Uranium is the main source for nuclear energy but also one of the most toxic heavy metals. The current methods for uranium removal from water present limitations, such as narrow pH operating range, limited tolerance to high salt concentrations, or/and high cost. We show here that a layered sulfide ion exchanger K(2)MnSn(2)S(6) (KMS-1) overcomes these limitations and is exceptionally capable in selectively and rapidly sequestering high (ppm) as well as trace (ppb) quantities of UO(2)(2+) under a variety of conditions, including seawater. KMS-1 can efficiently absorb the naturally occurring U traces in seawater samples. The results presented here reveal the exceptional potential of sulfide-based ion-exchangers for remediating of uranium-containing wastes and groundwater and for extracting uranium from the sea.

Metal sulfide ion-exchangers (MSIEs) have emerged as a new class of promising sorbents for the removal of toxic and radioactive metals from wastewater.

In this article, we report the family of robust layered sulfides K 2xMnxSn3-xS6 (x ‫؍‬ 0.5-0.95) (KMS-1). These materials feature hexagonal 2x؊ slabs of the CdI2 type and contain highly mobile K ؉ ions in their interlayer space that are easily exchangeable with other cations and particularly strontium. KMS-1 display outstanding preference for strontium ions in highly alkaline solutions containing extremely large excess of sodium cations as well as in acidic environment where most alternative adsorbents with oxygen ligands are nearly inactive. The implication of these results is that simple layered sulfides should be considered for the efficient remediation of certain nuclear wastes.chalcogenide ͉ environmental remediation ͉ ion exchange ͉ layered materials ͉ nuclear waste C urrent growing interest in nuclear power as a potential solution for global energy may also raise serious environmental and health concerns due to highly radioactive nuclear waste.90 Sr is one of the major heat producers and biohazards in nuclear wastes. The removal of radioactive strontium is essential to reducing the risk of human exposure to radiation and for the considerable cost savings due to minimization of the storage space requirements for the nuclear waste (1, 2). There is a long-standing and continuous research effort to develop highly selective strontium adsorbents for application in a variety of wastes. Inorganic ion exchangers possess a number of advantages as Sr 2ϩ adsorbents over the conventional organic ion-exchange resins, such as superior chemical, thermal, and radiation stability (3). The naturally abundant ion exchangers such as clays (3, 4) and zeolites (3) are not effective as strontium adsorbents in nuclear waste solutions with extreme pH values because of their immediate decomposition (i.e., dissolution of their aluminum). Commercial inorganic adsorbents capable for Sr 2ϩ adsorption in highly alkaline solutions with extremely high salt concentrations [i.e., conditions present in many nuclear waste types (1)] are mainly limited to titanates and silicotitanates (3,5,6). These materials, however, are not effective for Sr 2ϩ capture even at mildly acidic conditions (pH Ͻ 4-5) because protons inhibit ion exchange (7). Only doped antimony silicates represent Sr 2ϩ ion exchangers efficient in strongly acidic environment (pH Յ 1) (8). Finally, solvent extraction and extraction chromatography methods have proven promising for strontium decontamination of acidic and alkaline nuclear wastes (9-11).We show here that layered sulfide compounds with ionexchangeable interlayer cations are not inhibited by protons and can be very efficient Sr 2ϩ -ion-removers over a wide pH range. Layered chalcogenides with ion-exchange properties are relatively few (12-16) and are mainly limited to alkali intercalated early transition metal dichalcogenides A x MQ 2 (A ϭ alkali ion; M ϭ early transition metal from groups 4,5 and 6; Q ϭ S, Se, Te) (13-16). Such materials, however, are not suitable for practical applications because of their hydrolytic...

The development of efficient sensors for the determination of the water content in organic solvents is highly desirable for a number of chemical industries. Presented herein is a Mg(2+) metal-organic framework (MOF), which exhibits the remarkable capability to rapidly detect traces of water (0.05-5 % v/v) in various organic solvents through an unusual turn-on luminescence sensing mechanism. The extraordinary sensitivity and fast response of this MOF for water, and its reusability make it one of the most powerful water sensors known.