苯二甲酸,导致溶液中邻苯二甲酸浓度升高时,光电催化反应速率瞬时升高,然后持续升高,之后才呈缓慢下降的变化趋势。论文还对有机物的吸附类型、吸附系数、反应机制等进行了分析。上述研究表明,有机物的吸附性能影响着其光电催化反应性能,利用薄层反应器的耗竭氧化反应,有助于搞清有机物在电极表面的反应过程和微观机制。基于难降解有机物在薄层反应器的光电催化反应特性,论文研究了极难降解的有机物金刚烷胺的降解性能,发现难降解的金刚烷胺与葡萄糖之间存在着光电催化的协同作用。实验表明,在实验条件下直接光电催化降解COD浓度50mg/L的金刚烷胺,其降解效率仅能达到30%,然而向金刚烷中加入具有羟基官能团的葡萄糖时,可以大幅度提高金刚烷胺降解效率,当溶液中金刚烷与葡萄糖浓度比值达到1:2时,可以实现金刚烷胺的完全耗竭氧化。论文探讨了这一协同光电催化作用的机制,认为这种光电催化协同作用是由于葡萄糖中含有大量的羟基官能团,在光电催化下产生了大量的羟基自由基,促进了难降解有机物的光电催化降解。更多还原

【Abstract】 TiO₂ nanotube arrays （TNAs） materials have exhibit outstanding photo-generated electron transportation performances and high efficiency in photoelectrocatalytic degradation. This thesis studied the reaction activities and mechanisms of exhausted photoelectrocatalytic oxidation of organic compounds based on self-organized and highly ordered TNAs electrode and a thin-layer reactor, and also discussed how to improve the photoelectrocatalytic degradation efficiency of organic compounds.Glucose was used as a representative easily degradable organic compound while succinic acid and phthalic acid as representative refractory compounds to investigate the effect of different reactor volume on reaction activities and mechanisms of photoelectrocatalytic degradation of organic compounds using TNAs electrode in a thin-layer cell. We found that with the increase of the reactor thickness, the photoelectrocatalytic reaction time would increase. The partial voltage, electrolyte concentration and organic compound concentration for photoelectric catalytic reaction influence were also analyzed in this thesis.The kinetics and mechanisms of photoelectrocatalytic degradation of two kinds of compounds, glucose with weak adsorption and phthalic acid with strong adsorption on TNAs were investigated by using a thin layer reactor, in which organic compounds can be exhaustive oxidized rapidly. The photo-generated currents-time（I-t） profiles were used to analyze the micro-processes of photoelectrochemical catalytic degradation on TNA electrode. As for glucose, the I-t curve, increased sharply in the initial time and then decreased rapidly, followed with a slowly decrement. This could be ascribed to the weak adsorbability of glucose molecule and it was slowly adsorbed on the surface of TNA electrode from body solution. However, the I-t curve for phthalic acid revealed a quite different changing trend- increased sharply in the initial time, then continued to increase and decreased slowly at last, which was due to the strong adsorbability and the mass existence of phthalic acid on electrode, and in addition, the low degradability of phthalic acid. The adsorption properties and the adsorption coefficient of the organic compounds, the reaction mechanism were also analyzed in this paper. It could be concluded that the exhausted photoelectrocatalytic oxidation of organic compounds in a thin-layer cell could help investigate the surface reaction process and micro-mechanism of organic compounds degraded on TNA electrode.We also studied the photoelectrochemical degration of the difficult degradable nitrogen organic compounds- amantadine in a thin layer reactor. It found that only 30% amantadine could be oxidized when the COD concentration was 50mg/L. When glucose which has abundant hydroxyl groups were mixed with amantadine could improved the degradation rate of hydrochloride. This results could be attribute to the hydroxyl radical produced by glucose which had synergistic effect on the degradation of amantadine. The mechanism of the synergistic action was preliminary discussed in the paper.更多还原