Size effect of graphene oxide from quantum dot to nanoflake on the mobility of nanoplastics in seawater-saturated sand

Zhiqiang Dong; Zheng Chen; Junnan Rui; Weiying Li; Yuping Qiu

doi:10.1016/j.watres.2023.120491

Size effect of graphene oxide from quantum dot to nanoflake on the mobility of nanoplastics in seawater-saturated sand

Water Res. 2023 Oct 1:244:120491. doi: 10.1016/j.watres.2023.120491. Epub 2023 Aug 14.

Authors

Zhiqiang Dong¹, Zheng Chen², Junnan Rui², Weiying Li², Yuping Qiu³

Affiliations

¹ 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.
² 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.
³ 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. Electronic address: ypqiu@tongji.edu.cn.

PMID: 37598569
DOI: 10.1016/j.watres.2023.120491

Abstract

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_eff) 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_eff = 0%). In brackish water with 3.5 PSU, all GO-8, GO-250 and GO-850 achieved enhanced mobility of NP, with M_eff 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.

Keywords: Brackish water; Graphene oxides; Nanoplastics; Porous media; Seawater; Transport.

MeSH terms

Graphite*
Microplastics
Porosity
Quantum Dots*
Sand
Seawater

Substances

Sand
graphene oxide
Graphite
Microplastics