School of Physics and Optoelectronic Engineering, Yangtze University, 1 Nanhuan Road, Jingzhou, Hubei, 434023, China.
School of Physics and Optoelectronic Engineering, Yangtze University, 1 Nanhuan Road, Jingzhou, Hubei, 434023, China.
J Hazard Mater. 2018 Oct 5;359:414-420. doi: 10.1016/j.jhazmat.2018.07.041. Epub 2018 Jul 26.
Although photolysis of antibiotics in aqueous solution was widely studied for a better understanding of their photolytic behavior in aqueous phase, the knowledge about photodegradation of antibiotics adsorbed on solid surfaces is still very limited. In this study, photodegradation of ciprofloxacin (CIP), a fluoroquinolone antibiotic, adsorbed in the intracrystalline space of montmorillonite (MMT) was examined using a xenon light source (300 W, λ > 320 nm). The gradual decrease of basal spacing of MMT from 1.66 to 1.46 nm with irradiation confirmed CIP decomposition in the intracrystalline space under simulated solar irradiation. Nearly 70 percent of adsorbed CIP was degraded after 5 h irradiation, and the reaction followed the first-order kinetics with a rate constant roughly 3 times than that in aqueous solution, indicating more efficient photodegradation of CIP after being adsorbed in the intracrystalline space of MMT. Spectroscopic analysis revealed that direct photolysis was the main photolytic mechanism. The hydroxyl radical induced by irradiated MMT might play an important role. The major photoproducts were identified with liquid chromatography-tandem mass spectrometry, and the main degradation pathways were proposed. The results demonstrated that the photoproduct distribution and degradation pathways of CIP adsorbed in the intracrystalline space differed from those in aqueous solution.
虽然抗生素在水溶液中的光解已被广泛研究，以更好地了解其在水相中的光解行为，但关于吸附在固体表面上的抗生素的光降解的知识仍然非常有限。在这项研究中，使用氙灯光源（300 W，λ＞320nm）研究了吸附在蒙脱石（MMT）晶内空间的环丙沙星（CIP），一种氟喹诺酮类抗生素的光降解情况。随着辐照的进行，MMT 的基面间距从 1.66nm 逐渐减小到 1.46nm，这证实了在模拟太阳辐射下 CIP 在晶内空间的分解。经过 5 小时的辐照后，吸附在 MMT 晶内空间的近 70%的 CIP 被降解，反应遵循一级动力学，其速率常数大约是在水溶液中的 3 倍，这表明 CIP 在吸附到 MMT 的晶内空间后具有更高的光降解效率。光谱分析表明，直接光解是主要的光解机制。辐照 MMT 产生的羟基自由基可能起重要作用。通过液相色谱-串联质谱鉴定了主要的光产物，并提出了主要的降解途径。结果表明，吸附在晶内空间的 CIP 的光产物分布和降解途径与在水溶液中的不同。
