Effects of phosphate on the transport of graphene oxide nanoparticles in saturated clean and iron oxide-coated sand columns

In this study, transport behaviors of graphene oxide (GO) in saturated uncoated (i.e., clean sand) and goethite-coated sand porous media were examined as a function the phosphate. We found that phosphate enhanced GO over wide range solution chemistry pH 5.0–9.0 presence 10 mmol/L Na+ or 0.5 Ca2+). The results mainly ascribed to increase electrostatic repulsion between nanoparticles media. Meanwhile, deposition site competition induced by retained was another important mechanism leading promote transport. Interestingly, when concentration increased from 0.1 1.0 mmol/L, transport-enhancement effect much larger extent than sand. observations primarily related difference total mass iron oxide-coated columns, which resulted different degrees competitive When background contained Ca2+, could be bind sand/ surface cation bridging; consequently, promoted for sites, an Moreover, DLVO theory applicable describe absence Taken together, these findings highlight status role on fate colloidal subsurface environment.