Wang Lin, He Yang, Zhu Yanhong, Zhang Jianqiang, Zheng Shijie, Huang Wen
School of Environmental science and Engineering, Southwest Jiaotong University, Chengdu, People's Republic of China.
Environ Technol. 2025 Apr;46(9):1468-1480. doi: 10.1080/09593330.2024.2398812. Epub 2024 Sep 5.
The inevitable UV aging of microplastics (MPs) is one of the key factors affecting their interaction with antibiotics. In this study, polyethylene (PE) and polystyrene (PS) MPs were aged with UV irradiation. The adsorption isotherms and kinetics of ciprofloxacin (CIP) to virgin and aged MPs were investigated through various models, and the effects of pH on the adsorption amount were explored. Characterization revealed that the surfaces of aged MPs became rougher, and the hydrophilicity increased. These aged MPs were still in the early stage of aging on the basis of their carbonyl index (CI) (<0.2) and O/C (<0.04) values. The adsorption isotherms indicated that the adsorption mechanism of aged PE was different from that of virgin PE. Compared with virgin PE, the adsorption amount of aged PE increased by 87.80-95.45%, and the adsorption rate decreased by 65.52-80.74%. However, aging did not significantly affect the equilibrium adsorption amount or adsorption rate of aged PS. The external diffusion rate () (about 2.29-0.36 h) was almost 30 times greater than the internal diffusion rate () in the film-pore mass transfer (FPMT) model, indicating that CIP adsorption rate was dominated by external diffusion. A hydrated functional zone is thought to form around aged MPs, thus changing the adsorption mechanism and adsorption amount of aged PE. Therefore, more attention should be given to alterations in the hydrated functional zone in the early stage of MPs aging.
微塑料（MPs）不可避免的紫外线老化是影响其与抗生素相互作用的关键因素之一。在本研究中，聚乙烯（PE）和聚苯乙烯（PS）微塑料通过紫外线照射进行老化处理。通过各种模型研究了环丙沙星（CIP）对原始和老化微塑料的吸附等温线及动力学，并探讨了pH对吸附量的影响。表征结果显示，老化微塑料的表面变得更粗糙，亲水性增加。基于其羰基指数（CI）（<0.2）和O/C（<0.04）值，这些老化微塑料仍处于老化早期阶段。吸附等温线表明，老化PE的吸附机制与原始PE不同。与原始PE相比，老化PE的吸附量增加了87.80 - 95.45%，吸附速率降低了65.52 - 80.74%。然而，老化对老化PS的平衡吸附量或吸附速率没有显著影响。在膜 - 孔传质（FPMT）模型中，外部扩散速率（约2.29 - 0.36 h）几乎比内部扩散速率大30倍，这表明CIP的吸附速率受外部扩散主导。据认为，老化微塑料周围会形成一个水合功能区，从而改变老化PE的吸附机制和吸附量。因此，在微塑料老化早期阶段，应更多关注水合功能区的变化。
