College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou, Fujian, 350117, China; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou, Fujian, 350117, China; Institute of Environmental Science, Fujian Normal University, Fuzhou, Fujian, 350117, China.
College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou, Fujian, 350117, China; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou, Fujian, 350117, China.
Chemosphere. 2023 Nov;341:140021. doi: 10.1016/j.chemosphere.2023.140021. Epub 2023 Aug 31.
Tetracycline's (TC) incomplete self-photolysis by light irradiation generally produces toxic intermediate products, which posing serious harm to the aqueous environment. In order to diminish the environmental risks of TC self-photolysis, an iron(III)-alginate (Fe-SA) hydrogel assisted photocatalytic method was developed and the underlying mechanisms was also analyzed in this work. Under simulated sunlight, the photo-degradation efficiency of TC was 61.1% at pH 7.0 within 2 h. Importantly, four of the seven intermediate products that identified during the self-photolysis of TC were found toxic based on QSAR analysis. In contrast, the removal efficiency of TC could be improved to 87.4% by adding Fe-SA under the same conditions. Moreover, only two relatively weakly toxic intermediate products were detected after exposing to the Fe-SA photocatalytic system, indicating a significant reduction of the potential ecological risks caused by TC self-photolysis. Furthermore, the determination of reactive oxidation species (ROS) demonstrated that the addition of Fe-SA primarily facilitated the degradation of TC and the related toxic intermediate products through assisting the free radical (∙OH and ∙O) photocatalytic degradation pathway. Additionally, the photocatalytic application under actual sunlight conditions and the reusability experiments of Fe-SA further confirmed its effectiveness and low cost in removing TC. This study revealed the photodegradation mechanisms of TC from the perspective of the self-photolysis process, and also offering new insights into the removal of TC pollution in the environment.
四环素（TC）在光照下不完全自光解通常会产生有毒的中间产物，对水环境造成严重危害。为了降低 TC 自光解的环境风险，开发了一种铁（III）-海藻酸钠（Fe-SA）水凝胶辅助光催化方法，并在本工作中分析了其潜在的机制。在模拟太阳光下，在 pH 值为 7.0 时，2 小时内 TC 的光降解效率达到 61.1%。重要的是，在 TC 自光解过程中鉴定出的七种中间产物中有四种根据 QSAR 分析具有毒性。相比之下，在相同条件下添加 Fe-SA 可以将 TC 的去除效率提高到 87.4%。此外，在暴露于 Fe-SA 光催化体系后，只检测到两种相对较弱毒性的中间产物，表明 TC 自光解引起的潜在生态风险显著降低。此外，活性氧化物种（ROS）的测定表明，添加 Fe-SA 主要通过辅助自由基（∙OH 和 ∙O）光催化降解途径促进 TC 及其相关有毒中间产物的降解。此外，实际阳光条件下的光催化应用和 Fe-SA 的重复使用实验进一步证实了其在去除 TC 方面的有效性和低成本。本研究从自光解过程的角度揭示了 TC 的光降解机制，并为环境中 TC 污染的去除提供了新的见解。
