【作者】 梁斌勇；

【导师】 胡常伟；

【作者基本信息】 四川大学 ， 环境科学， 2005， 硕士

【摘要】 TiO₂/Ti等半导体电极作为阳极的光电降解技术已被广泛用于染料废水处理研究上,并发现光电降解过程存在着协同作用。通常情况下NaCl为电解质时的光电降解效果要高于其他电解质。在用NaCl做电解质时,一般认为降解是通过阳极光生氧化性空穴与电解Cl^-产生的含氯物种（如:Cl·、Cl₂·等）对有机物的共同氧化降解进行的。但是,光电过程产生协同作用的机理和NaCl在处理过程中所起的作用,目前仍未十分清楚。 为了探讨NaCl做电解质时光电反应机理,本论文通过自行设计的光电反应器主要进行了以下两部分的研究工作: 第一、本文分别以TiO₂/Ti,Sn_xSb_1-xO₂/Ti,Pd_xRu_1-xO₂/Ti为阳极,钛网为阴极,NaCl为电解质,研究了活性红X-3B的光化学降解、电化学降解以及光电共同降解行为。其中,活性红X-3B模拟水样的浓度为4.2×10^-5mol/L,NaCl浓度为1.7×10^-2mol/L。实验表明,经60min光电共同降解后,此三种电极体系中活性红X-3B的脱色率都超过了97%,这三种电极都存在着显著的光电协同效应。析氯能力强的贵金属氧化物涂层电极作为光电阳极时,染料的脱色效果要好于半导体阳极体系的脱色效果,初步推测含氯物种可能是光电降解过程中染料退色的主要氧化剂。 第二、以析氯能力强的Pd_xRu_1-xO₂/Ti为主要研究电极,以组分更为复杂的活性红3BS替代活性红X-3B为底物,对光电降解的中间活性物种进行深入的研究,并且使用NaClO为氧化剂进行对照实验。发现采用Pd_xRu_1-xO₂/Ti阳极先电解后光照的染料脱色过程与不通电时次氯酸钠对染料先直接降解后光降解的脱色过程基本一致。通过碘量法证实了染料溶液电解后存在活性氯。这些事实说明,光电协同作用的主要原因是:电化学氧化Cl^-产生具有氧化能力的HClO更多还原

【Abstract】 Photoelectrochemical oxidation process using semiconductor anodes such as TiO₂/Ti is widely used for wastewater treatment, and synergic effect has been found significantly important in these progresses. Generally, the effect of photoelectrochemical degradation in chloride medium is better than that in other electrolyte, and it is considered that the dye degradation is caused both by the active holes which are formed through UV irradiation and by the chlorine species （such as: Cl., Cl₂.） which are formed through the electrolysis of Cl^-. But the mechanism of the synergic effect and the role of NaCl in photoelectrochemical process are still not quite clear.In order to study the mechanism of photoelectrochemical degradation in chloride medium, two parts of work is carried out in the self-designed photoelectrochemical reactor:Part one: In the present work, photochemical, electrochemical and photoelectrochemical degradation of Reactive Brilliant Red X-3B are studied using TiO₂/Ti, Sn_xSb_1-xO₂/Ti and Pd_xRu_1-xO₂/Ti as anodes respectively. 400 ml 4.2×10^-5 mol/L Reactive Brilliant Red X-3B is used, and 1.7×10^-2 mol/L NaCl is chosen as supporting electrolyte. The results show that the photoelectrochemical discoloration efficiency over the three anodes could afford for more than 97% within 60 min. The synergic effect of photoelectrochemical process is observed over all the three anodes, that is, over both semiconductor anodes and conductor anodes. When Pd_xRu_1-xO₂/Ti（with the strongest ablility of chlorine evolution in the former three anodes） is used as photoanode, the effect of dye discoloration is better than the effect using semiconductor anode. It is tentatively inferred that chloride species may be the main oxidants in the photoelectrochemical discoloration of dyestuffs.Part two: The anode PdxRui.xO2/Ti with strong ability of chlorine evolution is used as the main anode in the further research of active species in photoelectrochemical degradation. Reactive Red 3BS with more complicated composition than Reactive Brilliant Red X-3B is used as the substrate. In additon, a controlled experiment is performed using NaCIO as a direct oxidant. A sudden increase of discoloration efficiency caused by photo irradiation is found in the system with NaCIO, just as in EP process with PdxRui.xO2/Ti anode. And active chlorine is found in the solution of electrochemical process by "iodine amount method". These facts suggest that in EP process, H0C1 and CIO’ from the hydrolyzation of CI2 generated by electrolysis is immediately photolyzed to HO-, CT and C1-, which can decolorize the solution very quickly. This may be the origin of the synergic effect in photoelectrochemical process. Effects of current density, concentration of electrolyte and pH value are investigated. It is found that in a certain limit, the photoelectrochemical discoloration efficiency of dye increases with the increase of current density and concentration of electrolyte. But for pH value, the best efficiency occurs in the range of 2 to 3.更多还原