Wei Shuyin, Zeng Feng, Zhou Yingyue, Zhao Jiawei, Wang Hao, Gao Rui, Liang Weiqian
School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
RSC Adv. 2023 Sep 5;13(38):26574-26580. doi: 10.1039/d3ra04027e. eCollection 2023 Sep 4.
Substantial amounts of extracellular polymeric substances (EPS) are present in sludge from wastewater treatment plants (WWTP), and EPS can significantly affect the fate, bioavailability, and toxicity of microplastics (MPs) that coexist in the effluent, however, the mechanism of action between EPS and microplastics remains unclear. In addition, ultraviolet (UV) disinfection is indispensable in the wastewater treatment process in WWTP, which can significantly affect the characteristics of EPS. Therefore, it is of great significance to study the photochemical characteristics of EPS and the effect on binding MPs. In this study, using multispectral technology and two-dimensional correlation spectroscopy analysis, indicates that the molecular weight and aromaticity of EPS after phototransformation were reduced. The results showed that the adsorption of EPS on PSMPs was in the order of TB-EPS > LB-EPS > S-EPS, which was positively correlated with the SUVA, but negatively correlated with O/C of EPS. This indicates that the main adsorption mechanisms of PSMPs on EPS were π-π and hydrophobicity. The adsorption capacity of S-EPS, LB-EPS and TB-EPS to PSMPs decreased with the increasing of illumination time. After phototransformation, the adsorption sensitivity and reaction sequence of EPS and PSMPs did not change much. This research provides a theoretical basis for understanding the photochemical transformation of extracellular polymers and the morphology and migration of microplastics in sewage treatment, and evaluating the impact of microplastics on ecosystems.
污水处理厂（WWTP）的污泥中存在大量的胞外聚合物（EPS），EPS会显著影响共存于废水中的微塑料（MPs）的归宿、生物可利用性和毒性，然而，EPS与微塑料之间的作用机制仍不清楚。此外，紫外线（UV）消毒在污水处理厂的废水处理过程中不可或缺，它会显著影响EPS的特性。因此，研究EPS的光化学特性及其对结合MPs的影响具有重要意义。在本研究中，使用多光谱技术和二维相关光谱分析表明，光转化后EPS的分子量和芳香性降低。结果表明，EPS对聚苯乙烯微塑料（PSMPs）的吸附顺序为TB-EPS > LB-EPS > S-EPS，这与SUVA呈正相关，但与EPS的O/C呈负相关。这表明PSMPs在EPS上的主要吸附机制是π-π作用和疏水性。随着光照时间的增加，S-EPS、LB-EPS和TB-EPS对PSMPs的吸附容量降低。光转化后，EPS与PSMPs的吸附敏感性和反应顺序变化不大。本研究为理解细胞外聚合物的光化学转化以及微塑料在污水处理中的形态和迁移，评估微塑料对生态系统的影响提供了理论依据。
