近年來，高級氧化技術(AOPs)常被使用於處理傳統方法無法處理或是難以生物降解之汙染物，處理過程中，許多的有機酸隨著汙染物的降解而產生，這些有機酸通常對氫氧自由基(‧OH)有較強的抵抗力，使得汙染物無法完全被礦化。
因此，為尋找一種有別於AOPs而能有效礦化有機酸的技術，本研究以氯化學為氧化機制、間接電化學氧化法為基礎技術，採用一新穎光電反應器，針對AOPs難礦化的有機酸進行探討，目標汙染物包括acetic acid、maleic acid、malonic acid、citric acid、oxalic acid、succinic acid等有機酸。本研究首先設計出一電解反應槽，尺寸為12×12×30 cm3，以DSA(Ti/RuO2/IrO2)電極作為陽極和陰極，實驗以批次處理先在2.5升水中加入200 mM的氯化鈉及5mM有機酸作為反應物，再通入直流電(電流密度:6.78×10-3A/cm2)將氯離子反應產生活性氯(Cl2、HOCl、OCl-)，並隨時間取樣量測TOC以探討氯電化學機制氧化有機酸之礦化效率。初步實驗結果顯示，oxalic acid能在兩小時反應時間內完全礦化，maleic acid及citric acid則分別有43%和49%的礦化效果，而其他有機酸則完全難以被礦化。接著，本研究在電化學反應器中架設紫外光燈管(254 nm, 2.04mW/cm2)以激發水中的HOCl產生‧OH及Cl‧，對有機酸做進一步的礦化，這是一種新的光催化電化學氧化法。實驗結果顯示除了acetic acid僅有83%的礦化率外，其他的有機酸皆可達到90%以上的礦化效果，成功解決過往AOPs技術難以礦化有機酸汙染物的問題。
最後，本研究以分子量較大的檸檬酸為研究對象，透過IC與LC/MS儀器分析反應過程的中間產物，以瞭解此一新穎光電化學氧化法破壞有機酸的機制，綜合整體分析結果發現活性氯攻擊檸檬酸的ROOH基並加以取代形成有機氯是關鍵反應途徑。研究結果並發現在最適化的操作參數下，上述有機氯可以利用本新穎光電化學氧化法完全降解、繼續礦化，終能以Cl-、CO2及H2O為最終成分，無二次汙染之虞。

In recent years, the advanced oxidation processes (AOPs) employed for the wastewater treatment which can efficiently degrade the recalcitrant pollutants. However, the decomposition of aromatic ring compounds leaves several kinds of organic acids which resist the hydroxyl radical attacking in the AOPs. This study successfully demonstrated a novel indirect photoelectro-chemical method for the mineralization of organic acid candidates, including acetic acid, maleic acid, malonic acid, citric acid, oxalic acid, succinic acid. The electrolytic reactor (6*6*30 cm3) could accommodate 2.5 L solution in a batch reaction in which both anode and cathode were made of titanium coated with RuO2/IrO2 (Ti-DSA). The electro-derived chlorine chemistry with a DC current (6.78 A/cm2) could generate several oxidants (Cl2, HOCl, OCl-) in the presence of NaCl. The TOC removal achieved at 100 %, 49 % and43 % for oxalic acid, citric acid and maleic acid in 2 hours only through 200 mM NaCl electrolysis, respectively, while very little amount of TOC removal occurred for other organic acids. Furthermore, the application of external photo-assistance (UV 254 nm) could result in above 90 % TOC removal for the rest of organic acid candidates. The enhancement in oxidation efficiency may be attributed to the generation of hydroxyl and chloric radicals from HOCl photolysis by 254 nm UV light. Finally, LC/MS suggested the reaction pathway of citric acid mineralization was initiated by the breaking of carboxylic groups, which were thus replaced by chloride ions. The almost 100 % TOC removal proved that the organochlorinated intermediates were ultimately mineralized to carbon dioxide and water.

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