State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China.
Chemosphere. 2011 Oct;85(5):892-7. doi: 10.1016/j.chemosphere.2011.07.008. Epub 2011 Jul 31.
Photolysis of Enro in water was investigated under simulated sunlight irradiation using a Xenon lamp. The results showed that Enro photolysis followed apparent first-order kinetics. Increasing Enro concentration from 5.0 to 40.0 mg L⁻¹ led to the decrease of the photolysis rate constant from 1.6 × 10⁻² to 3.0 × 10⁻³ min⁻¹. Compared with the acidic and basic conditions, the photolysis rate was faster at neutral condition. Both of nitrate and humic acid can markedly decrease the photolysis rate of Enro because they can competitively absorb photons with Enro. The electron spin resonance and reactive oxygen species scavenging experiments indicated that Enro underwent self-sensitized photooxidation via OH and ¹O₂. After irradiation for 90 min, only 13.1% reduction of TOC occurred in spite of fast photolysis of 58.9% of Enro, indicating that Enro was transformed into intermediates without complete mineralization. The photolysis of Enro involved three main pathways: decarboxylation, defluorination, and piperazinyl N⁴-dealkylation. The bioluminescence inhibition rate using Vibrio fischeri increased to 67.2% at 60 min and then decreased to 56.9% at 90 min, indicative of the generation of some more toxic intermediates than Enro and then the degradation of the intermediates. The results will help us understand fundamental mechanisms of Enro photolysis and provide insight into the potential fate and transformation of Enro in surface waters.
采用氙灯模拟太阳光辐射，研究了恩诺沙星在水中的光解情况。结果表明，恩诺沙星光解符合表观一级动力学。将恩诺沙星浓度从 5.0 增加到 40.0mg/L-1 会导致光解速率常数从 1.6×10-2 降低到 3.0×10-3 min-1。与酸性和碱性条件相比，中性条件下的光解速度更快。硝酸盐和腐殖酸都可以显著降低恩诺沙星的光解速率，因为它们可以与恩诺沙星竞争吸收光子。电子自旋共振和活性氧物种清除实验表明，恩诺沙星通过 OH 和 ¹O₂发生自敏化光氧化。光照 90 分钟后，尽管恩诺沙星快速光解了 58.9%，TOC 仅减少了 13.1%，表明恩诺沙星转化为中间产物而没有完全矿化。恩诺沙星的光解涉及三条主要途径：脱羧、脱氟和哌嗪基 N⁴-脱烷基化。发光细菌(Vibrio fischeri)的生物发光抑制率在 60 分钟时增加到 67.2%，然后在 90 分钟时降低到 56.9%，表明生成了一些比恩诺沙星更具毒性的中间产物，然后这些中间产物被降解。这些结果将有助于我们理解恩诺沙星光解的基本机制，并深入了解其在地表水环境中的潜在归趋和转化。
