Currently, the hidden risk of microplastics in the coagulation process has attracted much attention. However, previous studies aimed at improving the removal efficiency of microplastics and ignored the importance of interactions between microplastics and natural organic matter (NOM). This study investigated how polystyrene micro/nano particles impact the release of NOM during the aging of flocs formed by aluminum-based coagulants Al and AlCl. The results elucidated that nano-particles with small particle sizes and agglomerative states are more likely to interact with coagulants. After 7 years of floc aging, the DOC content of the nano system decreased by more than 40%, while the micron system did not change significantly. During coagulation, the benzene rings in polystyrene particles form complexes with electrophilic aluminum ions through π-bonding, creating new Al-O bonds. NOM tends to adsorb at micro/nano plastic interfaces due to hydrophobic interactions and conformational entropy. In the aging process, the structure of PS-Al or PS-AlCl flocs and the functional groups on the surface of micro/nano plastics control the absorption and release of organic matter through hydrophobic, van der Waals forces, hydration, and polymer bridging. In the system with the addition of nano plastics, several DBPs such as TCAA, DCAA, TBM, DBCM and nitrosamines were reduced by more than 50%. The reaction order of different morphological structures and surface functional groups of microplastics to Al and AlCl systems is aromatic C-H > C-OH > C-O > NH > aromatic CC > aliphatic C-H and C-O>H-CO> NH >C-OH> aliphatic C-H. The results provided a new sight to explore the effect of micro/nano plastics on the release of NOM during flocs aging.

中文翻译：

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聚苯乙烯微纳米塑料表面官能团对老化过程中絮体NOM释放的影响


目前，微塑料在混凝过程中隐藏的风险备受关注。然而，先前的研究旨在提高微塑料的去除效率，而忽略了微塑料与天然有机物（NOM）之间相互作用的重要性。本研究研究了聚苯乙烯微/纳米颗粒如何影响铝基混凝剂 Al 和 AlCl 形成的絮体老化过程中 NOM 的释放。结果表明，具有小粒径和团聚状态的纳米颗粒更容易与混凝剂相互作用。经过7年的絮体老化，纳米体系的DOC含量下降了40%以上，而微米体系没有明显变化。在凝结过程中，聚苯乙烯颗粒中的苯环通过π键与亲电铝离子形成络合物，产生新的Al-O键。由于疏水相互作用和构象熵，NOM 倾向于吸附在微/纳米塑料界面上。在老化过程中，PS-Al或PS-AlCl絮体的结构和微纳米塑料表面的官能团通过疏水性、范德华力、水化和聚合物桥联控制有机物的吸收和释放。在添加纳米塑料的体系中，TCAA、DCAA、TBM、DBCM和亚硝胺等多种DBP减少了50%以上。微塑料不同形态结构和表面官能团对Al和AlCl体系的反应顺序为芳香族C-H>C-OH>C-O>NH>芳香族CC>脂肪族C-H和C-O>H-CO>NH>C-OH>脂肪族C-H 。研究结果为探讨微纳米塑料对絮体老化过程中NOM释放的影响提供了新的视角。