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]_0.6Ga_2.2Sn_1.8S₈·H₂O (GaSnS-1; TAEA = Tris(2-aminoethyl)amine). GaSnS-1 features a three-dimensional (3D) zeolite-typed (RWY) framework structure of [Ga_2.2Sn_1.8S₈] _n^{2.2 n-} that is constructed by corner-sharing of supertetrahedral [Ga_2.2Sn_1.8S₁₀]^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 K_d 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.