Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/5577
標題: 以CVD法製備TiO2光觸媒去除水溶液中雙氯酚之研究
Photocatalytical Degradation of Dichlorophenols in Aqueous Solution on TiO2 Prepared by CVD Method
作者: 邱奕霖
關鍵字: TiO2;二氧化鈦;dichlorophenol;intermediates;雙氯酚;中間產物
出版社: 環境工程學系
摘要: 
本研究是以化學沉積法製備二氧化鈦薄膜反應器配合365nm波長紫外燈管,進行雙氯酚化合物光催化反應之探討。
實驗系統採迴流批次式,以HPLC、IC、TOC 分析方法探討在不同pH值下,2,3二氯酚、2,5二氯酚和3,4二氯酚的去除率,並比較氫氧根和氯相對位置不同下產生之中間產物的相異性及產量,以對後續在探討雙氯酚反應路徑有所幫助。
在直接光解結果顯示,365nm波長之紫外光對於高pH值下的雙氯酚有明顯的去除率和脫氯效果;若以HPLC圖譜觀察之,各種雙氯酚在不同pH值下的中間產物相同,而pH值提高則會使產物產量增加,2,3二氯酚有氯對二酚產物生成,而三種雙氯酚在pH=10時皆有脫去雙氯的產物形成。
在光催化系統結果則顯示,三種雙氯酚皆有在高pH值去除率較佳,而pH=4及pH=7差不多情形。而比較在pH=4與pH=7中,雖然對於雙氯酚的去除能力差不多,但pH=7中以酸類產物佔的比例較高,pH=4中大部分是以未開環產物存在,顯示pH值高時有利於氫氧自由基的產生,並對一級產物進行開環作用。而以圖譜觀察之,開環對於2,5-二氯酚在pH=7 以下的可能性不大。
若比較直接光解與光催化系統圖譜,直接光解中形成的產物在光催化系統中都進一步被氧化;而在光催化系統中,雖然氫氧自由基攻擊路徑不同,但三種雙氯酚皆有氯對二酚產物的形成,而3,4二氯酚和2,3二氯酚也有部份行脫氯作用之酚類產物再度進行鹵化作用而生成2,6二氯酚及3,4二氯酚。
而根據簡化後的Langmuir-Hinshelwood公式可描述二氧化鈦光催化下雙氯酚之反應動力模式。

This investigation used a tube reactor deposited with TiO2 thin film inside by chemical vapor deposition(CVD)method and a UV lamp with 365nm to study the reaction behavior of dichlorophenols in heterogeneous photocatalysis.
The experimental equipment was a batch recycle system. The degradation and dechlorination at different pH's for 2,3-DCP, 2,5-DCP and 3,4-DCP was determined by HPLC, IC and TOC. The intermediate compounds with the effect of different positions of Cl and OH groups were separated by C-8 column with eluent containing acetonenitrile/H2O (58:42) with 0.1M acetic acid and analysed by HPLC.
The results of direct photolysis by UV light indicated the obvious dechlorination of dichloriphenols at higher pH's. The aromatic intermediate of 2,3-DCP identified by HPLC was chlorohydroquinone(ClHQ). From the comparisons of both [C]/[C0] and Cl- data, it could be stated that complete-dechlorinated intermediates were formed.
In the results of the heterogeneous photocatalysis, the removal of dichlorophenols and release of Cl- at high pH's was better than that at low pH's. Although different pathway of hydroxyl radials attacking, the aromatic intermediate, ClHQ, was indentified in 2,3-DCP, 2,5-DCP and 3,4-DCP solutions. It was found that the dechlorination intermediate, like phenoxyl product, re-chlorinated in a secondary process. This was supported by the indentified intermediate products : 2,6-DCP from 3,4-DCP and 3,4-DCP from 2,3-DCP.
The photodegration of dichlorophenols followed a Lamgmuir-Hinshelwood kinetics, showing rate constant that enhanced with increasing pH's value.
URI: http://hdl.handle.net/11455/5577
Appears in Collections:環境工程學系所

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