Removal of mercury(II) from contaminated water by gold-functionalised Fe3O4 magnetic nanoparticles

ABSTRACTFe3O4 nanoparticles were prepared by co-precipitation of Fe2+ and Fe3+ and then modified with Au to produce an effective adsorbent (Fe3O4/Au) for aqueous Hg(II) in contaminated water. Rietveld refinement on the XRD pattern confirmed that the Fe3O4/Au was synthesised. Mossbauer spectra exhibited broad and asymmetric resonance lines with two sextets which can be assigned to tetrahedral Fe3+; and octahedral Fe3+/Fe2+. The quantitative analysis of magnetite confirms that the sample shows around 3 wt.% Au and 97 wt.% partially oxidised Fe3O4. High surface area: 121 m2 g−1, average pore sizes: 6.3 nm and pore volume: 1.64 cm3 g−1. The kinetics data were better fitted with a pseudo-second-order and Dubinin–Radushkevich isotherm suggests the Hg(II) adsorption onto Fe3O4/Au nanoparticles was mainly by chemical adsorption forming complex with the Au metal immobilised on Fe3O4 surfaces. Adsorption capacity of 79.59 mg g−1. Ionic strength and co-existing ions had a slight influence on the adsorption capacity.