| 摘要: | O3結合UV/H2O2程序可透過連串化學反應，產生氧化力極高的氫氧自由基，相較於其他種類的氧化系統組合，效果更佳。因此本研究以O3/UV/H2O2程序處理烷基苯酚(Alkylphenol,AP)水溶液，並探討溶液之初始pH、過氧化氫添加劑量、臭氧進流濃度、反應物初始濃度等控制因子對處理效率之影響。另外，探討此程序下烷基苯酚可能之降解途徑及評估反應後水溶液之生物毒性及雌激素活性。實驗結果顯示，反應15分鐘內即可將90%以上之烷基苯酚去除，相較紫外光及臭氧等組合程序反應時間更短，但水中總有機碳去除率卻僅達60%，原因為O3/UV/H2O2程序僅破壞了烷基苯酚本身的結構，但卻造成其他中間產物的生成，使得水中總有機碳無法有效地去除，若需提高礦化效率則需增加氧化時間。本研究結果顯示，以O3/UV/H2O2程序降解起始濃度5 mg/L之烷基苯酚，其最適操作條件為：[O3]=0.06mg/min、[H2O2]0=0.45~0.48mM ([H2O2]0/[AP]0 ratio=20)、光強度(I)=1.9×10-6 Einstein L-1s-1。此操作條件下，反應15分鐘後，OP可達91.94%去除率；NP可達90.41%去除率。由LC/MS分析結果顯示，烷基苯酚降解機制由削減烷基鏈開始，芳香環發生羥基化反應(hydroxylation)，使‧OH取代H。降解過程中可能之中間產物為：烷基苯二酚(Alkylcatechol)、間苯三酚(1,2,4-trihydroxybenzene)、氫醌(Hydroquinone)、Muconaldehyde與Muconic acid類物質，以及其他小分子物質，如：烷類、乙酸、羧酸類等化合物。烷基苯酚水溶液之Microtox，則會隨著降解時間的增加，毒性逐漸降低。而在雌激素活性方面，活性強度則隨時間增加而減低，結果顯示中間產物仍具有雌激素活性，原因可能為水溶液中多種中間產物產生，使得雌激素活性加成作用，提高了化合物本身之雌激素活性。The process of combining O3 with UV/H2O2 could make serial chemical reactions and produce more active hydroxyl radicals, which have stronger oxidation capacity than conventional oxidants. Consequently, the O3/UV/H2O2 process would be more effective compared to other types of oxidation combination systems. Accordingly, this study evaluates the treatment of alkylphenol aqueous solutions by using the O3/UV/H2O2 process. The effect of various operating parameters including initial pH, H2O2 dosage, initial rate of ozone concentration and initial substrate concentration on the removal of alkylphenols in the O3/UV/H2O2 process was investigated. Moreover, the possible degradation mechanism of alkylphenols in the O3/UV/H2O2 process, bio-toxicity tests (Microtox), and estrogenic activity of reaction aqueous solution were evaluated. The results of the investigation show that using the O3/UV/H2O2 process can remove 90% of alkylphenols within 15 minutes, and the reaction time is shorter than other processes. Nevertheless, the mineralization efficiency of alkylphenols in the O3/UV/H2O2 process was only 60%, the results indicated that the alkylphenols only destroyed their own structure and formed numerous intermediate products. However, removal of total organic carbon in solution was ineffective. In order to enhance mineralization of alkylphenols, the oxidation time must be increased.The optimum operating conditions for the O3/UV/H2O2 process to destroy alkylphenols found in this study were summarized as follows：UV light intensity = 1.9×10-6 Einstein L-1s-1, pH = 4, [O3] = 0.06mg/min, [H2O2]0/[AP]0 molar ratio = 20. In which, the treatment effectiveness of OP and NP were 91.94% and 90.41% after 15 minutes, respectively.The degradation products were analyzed by LC/MS, and revealed that the degradation of alkylphenols begins from shortening the alkyl chain. The following may be substitution of the hydrogen on chain with a hydroxyl radical, as well as an additional hydroxyl radical to the aromatic ring. The degradation intermediates are alkylcatechol, 1,2,4-trihydroxybenzene, hydroquinone, muconaldehyde, muconic acid, and other small fragments, such as alkanes, acetic acid, carboxylic acids and other compounds.With the oxidation time increasing, the bio-toxicity (Microtox) and estrogenic activity of alkylphenols aqueous solution was reduced. However, the results of the investigation show that the intermediate products still had estrogenic activity. The possible causes with the formation of numerous intermediate products to enhance the synergistic effect on the estrogenic activity after alkylphenol degradation, thus, increasing the estrogenic activity of the compounds themselves. |
