Key Laboratory of Surficial Geochemisty, Ministry of Education, School of Earth Sciences and Engineering, Hydrosciences Department, Nanjing University, Nanjing 210023, China.
Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, United States.
J Hazard Mater. 2019 May 5;369:334-341. doi: 10.1016/j.jhazmat.2019.02.042. Epub 2019 Feb 12.
Graphene oxide (GO) has been indicated to be biotoxic and risky in environment, its environmental behavior thus has received increasing attention in recent. In this study, homogeneous and heterogeneous sand tanks were used to examine the transport behaviors of GO nanoparticles in two-dimensional (2-D) porous media under various conditions. Light transmission visualization (LTV) technology was applied to visualize the real-time transport, retention, and release of GO. GO transport in 2-D porous media was simulated with a simplified Double Monod model. GO mobility decreased with the increasing solution ionic strength (IS) and decreasing media grain size. Preferential flow played an important role in GO transport in 2-D heterogeneous porous media. Even without vertical flow in the sand tanks, GO still spread vertically through dispersion, suggesting the importance of the dispersion process to nanoparticle fate and transport in 2-D porous media. LTV images and breakthrough curves showed that some of the previous retained GO particles were instantaneously remobilized with IS decreasing. With the consideration of the vertical dispersion, simulations of the Double Monod model matched the experimental data well. Findings from this work contribute to expand current knowledge of environmental fate and transport of GO, leading to better assessment and prediction of its environmental risks.
氧化石墨烯（GO）已被表明具有生物毒性和环境风险，因此其环境行为在最近受到了越来越多的关注。本研究采用均相和非均相砂槽，研究了在不同条件下二维（2-D）多孔介质中 GO 纳米颗粒的输运行为。采用透光可视化（LTV）技术实时可视化 GO 的输运、保留和释放。用简化的双单分子层模型模拟了 2-D 多孔介质中 GO 的输运。随着溶液离子强度（IS）的增加和介质粒径的减小，GO 在 2-D 多孔介质中的迁移性降低。优先流在 2-D 非均质多孔介质中 GO 的输运中起着重要作用。即使在砂槽中没有垂直流动，GO 仍然通过弥散垂直扩散，这表明在 2-D 多孔介质中，弥散过程对纳米颗粒的命运和输运非常重要。LTV 图像和穿透曲线表明，随着 IS 的降低，一些先前保留的 GO 颗粒会瞬间重新迁移。考虑到垂直弥散，双单分子层模型的模拟与实验数据吻合较好。这项工作的结果有助于扩展 GO 在环境中的归宿和输运的现有知识，从而更好地评估和预测其环境风险。
