Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China; Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China.
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China; Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China; Sino-French Research Institute for Ecology and Environment (ISFREE), School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China; WeiHai Research Institute of Industrial Technology of Shandong University, Weihai 264209, China.
Sci Total Environ. 2024 Jan 20;909:168484. doi: 10.1016/j.scitotenv.2023.168484. Epub 2023 Nov 14.
Zn(II) is a necessary additive during antibiotic production and aquaculture, leading to the coexistence of Zn(II) and antibiotics in aquatic environment, especially in receiving waters of pharmaceutical and aquaculture wastewater. However, the roles of Zn(II) in the photochemical behavior of antibiotics are still not clear, which limits the understanding of the fate of antibiotic in nature. In this study, tetracycline (TC) was selected as typical antibiotic to evaluate the effect of Zn(II) on antibiotic photolysis. The removal of TC was accelerated by 22.75 % with TC:Zn(II) molar ratio at 1:5. The mechanism of Zn(II)-induced TC photolysis was explored via reactive oxygen species (ROS) analysis and density functional theory (DFT) calculation for the first time. Zn(II) could enhance the formation of TC excited states and further produce more singlet oxygen (12.54 % higher than control group) to promote indirect photolysis. Besides, Zn(II) could react with TC via complexation, and the complex was more vulnerable to attack by reactive oxygen species due to more active sites. Furthermore, the structure and toxicity of intermediates were identified with mass spectrometer, T.E.S.T. and ECOSAR software. Zn(II) hardly changed the degradation path of TC, and TC was mainly degraded via ring opening, demethylation, deamidation, and hydrogen abstraction with more toxic intermediates than the parent molecule. This work is significant to better understand the environmental fate of antibiotics, and also provides new insight into wastewater treatment in the pharmaceutical and aquaculture industry.
锌（II）是抗生素生产和水产养殖过程中的必需添加剂，导致锌（II）和抗生素在水生环境中共存，特别是在制药和水产养殖废水的受纳水体中。然而，锌（II）在抗生素光化学行为中的作用仍不清楚，这限制了对抗生素在自然界中归宿的理解。在这项研究中，选择四环素（TC）作为典型抗生素来评估锌（II）对抗生素光解的影响。当 TC:Zn(II)摩尔比为 1:5 时，TC 的去除率提高了 22.75%。首次通过活性氧（ROS）分析和密度泛函理论（DFT）计算探索了 Zn(II)诱导 TC 光解的机制。Zn(II)可以增强 TC 激发态的形成，并进一步产生更多的单线态氧（比对照组高 12.54%），从而促进间接光解。此外，Zn(II)可以通过络合与 TC 反应，由于具有更多的活性位点，络合物更容易受到活性氧的攻击。此外，利用质谱仪、T.E.S.T.和 ECOSAR 软件鉴定了中间体的结构和毒性。Zn(II)几乎没有改变 TC 的降解途径，TC 主要通过开环、去甲基化、去酰胺化和氢提取降解，生成比母体分子更具毒性的中间体。这项工作对于更好地理解抗生素的环境归宿具有重要意义，也为制药和水产养殖行业的废水处理提供了新的思路。
