摘要
本文以涂覆法制备了固定态TiO_2薄膜，并对其进行了XRD、SEM和电化学阻抗等表征。以250W高压汞灯(365nm)为侧光源，该固定态TiO_2薄膜为工作电极，铜片为对电极，饱和甘汞电极为参比电极，建立了三电极的光电催化体系，选择具有代表性的难降解芳香族有机污染物之一—苯酚作为降解对象，对其在固定态TiO_2上的光电催化降解进行了研究。考察了外加电压，溶液的初始pH值，光强，苯酚溶液的初始浓度，TiO_2薄膜厚度等因素对苯酚降解速率的影响。并探索了苯酚光电催化降解后可能的中间产物以及O_2和金属离子(Fe~(3+)和Cu~(2+))作为电子受体在光电催化过程中的作用。
本文采用分光光度法测定苯酚降解过程的浓度；采用总碳分析仪来测定溶液的TOC值，以衡量苯酚溶液的矿化
太原理工大学硕士学位论文
程度;通过UV一VIS测定了苯酚的光电催化降解反应性能;
并通过GC一MC测定了苯酚降解后可能的中间产物。结果表
明:
与传统的TIOZ固定化方法相比，此涂覆法具有工艺简
单，廉价，易控制催化剂晶型等优点，制得的薄膜中的Ti认
均为锐钦矿晶型，具有良好的光电催化性能，可以有效的
降解水溶液中的苯酚。
苯酚在固定态TIOZ上的光电催化降解以及光催化降解
都服从准一级反应动力学方程。其中苯酚光电催化降解速
率优于光催化降解速率，更优于光氧化降解速率。
外加阳极偏压时苯酚的降解速率优于外加阴极偏压时
苯酚的降解速率，并且提高外加阳极偏压，光强，苯酚的
初始浓度，以及增加薄膜厚度都有利于苯酚的光电催化降
解，但上述因素都存在最佳值。
苯酚光电催化降解适宜的初始pH值为3。
苯酚光电催化降解过程中可能的中间产物有丙烯，丁
烯，丙烷，乙二酸，丁二酸等。
02作为电子受体可以大大提高苯酚的光电催化降解速
率。Fe3+和Cu2+由于具有较正的还原电位，也可以作为电子
II
太原理工大学硕士学位论文
受体参加反应，有利于苯酚的光电催化降解，同时Fe3+和
Cu2+的浓度也降低了，这种光电催化法对于既含有有机污染
物又含有无机污染物的废水的处理将具有深远的意义。
但在Fe3沐口CuZ‘作为电子受体时苯酚的降解速率不如仇
作为电子受体时的降解速率快，这与02还原后生成的·OH
具有强氧化性有关。
In this paper, immobilized TiO2 thin film was prepared by coating technique and was characterized by XRXK SEM and electrochemical impedence. A 250W UV lamp (365nm) was used as light source. The photoelectrochemical system consisted of three electrodes: immobilized TiOa thin film was used as the working electrode, Cu plate as the counter electrode and saturated calomel electrode as the reference electrode. One of the most typical and difficultly degradated aromatic compounds?phenol was the objective substance. The photoelectrocatalytic degradation of phenol on the immobilized TiO2 thin film was studied. The effects of some factors such as bias, initial pH value of solution, light intensity, initial concentration of phenol, thickness of thin film on the degradation rate of phenol were also investigated. The possible intermediates and the effects of O2 and metal ions (Fe3+ and Cu2+) as electron acceptors respectively were also studied. In this paper, the concentration of phenol was determined by a spectrophoto
meter; the
TOC value (mineralization of phenol) was determined by TC analyzer; the photoelectrocatalytic degradation characteristic of phenol was analysed by UV-VIS and the possible intermediates in the degradation process were determined by GC-MS. The results indicated :
Compared with traditional immobilized TiO2, the advantages of the coating technique are: simpler technology, lower-priced and easier to control the crystal phase and so on. The TiOi in the thin film is anatase. An excellent photoelectrocatalytic property is investigated, which could degradate phenol in aqueous solution effectively.
In our experimental conditions, the photocatalytic and photoelectrocatalytic degradations follow apparent first-order reaction kinetics. The rate of photoelectrocatalysis is quicker than that of photocatalysis, which is much quicker than that of photoxidation.
The phenol degradation rate with anodic bias is quicker than that with cathodic bias. With the increasing anodic bias, light intensity, initial concentration of phenol in solution and thickness of film, the rates of photoelectrocatalytic degradation increase. But there exist the optimal conditions. The optimal initial pH value of photoelectrocatalytic degradation is 3.
The possible intermediates in the photoelectrocatalytic degradation arepropene, butene, propane, ethanedioic acid, butanedioic acid etc.
With O2 as the electron acceptor the reaction rate of degradation is improved greatly. Due to Fe3+ and Cu2+ have more positive reduction potential, they can also capture photoelectron and improve the degradation rate, while the concentration of Fe3+ and Cu2+ in solution
decrease. This conclusion is very important for the treatment of wastewater not only containing organic pollutants but also containing inorganic ones.
However the reaction rate with Fe3+ and Cu2+ as electron acceptors are slower than that with O2 as electron acceptor. This result is related to the great oxidative capability of ?OH from the reduction of O2.
引文
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