Xing-Hui Qi

A two-dimensionally microporous thiostannate with superior Cs+ and Sr2+ ion-exchange property

The removal of highly radioactive and long-lived 137Cs+ and 90Sr2+ from solution is of significance for radionuclide remediation. Herein we prepared a two-dimensionally microporous thiostannate, namely (Me2NH2)4/3(Me3NH)2/3Sn3S7·1.25H2O (FJSM-SnS), and systematically investigated its Cs+ and Sr2+ ion-exchange performance in different conditions. The structural stabilities and variation, ion-exchange kinetic and isothermal behavior, pH-dependent distribution coefficients (Kd), ion-exchange in simulated groundwater and ion-exchange applied to chromatography have been investigated. The results indicated that the maximum Cs+ and Sr2+ ion-exchange capacities of FJSM-SnS were 408.91 mg g−1 and 65.19 mg g−1, respectively. In particular, FJSM-SnS showed quick ion-exchange ability and wide pH resistance (0.7–12.7) which make it outstanding among the ion-exchangers. An ion-exchange chromatographic column was firstly studied for chalcogenido ion-exchange materials, that is, a column filled with 3.0 g FJSM-SnS could remove 96–99% of Cs+ ion and near 100% of Sr2+ ion at low ionic concentrations in 900 bed volumes solutions. Furthermore, the title material could be synthesized on a large scale by a facile, one-pot and economical solvothermal method. The relatively low cost but remarkable ion-exchange performance makes it promising for radionuclide remediation.

Syntheses, Crystal Structures, Ion-Exchange, and Photocatalytic Properties of Two Amine-Directed Ge-Sb-S Compounds.

Among numerous heterometallic chalcogenidoantimonates, relatively a few amine-directed Ge-Sb-S compounds have been synthesized. Presented here are the solvothermal syntheses, crystal structures, and ion-exchange, optical, and photocatalytic properties of two novel amine-directed Ge-Sb-S compounds, namely, [CH3NH3]20Ge10Sb28S72·7H2O (1) and [(CH3CH2CH2)2NH2]3Ge3Sb5S15·0.5(C2H5OH) (2). The structure of 1 features an unprecedented two-dimensional Ge-Sb-S double-layer composed of two twofold rotational symmetry-related thick [Ge8Sb28S72]n(28n-) single layers adhered via vertex-sharing [GeS4] tetrahedra. Compound 2 features a unique [Ge3Sb5S15]n(3n-) slab perforated with large elliptic-like windows. Remarkably, compound 1 exhibited excellent Cs(+) ion-exchange property despite the presence of excess competitive cations, such as Na(+), K(+), Mg(2+), and Ca(2+) ions. In addition, compound 1 displayed visible-light-driven photocatalytic activity for degradation of rhodamine B.

[(Me)2NH2][BiGeS4]: the first organically directed bismuth thiogermanate with Rb+ ion exchange property

The first organically directed bismuth thiogermanate, namely [(Me)2NH2][BiGeS4] (), has been solvothermally synthesized and characterized. The structure features a two-dimensional anionic network of [BiGeS4]n(n-), with dimethylammonium as a counterion and a structure-directing agent. is able to undergo ion exchange with Rb(+) ions.

Synthesis, Structure, Band Gap, and Near-Infrared Photosensitivity of a New Chalcogenide Crystal, (NH4)4Ag12Sn7Se22

A new chalcogenide crystal, (NH4)4Ag12Sn7Se22 (FJSM-STS), has been solvothermally synthesized. The crystal structure, which is composed of arrays of [Sn3Se9]n(6n-) chains interconnecting [SnAg6Se10]n(10n-) and [Ag3Se4]n(5n-) layers, is unprecedented among the reported A/Ag/Sn/Q (A = cation; Q = S, Se, and Te) compounds. Optical absorption together with theoretical calculations of the band structure indicate a direct band gap of 1.21 eV for FJSM-STS, which is close to the ideal band gap to maximize the photoconversion efficiency proposed by Shockley and Queisser. The toxic-metal-free crystal of FJSM-STS exhibits obvious photosensitivity in the near-infrared range. The variates of power and temperature on the photosensitivity have been studied.

Efficient Removal of [UO2]2+, Cs+, and Sr2+ Ions by Radiation-Resistant Gallium Thioantimonates

Unconventional ion exchangers can achieve efficient removal of [UO2]2+, Cs+, and Sr2+ ions from complex aqueous solutions and are of great interest for environmental remediation. We report two new gallium thioantimonates, [Me2NH2]2[Ga2Sb2S7]·H2O (FJSM-GAS-1) and [Et2NH2]2[Ga2Sb2S7]·H2O (FJSM-GAS-2), which present excellent ion exchange properties for [UO2]2+, Cs+, and Sr2+ ions. They exhibit high ion exchange capacities for [UO2]2+, Cs+, and Sr2+ ions ( qmU = 196 mg/g, qmCs = 164 mg/g, and qmSr = 80 mg/g for FJSM-GAS-1, qmU = 144 mg/g for FJSM-GAS-2) and short equilibrium times for [UO2]2+ ion exchange (5 min for FJSM-GAS-1 and 15 min for FJSM-GAS-2, respectively). Both compounds display active ion exchange with [UO2]2+ in the pH range of 2.9-10.5. Moreover, the sulfide compounds could maintain high distribution coefficients KdU even in the presence of excess Na+, Ca2+, and HCO3-. The distribution coefficient KdU of 6.06 × 106 mL/g exhibited by FJSM-GAS-1 is the highest among the reported U adsorbents. The [UO2]2+-laden products can be recycled by conveniently eluting the uranium with a low-cost method. These advantages combined with facile synthesis, as well as β and γ radiation resistance, make FJSM-GAS-1 and FJSM-GAS-2 promising for selective separations in nuclear waste remediation.