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Title: Transport, retention, and size perturbation of graphene oxide in saturated porous media: Effects of input concentration and grain size

Author
item SUN, YUANYUAN - Nanjing Agricultural University
item GAO, BIN - University Of Florida
item Bradford, Scott
item WU, LEI - University Of Florida
item CHEN, HAO - University Of Florida
item SHI, XIAOQING - Nanjing Agricultural University
item WU, JICHUN - Nanjing Agricultural University

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2014
Publication Date: 10/2/2014
Citation: Sun, Y., Gao, B., Bradford, S.A., Wu, L., Chen, H., Shi, X., Wu, J. 2014. Transport, retention, and size perturbation of graphene oxide in saturated porous media: Effects of input concentration and grain size. Water Research. 68:24-33.

Interpretive Summary: Graphene oxide (GO) is an emerging class of carbon nanomaterials that is increasing being used in many industrial applications and is known to be toxic to many organisms. In order to evaluate the environmental impact and potential risk of this new material, an understanding of the transport behavior of GO in soil is needed. Experimental studies were therefore conducted to determine the influence of sand grain size and input concentration on the transport, retention, and aggregation behavior of GO. The transport of GO increased with increasing sand grain size and input concentration level. The size of GO was found to increase with transport distance due to aggregation induced by the flow through the sand. This information will be of use to scientists, engineers, regulators and health professionals concerned with assessing the risks of GO contamination to water resources.

Technical Abstract: Accurately predicting the fate and transport of graphene oxide (GO) in porous media is critical to assess its environmental impact. In this work, sand column experiments were conducted to determine the effect of input concentration and grain size on transport, retention, and size perturbation of GO in saturated porous media. The mobility of GO in the sand columns reduced with decreasing grain size and almost all GO were retained in fine sand columns for all of the tested conditions. This result can be explained with colloid filtration and XDLVO theories. Input concentration also influenced the retention and transport of GO in the sand columns because of the ‘blocking’ mechanism that reduces the particle retention rate. After passing through the column, average GO sizes increased dramatically. In addition, the sizes of GO retained in the sand also increased with travel distance. These results suggested that transport through the porous media induced GO aggregation. A mathematical model based on the advection-dispersion equation coupled with the second-order kinetics to reflect the blocking effect simulated the experimental data well.