UV/H2O2光催化程序對於控制消毒副產物前驅物質的影響

The effects of UV/H2O2 process on controlling DBPs precursors

方立婷(Li-Ting Fang)

指導教授 ： 王根樹

國立臺灣大學/公共衛生學院/環境衛生研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.02566

摘要

加氯消毒是台灣目前最普遍的消毒方式之一，此項消毒過程擁有殺菌力強、便宜、快速等優點，但其伴隨而來的消毒副產物問題卻也成為不容忽視的課題。三鹵甲烷等消毒副產物的形成起因於水中有機物質與氯、溴反應而生成。為有效降低水中三鹵甲烷之生成，最佳之辦法即在消毒副產物生成前先將有機前質予以去除。高級氧化處理程序 (Advanced Oxidation Process, AOPs) 的目的即藉由氫氧自由基的強氧化力氧化水中有機前質，避免其與氯、溴反應生成消毒副產物。本研究之目的即在探討以UV/H2O2光催化程序處理水中消毒副產物前趨物之效應。
研究採用resorcinol、phloroglucinol、hydroquinone及1,7-heptanediol等四種物質代表水中不同結構之前趨物質，首先探討不同結構性及不同官能基對三鹵甲烷 (Trihalomethanes, THM) 生成之影響，另以UV/H2O2光催化程序處理觀察THM生成及有機物官能基的變化。
前質試驗結果顯示，加氯量為10、20 mg/L時，resorcinol及phloroglucinol兩者皆沒有Br-THM的出現，且THM總產量極低。為確保消毒副產物生成潛能反應7日後水樣中仍殘有餘氯，因此進而增加NaOCl劑量至100 mg/L，此時可以看到四種前趨物質皆有Br-THM的出現，且resorcinol、phloroglucinol總產量遠高於hydroquinone及1,7-heptanediol。推測造成此結果之原因為resorcinol及phloroglucinol具有較高之立體障礙效應 (steric hindrance)，因此無法生成Br-THM，而較高之加氯量提供了氧化反應的作用，改變有機前質之結構，除促使THM生成量增加外，Br-THM亦隨之產生。
而UV/H2O2光催化程序對於三種環狀性有機前質皆具有良好之氧化效果，其在反應時間為0分鍾時皆具有最高之THM產量，並隨著時間增長而遞減。而直鏈狀有機前質本身並非容易生成THM之前驅物質，因此其THM產量最高點反而出現在反應時間為10分鍾時，隨著時間增長至30分鍾THM生成亦能有效降低。依照環狀性前質FTIR圖譜看來，反應時間0分鍾時皆具有代表環狀結構C=C、C=O基的波峰出現，在10、30分鍾時則出現-OH、C-H及-COOH等小分子物質的波峰，當反應時間增長至60分鍾時只殘有一些微小的波峰。此項結果與THM產量相呼應，證實UV/H2O2光催化程序對於消毒副產物前質有良好的控制效果，可有效降解水中有機物質，並減低消毒副產物之生成。

關鍵字

有機前質 ； 三鹵甲烷 ； 高級氧化程序 ； 紫外光 ； 過氧化氫

並列摘要

Chlorination is a common disinfection process in Taiwan with the advantages of efficient microorganism control, low cost and fast. However, it also generates toxic disinfection by-products because of the reaction between organic matter and chlorine. The best way to reduce the formation of THM is removing the organic precursors, and advanced oxidation processes has been shown to be effective to remove the organic precursors. The objective of this study is to evaluate the effects of UV/H2O2 process on DBPs precursors’ removal.
Four organic precursors were selected in this study to evaluate the effect of different structures and functional groups on THM formation. The variation of THM formation and changes on precursors’ functional groups by UV/H2O2 process was also evaluated.
At lower chlorine doses (10 and 20 mg/L), the total THM formation decrease with increasing DOC concentrations and no Br-THM species was observed when resorcinol and phloroglucinol were tested. When higher chlorine dosage (100 mg/L) is applied, Br-THM species is obtained and the total THM formation increased dramatically. It is inferred that resorcinol and phloroglucinol have higher steric hindrance which block the reaction of bromine, and higher chlorine dosage provides oxidative force to change the structure of resorcinol and phloroglucinol and thus promote Br-THM and higher THM formation.
When the organic precursors were treated with UV/H2O2 process, the THMFP of three aromatic precursors decreased with photolysis time. However, the highest THMFP for aliphatic 1,7-heptanediol was observed after 10 minutes of UV photolysis. The FTIR spectrum revealed that peaks of hydroxyl, hydrocarbon and carboxylic structures were observed after UV photolysis. This provided some information to demonstrate the change of the functional groups during the photolysis and the oxidation efficacy of UV/H2O2 process for organic precursors.

並列關鍵字

precursors ； THM ； AOPs ； UV ； H2O2

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