A novel Sulfur-functionalized alkynyl carbon material for highly efficient removal of Hg(II) from water

Abstract

In this work, a novel sulfur-functionalized alkynyl carbon materials (SACMs) were synthesized by mechanochemical reaction of CaC2 and CS2 with rich sulfur and alkynyl functional groups, as well as high porosity and surface area. Their sulfur content varies from 4.1 % to 39.8 %, depending on the stoichiometric ratio of the reactants used. The SACM-2 exhibits extremely high mercury uptake capacity (500 mg-Hg⋅g−1 at ca. 2 μg.g-1 of equilibrium Hg(II) concentration), being one of the best adsorbents, and it showed favorable recyclability after 5 cycles. The adsorption behavior follows the Freundlich and the pseudo second-order kinetic model, respectively. The SACM-2 was examined for aqueous phase adsorption of mercury, cadmium, lead, and copper ions. Its affinity for neat heavy metals was in the order of Hg(II) > Cd (II) > Pb(II) > Cu(II). The high-efficiency adsorption of Hg(II) was mainly attributed to the sulfur and alkynyl functional groups as well as their synergestic effect for specific soft acid-soft base interaction between adsorbent and the heavy metal ions. Overall, our work not only reports a promising material for removal of heavy metals-containing wastewater, but inspires the value-added utilization of CS2 in preparing other highly sulfureted materials.