Transport and numerical simulation of Cu2+ in saturated porous medium in the presence of magnetic nanoparticles.

Fe3O4 magnetic nanoparticles (MNPs) can control and remove heavy metal pollution from wastewater. This approach has gained broad attention due to its excellent surface properties. However, there have been limited studies for Cu2+ retention and transfer regulation in saturated porous media in the presence of MNPs. The objectives of this study were to analyze the migration and deposition mechanism of Cu2+ under different conditions through static adsorption and numerical models. The results indicated that the MNPs-quartz sand had better adsorption capacity for Cu2+ (59.1 mg/kg) than quartz sand only (26.84 mg/kg), and thus it inhibited the migration of Cu2+; the effect improved with increasing MNP content. Furthermore, high ion strength (IS) and flow velocity were beneficial to the migration of Cu2+, and a high pH inhibited the migration of Cu2+. The numerical simulation results showed that the two-site model (TSM) nicely fitted the migration of Cu2+ in quartz sand and MNPs-sand. The migration of Cu2+ in both media was affected by chemical nonequilibrium. We also found that the presence of MNPs had little impact on the dispersion of porous media by observing the fitting parameters D (dispersion coefficient) 0.202 for both media. Our results can evaluate the risk of heavy metal migration and retention in saturated porous media in the presence of nanoparticles; this can prevent aquifer pollution.