Fast and Effective Decontamination of Aqueous Mercury by a Highly Stable Zeolitic-like Chalcogenide.

Highly efficient and effective removal of mercury from water, especially at very low ionic concentration, remains a grand challenge for ecosystem protection and human health. Herein, we present the synthesis, crystal structure, and mercury uptake performance of a new heterometallic chalcogenidometalate, namely, [TAEAH][TAEAH2]0.6Ga2.2Sn1.8S8·H2O (GaSnS-1; TAEA = Tris(2-aminoethyl)amine). GaSnS-1 features a three-dimensional (3D) zeolite-typed (RWY) framework structure of [Ga2.2Sn1.8S8] n2.2 n- that is constructed by corner-sharing of supertetrahedral [Ga2.2Sn1.8S10]6.2- T2 clusters. The equilibrium model study indicated that the maximum Hg2+ saturation capacity of GaSnS-1 was 213.9 mg/g. GaSnS-1 possessed extremely rapid adsorption kinetics following the pseudo-second-order model with a k2 of 5.65 × 102 g·mg-1·min-1. Particularly, GaSnS-1 exhibited excellent selectivity for Hg2+ ions with a high distribution coefficient Kd value of 1.62 × 107 mL/g and high removal efficiency of close to 100%. The superior Hg2+ ion adsorption performance was also impressive despite the presence of excessive competing cations and the acidic/basic conditions. Furthermore, a simple chromatographic column loaded with GaSnS-1 microcrystals is capable of rapidly and effectively capturing Hg2+ ions far below the upper limit (2 ppb, USA-EPA) of drinking water. These advantages of GaSnS-1 make it a promising candidate for the fast and efficient remediation of Hg2+-contaminated water sources.