Adsorption of Hg(II) from aqueous solution using amino-functionalized graphite nanosheets decorated with Fe3O4 nanoparticles

In this study, the property of 3-aminopropyltriethoxysilane modified graphite nanosheets (GNS) decorated with Fe3O4 nanoparticles (Fe3O4-GNS-NH2 hybrids) for adsorption of Hg(II) in aqueous solution were evaluated by batch methods. The adsorption mechanism was also studied by X-ray photoelectron spectroscopy. The effect of factors, such as pH, contact time, initial concentration of Hg(II) and the GNS content (wt.%) for Fe3O4 in Fe3O4-GNS-NH2 hybrid materials on Hg(II) removal were investigated. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm models. The pseudo-first-order adsorption and the pseudo-second-order adsorption models were used to fit kinetics experimental data. The results showed that the main adsorption mechanism for Hg(II) was the formation of N-metal ions chemical complex, the solution pH value had a major impact on Hg(II) adsorption with optimal removal observed around pH 4.0-6.0, the Langmuir isotherm model was found to be suitable for the Hg(II) adsorption and the adsorption kinetic followed the pseudo-second-order equation for Fe3O4-GNS-NH2 hybrid materials.