Transport of graphene oxide in saturated quartz sand containing iron oxides

Zhichong Qi; Tingting Du; Pengkun Ma; Fangfei Liu; Wei Chen

doi:10.1016/j.scitotenv.2018.12.143

Transport of graphene oxide in saturated quartz sand containing iron oxides

Sci Total Environ. 2019 Mar 20:657:1450-1459. doi: 10.1016/j.scitotenv.2018.12.143. Epub 2018 Dec 11.

Authors

Zhichong Qi¹, Tingting Du², Pengkun Ma², Fangfei Liu², Wei Chen³

Affiliations

¹ College of Chemistry and Chemical Engineering, Henan Joint International Research Laboratory of Environmental Pollution Control Materials, Henan University, Kaifeng, Henan 475004, China; College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China.
² College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China.
³ College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China. Electronic address: chenwei@nankai.edu.cn.

PMID: 30677911
DOI: 10.1016/j.scitotenv.2018.12.143

Abstract

The environmental implications of graphene oxide (GO) have received much attention. Transport of GO in subsurface environment is a critical process affecting the migration and potential risks of this important class of carbonaceous nanomaterials. To date, the effects of heterogeneity in porous media, in particular, iron oxides, on GO transport are not well studied. In this study, we investigated the transport properties of GO in saturate quartz sand as affected by the presence of iron oxides, using goethite, hematite and ferrihydrite as the model iron oxide species, and applied a two-site transport model (which accounts for both attachment and straining) to fit the transport data. We found that iron oxide coating on sand surfaces markedly inhibited GO transport, mainly due to increased electrostatic attraction between particles and collectors, as the positively charged iron oxides provided favorable deposition sites for the negatively charged GO nanosheets. Additionally, increased surface roughness was likely an additional mechanism leading to the enhanced GO deposition. The extent of transport inhibition by iron oxides also depended on the morphology iron oxides, in that at the same Fe loading a larger effect was observed when iron oxides existed as the coating on sand surface than as discreet particles. The presence of iron oxide coatings (tested using goethite) could magnify the effects of cations on GO transport. Specifically, the presence of goethite facilitated the accumulation of cations on the surface of sand, and in the case of Ca²⁺, the binding of GO via the cation-bridging mechanism was enhanced, as goethite contained abundant surface hydroxyl groups that are strong metal-complexing moieties.

Keywords: Cation bridging; Graphene oxide; Iron oxides; Porous media; Transport.