Sun Ningyu, Wang Huimin, Zhang Xinbo, Chen Zeyou, Peng Anping
Tianjin Key Laboratory of Aquatic Science and Technology, School of Environmental and Municipal Engineering, Tianjin Chengjian University, No.26, Jinjing Rd, Xiqing District, Tianjin, 300384, China.
Joint Research Centre for Protective Infrastructure Technology and Environmental Green Bioprocess, School of Environmental and Municipal Engineering, Tianjin Chengjian University, No.26, Jinjing Rd, Xiqing District, Tianjin, 300384, China.
Environ Sci Pollut Res Int. 2024 Dec;31(59):67024-67034. doi: 10.1007/s11356-024-35719-z. Epub 2024 Dec 10.
Norfloxacin (NOR) is frequently detected in various water bodies and has the potential to promote the proliferation of NOR-resistant bacteria/genes in the environment. Efficiently removing residual NOR and NOR-resistant bacteria from contaminated water is critical to mitigating their environmental risks. This study investigated the ability of two common clay minerals, kaolinite and montmorillonite, to remove NOR and NOR-resistant bacteria from five different water environments (ultrapure water, simulated and real freshwater, and simulated and real seawater) and explored the underlying removal mechanisms. The results showed that both clays adsorbed NOR according to a pseudo-first-order kinetic model. In simulated and actual freshwater and seawater, the adsorption of NOR by kaolinite was 0.199, 0.120, 0.094, and 0.010 mg g, while montmorillonite adsorbed NOR at significantly higher levels, with values of 2.880, 2.208, 0.433, and 0.067 mg g, respectively. The primary mechanisms of adsorption included electrostatic interactions, cation exchange, and cation bonding and bridging. In addition to NOR sorption, culture tests revealed that montmorillonite exhibited significant antibacterial activity against NOR-resistant bacteria, achieving an inhibition ratio of 83.84 ± 4.01% when the initial concentrations of bacteria and montmorillonite were 1.68 ± 1.00 × 10 CFU·mL and 40 mg mL, respectively. Remarkably, montmorillonite maintained its high sorption capacity and antibacterial activity even after multiple reuse cycles. These findings highlight the promising application potential of montmorillonite, particularly in terms of its storage and long-distance distribution capabilities, making it an effective material for removing both NOR and NOR-resistant bacteria from the environment. However, it is important to note that under estuarine conditions, clay-bound NOR could be released if water quality changes. Therefore, we conclude that strategies to degrade and remove antibiotics adsorbed onto clay minerals should be developed to prevent the release of antibiotics when clay particles enter the ocean, thus avoiding further environmental contamination.
诺氟沙星（NOR）在各种水体中经常被检测到，并且有可能促进环境中耐诺氟沙星细菌/基因的增殖。从受污染的水中有效去除残留的诺氟沙星和耐诺氟沙星细菌对于减轻其环境风险至关重要。本研究调查了两种常见的粘土矿物高岭土和蒙脱石从五种不同水环境（超纯水、模拟和实际淡水以及模拟和实际海水）中去除诺氟沙星和耐诺氟沙星细菌的能力，并探讨了潜在的去除机制。结果表明，两种粘土均根据准一级动力学模型吸附诺氟沙星。在模拟和实际淡水及海水中，高岭土对诺氟沙星的吸附量分别为0.199、0.120、0.094和0.010 mg/g，而蒙脱石对诺氟沙星的吸附量明显更高，分别为2.880、2.208、0.433和0.067 mg/g。吸附的主要机制包括静电相互作用、阳离子交换以及阳离子键合和桥连。除了诺氟沙星吸附外，培养试验表明蒙脱石对耐诺氟沙星细菌表现出显著的抗菌活性，当细菌和蒙脱石的初始浓度分别为1.68±1.00×10 CFU·mL和40 mg/mL时，抑制率达到83.84±4.01%。值得注意的是，即使经过多次重复使用循环，蒙脱石仍保持其高吸附容量和抗菌活性。这些发现突出了蒙脱石的潜在应用潜力，特别是在其储存和长距离分布能力方面，使其成为从环境中去除诺氟沙星和耐诺氟沙星细菌的有效材料。然而，需要注意的是，在河口条件下，如果水质发生变化，粘土结合的诺氟沙星可能会释放。因此，我们得出结论，应制定降解和去除吸附在粘土矿物上的抗生素的策略，以防止粘土颗粒进入海洋时抗生素的释放，从而避免进一步的环境污染。
