Fabrication of novel magnetic graphene oxide nanocomposites for selective adsorption of mercury from aqueous solutions

In this work, a novel functionalized graphene oxide (GO) was used as an effective and selective adsorbent for removal of mercury (Hg²⁺). The magnetic nanocomposite adsorbent (MNA) based on GO was prepared through surface reversible addition–fragmentation chain transfer copolymerization of acrylic monomers and then the formation of Fe₃O₄ nanoparticles. The structure of MNAs was characterized by using FTIR, SEM, TEM, VSM, XRD, and nitrogen adsorption/desorption isotherms. The results of ion adsorption of MNAs demonstrated high selectivity and adsorption efficiency for Hg²⁺ in the presence of competing ions. Furthermore, the removal of Hg²⁺ obeyed a pseudo-second-order model and fitted well to the Langmuir isotherm model with the maximum Hg²⁺ uptake of 389 mg g⁻¹. The MNA was also confirmed as good materials for re-use and maintained 86% of its initial adsorption capacity for mercury after the fifth regeneration cycles. Finally, the experimental results demonstrated that the solution pH, ion concentration, and temperature had a major impact on Hg(II) adsorption capacity. The results indicate that the MNAs with high adsorption abilities could be very promising adsorbents for the selective recovery of ions in wastewater treatment process.