One-step synthesis of water-dispersible cysteine functionalized magnetic Fe3O4 nanoparticles for mercury(II) removal from aqueous solutions

Cysteine functionalized Fe 3 O 4 magnetic nanoparticles (Cys-Fe 3 O 4 MNPs) were prepared facilely for Hg(II) removal from aqueous solutions. Using Fe 2+ as precursors, air as oxidant and Cys as protectant, this novel material was one-pot synthesis at room temperature by oxidation–precipitation method with the assistance of sonication. The MNPs were characterized by TEM, VSM, FTIR, X-ray powder diffraction analysis (XRD) and TGA methods. Under the optimum experimental conditions, the removal efficiency was as high as 95% and the maximum sorption capacity is found to be 380   mg/mol for Hg(II). Study on adsorption kinetics shows that adsorption of Hg(II) onto Cys-Fe 3 O 4 MNPs follows pseudo-first-order kinetic model and the adsorption rate constant was 0.22   min −1 . Additionally, the Hg(II)-loaded Cys-Fe 3 O 4 MNPs could be easily regenerated up to 95% using 1.0   M acetic acid. These results indicated that Cys-Fe 3 O 4 MNPs is a potentially attractive material for the removal of Hg(II) from water.