Study on the adsorption of Hg(ii) by one-pot synthesis of amino-functionalized graphene oxide decorated with a Fe3O4 microsphere nanocomposite

Abstract

An easy one-pot solvothermal strategy approach has been reported on the preparation of ethylenediamine (EDA) decorated with magnetite/graphene oxide (EDA–Fe₃O₄/GO) nanocomposites and employed as a recyclable adsorbent for Hg(II) in aqueous solution. Taking advantage of the combined benefits of graphene and magnetic nanoparticles, these EDA–Fe₃O₄/GO nanocomposites exhibit an excellent adsorption capacity (127.23 mg g⁻¹) much higher than that of Fe₃O₄ microspheres and rapid separation from aqueous solution by an external magnetic field. The adsorption isotherm data and the kinetics of the adsorption process were fitted using the Langmuir equation and a pseudo-second-order kinetic model. The results of the thermodynamic parameters ΔH, ΔS and ΔG showed that the adsorption process was endothermic and spontaneous. The graphene oxide (GO) sheets could not only prevent agglomeration of the Fe₃O₄ microspheres and enable a good dispersion of these oxide microspheres, but also substantially enhance the specific surface area of the composite. Therefore, the EDA–Fe₃O₄/GO nanocomposites may be a promising sorption material for the separation and preconcentration of heavy metal ions from aqueous solutions in environmental pollution cleanups.