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Removal of Ketoprofen from Water by using Ultrasonic with Persulfate Oxidant
chemical probe,hydroxyl radical,ketoprofen,persulfate,ultrasound,
|Publication Year :||2019|
|Abstract:||隨著醫學的發展，大量的人工合成藥物被廣泛使用，非類固醇類消炎藥(Nonsteroidal anti-inflammatory drugs, NSAIDs)為近年來個人保健用品(Pharmaceuticals and personal care products, PPCPs)中較受關注的一類，主要用於治療各類發炎及減緩疼痛。然而傳統污水處理廠並無法有效處理NSAIDs藥物，含有殘留藥物的放流水或是藥物的代謝產物流入土壤、河川或是地表水中影響生態環境。酮洛芬(Ketoprofen, KET)為天然水體及污水處理廠放流水中常被偵測到的NSAIDs藥物，本研究評估使用超聲波(ultrasound, US)化學氧化及超聲波活化過硫酸鹽氧化系統(sono-activated persulfate system, US/PS)處理KET之可行性，探討在不同重要操作參數之反應條件下，以超聲波去除KET之效率及其反應動力，其中重要操作參數包含藥物初始濃度、溶液初始酸鹼值、超聲波功率及氧化劑添加濃度，此外，於超聲波化學氧化系統中添加不同陽離子界面活性劑，探討其對超聲波去除KET之氧化效果影響。最後，藉由添加第三丁醇(tert-butyl alcohol, TBA)化學探針，更進一步地鑑定US及US/PS系統中優勢自由基物種。
在超聲波功率為250 W時，超聲波化學氧化反應90分鐘後，於pH 4、7、9.5環境下的去除率分別為23.0、24.0及24.7% (k = 0.0029、0.0033、0.0031 min-1)；而經超聲波活化過硫酸鹽氧化系統反應90分鐘後，KET在鹼性環境下有較佳的去除效果，於pH 4、7、9.5環境下的去除率分別為26.0、28.4及41.2% (k = 0.0035、0.0037、0.0062 min-1)。在超聲波功率為500 W時，超聲波化學氧化反應90分鐘後，於pH 4、7、9.5環境下的去除率分別為66.7、56.0及59.0% (k = 0.0126、0.0094、0.0101 min-1)；而經超聲波活化過硫酸鹽氧化系統反應90分鐘後，於pH 4、7、9.5環境下的去除率分別為68.6、66.4及69.2% (k = 0.0132、0.0123、0.0138 min-1)。由前述結果可觀察到中性及鹼性環境下，添加過硫酸鹽可使KET去除率明顯提升，故推論目標污染物主要是受氫氧根自由基(hydroxyl radical, HO.)氧化降解。此外，於鹼性條件下，隨PS氧化劑添加濃度增加，KET去除效果亦增加。最終藉由添加化學探針TBA於US及US/PS系統，證實HO.確實為兩系統中之優勢自由基。此研究建立超聲波化學氧化降解藥物之操作資訊，可提供未來超聲波系統應用上之參考依據。
With the development of medicine, large numbers of synthetic drugs have been widely used. Nonsteroidal anti-inflammatory drugs (NSAIDs) have been one of the most concerned pharmaceuticals and personal care products (PPCPs) in recent years, which are used for anti-inflammation and relieving pain. However, traditional wastewater treatment plants (WWTPs) could not remove the NSAIDs pharmaceutical compounds effectively. Residual drugs and their metabolites in wastewater effluents flow into soil, rivers or surface water may affect the ecological environment. Ketoprofen (KET), one of the widely used NSAIDs pharmaceutical compound, has been frequently detected in natural water and wastewater effluents. This study evaluates the feasibility of treating KET with ultrasound (US) and sono-activated persulfate system (US/PS). Under different reaction parameters, the efficiency of KET removal by ultrasound and reaction kinetics were discussed. Experimental parameters were varied including initial pharmaceutical compound concentration (C0), initial pH, ultrasonic power input, and the concentration of persulfate oxidant. Besides, different cationic surfactants were added into US system to investigate the effect of KET removal. Furthermore, tert-butyl alcohol (TBA) was used as a chemical probe for identifying the predominant radicals in US and US/PS system.
When ultrasonic power input was 250 W and the reaction time was 90 min. The removal of KET at different pH values (pH = 4, 7, 9.5) were 23.0, 24.0 and 24.7% (k = 0.0029, 0.0033, and 0.0031 min-1) in US system, respectively. Whereas, the removal of KET at different pH values (pH = 4, 7, 9.5) were 26.0, 28.4 and 41.2% (k = 0.0035, 0.0037, and 0.0062 min-1) in US/PS system. The efficiency of KET removal at different pH values (pH = 4, 7, 9.5) increased to 66.7, 56.0 and 59% (k = 0.0126, 0.0094, and 0.0101 min-1) while ultrasonic power input increased to 500 W after 90 min reaction in US system. After 90 min reaction in US/PS system, the efficiency of KET removal at different pH values (pH = 4, 7, 9.5) increased to 68.6, 66.4 and 69.2% (k = 0.0132, 0.0123, and 0.0138 min-1) when ultrasonic power input was 500 W. According to the results above, it demonstrated that persulfate oxidant could be activated by US under neutral and alkaline condition. Also, KET was mainly degraded by hydroxyl radicals (HO.) which were generated from the activation of persulfate oxidant. Under the alkaline condition, the removal efficiency of KET improved as the addition of persulfate oxidant increased. HO. is the dominant radical at a more basic pH in both US and US/PS system, which was verified by TBA probe addition. These results may provide references for the application of treating pharmaceutical compounds by ultrasound.
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