Release of deposited MnO2 nanoparticles from aqueous surfaces

In this study, the release of MnO2 nanoparticles was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D), and different environmental surface types, solution pH values and representative macromolecular organics were considered. MnO2 nanoparticles were first deposited on crystal sensors at elevated NaNO3 concentrations before being rinsed with double-deionized water to induce their remobilization. The results reveal that the release rate of MnO2 depends on the surface type, in the decreasing order: SiO2> Fe3O4 > Al2O3, resulting from electrostatic interactions between the surface and particles. Moreover, differences in solution pH can lead to variance in the release behavior of MnO2 nanoparticles. The release rate from surfaces was significantly higher at pH 9.8 that at 4.5, indicating that alkaline conditions were more favorable for the mobilization of MnO2 in the aquatic environment. In the presence of macromolecular organics, bovine serum albumin (BSA) can inhibit the release of MnO2 from the surfaces due to attractive forces. In presence of humic acid (HA) and sodium alginate (SA), the MnO2 nanoparticles were more likely to be mobile, which may be associated with a large repulsive barrier imparted by steric effects.Graphical abstract
Source: Journal of Environmental Sciences - Category: Environmental Health Source Type: research