pH值和DO對UVA睱ED光降解氧氟沙星的影響：動力學、機理及路徑

姚娟娟 甘敬業 夏彬

摘要：在UVALED光照射下，考察了氧氟沙星在不同的pH值（3、7、11）和溶解氧濃度（DO=9、0 mg/L）條件下超純水中的光降解過程。結果表明：其光降解過程符合一級反應動力學，主要為直接光降解，DO存在時，自敏化光降解有顯著促進作用。在不同DO條件下，其光降解效率及速率均在pH值為7時最快，pH值為11時次之，pH值為3時最慢，氧氟沙星的光量子產率隨pH值變化而變化是導致差異產生的主要原因。對降解產物及其生成過程進行分析表明，氧氟沙星的降解路徑為脫甲基、哌嗪環的裂解和氧化、羥基化和脫羧基反應，不同pH值和DO條件下的降解路徑及其產物差別細微，但其對產物在降解過程中的生成和進一步降解隨時間的變化有顯著影響。研究成果闡明了pH值和DO對氧氟沙星光降解的影響。

關鍵詞：氧氟沙星;pH值;溶解氧;自敏化光降解;降解產物

中圖分類號：X52 文獻標志碼：A 文章編號：20966717（2020）03014108

Abstract： The photodegradation process of ofloxacin in ultrapure water at different pH （3，7 and 11） and dissolved oxygen concentration （DO=9 and 0 mg/L） was investigated under UVALED irradiation. The results showed that the photodegradation follows firstorderkinetics， mainly direct photolysis. When dissolved oxygen exists， the selfsensitized photolysis could significantly promote the photodegradation. Under different DO conditions， the photodegradation efficiency and rate were the fastest at pH=7， followed by pH=11 and the slowest at pH=3. The main reason for the difference is that the photonic yield of ofloxacin varies with pH value. The analysis of degradation products and their formation process showed that the degradation pathways of ofloxacin was mainly demethylation， piperazinyl ring cleavage/oxidation， hydroxylation and decarboxylation. The degradation pathways and products of ofloxacin under different pH and DO conditions were slightly different， but have a significant influence on the process of products generation and further degradation over time. The above research results clarified the effects of pH and DO on the photodegradation of ofloxacin.

Keywords：ofloxacin;pH value;dissolved oxygen;selfsensitized photolysis;degradation products

氧氟沙星（C18H20FN3O4）是一種應用最廣泛的氟喹諾酮類抗生素之一，主要作用于人類和動物的細菌感染，特別是在畜禽飼養和水產養殖等領域使用量巨大，主要通過生產及使用過程進入水環境[13]。由于它抵抗水解、熱分解和生物降解，傳統的水處理工藝很難將其完全去除[45]。近年來，世界范圍內水環境中殘留的氧氟沙星檢出率高，其濃度范圍為ng/L到μg/L，遍及地表水、地下水等多種水體，且在市政污水處理廠出水和醫院廢水中檢出含量分別高達5 700 ng/L和35 500 ng/L[69]。氧氟沙星等抗生素不斷進入生態環境，將會導致生物毒性和抗性基因的產生，從而引起環境風險和生態風險[1011]。……