Alkynyl carbon materials as novel and efficient sorbents for the adsorption of mercury(II) from wastewater

Abstract

For the first time, a series of alkynyl carbon materials (ACMs) were prepared via the mechanochemical reaction of CaC2 with six polyhalogenated precursors, namely CCl4, C2Cl6, C2Cl4, C6Cl6, C6Br6, and C14H4Br10 (ACM-1, ACM-2, ACM-3, ACM-4, ACM-5, and ACM-6, respectively) and used for the adsorptive removal of mercury from aqueous solutions. Based on preliminary investigations, the adsorption of mercury on ACM-5 was studied in depth. Specifically, the effect of pH on mercury adsorptivity, adsorption kinetics, thermodynamics, isotherms, and recyclability was studied. The adsorptivity of mercury on ACMs was found to be closely related to the hydrocarbon precursor, specific surface area of sorbent, and the alkynyl content. ACM-5 showed the best performance and is among the best raw carbonaceous sorbents reported so far, with a Langmuir saturated adsorption capacity of 191.9mgg−1. The promising mercury adsorption performance mainly arises from the strong Lewis soft acid–soft base interactions between the alkynyl groups and mercury ions. The adsorption isotherms could be satisfactorily correlated with the Langmuir equation. The results show that the ACMs can be used as efficient sorbents for the removal of mercury and may also be useful for the adsorption of other heavy metals.