Ma Haozhe, Zhang Chi, Zhang Ziheng, Zhou Zhiyu, Xu Yongliang, Xi Mengning, Zhu Kecheng, Jia Hanzhong
College of Natural Resources and Environment, Northwest A & F University, Xianyang 712100, China.
College of Natural Resources and Environment, Northwest A & F University, Xianyang 712100, China; Key Laboratory of Low-Carbon Green Agriculture in Northwestern China, Ministry of Agriculture and Rural Affairs, Xianyang 712100, China.
Water Res. 2025 Aug 15;282:123638. doi: 10.1016/j.watres.2025.123638. Epub 2025 Apr 12.
The interfacial adsorption, aggregation and deposition processes of nanoplastics (NPs) on clay mineral surfaces critically regulate their environmental mobility, transformation pathways, and ecotoxicological risks in aquatic ecosystems. A quantitative understanding of the nanoscale interfacial processes is essential. This study employs molecular dynamics (MD) simulations and density functional theory (DFT) calculations to elucidate the aggregation and deposition mechanisms of three types of NPs in their pristine and aged states in the nanopore solution of montmorillonite (Mt). In the wet environment, NPs tend to form aggregates in the nanopore and migrate in solution, increasing environmental risk, while in the dry environment, NPs are more likely to deposit on the basal surface to form larger aggregates, consequently reducing their mobility. Results show hydrophobic interactions play as the primary driving force for the aggregation of pristine NPs, and both hydrophilic and hydrophobic interactions contribute to the aggregation of aged NPs. Aged NPs exhibit stronger binding affinity to Mt through mechanism such as Ca²⁺ bridging and hydrogen bonding, compared to their pristine counterparts. DFT calculations further reveal the formation of hydrogen bonds between the hydroxyl groups of aged NPs and the tetrahedral oxygen atoms in Mt. Through atomic-level characterization of interfacial processes, this work establishes a predictive framework for NP environmental behavior by resolving migration dynamics and retention processes in nanopore water.
纳米塑料（NPs）在粘土矿物表面的界面吸附、聚集和沉积过程，对其在水生生态系统中的环境迁移性、转化途径和生态毒理学风险起着关键的调控作用。对纳米尺度界面过程进行定量理解至关重要。本研究采用分子动力学（MD）模拟和密度泛函理论（DFT）计算，以阐明三种类型的纳米塑料在蒙脱石（Mt）纳米孔溶液中原始状态和老化状态下的聚集和沉积机制。在潮湿环境中，纳米塑料倾向于在纳米孔中形成聚集体并在溶液中迁移，增加环境风险；而在干燥环境中，纳米塑料更有可能沉积在基面以形成更大的聚集体，从而降低其迁移性。结果表明，疏水相互作用是原始纳米塑料聚集的主要驱动力，亲水和疏水相互作用都对老化纳米塑料的聚集有贡献。与原始纳米塑料相比，老化纳米塑料通过Ca²⁺桥接和氢键等机制对蒙脱石表现出更强的结合亲和力。DFT计算进一步揭示了老化纳米塑料的羟基与蒙脱石中的四面体氧原子之间形成氢键。通过对界面过程的原子级表征，本研究通过解析纳米孔水中的迁移动力学和保留过程，建立了一个预测纳米塑料环境行为的框架。
