Mobility of Li+, Na+, and Cs+ cations in Nafion membrane,as studied by NMR techniques

The local mobility and diffusion of Li⁺, Na⁺, and Cs⁺ cations in Nafion 117 membrane were explored by ⁷Li, ²³Na, and ¹³³Cs spin relaxation and pulsed field gradient NMR techniques. It was shown that the macroscopic mass transfer of cations is controlled by ion motion near sulfonate groups. Lithium and sodium cations, whose hydrated energy is higher than the water hydrogen bond energy, are moving together with water molecules, but cesium cations possessing a low hydrated energy are jumping directly between the neighboring sulfonate groups.     

Highly conducting solid electrolytes based on poly (ethylene oxide-co-propylene oxide)

The conducting properties of solid electrolytes comprising random poly(ethylene oxide-co-propylene oxide) (of 84 : 16 monomer units mole ratio) and lithium, sodium, potassium, cesium, and rubidium salts have been studied. The systems containing some lithium or sodium salts achieved conductivity levels as high as 10^?5–10^?4 S/cm at ambient temperature and greater than 10^?3 S/cm at 100°C. However, the systems with rubidium and cesium salts exhibit conductivities a few orders of magnitude smaller. DSC studies show that the electrolytes studied are characterized by a high content of an amorphous phase (95–100%). It is suggested that the copolymer exhibits lower complexing abilities than that of poly(ethylene oxide), which results in a higher flexibility of electrolytes containing small cations and poor dissociation of the salts having large cations. © 1995 John Wiley & Sons, Inc.     

FIA Potentiometric and Solvent Extraction Studies of Alkali Metal and Alkaline Earth Cation Complexation by bis(Tert-butylbenzo)-21-crown-7

Abstract

A flow injection analysis study of the potentiometric selectivity of bis[4(5)-tert-butylbenzo]-21-crown-7 (D(tBB)21C7) for cesium over the other alkali metal cations and three alkaline earth cations has been conducted. A PVC matrix membrane containing D(tBB)21C7 as an ionophore was coated on the tip of a silver wire incorporated in a flow cell. No selectivity for cesium over rubidium and only low selectivity over potassium were noted. However, very high selectivities for cesium over sodium, lithium, strontium, calcium, and magnesium were observed. Selectivity of D(tBB)21C7 in the solvent extraction of alkali metal cations was determined by the picrate extraction method. The percent extraction into deuteriochloroform decreased in the order cesium, rubidium > potassium » sodium » lithium. Thus good agreement was observed between the responses of D(tBB)21C7 towards alkali metal cations in polymeric membrane electrodes and in solvent extraction.     

Interaction of the cesium cation with mono-, di-, and tricarboxylic acids in the gas phase. A Cs+ affinity scale for cesium carboxylates ion pairs

Humic substances (HS), including humic and fulvic acids, play a significant role in the fate of metals in soils. The interaction of metal cations with HS occurs predominantly through the ionized (anionic) acidic functions. In the context of the effect of HS on transport of radioactive cesium isotopes in soils, a study of the interaction between the cesium cation and model carboxylic acids was undertaken. Structure and energetics of the adducts formed between Cs⁺ and cesium carboxylate salts [Cs⁺RCOO⁻] were studied by the kinetic method and density functional theory (DFT). Clusters generated by electrospray ionization mass spectrometry from mixtures of a cesium salt (nitrate, iodide, trifluoroacetate) and carboxylic acids were quantitatively studied by CID. By combining the results of the kinetic method and the energetic data from DFT calculations, a scale of cesium cation affinity, CsCA, was built for 33 cesium carboxylates representing the first scale of cation affinity of molecular salts. The structural effects on the CsCA values are discussed.     

Author index for volume 52

Dehydrated samples of zeolite Y containing alkali-metal cations have been reacted with alkali-metal vapor in sealed silica tubes, and the products studied by electron-spin resonance (ESR) spectroscopy. Two distinct species were detected following the reaction of sodium-exchanged zeolite Y with sodium, potassium, or rubidium vapor. Exposure to a low concentration of metal vapor resulted in brightly colored samples with ESR signals characteristic of a stable ionic cluster species Na³⁺₄, in which an unpaired electron is trapped on four equivalent sodium cations in the sodalite cages of the zeolite. Exposure to higher concentrations of metal vapor resulted in dark-colored samples with ESR signals characteristic of small metallic particles located inside the zeolite cavities. A similar ionic cluster species K³⁺₄ was detected following the reaction of potassium-exchanged zeolite Y with sodium or potassium vapor although the potassium cluster was less stable than its sodium counterpart and an ESR signal from small metallic particles was observed at the same time. The corresponding Rb³⁺₄ ionic cluster species was not detected following the reaction of rubidium-exchanged zeolite Y with rubidium vapor; only an ESR signal from small metallic particles was observed. The narrow linewidths of the ESR signals from the small metallic particles suggest an inhibition of the spin-relaxation mechanisms in the bulk metals.     

Extraction of cesium and barium by dicarbollide and polyethylene glycol in the presence of alkylammonium cations

The extraction of cesium and barium cations into nitrobenzene and 60% (vol.%) nitrobenzene +40% CCl₄ mixture in the presence of dicarbollide (+Slovafol 909), and primary alkylammonium cations has been studied. Extraction constants determined for three methylammonium cations correlate well with their hydration enthalpies. Reverse order of the hydrophobicity of methylammonium cations (competition with bare Cs⁺ ion) and of their tendency to enter the polyethylene glycol complex (competition with polyethylene glycol complexed Cs⁺ and Ba²⁺ ions) is recorded. The possibility of the regeneration of the organic phase after stripping of Cs⁺ and Ba²⁺ ions with methylammonium cations has been investigated.     

A new hetero-bimetallic coordination polymer, cesium, and sodium complex of styphnate trihydrate [CsNa(TNR)(H2O)3] n

A new hetero-bimetallic coordination polymer, cesium, and sodium complex of styphnate trihydrate [CsNa(TNR)(H₂O)₃] _n (TNR: 2,4,6-trinitroresorcinol dianion, the dianion of styphnic acid) was synthesized. The title complex was characterized by X-ray single crystal diffraction, element analysis, FT-IR, DSC, TG-DTG studies. In the title polymer molecule, the cesium cation is coordinated by 13 oxygen atoms: three originated from the water molecule and the others are from the nitro group and the phenolic hydroxyl group of TNR; the sodium cation is surrounded by six oxygen atoms from water molecules and TNR forming a distorted octahedron. The coordination polymer crystal was formed by the bridging ligands of water molecules and TNR connected with different cesium and sodium cations.     

The effect of the synthesis method on the parameters of pore structure and selectivity of ferrocyanide sorbents based on natural minerals

Ferrocyanide sorbents were obtained via thin-layer and surface modification of natural clinoptilolite and marl. The effect of modification method on surface characteristics of these sorbents and their selectivity for cesium was studied. It was shown that the modification resulted in an increase of selectivity of modified ferrocyanide sorbents to cesium as compared with the natural clinoptilolite in presence of Na⁺, as well as in an increase of cesium distribution coefficients in presence of K⁺. The nickel–potassium ferrocyanide based on the clinoptilolite showed the highest selectivity for cesium at sodium concentrations of 10^?4—2 mol L^?1: cesium distribution coefficient was lg K _d = 4.5 ± 0.4 L kg^?1 and cesium/sodium separation factor was α(Cs/Na) = 250. In the presence of NH₄ ⁺, all modified sorbents showed approximately equal selectivity for ¹³⁷Cs. Probable applications of the sorbents were suggested.     

Syntheses and crystal structures of three cesium salts: Cesium 5-sulfosalicylate, cesium 3,5-dinitrosalicylate and cesium 2,4-dinitrophenoxide monohydrate

In an attempt to probe a potential template role of the large alkali-metal cation cesium in organization of biorelevant ligands, 5-sulfosalicylate, 3,5-dinitrosalicylate and 2,4-dinitrophenol complexes of cesium were prepared and structurally investigated. The structures of cesium 5-sulfosalicylate, cesium 3,5-dinitrosalicylate and cesium 2,4-dinitrophenoxide monohydrate have been determined through X-ray diffraction analysis. The 5-sulfosalicylate anion has lost the proton at the −SO₃H group while the 3,5-dinitrosalicylate anion at −COOH group but both retains the usual intermolecular hydrogen bond between phenolic and carboxylic oxygen. In cesium 2,4-dinitrophenoxide monohydrate, the Cs⁺ cation is 12-coordinate by O atoms in anions and water molecules while the metal atoms in cesium 5-sulfosalicylate and cesium 3,5-dinitrosalicylate have coordination numbers 10 and 11, respectively, with an irregular coordination sphere made up exclusively of oxygen atoms. Even more in cesium 2,4-dinitrophenoxide monohydrate, the water molecules are in rare triply bridging positions between these cations. Both complexes have layer structures containing the cations and polar groups of the ligands in core domains sandwiched by the aromatic rings above and below. The organization of all layer structures appears to be governed mainly by steric effects and electrostatic forces with very little directional influence of the cations.     

Synthesis and Crystal Structure of the Cesium Silver ­Permanganate Cs3Ag[MnO4]4

After successful syntheses and structural refinements of the already known permanganates of cesium (Cs[MnO₄]) and silver (Ag[MnO₄]) we started to blend aqueous solutions of both components in various molar ratios. From crystallization experiments of these mixtures only three species of crystals with different chemical compositions were obtained: tricesium monosilver tetrakispermanganate (Cs₃Ag[MnO₄]₄) and, depending upon the respective ratio, either additional silver permanganate or surplus cesium permanganate, namely. The new title compound crystallizes in the orthorhombic space group Pnnm (no. 58) with two formula units per unit cell and cell dimensions of a = 764.53(4), b = 1883.57(9) and c = 584.34(3) pm. The crystal structure of Cs₃Ag[MnO₄]₄ consists of two crystallographically distinguishable cesium cations. (Cs1)⁺ is surrounded by fourteen oxygen atoms constructing a slightly distorted bicapped hexagonal prism. These polyhedra are connected through edge‐sharing with two other polyhedra of this kind to form chains along [001]. The chains are linked to each other via sixfold coordinated Ag⁺ cations (d(Ag–O) = 238–246 pm), arranged in such a manner that they link three oxygen atoms of two cesium polyhedra, leading to a two‐dimensional layer spreading out parallel to the (001) plane. Together with the two crystallographically different tetrahedral oxomanganate(VII) anions [MnO₄]^– (d(Mn–O) = 161–162 pm) the other kind of cesium cations ((Cs2)⁺ with CN = 13) finally connect these layers three‐dimensionally.     

Electroreduction of Oxalate Complexes of Ruthenium(III) on a Dropping Mercury Electrode: Effect of Alkali Metal Cations and Solution Acidity

It is established that the reaction of recharging trioxalate complexes of ruthenium(III) occurs in the case of solutions with excess supporting oxalate salts of alkali metals K⁺, Na⁺, and Cs⁺ in reversible conditions, and limiting recharge currents are caused by diffusion. At the same time, values of diffusion coefficients for complex anion [Ru(C₂O₄)₃]^–3 decrease by almost two times upon going from potassium to sodium and cesium electrolytes. Substantial differences in the limiting currents in solutions containing excess amounts of the above salts are explained by the formation, at least in the case of cesium and sodium electrolytes, of ionic associates whose reduction rate at a fixed potential is lower than that of nonassociated anion [Ru(C₂O₄)₃]^–3. With solution dilution by supporting salts, transition is observed from reversible recharge conditions to absolutely irreversible conditions and a change in the above sequence of the effect of supporting cations on the recharge rate; at a fixed potential, the process decelerates in the series Cs⁺ > K⁺ > Na⁺. The reduction wave of the ruthenium(II) oxalate complexes in solutions with excess supporting electrolyte happens to depend on pH and, probably, is determined by simultaneous formation of adsorbed atoms of hydrogen (or ruthenium hydride) on atoms of ruthenium(0).     

Comparative analysis of the binding of thiacalix[4]arene-monocrown-ethers with monovalent metal salts using MALDI mass spectrometry

MALDI mass spectrometry is used for the first time for the rapid assessment of the binding of thiacalix[4]arene-monocrown-ethers with metal cations (Li, Na, K, Cs, Cu, Ag). The work is performed on examples of thiacalix[4]arene-monocrown-ethers in 1,3-alternate conformation with various numbers (m) of ethylene oxide units and various substituents in phenol groups. It is shown that thiacalix[4]arene-monocrown- ethers with m = 3, 4, 5, and 6 bind lithium, sodium, potassium, and cesium cations, respectively; in addition, the binding of cesium cations is stronger in the presence of aromatic substituents in the lower rim of thiacalix[4]arene-monocrown-ethers. Silver cations bind with calixarenes under study more intensely than copper ions. When aromatic substituents are present, the binding of silver cations is stronger than that of alkali metal ions with the studied thiacalix[4]arene-monocrown-ethers.     

Alkali Metal Cation Affinities of Anionic Main Group‐Element Hydrides Across the Periodic Table

We have carried out an extensive exploration of gas‐phase alkali metal cation affinities (AMCA) of archetypal anionic bases across the periodic system using relativistic density functional theory at ZORA‐BP86/QZ4P//ZORA‐BP86/TZ2P. AMCA values of all bases were computed for the lithium, sodium, potassium, rubidium and cesium cations and compared with the corresponding proton affinities (PA). One purpose of this work is to provide an intrinsically consistent set of values of the 298 K AMCAs of all anionic (XH_{n ‐1}⁻) constituted by main group‐element hydrides of groups 14–17 along the periods 2–6. In particular, we wish to establish the trend in affinity for a cation as the latter varies from proton to, and along, the alkali cations. Our main purpose is to understand these trends in terms of the underlying bonding mechanism using Kohn–Sham molecular orbital theory together with a quantitative bond energy decomposition analyses (EDA).     

Sorption of cesium from water solutions on potassium nickel hexacyanoferrate-modified <Emphasis Type="Italic">Agaricus bisporus</Emphasis> mushroom biomass

In order to gain biosorbent that would have the ability to bind cesium ions from water solution effectively, potassium nickel hexacyanoferrate(II) (KNiFC) was incorporated into the mushroom biomass of Agaricus bisporus. Cesium sorption by KNIFC-modified A. bisporus biosorbent was observed in batch system, using radiotracer technique using ¹³⁷Cs radioisotope. Kinetic study showed that the cesium sorption was quite rapid and sorption equilibrium was attained within 1 h. Sorption kinetics of cesium was well described by pseudo-second order kinetics. Sorption equilibrium was the best described by Freundlich isotherm and the distribution coefficient was at interval 7,662–159 cm³ g⁻¹. Cesium sorption depended on initial pH of solution. Cesium sorption was very low at pH₀ 1.0–3.0. At initial pH 11.0, maximum sorption of cesium was found. Negative effect of monovalent (K⁺, Na⁺, NH₄ ⁺) and divalent (Ca²⁺, Mg²⁺) cations on cesium sorption was observed. Desorption experiments showed that 0.1 M potassium chloride is the most suitable desorption agent but the complete desorption of cesium ions from KNiFC-modifed biosorbent was not achieved.     

Modification of Potassium Chabazites Derived from Fly Ash by Dosing Extra Cations: Promoted CO2 Adsorption Capacities and Fine‐Tuned Frameworks

Potassium chabazite (K‐CHA), a typical microporous zeolite with excellent CO₂ separating properties, was synthesized with waste fly ash and modified via cation dosing treatments using cesium and zinc cations, respectively. The resulting CHAs were analyzed by XRF, XRD, FT‐IR, SEM, and N₂ physisorption, whose CO₂ adsorption properties were then tested on the reorganized TGA apparatus. It showed from XRF data that cesium and zinc cations were successfully imported in the original K‐CHA by cation dosing, but the CHA microstructures and morphologies of K‐CHA were perfectly retained as confirmed by XRD, FT‐IR, SEM and N₂ physisorption. Since there were still over 9 potassium cations per unit cell in cation dosed Cs‐CHA and Zn‐CHA, they both maintained the favored properties of K‐CHA as “molecular trapdoors”. In the following adsorption experiments, the CO₂ uptakes of Cs‐CHA and Zn‐CHA at 333 K and 1 bar, compared with K‐CHA, elevated from 1.70 mmol · g^–1 to 2.34 and 2.03 mmol · g^–1, and the import of zinc cation also presented a positive effect on the adsorption kinetics. Detailed comparisons suggested modifications with cesium and zinc cations fine‐tune the CHA complying with different mechanisms, and CHAs modified via cation perform more approvingly than fully ion‐exchanged ones, providing us important insights into CHA modifications and applications in practice.     

Adsorption behaviour of microamounts of cesium on manganese dioxide

The adsorption of cesium on manganese dioxide from aqueous solutions has been studied in relation to pertinent variables such as shaking time, pH, composition of aqueous solutions, mass of adsorbent (10 mg–1 g) and concentration of adsorbate (10^–6–5·10^–3 M), using a radiotracer technique. The influence of various anions and cations on cesium adsorption was examined. The distribution coefficient of a variety of other elements was determined under similar conditions. The adsorption of cesium obeys a Freundlich-type isotherm over the entire concentration range investigated, whereas the Langmuir-type isotherm is followed only at moderate concentrations.     

Mesopores in USY Zeolites II

Microporous zeolites Na‐Y and K‐Y were converted into the NaNH₄‐Y and KNH₄‐Y modifications by ion exchange being active in dealumination. Removal of framework aluminium and silicon is accompanied by formation of secondary mesopores. Internal mesopores are formed in the centre of zeolite crystals and external pores at their surface. Formation of mesopores changes the sorption behaviour.Residual alkali metal cations as Na⁺ or K⁺ stabilise, however, the framework ≡Si‐O‐Al≡ bonds. Because of inhomogeneous distribution of sodium ions, in NaNH₄‐Y less internal but more external mesopores are formed. Potassium ions of KNH₄‐Y are more homogeneous distributed over the framework why a more balanced formation of secondary pores takes place.     

A rapid separation of radioactive cesium by nitrobenzene extraction using the chromium complex [Cr(aniline)2(NCS)4]−

A rapid separation of radioactive cesium by the solvent extraction method was investigated. Cesium ions are quantitatively extracted with [Cr(NH₂C₆H₅)₂(NCS)₄]⁻ into nitrobenzene. EDTA is an effective masking agent for other polyvalent cations. The extracted cesium can be back-extracted into the aqueous phase by shaking with 6N HCl. The method was applied to samples of a natural mixture of fission products and a reactor coolant. The decontamination factors for other predominant isotopes in fission products were 10²∼10⁴. The separation of^137m Ba from a mixture of¹³⁷Cs and^137m Ba is also described.     

Uptake behavior of titanium molybdophosphate for cesium and strontium

This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 °C using column packed with H₃O⁺ form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH₄Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution.     

Synthesis,Complexation and Photophysics of 1,3-alternate Calix[4]arene-crowns-6 Bearing Fluorophoric Units on the Bridge

Abstract

Three new calix[4]arene-crown-6 derivatives bearing a fluorophoric unit on the ether bridge were synthesized. All these compounds complex alkali metal picrates in chloroform, and the naphthocrown (2) shows the highest efficiency for cesium ion binding among the calix-crown-6 known so far. Cesium over sodium selectivity is remarkably higher in acetonitrile than in chloroform solution. ¹H NMR studies, carried out in CDCl₃ on the cesium picrate complex of ligand 2, show that the anion is involved in a π-π stacking with the naphthyl unit The lariat calix[4]-crown-6 (4) does not show any relevant change in absorption and fluorescence spectra upon cesium binding, thus indicating that the dansyl unit is not perturbed by metal ion complexation. On the contrary, for ligands 2 and 3 a luminescence intensity decrease is observed upon cation binding, which allows an easy detection of cesium even at very low concentrations (10^?7M).