臭氧處理抗癌藥物

Abstract

台灣污水處理廠大多為二級以下處理廠，傳統處理方法無法有效去除新興汙染物。因此，抗癌藥物及其他醫療用藥常在環境水體中被檢測出。製藥廠、汙水處理廠放流水及醫院為主要測出來源。臭氧處理為目前常用的高級處理方法，故本論文研究目標為利用臭氧去除三種抗癌藥物(5-fluorouracil、ifosfamide、cyclophosphamide)及血管擴張劑 (pentoxifylline。此四種化合物在初始濃度5ppm下皆可在30分鐘內去除60%，但反應速率受pH值和化合物結構有關。pH 值影響水中溶臭氧量和氫氧自由基比例，進而影響反應機制，化合物結構影響是否易於和臭氧反應。含不飽和鍵多的化合物在高pH下被氫氧自由基反應，在低pH下可和臭氧或自由基反應；沒有不飽和鍵的化合物在高pH下和氫氧自由基反應和在低pH下較難和臭氧反應。 Pentoxifylline和5-fluorouracil在5ppm起始濃度和三個不同的起始pH值(pH 5.6, pH9, pH11)下反應沒有顯著差別，皆在1分鐘內達到100%降解。Ifosfamide和 cyclophosphamide初始pH值為 5.6和9時有明顯卻類似的反應結果，ifosfamide在30分鐘的降解效率(pH 5.6為77%，pH 9為88%)，分別比cyclophosphamide在兩個pH的降解程度高約10%。此結果說明，在pH 11時四種化合物都和反應力極強選擇性卻低的氫氧自由基反應而降解。結構中含有較多不飽和鍵的pentoxifylline和5-fluorouracil在pH 9和5.6下易和臭氧直接反應而完全降解，在較多臭氧而較少氫氧自由基的環境中，含有較少不飽和鍵的ifosfamide及 cyclophosphamide不易和臭氧反應，降解速率較低。而cyclophosphamide可能在結構上相較於ifosfamide有較大的立體障礙阻擋臭氧直接反應，使cyclophosphamide在初始pH為5.6和9的反應中降解效率比ifosfamide少約10%。 在鹼性條件及高初始濃度(20ppm)使用臭氧處理四個藥物皆可在10分鐘達到99%去除效率，但未完全礦化，測得總有機碳(TOC)的濃度改變量只減少約50%，表示仍有一半的副產物殘留於水中。生物急毒性測試顯示，對於ifosfamide 和 cyclophosphamide所產生的副產物急毒性隨時間有上升趨勢，顯示過長的臭氧接觸時間反而會將殘餘物轉換成有害物種。

The wastewaters are typically secondary treated in the wastewater treatment plants (WWTP) in Taiwan; however, it is often found insufficient for removing emerging contaminants from the treated effluents. As a result, pharmaceuticals such as antineoplastic drugs and hemorrheologic agent are often detected in receiving natural waters. In addition, effluents from pharmaceutical production facilities and hospital wastewaters are also the main sources. Ozonation is an advanced treatment often used, so the thesis aims to use ozonation to remove three of the antineoplastic drugs and hemorrheologic agent. All of the compounds can be removed at least 60% with 5 ppm initial concentration within 30 minutes of reaction, but the reaction rate is affected by pH and the chemical structure. In the system, pH determines the ratio of dissolved ozone concentration and hydroxyl radicals, while chemical structure influences the reactivity of the target compounds with ozone. pH 5.6, 9 and 11 were tested for all target compounds. Pentoxifylline and 5-fluorouracil were removed completely within 1minutes of ozonation and pH does not influence. However, ifosfamide and cyclophosphamide behaved differently; the removal rates were fastest at pH11, followed by pH 9 and 5.6. Ifosfamide and cyclophosphamide reached 100% removal within 3 minutes at pH 11 while at pH 9 and 5.6, they were only 78%-88% and 67-77% degraded after 30 minutes of ozonation. With higher initial concentration (20ppm), four compounds can be degraded to 99% in 10 minutes at pH 11; however, the ozonation did not lead to mineralization. The total organic carbon were only 50% decreased, indicating that there were significant amount of byproducts formed and remained in the system. The MicrotoxR result showed that the toxicities increased with time for ifosfamide and cyclophosphamide ozonation, again indicating that ozone could transform the target compounds and byrproducts into more toxic during ozonation treatment process.