Dong Zhiqiang, Chen Zheng, Rui Junnan, Li Weiying, Qiu Yuping
College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China; Municipal Environmental Protection Engineering Co., Ltd of CERC Shanghai Group, Shanghai, 201906, China; China Railway Engineering Group Co., Beijing, 100039, China.
College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China.
Water Res. 2023 Oct 1;244:120491. doi: 10.1016/j.watres.2023.120491. Epub 2023 Aug 14.
Marine sedimentary environment serves as an important sink of terrigenous nanoplastics (NP) and graphene oxides (GO). In this study, we discovered that GO of varying sizes exhibited distinct binding modes with 200 nm NP in 35 practical salinity unit (PSU) seawater, resulting in varying impacts on the mobility of NP in porous media. GO-8, with a size of 8±2 nm, firmly adhered to the surface of NP and formed stable primary heterogeneous aggregates, which promoted NP mobility and increased the mass recovery of effluent (M) from 24.74% to 31.08%. GO-250 (246±10 nm) partly enveloped NP and only slightly increased the volume of heteroaggregates, which had minimal effect on NP transport. Conversely, GO-850 (855±55 nm) wrapped numerous NP particles to form large secondary heteroaggregates that clung to sand surfaces, providing additional attachment sites for NP, resulting in complete inhibition of NP mobility in porous media (M = 0%). In brackish water with 3.5 PSU, all GO-8, GO-250 and GO-850 achieved enhanced mobility of NP, with M increasing from 50.35% to 85.62%, 69.45% and 75.41%, respectively. The results indicate that GO size effects on NP mobility are also salinity-dependent.
海洋沉积环境是陆源纳米塑料（NP）和氧化石墨烯（GO）的重要汇。在本研究中，我们发现不同尺寸的GO在35实用盐度单位（PSU）海水中与200 nm的NP表现出不同的结合模式，从而对NP在多孔介质中的迁移产生不同影响。尺寸为8±2 nm的GO-8牢固地附着在NP表面，形成稳定的初级异质聚集体，促进了NP的迁移，并使流出物的质量回收率（M）从24.74%提高到31.08%。GO-250（246±10 nm）部分包裹NP，仅略微增加了异质聚集体的体积，对NP的迁移影响最小。相反，GO-850（855±55 nm）包裹了许多NP颗粒，形成大的次级异质聚集体，这些聚集体附着在沙子表面，为NP提供了额外的附着位点，导致NP在多孔介质中的迁移完全受到抑制（M = 0%）。在盐度为3.5 PSU的微咸水中，所有的GO-8、GO-250和GO-850都实现了NP迁移的增强，M分别从50.35%增加到85.62%、69.45%和75.41%。结果表明，GO对NP迁移的尺寸效应也取决于盐度。
