College of Natural Resources and Environment, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, South China Agricultural University, 483 Wushan Road, Guangzhou, Guangdong 510642, China.
Department of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, NJ 08901, United States.
Water Res. 2024 Nov 15;266:122399. doi: 10.1016/j.watres.2024.122399. Epub 2024 Sep 8.
Nanosized activated carbon (NAC) as emerging engineered nanomaterials may interact with nanoplastics prevalent in aquatic environments to affect their fate and transport. This study investigated the effects of particle property (charge and concentration), water chemistry [electrolytes, pH, humic acid (HA), and sodium alginate (SA)], and hydrodynamic condition [wave (i.e., sonication) and turbulence (i.e., stirring)] on the heteroaggregation, disaggregation, and migration of NAC with positively charged amino-modified polystyrene (APS) or negatively charged bare polystyrene (BPS) nanoplastics. The homoaggregation rate of APS was slower than its heteroaggregation rate with NAC, with critical coagulation concentrations (CCC) decreasing at higher NAC concentrations. However, the homoaggregation rate of BPS was intermediate between its heteroaggregation rates under low (10 mg/L) and high (40 mg/L) NAC concentrations. The heteroaggregation rate of APS+NAC enhanced as pH increasing from 3 to 10, whereas the opposite trend was observed for BPS+NAC. In NaCl solution or at CaCl concentration below 2.5 mM, HA stabilized APS+NAC and BPS+NAC via steric hindrance more effectively than SA. Above 2.5 mM CaCl, SA destabilized APS+NAC and BPS+NAC by calcium bridging more strongly than HA. The migration process of heteroaggregates was simulated in nearshore environments. The simulation suggests that without hydrodynamic disturbance, APS+NAC (971 m) may travel farther than BPS+NAC (901 m). Mild wave (30-s sonication) and intense turbulence (1500-rpm stirring) could induce disaggregation of heteroaggregates, thus potentially extending the migration distances of APS+NAC and BPS+NAC to 1611 and 2160 m, respectively. Conversely, intense wave (20-min sonication) and mild turbulence (150-rpm stirring) may further promote aggregation of heteroaggregates, shortening the migration distances of APS+NAC and BPS+NAC to 262 and 552 m, respectively. Particle interactions mainly involved van der Waals attraction, electrostatic repulsion, steric hindrance, calcium bridging, π-π interactions, hydrogen bonding, and hydrophobic interactions. These findings highlight the important influence of NAC on the fate, transport, and risks of nanoplastics in aquatic environments.
纳米级活性炭 (NAC) 作为新兴的工程纳米材料，可能会与水生环境中普遍存在的纳米塑料相互作用，从而影响它们的归宿和迁移。本研究考察了颗粒性质（电荷和浓度）、水化学（电解质、pH 值、腐殖酸 (HA) 和海藻酸钠 (SA)）和水动力条件（波（即超声）和湍流（即搅拌））对带正电的氨基改性聚苯乙烯 (APS) 或带负电的裸聚苯乙烯 (BPS) 纳米塑料与 NAC 的异质聚集、解聚集和迁移的影响。APS 的均聚速率比其与 NAC 的异质聚集速率慢，随着 NAC 浓度的升高，临界聚沉浓度 (CCC) 降低。然而，BPS 的均聚速率在低 (10 mg/L) 和高 (40 mg/L) NAC 浓度下的异质聚集速率之间。当 pH 值从 3 增加到 10 时，APS+NAC 的异质聚集速率增加，而 BPS+NAC 的异质聚集速率则相反。在 NaCl 溶液或 CaCl 浓度低于 2.5 mM 时，HA 通过空间位阻比 SA 更有效地稳定 APS+NAC 和 BPS+NAC。在 2.5 mM CaCl 以上时，SA 通过钙桥联比 HA 更强烈地使 APS+NAC 和 BPS+NAC 不稳定。在近岸环境中模拟了异质聚集体的迁移过程。模拟表明，在没有水动力干扰的情况下，APS+NAC（971 m）可能比 BPS+NAC（901 m）传播得更远。轻度波（30 秒超声）和强烈的湍流（1500 rpm 搅拌）可能会导致异质聚集体的解聚集，从而使 APS+NAC 和 BPS+NAC 的迁移距离分别延长至 1611 m 和 2160 m。相反，强烈的波（20 分钟超声）和温和的湍流（150 rpm 搅拌）可能会进一步促进异质聚集体的聚集，使 APS+NAC 和 BPS+NAC 的迁移距离分别缩短至 262 m 和 552 m。颗粒相互作用主要涉及范德华吸引力、静电排斥、空间位阻、钙桥联、π-π 相互作用、氢键和疏水相互作用。这些发现强调了 NAC 对水生环境中纳米塑料归宿、迁移和风险的重要影响。
