Department of Environmental Science, College of Environmental Science and Engineering, Tongji University, State Key Laboratory of Pollution Control and Resources Reuse, Shanghai 200092, China; Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
Water Res. 2024 Aug 1;259:121807. doi: 10.1016/j.watres.2024.121807. Epub 2024 May 20.
This study examined the distinct effects of algae polysaccharides (AP), namely sodium alginate (SA), fucoidan (FU), and laminarin (LA), on the aggregation of nanoplastics (NP) in seawater, as well as their subsequent transport in seawater-saturated sea sand. The pristine 50 nm NP tended to form large aggregates, with an average size of approximately 934.5 ± 11 nm. Recovery of NP from the effluent (M) was low, at only 18.2 %, and a ripening effect was observed in the breakthrough curve (BTC). Upon the addition of SA, which contains carboxyl groups, the zeta (ζ)-potential of the NP increased by 2.8 mV. This modest enhancement of electrostatic interaction with NP colloids led to a reduction in the aggregation size of NP to 598.0 ± 27 nm and effectively mitigated the ripening effect observed in the BTC. Furthermore, SA's adherence to the sand surface and the resulting increase in electrostatic repulsion, caused a rise in M to 27.5 %. In contrast, the introduction of FU, which contains sulfate ester groups, resulted in a surge in ζ-potential of the NP to -27.7 ± 0.76 mV. The intensified electrostatic repulsion between NP and between NP and sand greatly increased M to 45.6 %. Unlike the effects of SA and FU, the addition of LA, a neutral compound, caused a near disappearance of ζ-potential of NP (-3.25 ± 0.68 mV). This change enhanced the steric hindrance effect, resulting in complete stabilization of particles and a blocking effect in the BTC of NP. Quantum chemical simulations supported the significant changes in the electrostatic potential of NP colloids induced by SA, FU and LA. In summary, the presence of AP can induce variability in the mobility of NP in seawater-saturated porous media, depending on the nature of the weak, strong, or non-electrostatic interactions between colloids, which are influenced by the structure and functionalization of the polysaccharides themselves. These findings provide valuable insights into the complex and variable behavior of NP transport in the marine environment.
本研究考察了海藻多糖（AP），即海藻酸钠（SA）、岩藻聚糖（FU）和昆布多糖（LA），对海水中纳米塑料（NP）聚集的独特影响，以及它们随后在海水饱和海砂中的传输。原始的 50nm NP 倾向于形成大的聚集体，平均大小约为 934.5 ± 11nm。从流出物（M）中回收 NP 的效率很低，只有 18.2%，并且在穿透曲线（BTC）中观察到成熟效应。当加入含有羧基的 SA 时，NP 的 ζ-电位增加了 2.8 mV。这种与 NP 胶体的静电相互作用的适度增强导致 NP 的聚集尺寸减小到 598.0 ± 27nm，并有效地减轻了 BTC 中观察到的成熟效应。此外，SA 附着在砂表面并导致静电排斥增加，导致 M 增加到 27.5%。相比之下，引入含有硫酸酯基团的 FU 导致 NP 的 ζ-电位突升至-27.7 ± 0.76mV。NP 之间以及 NP 和砂之间的静电排斥的加剧大大增加了 M 至 45.6%。与 SA 和 FU 的影响不同，添加中性化合物 LA 导致 NP 的 ζ-电位几乎消失（-3.25 ± 0.68mV）。这种变化增强了空间位阻效应，导致颗粒完全稳定，并在 NP 的 BTC 中产生阻塞效应。量子化学模拟支持了 SA、FU 和 LA 引起的 NP 胶体静电势的显著变化。总之，AP 的存在可以根据胶体之间的弱、强或非静电相互作用的性质，导致海水中饱和多孔介质中 NP 的迁移率发生变化，这受多糖本身的结构和功能化的影响。这些发现为 NP 在海洋环境中的复杂和多变的传输行为提供了有价值的见解。
