Supramolecular receptors in solid phase: developing sensors for anionic radionuclides

Abstract

New solid-phases for the binding, separation and extraction of perrhenate and pertechnetate (ReO(4)(-) and TcO(4)(-)) from water solutions have been developed from a selective molecular receptor. Host compounds being capable of encapsulating these oxoanions are of great interest. The azacryptand, containing two tripodal tetra-amine subunits covalently linked by p-xylyl spacers, is known to display high affinity for ReO(4)(-) and TcO(4)(-) in water. The syntheses of new solid phases, obtained by fixing the receptor on mesoporous silica MCM-41 and Amberlite CG50 supports, are here described. FT-IR, micro-Raman, elemental analysis (CHN), sorption isotherms, (29)Si MAS NMR, and SEM/EDS were employed for solids characterisation. Promising performances were found for silica derivatives, for which the amount of the receptor fixed on silica ranged from 0.2 to 0.3 mmol g(-1). The perrhenate sorption mechanism was investigated with the aim to select the conditions for application in batch and fixed bed column systems.

Anion-adaptive crystalline cationic material for 99TcO4− trapping

“…A rational approach for improving the selectivity of solid sorbents is to give sorbent materials an ideal ion-recognition capability by direct functionalization of traditional solid sorbents with covalently attached anion receptors (Fig. 1a) 30,31 , but unfortunately, chemical modification method generally suffers from the necessity for elaborate syntheses and possible deactivation of functional recognition groups after implanting in bulk materials. Herein, inspired by molecular recognition of anion receptors, we put forward an alternative tactic that circumvents this drawback via an easily prepared anion-adaptive sorbent material that can behave like an anion receptor itself (Fig.…”

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

“…TcO 4 – is the most dominant environmental form of the radioelement Tc present in groundwater matrices; the most stable isotope of the element technetium-99 ( 99 Tc) is produced in the nuclear fuel cycle as a fission product of uranium-235 ( 235 U) and plutonium-239 ( 239 Pu) . The long half-life of 99 Tc (2.13 × 10 5 years) and highly mobile subsurface transport properties of 99 TcO 4 – generate considerable environmental and health concerns and render 99 Tc to be among the most hazardous radiation-derived contaminants in nuclear waste and the effluents therefrom . In situ monitoring of 99 Tc in water systems can be challenging due to the low detection limits required for safe drinking water (for example, the safe drinking water limit established by the Environmental Protection Agency of the United States is 5.2 × 10 –10 M or 900 pCi/L).…”

Weak and Reversible Binding of Alkali Metal Ions (Na+/K+) by an Aza‐Oxa Cryptand

“…These cages can be used for capturing cations, anions as well as small molecules according to the cavity size and presence of donor atoms or functional groups at strategic positions . Capturing of the guest is effective when cryptands are immobilized in a solid phase or nanomaterials . Presence of donor atoms such as N, P or S in a cryptand have a strong tendency to bind transition and heavy metal ions inside the cavity.…”