Functionalized three-dimensional (3D) graphene composite for high efficiency removal of mercury

Abstract

The synthesis of a thiol-functionalized graphene composite with a unique three-dimensional porous structure composed of graphene nanosheets decorated with αFeOOH and porous silica microparticles (diatomaceous earth) is presented. The performance of this material for the removal of mercury ions (Hg²⁺) from water is evaluated using a batch adsorption and membrane separation approach. An outstanding adsorption performance of >800 mg g⁻¹ (at 400 mg L⁻¹ Hg²⁺) was demonstrated significantly exceeding currently available benchmark adsorbents. An excellent adsorption performance was confirmed for the efficient (~100%) removal of a low (4 mg L⁻¹) and high (120 mg L⁻¹) concentration of Hg in real water samples using this composite in the form of membranes. The results indicate the versatility of the developed composite to be used in different forms for several water purification scenarios (batch, column, membranes) relevant for both drinking and wastewater treatments. Based on their outstanding performance, low cost, and simple and scalable preparation, the presented 3D graphene composites have a considerable potential for the development of efficient and cost-competitive adsorbents and membranes for environmental applications.