姚娟娟 甘敬业 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）和溶解氧浓度（DO=9、0 mg/L）条件下超纯水中的光降解过程。结果表明：其光降解过程符合一级反应动力学，主要为直接光降解，DO存在时，自敏化光降解有显著促进作用。在不同DO条件下，其光降解效率及速率均在pH值为7时最快，pH值为11时次之，pH值为3时最慢，氧氟沙星的光量子产率随pH值变化而变化是导致差异产生的主要原因。对降解产物及其生成过程进行分析表明，氧氟沙星的降解路径为脱甲基、哌嗪环的裂解和氧化、羟基化和脱羧基反应，不同pH值和DO条件下的降解路径及其产物差别细微，但其对产物在降解过程中的生成和进一步降解随时间的变化有显著影响。研究成果阐明了pH值和DO对氧氟沙星光降解的影响。

关键词：氧氟沙星;pH值;溶解氧;自敏化光降解;降解产物

中图分类号：X52 文献标志码：A 文章编号：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）是一种应用最广泛的氟喹诺酮类抗生素之一，主要作用于人类和动物的细菌感染，特别是在畜禽饲养和水产养殖等领域使用量巨大，主要通过生产及使用过程进入水环境[13]。由于它抵抗水解、热分解和生物降解，传统的水处理工艺很难将其完全去除[45]。近年来，世界范围内水环境中残留的氧氟沙星检出率高，其浓度范围为ng/L到μg/L，遍及地表水、地下水等多种水体，且在市政污水处理厂出水和医院废水中检出含量分别高达5 700 ng/L和35 500 ng/L[69]。氧氟沙星等抗生素不断进入生态环境，将会导致生物毒性和抗性基因的产生，从而引起环境风险和生态风险[1011]。……