奈米級氧化鋅觸媒之合成及材料特性與其降解三苯甲烷類染料的效率和機構探討

Synthesis and properties of nano-catalysts and its efficiencies, mechanisms of catalystic degradation with triphenylmethane dyes

吳嘉偉(Chia-Wei Wu)

指導教授 ： 林昭田

中山醫學大學/健康管理學院/應用化學系碩士班/碩士(2009年)

https://doi.org/10.6834/CSMU.2009.00049

摘要

氧化鋅、二氧化鈦等光觸媒對於染料或有機等汙染物所產生光催化降解作用已有應用成功的例子。本研究亦選擇高級氧化作用之光觸媒催化程序來降解難以分解染料，並探討其降解情形及影響催化的因子。研究內容有三個主題，第一個主題在於為更進一步的了解氧化鋅與二氧化鈦對於Victroia Blue R (簡稱VBR)染料在可見光下，其光催化效率有何不同，其中探討染料初始濃度、催化劑添加的量和溶液初始的pH值等影響因子，降解過程中的機構亦提出可能的路徑。其中在光降解過程中共有六十三個中間產物被分離發現，並以HPLC-ESI-MS成功鑑定之。
第二個主題為二氧化鈦改質後的光催化活性測試實驗，同樣以VBR作為測試對象的染料，過去利用修飾二氧化鈦的表面來達到增進光觸媒活性的研究已行之有年，本主題成功改質二氧化鈦並提升其對VBR染料的光催化降解活性，除了效率的探討外，亦針對其反應機構作確認是否與過往不同。
另外過去鋅板成功作為氧化鋅薄膜之固定床基板的例子，是以水熱法方式處理，最後一個主題的研究中意外發現鋅板表面在尚未前處理時，在水溶液中即自發性的形成氧化鋅奈米晶體，搜尋文獻後發現過去已經有這樣的報導(C. Yan et al., 2008；L. S. Panchakarla et al., 2007)，於是在第三部份接著我們先試以鋅板降解染料，並選擇Ethyl Violet (簡稱EV)染料測試降解的活性，結果鋅板不但可以降解染料，還可以在不照光的情形下使EV染料降解，得到的這樣結果促使我們再選擇不同基材的鋅粉做一系列的效率比較，各種影響因子與效率和機構之探討。我們想到廢電池中的陽極亦為鋅板材料，於是嘗試以其替代純鋅板來降解染料，並成功得到結果，此實驗結果是首次被發現的。同時發現相較於市售鋅板與鋅粉，皆可不透過光的輔助催化降解染料，並且得到更快的降解速率，接著以我們做一系列的降解效率與針對其特別的非光化學程序作出機構探討。

關鍵字

鋅板 ； 氧化鋅 ； 鋅粉 ； VBR ； EV ； 降解 ； 二氧化鈦 ； 乾電池

並列摘要

The TiO2(ZnO)-mediated photocatalysis process was used to successfully degrade dye pollutants. To better understand the degradation of mechanistic between different catalysts. Three part of topics was discussed in this study.
The fiest part, the ZnO-mediated photocatalysis process was used to successfully degrade Victoria Blue R (VBR) under visible light irradiation. The effects of the influencing factors, including initial concentration of dye, catalyst dosage, and initial pH, were studied. 63 intermediates of VBR of the photodegradation were separated, identified, and characterized by HPLC-PDA-ESI-MS techniques. The results indicated that the N-de-alkylation and oxidative degradation of VBR dye took place with N-hydroxyalkylated intermediates generated during the process.
Second, the purposes of this topic were to study the effects of two modified photocatalysts, Nafion-coated TiO2 and fluorinated TiO2, and photocatalytic degradation of Victoria Blue R in aqueous solution. Degradation effect of Victoria Blue R was accelerated by the modified photocatalysts. Bulk and surface characterizations of the resulting powders were carried out. Attachment of the anions to the TiO2 surface using the nafion-coated-TiO2 possibly results in increased adsorption of the cationic dye, and the degradation rate is larger for the cationic dye. It was found that Victoria Blue R on the two illuminated TiO2 surfaces underwent very different changes. Several probable photodegradation pathways were also proposed and discussed.
In third part, through a simple one-step synthesized by the reaction of Zn foil and nano-Zn powder in aqueous solution at room temperature with or without UV or visible light irradiation, we have fabricated nanostructured crystalline ZnO with simultaneous photocatalytic properties. Here, we report results on the synthesis, characterization, and application and implication of nano-ZnO. The Zn foils and nano-Zn powders materials were highly efficient in the decomposition of ethyl violet (EV) dye. The removal of dyestuffs from industrial wastewaters by Zn-foils of dry cell has not been studied before. The Zn-foils of dry cell have been treated by same synthesis method as compared to the samples above. In order to obtain a better handing on the mechanistic details of this Zn oxidation degradation of the EV dye with UV or visible light irradiation, the intermediates decomposed during the process were separated, identified and characterized by HPLC-PDA-ESI-MS technique in this topic. Possible mechanism of electron transfer was proposed. For decolorization of dyes, the possible photodegradation pathways were proposed and discussed on the basis of the evidence of intermediates formation.

並列關鍵字

Zn foil ； ZnO ； Zn powder ； VBR ； EV ； degradation ； TiO2 ； dry cell

參考文獻

【79】 劉守靜，「研究奈米光觸媒之合成及處理染料之效率及降解機構」，碩士論文，中山醫學大學應用化學系暨碩士班，2008。

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