Adsorption and Desorption of Heavy Metals from Water using Aminoethyl Reduced Graphene Oxide

Adsorption is a promising method for removing heavy metal ions from wastewater. Primary amine groups can coordinate with most of heavy metal ions to form coordination compounds; therefore, materials with primary amine groups have been employed to adsorb heavy metal ions. Water-dispersible two-dimensional (2D) materials, reduced graphene oxide (RGO) containing primary amine groups, could be a good adsorbent for adsorbing heavy metal ions. In this article, aminoethyl RGO (AERGO) was synthesized by grafting aminoethyl groups on RGO, which contains a lot of hydroxyl groups on its surfaces. The maximum adsorption capacities of AERGO (per gram) were obtained for Pb(II), Ni(II), Cu(II), Co(II), and Zn(II) to be 173.6, 46.2, 58.6, 41.2, and 54.4mg, respectively. Adsorption equilibrium time values of studied heavy metal ions on AERGO were measured to be less than 20min. After four times adsorption/desorption of ions on AERGO, removal efficiencies of regenerated AERGO for Pb(II), Ni(II), Cu(II), Co(II), and Zn(II) were 99.6%, 99.6%, 98.0%, 98.0%, and 98.6%, respectively. AERGO materials exhibited thermo, acid, and basic stabilities. Therefore, AERGO would be an effective and reusable adsorbent for removal of heavy metal ions from wastewater. Adsorption mechanism of AERGO for heavy metal ions was suggested.