Synthesis and characterization of sulfur functionalized graphene oxide nanosheets as efficient sorbent for removal of Pb2+, Cd2+, Ni2+ and Zn2+ ions from aqueous solution: A combined thermodynamic and kinetic studies

Abstract

Abstract A very simple, one pot method was used for preparation of sulfur functionalized graphene oxide (GO-SO x R) with sodium sulfide and water in reflux condition. The elemental analysis data showed high sulfur content up to 15%. EDS and XPS analysis also proved introduction of sulfur element. To make the sorbent more efficient operationally, the GO-SO x R was coated with a mesoporous shell of TiO 2 or SiO 2 . The prepared sorbents were characterized by SEM, TEM, TGA, XPS, XRD, IR and EDS. GO-SO x R@TiO 2 and GO-SO x R@SiO 2 composites were tested for removal of Pb(II), Cd(II), Ni(II) and Zn(II) as heavy metal ions from aqueous solution in batch method. Adsorption of the heavy metal ions was studied kinetically, and the adsorption capacities of GO-SO x R, GO-SO x R@TiO 2 , and GO-SO x R@SiO 2 were evaluated using equilibrium adsorption isotherms, and compared to other adsorbents used for removal of these heavy metals. Kinetic studies showed that the experimental data was fitted with pseudo second order model. The adsorption capacity of GO was significantly improved by sulfur functionalization and TiO 2 coating .