Aqueous Solutions Of CsCl Research Articles

Alkali Metal Cation (K+, Cs+) Induced Dissolution/Reorganization of Porous Metal Carboxylate Coordination Networks in Water

Porous metal-organic coordination networks (MOCNs) {A(2)[M(3)(btec)(2)(H(2)O)(4)]}(n) (1, A=K, M=Co; 2, A=K, M=Ni; 3, A=Cs, M=Co; and 4, A=Cs, M=Ni; btec=benzene-1,2,4,5-tetracarboxylate) with nearly identical structural features were hydrothermally prepared. These compounds adopt (4,8)-connected scu nets but exhibit subtle differences in the topology of the final three-dimensional architectures. Compound 1 has a regular net with the largest solvent void (21.1 %), while the nets of the other three (2-4) are slightly distorted from a regular shape and have malformed pores with smaller solvent voids (5.4-11.4 %). Likely, the different supramolecular environments among 1-4 subtly depend on the eight-connected binodal cubical vertices/four-connected square-planar connectivity between the trimetallic clusters and the btec ligands. Cobalt species 3 dissolved in an aqueous solution of KCl, and then reorganized to form 1 at ambient temperature. Interestingly, under similar conditions, 1 dissolved and then was regenerated to give the same structure. Nickel species 2 and 4 also underwent a dissolution/reorganization process in an aqueous solution of KCl to afford new metal-carboxylate product {K(2)[Ni(3)(btec)(2)(H(2)O)(4)]}(n) (2'). This compound forms a (4,8)-connected scu net with regular pores, which is isostructural and isomorphous with 1, and is a supramolecular isomer of 2. Similarly, in an aqueous solution of CsCl, 1-4 were converted to 1D zigzag chain structures {Cs(2)[M(btec)(H(2)O)(4)]}(n) (5, M=Co; 6, M=Ni) that enlarged to hydrogen-bonded 3D porous supramolecular networks. Remarkable, reversible alkali metal cation induced structural transformations between 1 and 5 occurred via dissolution/reorganization processes. Thermogravimetric analyses showed that these metal-carboxylate species have high thermal stability (T>300 degrees C).

From Repulsion to Attraction and Back to Repulsion: The Effect of NaCl, KCl, and CsCl on the Force between Silica Surfaces in Aqueous Solution

The force between silica surfaces in NaCl, KCl and CsCl aqueous solutions is studied at pH 5.5 using an atomic force microscope (AFM). As ion concentration is increased, more cations adsorb to the negatively charged silica, gradually neutralizing the surface charge, hence, suppressing the electrostatic double layer repulsion and revealing van der Waals attraction. At even higher salt concentrations, repulsion reemerges due to surface charge reversal by excess adsorbed cations. Adsorption grows monotonically with cation radius. At pH 5.5 the smallest ion, Na+, neutralizes the surface at 0.5-1 M, K+ at 0.2-0.5 M, and Cs+ at approximately 0.1 M. Titration with HCl to pH 4.0 shifts surface neutralization and charge reversal to lower salt concentrations compared with pH 5.5. When attraction dominates, the force curves are practically identical for the three salts, independent of their concentration.

Chirp effect in hard X-ray generation from liquid target when irradiated by femtosecond pulses

The chirp effect on a X-ray emission intensity from a CsCl aqueous solution jet irradiated by femtosecond pulses was systematically studied. The p-polarized chirped pulses were more efficient as compared with the shortest pulses determined by the spectral bandwidth. The negatively-chirped pulses of approximately 240 fs duration produced up to 10 times larger X-ray intensity as compared with the transform-limited 160 fs pulses. The angular dependence of X-ray generation can be explained by the resonant absorption. Numerical simulations of electron density evolution due to the avalanche and multi-photon absorption supports qualitatively well the experimental observations.

Partitioning of salt ions in FT30 reverse osmosis membranes

FT30 membranes consist of a polyamide active layer interfacially polymerized on a porous polysulfone support. The ion partition coefficient κ in the active layer is a key thermodynamic parameter that partially controls the ability of the membrane to desalinate water. Membranes are soaked in aqueous solutions of CsCl, KBr, or Na2WO4 with salt concentrations of 0.002M<Cs<2M, freeze dried to remove water without disturbing ion distribution, and analyzed by Rutherford backscattering spectrometry. For Cs<0.01M, κ is surprisingly large and independent of Cs, κ=6±2. The porosity ϕ of the top 500nm of the support layer is also extracted from the RBS data: ϕ=0.45±0.05.

π-Complexes of Cu(I) with Alkynes. Synthesis and Crystal Structure of Cs[CuCl2(HOCH2C≡CCH2OH)] ⋅ H2O

Crystals of anionic π-complex Cs[CuCl2(HOCH2C≡CCH2OH)] ⋅ H2O were synthesized by reaction of 2-butyne-1,4-diol with CuCl in a saturated aqueous solution of CsCl at 90°C and studied by X-ray diffraction analysis. The crystals are triclinic (space group $$P\bar 1$$ ; a = 10.155(4) A, b = 7.828(4) A, c = 7.115(3) A, α = 102.62(4)°, β = 100.77(3)°, γ = 106.71(4)°, V = 509(1) A3, Z = 2) and consist of stacks of individual anions [CuCl2(HOCH2C≡CCH2OH)]− and hydrated [Cs ⋅ H2O]+ cations between the stacks. The Cu(I) atom has trigonal surrounding of two Cl atoms and the C≡C bond of 2-butyne-1,4-diol molecule. The Cu-(C≡C) distance in the π-core is 1.905(8) A; the C≡C bond is elongated to 1.223(11) A. In addition to hydrogen bonds O-H⋯Cl, crystals of the complex also contain O(w)⋯H-O and O(w)⋯Cl bonds stabilizing their structure.

Volumetric properties and volumetric interaction parameters for the CsCl–monosaccharide ( d-galactose, d-xylose and d-arabinose)–water systems at T=298.15 K

Density measurements have been carried out at T=298.15 K for the CsCl–monosaccharide ( d-galactose, d-xylose and d-arabinose)–water systems. The apparent molar volume of saccharides V φ,S in the ternary solutions, the corresponding infinite dilution apparent molar volume V φ,S ∘, and the standard transfer volume Δ t V φ,S ∘ of saccharides from water to aqueous CsCl solutions have been determined. The McMillan–Mayer theory was employed to relate the excess thermodynamic functions to a series of interaction parameters to obtain the volumetric interaction parameters of CsCl with monosaccharide in water. These parameters are interpreted by the group additivity principle and the stereochemistry of these monosaccharide molecules.

Diffusivity measurement of heavy ions in Wyoming montmorillonite gels by X-ray computed tomography

Medical X-ray computed tomography (CT) was applied to the measurement of the diffusion coefficients of heavy ions in an artificial barrier material for the disposal of nuclear wastes. Cs +, Sr 2+, I −, and Br − are the heavy ions measured and the barrier used is the water-rich gel of Wyoming montmorillonite (86.5–100 wt.% H 2O). X-ray CT yields an inevitable artifact (beam-hardening) in the obtained images. Before the diffusion experiments, the polychromatic primary X-ray spectrum of the CT scanner was measured by a CdZnTe detector, and the effects of the artifact were examined for an aqueous CsCl solution sample. The results show that the beam-hardening artifact derived from the polychromatic photon energy distribution can be suppressed by applying a special image reconstruction method assuming the chemical composition of samples. The transient one-dimensional diffusion of heavy ions in a plastic container filled with the gel was imaged nondestructively by the X-ray CT scanner with an in-plane resolution of 0.31 mm and slice thickness of 2 mm. The results show that diffusivities decrease with increasing clay weight fraction. The degree of the diffusivity decrease was high for cations (Cs + and Sr 2+) and low for anions (I − and Br −). The quantitative decomposition of the contribution of the geometrical tortuosity and of the sorption to the diffusivity was performed by subtracting the diffusivity of nonsorbing I − from the measured diffusivities. The results show that the contribution of the sorption is large for Cs +, Sr 2+ and small for Br −. Because X-ray CT allows nondestructive and quick measurements of diffusivities, the technique would be useful particularly for measuring the diffusive migration of harmful radioactive elements.

Structural and catalytic properties of sodium and cesium exchanged X and Y zeolites, and germanium-substituted X zeolite

The conversion of isopropanol in a fixed bed flow reactor was used as a test reaction for a number of faujasite-type zeolites which were modified in order to increase their basicity. Samples included a CsY zeolite with an intact faujasite structure and an exchange degree of nearly 100% prepared by solid-state ion exchange, a CsNaY obtained from CsY through exchange with aqueous NaCl solution, a CsNaX obtained from NaX and aqueous CsCl solution, and a Na(Ge)X, with Si replaced by Ge. At 623 K, an isopropanol partial pressure of 5 kPa in He, and a total feed flow of 90 ml/min, a catalyst mass of 50 mg, initial yields were as follows: NaY: 62% propene, CsNaY: 78% propene, NaCsX: 10% propene, 0.37% acetone, Na(Ge)X: 8% propene, 11% acetone. Conversion in the presence of CsY was <1%. CO 2 adsorption and infrared (IR) spectroscopy were used to probe basicity, and Na(Ge)X was the only sample to form monodentate carbonates upon CO 2 adsorption (bands at 1477 and 1428 cm −1). Further characterization with X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal analysis, nitrogen sorption, and isopropanol sorption was necessary to properly interpret catalytic results by identifying samples which contained impurities, had blocked pore systems, or decomposed partially during activation or reaction.

Infrared spectra of cesium chloride aqueous solutions

The aqueous solutions of CsCl were studied at room temperature by infrared (IR) spectroscopy in the entire solubility range, 0–1200 g/L, using attenuated total reflection (ATR) sampling. The influence of anomalous dispersion on the IR–ATR spectra was evaluated by calculating the imaginary refractive index, k(ν), of each sample. Factor analysis (FA) was used to determine the number and abundance of species in the solutions. FA applied to both k(ν) spectra and IR-ATR spectra produced two principal spectra with a similar abundance of species. This result indicates that, even at high salt concentration, the optical effects do not influence the chemical analysis of IR–ATR spectra. The spectral modifications related to the salt concentrations are mainly first order. Second order effects were observed, but being weak, were not investigated. The two principal spectra are related to the two species present in the solution: pure water and CsCl–solvated water. From the latter, 2.8±0.4 water molecules were calculated to be associated with each close-bound Cs+/Cl− ion pair. In the case of KCl and NaCl aqueous solutions, both of which showed the same number of species, the number of water molecules associated to an ion pair was 5.0±0.4. That the latter number is different from that of CsCl indicates that the interaction between water molecules and ion pairs is different when cation Na or K in the chloride salt is replaced by Cs.

The origin of soot in flames: is the nucleus an ion?

There are two schools of thought on how soot originates in a fuel-rich flame. On the one hand, the ionic theory postulates that small ions, such as C3H3+, act as nuclei, so that species such as C2H2 and C4H2 add on to them, and occasionally liberate H2 in a repetitive growth process. Once these ions become large (≈2000 a.m.u.) they supposedly dissociate and produce an uncharged, but large, hydrocarbon “molecule,” which can grow, coalesce or coagulate to give soot particles. Simultaneously this dissociation produces a very small ion, which repeats the process of adding on C2, C3, and C4 species, etc. The other school of thought believes that fairly similar processes occur, but the species involved are not ions, but uncharged radicals and molecules. This present study has spectroscopically monitored the level of sooting in the earliest stages of its production in a premixed, oxyacetylene flame at 1 atm. If soot originates from ions such as C3H3+, the addition of a relatively large quantity of easily ionized cesium removes C3H3+ ions from the flame. In that case there should also be less soot produced. When either distilled water or a strong aqueous solution of CsCl was nebulized into the sooting flame, the intensity of the emission fell by the same amount. This was by only ∼ 1% in the earliest part of the burned gas, but rose to a larger drop farther downstream of the reaction zone. Thus cesium itself has no effect on the sooting level early in this premixed flame, indicating that there is no evidence here for ions acting as nuclei for soot. However, the addition of water alone does inhibit the production of soot.

Cs immobilization by sintered lead iron phosphate glasses

Lead iron phosphate glass frits were obtained from a mixture of NH 4H 2PO 4, PbO and Fe 2O 3 melted in an induction furnace. After milling, the material was pressed in a die, sintered, and sintered a second time. Three amorphous X-ray diffraction halos were observed in samples produced from non-homogenized powders while two halos were observed from homogeneous ones. These halos were assigned different phosphate compounds. Sintered pellets were immersed in a CsCl aqueous solution and the absorption of Cs was determined by scanning electron microscopy. The crystallization temperatures and activation energies were determined by differential thermal analysis and by the Kissinger Method, respectively. The weight loss and atomic absorption were used to measure the dissolution rate in deionized water. The weight loss of sintered glasses was 3 × 10 −2 g/m 2 d after 28 days at 90°C. The homogenized samples have an improved corrosion resistance.

Activities of Individual Ions From Infinite Dilution to Saturated Solutions.

A new procedure, which provides a closer approximation for the junction potentials than the Henderson equation, is tested to reduce new emf data for the chloride ion in CsCl solutions and previously measured data for individual ions in aqueous solutions of KCl, NaCl, and NaBr. The liquid junction potential is calculated from numerical integration of its basic equation without assuming constant mobility or using concentrations instead of activities. The mean ionic activity coefficients of the salts, obtained from the activity coefficients of the individual ions, show good agreement with values reported in the literature. The activity coefficients of the individual chloride ion at 25°C in aqueous solutions of CsCl up to 3 molal and in KCl solutions were measured using a chloride ion-selective electrode. It has been confirmed that the activity of the chloride ion is equal to the activity of the cation in CsCl solutions and, contrary to the prediction of hydration theory, it is higher than the activity of the cation in aqueous KCl solutions. The “New Hydration Theory” has been developed to overcome the shortcomings of the older hydration theory and has been used to smooth the experimental activity coefficients of the individual ions in aqueous solutions and to extrapolate them up to the saturated solution.

Lead Iron Phosphate Powders Produced by Melting and Fast Cooling

Lead iron phosphate glasses are potentially useful for nuclear waste immobilization, and others applications. Lead iron phosphate glass powders were obtained from a mixture of NH 4 H 2 PO 4 , PbO and Fe 2 O 3 melted in an induction furnace and fast cooled. After milling, the material was pressed in a die and finally sintered. The particle size distribution, specific surface area, density values and crystalline phases were determined. Three amorphous halos were observed with intensities depending on the particle size distribution, These halos were assigned to be from ferric metaphosphate (Fe(PO 3 ) 3 , lead orthophosphate Pb 3 (PO 4 ) 2 and lead metaphosphate Pb(PO 3 ) 2 compounds. It is proposed that ferric metaphosphate is the main compound on the surface of the particles and lead orthophosphate and lead metaphosphate are in the inner part of the particles. The milling process allows to exhibit these compounds which are then detected by the X-rays diffraction. Pre-sintered pellets were exposed to CsCl aqueous solution and the absorption of Cs has been determined by SEM. Crystallization temperatures were determined by thermal analyses, and it is noted that the maximum is displaced from 534 to 543°C for samples containing CsCl. The surface area was determined to be 29 cm 2 /g after milling.

Membrane Surface-Charge Titration Probed by Gramicidin A Channel Conductance

We manipulate lipid bilayer surface charge and gauge its influence on gramicidin A channel conductance by two strategies: titration of the lipid charge through bulk solution pH and dilution of a charged lipid by neutral. Using diphytanoyl phosphatidylserine (PS) bilayers with CsCl aqueous solutions, we show that the effects of lipid charge titration on channel conductance are masked 1) by conductance saturation with Cs + ions in the neutral pH range and 2) by increased proton concentration when the bathing solution pH is less than 3. A smeared charge model permits us to separate different contributions to the channel conductance and to introduce a new method for “bilayer pKa” determination. We use the Gouy-Chapman expression for the charged surface potential to obtain equilibria of protons and cations with lipid charges. To calculate cation concentration at the channel mouth, we compare different models for the ion distribution, exact and linearized forms of the planar Poisson-Boltzmann equation, as well as the construction of a “Gibbs dividing surface” between salt bath and charged membrane. All approximations yield the intrinsic p K a in of PS lipid in 0.1 M CsCl to be in the range 2.5–3.0. By diluting PS surface charge at a fixed pH with admixed neutral diphytanoyl phosphatidylcholine (PC), we obtain a conductance decrease in magnitude greater than expected from the electrostatic model. This observation is in accord with the different conductance saturation values for PS and PC lipids reported earlier (Apell et al., 1979, Biochim. Biophys. Acta. 552:369–378) and verified in the present work for solvent-free membranes. In addition to electrostatic effects of surface charge, gramicidin A channel conductance is also influenced by lipid-dependent structural factors.

The vibration-rotation motions of water molecules in a 2M aqueous CsCl solution

An analysis of the generalized frequency distribution of hydration water molecules in a 2M aqueous CsCl solution, extracted from results of an inelastic neutron scattering experiment, is presented. The significant area reduction of the low-frequency part and some shift of the libration mode to lower frequencies in comparison with pure water are found, suggesting that Cs + ion acts as a “structure breaker” disrupting the hydrogen bond network of water molecules comprising its hydration shell.

Synthesis and crystal structure of a hexanuclear rhenium cluster complex Cs 3K[Re 6( μ3-S) 6 ( μ3-Te 0.66S 0.34) 2(CN) 6]. Cationic control over orientation of the cluster anion

The hexanuclear complex rhenium salt Cs 3K[Re 6( μ 3-S) 6( μ 3-Te 0.66S 0.34) 2(CN) 6] ({Bd1}) has been prepared by the reaction of Re 6Te 15 with molten KSCN and subsequent treatment with an aqueous solution of CsCl. Its crystal structure has been determined by X-ray structural analysis. The anion has the site symmetry 3 . The Re 6 octahedron is coordinated to six μ 3-S and two trans mixed μ 3-X ligands of the refined composition 66(3)%Te+34(3)%S. In addition there are six almost linear terminal CN ligands in its environment. The ReRe distances [2.630(2) Å] in the Re 3 faces capped by the μ 3-X ligands are significantly longer than those in the faces capped by the μ 3-S ligands [2.615(2) Å].

Study of the structure-breaking effect in aqueous CsCl solutions based on H2O/D2O isotope effects on transport coefficients and microdynamical properties

We have studied the effect of H2O/D2O isotopic substitution upon various transport and microdynamical properties in aqueous solutions of structure-breaking salts, using aqueous CsCl in the concentration range up to 6 mol kg–1 as a representative example. We report on isotope effects upon the self-diffusion coefficients of water and of Cs+ and Cl– ions, upon the reorientational correlation times of water deduced from 2H magnetic relaxation rates, and upon the magnetic relaxation rates of the quadrupolar relaxing ionic nuclei 133Cs+ and 35Cl– in these solutions. Comparison is made with the isotope effect upon the viscosity, and some subtle differences are outlined. The most substantial one is related to the isotope effects upon 133Cs+ and 35Cl– relaxation which selectively probe motions in the firsts cosphere of the ions. These are substantially lower than those observed with the other dynamical quantities, showing that dynamical isotope effects in the first cosphere may differ substantially from those in the bulk. It is concluded that the structure-breaking effect extends to the first co-sphere of the ions.

133Cs NMR in C 60 superconductors: CsxRb3− xC60( x=1,2)

133Cs NMR study in superconductors Cs xRb 3-xC 60 (x=1,2) above 77K is reported. For x=1, single absorption line was observed at −370±15 ppm with respect to that of CsCl aqueous solution at 300K, while for x=2 two lines at −120±25 ppm and −380±20 ppm were observed. The signal around −370 (−380) ppm was assigned to the Cs atoms intercalated in octahedral sites of fcc lattice in both of x=1 and 2, and the other line at −120ppm in x=2 to tetrahedral sites. These line positions (Knight shift) are close to that for second stage Cs-graphite intercalation compound, and are far from +1.48% of Knight shift in Cs-metal, indicating a negligible electronic density of state at the Fermi-level in the Cs sites.

Determination of Na and K in the rat lens by atomic absorption spectrophotometry

A new procedure is described for determination of sodium and potassium in rat lenses with atomic absorption spectrophotometry. Samples were prepared by soaking of the ground or the intact lens in deionized water. For potassium determinations HNO3 dissolution was also tried. Deionized water or CsCl aqueous solution was adopted for dilution for measurement. At absorbances up to 1.0 absorbance unit only measurements on HNO3 dissolved lenses diluted in deionized water were compatible with a linear absorbance function. At absorbances below 0.2-0.3 absorbance units all combinations were in agreement with a linear absorbance function. Grinding of the lens was found to increase the variability but did not change the level. HNO3 dissolution did not increase the level. Dilution with CsCl increased the sensitivity and decreased the variability. A schedule is proposed for determination of sodium and potassium in which lens samples are obtained by soaking in deionized water. Aqueous solution of CsCl is suggested for dilution.

The hydration of alkali chlorides in aqueous solutions

The temperature dependence of the adiabatic compressibility of solution of lithium chloride in water has been determined for different solute concentrations from 4 to 8 wt%. A simple model has been employed to interpret the data in terms of the size and compressibility of the hydration shells. The data have been compared with previously obtained compressibility data for NaCl, KCl and CsCl aqueous solutions.