Multifunctional Binding Chemistry on Modified Graphene Composite for Selective and Highly Efficient Adsorption of Mercury

Engineering of multifunctional binding chemistry on graphene composites using thiol-ene click reaction for selective and highly efficient adsorption of mercury(II) is demonstrated. Graphene oxide (GO) is used as an initial material for covalent attachment of cysteamine molecules by thiol-ene click reaction on C═C groups to achieve a partially reduced graphene surface with multiple binding chemistry such as O, S, and N. Batch adsorption studies showed remarkable adsorption rate with only 1 mg L^-1 dosage of adsorbent used to remove 95% Hg (II) (∼1.5 mg L^-1) within 90 min. The high adsorption capacity of 169 ± 19 mg g^-1, high selectivity toward Hg in the presence of 30 times higher concentration of competing ions (Cd, Cu, Pb) and high regeneration ability (>97%) for five consecutive adsorption-desorption cycles were achieved. Comparative study with commercial activated carbon using spiked Hg (II) river water confirmed the high performance and potential of this adsorbent for real mercury remediation of environmental and drinking waters.