謝淑婷－分光光度計監測及以光催化處理水中背景有機物之研究
Monitoring and Photocatalysis of Natural Organic Matter in Drinking Water
自來水中的背景有機物（Natural organic water）泛指天然水源中所含的複雜有機組成。由於背景有機物之存在為自來水無法避免之問題，且其為加氯消毒產生的消毒副產品之重要因素，但自來水傳統處理方法對腐植質並不具備良好的處理效果。而國內各自來水中之腐植質濃度偏高（尤其與南部各水廠為甚），水中腐植質對自來水廠處理之影響應加以重視。
本本研究利用分光光度計的原理，根據不同濃度的腐植酸在特定波長下應表現出不一樣的吸光度（Beer's law），朝此方向探討，嘗試建立一套簡單、有效率、更具可信度以測定水中腐直酸濃度的方法。並以UV/2O2的均相光氧化反應來處理水中腐直酸，同時評估於不同條件下（燈罩材質、催化劑支輛、腐植酸濃度、鹼度、照光時間……等）的處理效果。
本研究結果顯示波長越低，腐植酸吸光度越高，且其濃度在測試範圍內與吸光度下的積分面積成正比；試驗結果顯示水樣經過濾後以波長250∼350 nm量測吸光度所受到的干擾最小。所以含腐植酸水樣經適當的過濾後，在特定範圍波長（λ＝250∼350 nm）下腐植酸濃度與吸光度曲線下面積有正比關係，且較不受水中濁度之影響。
而以一定比例的腐植質-催化劑濃度，以紫外燈照射3小時，可以達到有效的有機碳去除效果（80％∼90％），但處理效果因腐植酸- H2O2之比例不同而有所差異，顯示反應物和催化劑之間有一最佳的比例關係存在（本實驗中則選擇腐植酸初始NPOC＝5 mg/L，H2O2＝0.002％之比例較佳）。且光催化實驗結果趨向二階段反應。試驗結果顯示光催化處理腐植酸受到反應物初始濃度、催化劑劑量、燈罩材質、鹼度等因子之影響，而催化劑H2O2濃度（V/V）若添加0.1％以下，在反應3小時候，不會有H2O2殘留的問題。
The presence of natural organic matter (NOM) in drinking water affect s water treatment processes including coagulation and adsorption of synthetic organic like pesticides and herbicides, it also causes disinfection byproducts (DBPs) during disinfection process. It has been shown that treatment processes such as coagulation with alum, filtration or softening can effectively remove an average of 30% high molecular weight humic substances, predominantly humic acids. In general, the TOC removal in conventional drinking water treatment processes is low, between 10 and 50 percent. Advanced Oxidation Processes (AOP) is the one that deserves more study for potential applications in drinking water treatment. AOP can effectively mineralize many organic contaminants and have made them attractive for control of synthetic organic compounds in waste water treatments. The combination of the H2O2/UV process was used in this study to evaluate the suitability for control of NOM in drinking water. The results showed that the rate constant decreases as the initial NPOC concentration increases at constant H2O2 concentration. In UV/H2O2 system, it is important to calculate the relative concentrations (or molar ratios) between H2O2 and target compounds to find optimum H2O2 concentration. In order to maintain a suitable rate constant, the H2O2 concentration should be raised to increase the collision frequency When the quartz tube is used as the filter in the experiments, the short wavelength UV can pass through the filter and be utilized for NOM oxidation. More than 80 percent of the NPOC was removed after three hours of irradiation. Compared to the 30 to 60 percent oxidation with PYREX filter, this demonstrates the great oxidation power of the short wavelength UV light. It is important to look at the correlation between the H2O2 addition and the quantity of NPOC removed (or the rate constants). The optimum H2O2 concentration is between 0.1% and 0.3%, and the increase in the H2O2 concentration reduce the treatment efficiency. The optimum H2O2 concentration in a UV/H2O2 system depends on the intensity of the UV light and the target compounds to be removed. In general, the increase of the H2O2 concentration will increase the concentration of hydroxyl radicals and increase the reaction rates. However, the increase in H2O2 concentration will reduce the depth that light can penetrate in water and thus inhibit the oxidation reaction for NOM.Bicarbonate ion is a hydroxyl radical trap, and will affect the AOP treatment process. The results showed that the presence of the alkalinity will reduce the rate constant in the UV oxidation of the NOM in drinking water. However, the efficiency of AOP in this study was not affected by the presence of hardness and sulfates.As a conclusion, this study shows that catalytic photochemical oxidation provides an effective method for the control of NOM. The NOM oxidation process followed simple first-order kinetics in the batch system used in this study. With suitable H2O2 addition, UV light can effectively oxidize the NOM in aqueous phase. Increasing the H2O2 concentration above the optimum dose (0.1 - 0.3% H2O2 in this study) has minor or no improvement on NOM destruction. Alkalinity has minor effects on NOM oxidation when PYREX filter is used. However, the NOM reduction greatly affected by alkalinity when quartz tube is used to allowed the transparency of short wavelength UV.