College of Ocean Technology and Environment, Dalian Ocean University, Dalian 116023, China; Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China.
Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China.
Chemosphere. 2014 Sep;111:278-82. doi: 10.1016/j.chemosphere.2014.04.052. Epub 2014 May 13.
Thiamphenicol and florfenicol are two phenicol antibiotics widely used in aquaculture and are ubiquitous as micropollutants in surface waters. The present study investigated their photodegradation kinetics, hydroxyl-radical (OH) oxidation reactivities and products. Firstly, the photolytic kinetics of the phenicols in pure water was studied as a function of initial concentrations (C0) under UV-vis irradiation (λ>200nm). It was found that the kinetics was influenced by C0. A linear plot of the pseudo-first-order rate constant vs C0 was observed with a negative slope. Secondly, the reaction between the phenicol antibiotics and OH was examined with a competition kinetic method under simulated solar irradiation (λ>290nm), which quantified their bimolecular reaction rate constants of (2.13±0.02)×10(9)M(-1)s(-1) and (1.82±0.10)×10(9)M(-1)s(-1) for thiamphenicol and florfenicol, respectively. Then the corresponding OH oxidated half-lives in sunlit surface waters were calculated to be 90.5-106.1h. Some main intermediates were formed from the reaction, which suggested that the two phenicols underwent hydroxylation, oxygenation and dehydrogenation when OH existed. These results are of importance to assess the phenicol persistence in wastewater treatment and sunlit surface waters.
噻苯隆和氟苯尼考是两种在水产养殖中广泛使用的酚类抗生素，作为地表水中的普遍存在的微量污染物。本研究考察了它们的光降解动力学、羟基自由基（OH）氧化反应活性和产物。首先，研究了在纯水中酚类抗生素在 UV-vis 辐射（λ>200nm）下随初始浓度（C0）的光解动力学。结果表明动力学受 C0 影响。观察到伪一级速率常数与 C0 的线性图具有负斜率。其次，采用模拟太阳辐射（λ>290nm）下的竞争动力学方法研究了酚类抗生素与 OH 的反应，定量了它们的双分子反应速率常数分别为（2.13±0.02）×10(9)M(-1)s(-1)和（1.82±0.10）×10(9)M(-1)s(-1)。然后计算了在阳光照射的地表水中相应的 OH 氧化半衰期为 90.5-106.1h。从反应中形成了一些主要的中间产物，这表明当存在 OH 时，两种酚类抗生素经历了羟化、氧化和脱氢反应。这些结果对于评估废水处理和阳光照射的地表水中酚类抗生素的持久性具有重要意义。
