title: Effects of solution chemistry on the transport of graphene oxide in saturated porous media.
abstract: A transport study was performed in saturated porous media through a packed bed column to simulate fate of graphene oxide nanoparticles (GONPs) in the subsurface environment. Transport experiments, along with mass balances and column dissections, were conducted as a function of ionic strength (IS, 10(-3)-10(-1) M). Additionally, an extensive evaluation of the electrokinetic properties and hydrodynamic diameters of GONPs were determined as a function of IS and pH. The measured hydrodynamic diameter and the electrophoretic mobility (EPM) of GONPs indicated an insensitivity to pH, although IS did play a role. Results from a stability study indicated that the hydrodynamic diameter of GONPs was stable and unchanging at the lower range of IS (10(-3) and 10(-2) M) then became unstable when IS ≥ 10(-1.5) M KCl was achieved. Specifically, for IS ≥ 10(-1.5) M KCl, the hydrodynamic diameter became greater and showed a larger size range of particles than at the lower IS range (10(-3) and 10(-2) M). In addition, the EPM of GONPs became less negative over the IS range of 10(-3) and 10(-2) M KCl. Furthermore, GONPs were found to be increasingly mobile for IS ≤ 10(-2) M KCl. When GONPs were passed through the packed bed column at 10(-2) and 10(-1) M KCl, 5% and 100% of the GONPs were retained in the column, respectively. Finally, mass balances and column dissections revealed that in the first cm of the column 7% and 95% of the GONPs were deposited at 10(-2) and 10(-1) M KCl, respectively, confirming that the transport of GONPs is a function of IS. The fraction of GONPs eluted during the transport experiments provides insight into the contribution of aggregation and reversibly bound fraction of GONPs in saturated porous media.
authors.affiliation: Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA.
authors.forename: Jacob D
authors.initials: JD
authors.lastname: Lanphere
authors.forename: Corey J
authors.initials: CJ
authors.lastname: Luth
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Walker
mesh_terms: D024202:Electrophoretic Mobility Shift Assay; D004777:Environment; D006108:Graphite / Q000737:chemistry*; D057446:Hydrodynamics; D053758:Nanoparticles; D009994:Osmolar Concentration; D010087:Oxides / Q000737:chemistry*; D012996:Solutions
chemical_list: D010087:Oxides; D012996:Solutions; D006108:Graphite