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The detection of antibiotics in environmental water or food is of great importance for protecting human health. New facile methods and high-performance sensory materials for the detection of antibiotics are highly desirable. Herein, we present two isomeric In(III)-MOFs, BUT-172 and BUT-173, which have slightly different three-dimensional (3D) open framework structures consisting of 1D infinite secondary building units (SBUs) and bridging tritopic carboxylate ligands. Both of the MOFs show a high porosity, and their micropore volumes and BET surface areas were estimated to be 0.66 and 0.67 cm3 g−1, and 1357 and 1366 m2 g−1, respectively. Stability tests revealed a high stability of the two MOFs in liquid water at room temperature. BUT-172 even retained its structural integrity in aqueous solutions with the pH values ranging from 3 to 10 at room temperature, and in boiling water for 24 hours. Unexpectedly, BUT-173 was gradually degraded under the same conditions, although the two MOFs are isomeric and have similar 1D infinite SBUs. The stability difference is believed to be related to the different structural symmetries of the two MOFs. In addition, the fluorescence of the two MOFs (suspension in water) can be efficiently and selectively quenched by many fluoroquinolone antibiotics, including ciprofloxacin, one of the most widely used antibiotics worldwide. The limits of detection for sensing the fluoroquinolone antibiotics reach nearly 50 ppb. In contrast, many antibiotics of other types, and even the quinolone antibiotics without a fluorine atom did not show such a strong quenching effect on the fluorescence of the MOFs. The fluorescence detection performance towards the fluoroquinolone antibiotics was not obviously interfered with by various substances (including metal ions, acid, base, and some antibiotics other than fluoroquinolones) that co-existed in the analysis system, and the MOF sample after a detection test could be regenerated for repeated use without an apparent loss of function. The experimental results suggested that the MOFs may serve as potentially useful sensory materials for the detection of a class of important antibiotics, and this work also demonstrates that highly hydrolytically stable In(III)-MOFs could be constructed and used for some meaningful applications in water.

Hexagonal tungsten oxide (hex-WO3) with exchangeable sodium and ammonium cations located in hexagonal channel was synthesized by a facile hydrothermal treatment of sodium tungstate dihydrate in concentrated HCl solution in the presence of ammonium sulfate. An attempt was made to assess the potential of hex-WO3 for the adsorption of Sr2+ ions from acidic radioactive waste solutions. Adsorption of Sr2+ reached equilibrium very quickly in 2 h in acidic aqueous solution. Maximum removal of Sr2+ ions occurred at pH 4. Equilibrium studies showed that the extent of Sr2+ ions uptake by hex-WO3 was better described by the Freundlich isotherm in comparison with the Langmuir model. The thermodynamic parameters showed that the adsorption of Sr2+ ions onto hex-WO3 was spontaneous and exothermic under the studied conditions.

Strontium-90 (90Sr) is the most abundant radionuclide in radioactive wastes, and is typically isolated by treatment with an inorganic ion-exchange material. Most inorganic ion-exchange materials contain oxygen. The ion-exchange chemistry of layered metal sulfides is relatively poorly explored compared with that of oxide ion-exchange materials. Here, a layered metal sulfide (UCR-28), constructed from [ZnGe3S9(H2O)]4− supertetrahedral clusters, was prepared under hydrothermal conditions and used for the removal of Sr2+ ions from aqueous solution. Batch experiments showed that UCR-28 had affinity for Sr2+ ions at pH values ranging from 1 to 10 and the maximum ion-exchange capacity of UCR-28 (50.1 mg/g) was achieved at pH 7. Thermodynamic parameters for the ion-exchange process were evaluated, and the enthalpy and Gibbs free energy results suggested the Sr2+ ion-exchange process was endothermic and spontaneous. The ion-exchange data were a good fit to the Langmuir model. In addition, the metal sulfide reporte...

The adsorption of 125I on palladium coated silver wires was studied in this paper. The experimental conditions, e.g., reaction volume, carrier concentration, reaction time, reaction temperature, pH of the reaction mixture, were systematically optimized to obtain quantitative adsorption of 125I on palladium coated silver wires. The experiments were performed using potassium iodide 8–9 μg as carrier in a reaction volume of 100 μL incubated in ~50 °C water bath for ~1 h, and the pH of the reaction system was controlled at 2–2.5. The distribution of activity on palladium coated silver wire was uniform, and the source cores can be easily sealed by laser welding into titanium capsules.