Effective and regenerable Ag/graphene adsorbent for Hg(II) removal from aqueous solution

A novel Ag/graphene adsorbent was synthesized for the Hg(II) removal from waste water. The Ag/graphene was characterized by Fourier Transformation Infrared Spectrum (FT-IR), X-ray Diffraction (XRD), Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) devices. The results showed that graphene acted as a good support for Ag particles on its huge surface. The removal efficiency of Hg2+ was higher than 98% after 120 min adsorption. The optimized pH value was 5.0. There are no obvious effects of co-existed metal ions (Mn2+, Mg2+, Ca2+, Al3+ and Na+) on Hg2+ removal. Meanwhile, the adsorption isotherms and adsorption kinetics were applied to analyze the experimental data. The best interpretation was given by Freundlich isotherm equation. The kinetic adsorptions were well described by a pseudo-second-order reaction model. Furthermore, the performance of regeneration and reutilization were also investigated. The results indicated that the adsorption capacity remained stable after 6 reuse cycles. (C) 2017 Elsevier Ltd. All rights reserved.