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

Abstract

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.

Keywords:

• 3-aminopropyltriethoxysilane
• Hybrid materials
• Hg(II)
• Adsorption
• Mechanism

Acknowledgements

The work was financially supported by the National Natural Science Foundation of China (grant number 51403091), the Natural Science Foundation of Gansu Province (grant number 2013GS09508) and the Opening Foundation of State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals of China (grant number SKL1315).