College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tong Yan Road 38, Tianjin 300350, China.
Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China.
Sci Total Environ. 2022 Nov 25;849:157800. doi: 10.1016/j.scitotenv.2022.157800. Epub 2022 Aug 4.
Considering the large volumes of treated water and incomplete elimination of pollutants, wastewater treatment plants (WWTPs) remain a considerable source of microplastics (MPs). Chlorine, the most frequently used disinfectant in WWTPs, has a strong oxidizing impact on MPs. However, little is documented, to date, about the impact of chlorination on the transformation of MPs and the subsequent environmental behaviors of the chlorinated MPs when released into the aquatic environment. This study explored the response of the physicochemical properties of specific thermoplastics, namely polyurethane (TPU) MPs and polystyrene (PS) MPs, to chlorination and their emerging pollutant [tetracycline (TC)] adsorption behavior in aqueous solution. The results indicated that the O/C ratio of the MP surface did not significantly change, and that there were increases in the O-containing functional groups of the TPU and PS MPs, after chlorination. The surface area of the chlorinated TPU MPs increased by 45 %, and that of the chlorinated PS increased by 21 %, compared with the pristine ones, which contributed to the TC adsorption. The adsorption isotherm fitting parameters suggested that the chlorinated TPU fitted the multilayer adsorption, and the chlorinated PS was inclined to the monolayer adsorption. The relative abundance of the O-containing functional groups, on the TPU surface, led to the release of CHCl molecules, and the clear surface irregularities and fissures occurred after chlorine treatment. No fissures were found on the surface of the chlorinated PS MPs. The hydrophobicity and electrostatic adsorption were proved to be the major impacts on the TC adsorption of the chlorinated MPs, and the subsequently formed hydrogen bonds led to the stronger adsorption capacity of the chlorinated TPU than the chlorinated PS MPs.
考虑到处理水的巨大体积和污染物的不完全消除，废水处理厂（WWTP）仍然是微塑料（MPs）的一个相当大的来源。氯是 WWTP 中最常用的消毒剂，对 MPs 具有很强的氧化作用。然而，迄今为止，关于氯化对 MPs 转化的影响以及氯化 MPs 释放到水生环境后随后的环境行为的记录很少。本研究探讨了特定热塑性塑料，即聚氨酯（TPU）MPs 和聚苯乙烯（PS）MPs 的物理化学性质对氯化的响应，以及它们在水溶液中对新兴污染物[四环素（TC）]的吸附行为。结果表明，MP 表面的 O/C 比没有明显变化，并且在氯化后，TPU 和 PS MPs 的含氧官能团增加。与原始 MP 相比，氯化 TPU MP 的比表面积增加了 45%，而氯化 PS 的比表面积增加了 21%，这有助于 TC 的吸附。吸附等温线拟合参数表明，氯化 TPU 符合多层吸附，而氯化 PS 倾向于单层吸附。TPU 表面含氧官能团的相对丰度导致 CHCl 分子的释放，并且在氯气处理后表面出现明显的不规则和裂缝。氯化 PS MPs 的表面没有发现裂缝。证明疏水性和静电吸附是氯化 MPs 对 TC 吸附的主要影响，随后形成的氢键导致氯化 TPU 的吸附能力强于氯化 PS MPs。
