title: Cation-Inhibited Transport of Graphene Oxide Nanomaterials in Saturated Porous Media: The Hofmeister Effects.
abstract: Transport of negatively charged nanoparticles in porous media is largely affected by cations. To date, little is known about how cations of the same valence may affect nanoparticle transport differently. We observed that the effects of cations on the transport of graphene oxide (GO) and sulfide-reduced GO (RGO) in saturated quartz sand obeyed the Hofmeister series; that is, transport-inhibition effects of alkali metal ions followed the order of Na+< K+< Cs+, and those of alkaline earth metal ions followed the order of Mg2+< Ca2+< Ba2+. With batch adsorption experiments and microscopic data, we verified that cations having large ionic radii (and thus being weakly hydrated) interacted with quartz sand and GO and RGO more strongly than did cations of small ionic radii. In particular, the monovalent Cs+and divalent Ca2+and Ba2+, which can form inner-sphere complexes, resulted in very significant deposition of GO and RGO via cation bridging between quartz sand and GO and RGO, and possibly via enhanced straining, due to the enhanced aggregation of GO and RGO from cation bridging. The existence of the Hofmeister effects was further corroborated with the interesting observation that cation bridging was more significant for RGO, which contained greater amounts of carboxyl and phenolic groups (i.e., metal-complexing moieties) than did GO. The findings further demonstrate that transport of nanoparticles is controlled by the complex interplay between nanoparticle surface functionalities and solution chemistry constituents.
authors.affiliation: 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.
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Xia
authors.affiliation: 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.
authors.forename: Yu
authors.initials: Y
authors.lastname: Qi
authors.affiliation: 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.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: 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.
authors.forename: Zhichong
authors.initials: Z
authors.lastname: Qi
authors.affiliation: 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.
authors.forename: Wei
authors.identifier: 0000-0003-2106-4284
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Civil and Environmental Engineering, Center for the Environmental Implications of NanoTechnology, Duke University , Durham, North Carolina 27708, United States.
authors.forename: Mark R
authors.identifier: 0000-0001-7152-7852
authors.initials: MR
authors.lastname: Wiesner
mesh_terms: D002412:Cations; D006108:Graphite / Q000737:chemistry*; D049329:Nanostructures; D010087:Oxides / Q000737:chemistry*; D016062:Porosity
chemical_list: D002412:Cations; D010087:Oxides; D006108:Graphite