水中的臭氧氧化反應包含直接臭氧分子攻擊與間接氫氧自由基氧化反應，此二反應途徑也許會有效的攻擊與氧化有機物之官能基，但在臭氧反應的同時亦會產生消毒副產物。 臭氧反應之直接與間接攻擊比率也許會受臭氧氧化狀況之影響。 因此，了解臭氧氧化之二個反應途徑之機制是有必要的。 本研究利用碳酸鹽及重碳酸鹽做為抑制劑，利用碳酸鹽與重碳酸鹽快速與間接臭氧反應所生成之氫氧自由基結合之特性，藉此抑制間接氫氧自由基之反應。 在臭氧反應中添加抑制劑，水中之反應由於氫氧自由基被抑制，將只有臭氧分子之直接攻擊部分。 因此，水中的臭氧反應可藉由抑制劑之添加，可將直接臭氧分子攻擊及間接氫氧自由基氧化加以分離及研究。 在本研究中，含有腐植酸之天然水樣與人工合成腐植酸的水樣均進行添加抑制劑之抑制實驗及無添加抑制劑之臭氧實驗。 實驗結果指出間接反應的貢獻隨著抑制劑劑量的增加而降低。 在鹼性腐植酸水樣中，其直接與間接攻擊貢獻比率介於3至19。 本研究之氧化還原電位連續監測是利用氧化還原電位電極連接示波器而進行線上監測。 利用Nernst equation 及線上監測之氧化還原電位可發展水中臭氧程序的即時監測及控制。 13C-NMR 光譜指出直接臭氧分子反應可降低carbohydrate carbons (60- 90 ppm) 及aromatic carbons/ double bond carbons (90- 165 ppm) 。 而在反應初期，氫氧自由基可以消耗aliphatic carbons (0- 60 ppm) 。 臭氧分子反應主要攻擊大分子物質的支鏈而產生aliphatic carbons (0- 60 ppm)、 carbohydrate carbons (60- 90 ppm) 及 aromatic carbons/ double bond carbons (90- 165 ppm) 。 Ozone oxidation reaction consists of direct ozone molecule and indirect hydroxyl radical oxidations. These two reactions may target and oxidize organic functional groups effectively. Unfortunately, it also generate disinfection by-product at the same time. The ratio of direct and indirect attack may affected by the conditions that the ozonation oxidation is carried out. Understanding the mechanisms of these two ozone oxidation pathways are valuable. This study are adapts carbonate and bicarbonate as scavenger to inhibit the formation of hydroxyl radicals which will lead to an indriect ozone attack. Ozonation of samples with scavenger will undergo only direct ozone molecular oxidation. Thus, the direct and indirect ozone oxidation can be separated and investigated individually. In this study, synthetic and natural samples containing humic acids (HA) have been investigated for the inhibited and non-inhibited ozone oxidation. The results indicate that the contribution of indirect reaction is decreasing with the increasing amounts of inhibitor dosing. Ratio of direct and indirect attack is ranging from 3 to 19 in basic HA solution. The process oxidation reduction Potential (ORP) is monitored continuously with an on-line ORP sensor connected to oscilloscope. A real-time monitoring and controlling of ozone process has been developed using the Nernst equation based on on-line ORP measurement. 13C-NMR spectrums indicate that direct reaction can decrease the amount of carbohydrate carbons (60- 90 ppm) and aromatic carbons/ double bond carbons (90- 165 ppm). Hydroxyl free radical can consume aliphatic carbons (0- 60 ppm) at the beginning of ozonation. The molecular ozone direct attack reaction mainly decomposes the side chain of macromolecule to generate aliphatic carbons (0- 60 ppm), carbohydrate carbons (60- 90 ppm) and aromatic carbons/ double bond carbons (90- 165 ppm).
