Aluminum phosphate dispersed on a cellulose acetate fiber surface: Preparation, characterization and application for Li, Na and K separation

Cellulose acetate fibers with supported highly dispersed aluminum phosphate were prepared by reacting aluminum-containing cellulose acetate (Al₂O₃=3.5 wt.%; 1.1 mmol g⁻¹ aluminum atom per gram of the material) with phosphoric acid. Solid-state NMR spectra (CPMAS ³¹P NMR) data indicated that HPO₄²⁻ is the species present on the fiber surface. The specific concentration of acidic centers, determined by ammonia gas adsorption, is 0.50 mmol g⁻¹. The ion exchange capacities for Li⁺, Na⁺ and K⁺ ions were determined from ion exchange isotherms at 298 K and showed the following values (in mmol g⁻¹): Li⁺=0.03, Na⁺=0.44 and K⁺=0.50. The H⁺/Li⁺ exchange corresponds to the model of the ideal ion exchange with a small value of the corresponding equilibrium constant K=1.1×10⁻². Due to the strong cooperative effect, the H⁺/Na⁺ and H⁺/K⁺ ion exchange is non-ideal. These ion exchange equilibria were treated with the use of models of fixed bi- or tridentate centers, which consider the surface of the sorbent as an assemblage of polyfunctional sorption centers. Both the observed ion exchange capacities with respect to the alkaline metal ions and the equilibrium constants were discussed by taking into consideration the sequence of the ionic hydration radii for Li⁺, Na⁺ and K⁺. The matrix affinity order for the ions decreases as the hydration radii of the cations increase, i.e. Li⁺>Na⁺>K⁺. The high values of the separation factors S_Na⁺/Li⁺ and S_K⁺/Li⁺ (up to several hundred) provide quantitative separation of Na⁺ and K⁺ from Li⁺ from a mixture containing these three ions.     

Properties of new inorganic membranes prepared by metal alkoxide methods. Part III: New inorganic lithium permselective ion exchange membrane

Inorganic lithium permselective ion exchange membranes were prepared on a microporous alumina substrate by dip-coating solution containing Si(OC₂H₅)₄, LiOC₂H₅, Mn(OC₂H₅)₂ and C₂H₅OH. The membranes showed ion-selectivity for cation over anion and permselectivity for Li⁺ over Na⁺. The static transport number for cation [K⁺] is 0.75 and the permselectivity for Na⁺ over Li⁺ is 0.29, comparing 2.57 for ordinary organic ion exchange membrane.     

Cation exchange properties of crown ether-phosphotungstic acid precipitates

Precipitate formation between phosphotungstic acid and crown ethers is a general phenomenon, producing solids with selective ion exchange behavior for the alkali metal ions. Distribution coefficients for Li⁺, Na⁺, K⁺, and Cs⁺ were measured for a series of these precipitates with different crown ethers. The sorption data are more complicated than for the corresponding phosphomolybdates and indicate a variability in the number of exchangeable sites with H⁺ and M⁺ concentration. The crown ether used markedly affects the cation selectivity of the phosphotungstate precipitates.     

Floating spherical Gaussian orbital (FSGO) studies with a model potential: Application to two-valence-electron systems

A Gaussian based model potential is used within FSGO formalism to study a series of two-valence-electron diatomics (Li₂, Na₂, K₂, LiH, NaH, KH, MgH⁺, CaH⁺, LiNa, LiK and NaK) and triatomic ions (H₂Li⁺, H₂Na⁺, Li₂Na⁺, Na₂Li⁺, Li ₃ ⁺ , Na ₃ ⁺ , Li₂H⁺ and Na₂H⁺). Results for calculated equilibrium geometries, force constants, and energy changes for certain chemical reactions are compared to the corresponding quantities from available all-electronab initio studies and experimental results. The predicted results are generally satisfactory.Aided by grants to the University of North Carolina from the National Institute of Health and the National Science Foundation.     

Complexation Properties of a Carbon-Bridged Cryptand with Metal Ions in Aqueous Solution at 25°C

Abstract

Thermodynamic quantities (log K, ΔH, and ΔS) for the interactions of a carbon-bridged cryptand with Li⁺, Na⁺, K⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺ were determined at 25° C by calorimetric titration in aqueous solution. The cryptand forms complexes with Na⁺, Sr²⁺, Ba²⁺, and Pb²⁺ with log K ≤ 2. Complexation was not detected for Li⁺, K⁺, and Ca²⁺. Weak interactions with Li⁺ and K⁺ and a log K value of 2.4 for Na⁺ suggest that the cavity size of the cryptand is close to that of Na⁺ but too small for K⁺ and too large for Li⁺. The carbon-bridged cryptand selectively binds Sr²⁺ (log K = 3.2) over Ca²⁺ and Ba²⁺ by more than one order of magnitude.     

Complex formation of O-carboxymethylcalix[4]resorcinolarene with alkaline metal and ammonium ions

Complex formation of 3,5,10,12,17,19,24,26-octa(carboxymethoxy)-1,8,15,22-tetraundecylcalix[4]arene (H₈X) with Li⁺, Na⁺, K⁺, and NH₄ ⁺ ions was studied by ¹H NMR spectroscopy and pH-metry in water—DMSO solutions. Binding of one cation occurs during the stepped deprotonation of four carboxymethyl groups in H₈X. The K⁺ ion was found to be bound more efficiently than Li⁺ and Na⁺. The further deprotonation to the penta- and hexaanion leads to the coordination with two cations. The most stable binuclear complex is formed with the Li⁺ ion.     

WQD-1沸石离子交换性能的研究

测定了W_QD-1沸石在一价碱金属离子混合溶液中的分配系数、饱和交换量和在25℃时，NH⁺₄/K⁺、NH⁺₄/Na⁺交换等温线。得出该沸石一价离子选择性序列为：Cs⁺>Rb⁺>K⁺>Na⁺>Li⁺, Na⁺/K⁺交换自由焓变ΔG(T,P)=-6.745 KJ/mol。     

Selective Ion Exchange in Supramolecular Channels in the Crystalline State

Artificial ion channels are of increasing interest because of potential applications in biomimetics, for example, for realizing selective ion permeability through the transport and/or exchange of selected ions. However, selective ion transport and/or exchange in the crystalline state is rare, and to the best of our knowledge, such a process has not been successfully combined with changes in the physical properties of a material. Herein, by soaking single crystals of Li₂([18]crown‐6)₃[Ni(dmit)₂]₂(H₂O)₄ ( 1 ) in an aqueous solution containing K⁺, we succeeded in complete ion exchange of the Li⁺ ions in 1 with K⁺ ions in the solution, while maintaining the crystalline state of the material. This ion exchange with K⁺ was selectively conducted even in mixed solutions containing K⁺ as well as Na⁺/Li⁺. Furthermore, remarkable changes in the physical properties of 1 resulted from the ion exchange. Our finding enables not only the realization of selective ion permeability but also the development of highly sensitive biosensors and futuristic ion exchange agents, for example.     

Die Selektivität Kristalliner Cer(IV)-Phosphatsulfathydrate gegenüber Li+, Na+, K+, Rb+, Cs+ und NH in absolutem Methanol und absolutem Dimethylsulfoxid

Selectivity of Crystalline Ce^IV Phosphate Sulphate Hydrates for Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and NH in Absolute Methanol and Absolute Dimethylsulphoxide The sequence of exchange capacities of Cerium(IV) phosphate sulphate hydrate (CePO₄)₂(HPO₄)_0.74(SO₄)_0.26 · 4,74 H₂O for alkalimetal ions and ammoniumions in absolute methanol at 25°C for the case of a small excess of the exchanger (in relation to the equivalent amount) is given by K⁺ > Rb⁺ ≥ NH₄⁺ > Cs⁺ > Na⁺ > Li⁺. Between the exchange capacity A of these cations and their ionic radii r (given by Ladd) exists the simple relation A = const./r. For Na⁺ the radius of the inner hydration shell must be considered. In absolute dimethyl-sulphoxide under the same conditions the sequence is K⁺ ≥ NH₄ > Rb⁺ > Na⁺ > Cs⁺ > Li⁺. For K⁺, NH₄, Rb⁺ and Cs⁺ the exchange capacity is given by A = const./r + const. · r⁴. The sequences of the alkali ions in both solvents are among the group of 13 sequences which are physicaly significant according to EISENMANNS 's theory. The results are compared with the observations made with water as solvent.     

Structural and dynamic investigations of aqueous clusters of Na+ and K+

Using computer modeling, we have studied Na⁺–24H₂O and K⁺–24H₂O clusters. We propose ion-water interaction potentials. We obtain structural, energy, and dynamic characteristics of the studied clusters. We show different mechanisms for exchange of water molecules surrounding the Na⁺ and K⁺ ions: single-particle in the case of Na⁺, and close to K⁺, along with single-particle exchange, a large percentage of multiparticle cooperative exchange of water molecules. This difference is explained by the different degrees of orientation of the water molecules surrounding these ions, by the presence of a unified deformed network of H bonds in the K⁺ cluster and its absence in the Na⁺ cluster. We propose a negative hydration mechanism for the K⁺ ion.Institute of General and Inorganic Chemistry, Russian Academy of Sciences. Institute of Physical Chemistry, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 96–104, March–April, 1993.     

A new Na+ and K+ carrier from chemically modified monensin studied in human erythrocytes by 23Na nuclear magnetic resonance,K+ atomic absorption and H+ potentiometry

The transporting ability of a new monensin derivative 26-(1,2-diphenyl-1-ethoxy) monensin, highly active against Gram-positive bacteria, was explored with the human erythrocyte model using three technical approaches: ²³Na nuclear magnetic resonance (internal Na⁺), K⁺ atomic absorption (external K⁺) and H⁺ potentiometry (external H⁺) and compared with monensin 1 and 26-(4-chlorophenylurethane) monensin 3 of known transport selectivities for sodium and potassium respectively. Compound 2 proved to be a good carrier for both Na⁺ and K⁺ under our experimental conditions, thus constituting a new type of monensin derivative. The introduction of Li⁺, Rb⁺ or Cs⁺ in the external buffer as a replacement for Na⁺ led us to propose the transport sequence K⁺, Na⁺ ⪢ Rb⁺ > Li⁺ > Cs⁺ for 2.     

Zum Ionenaustausch einwertiger Kationen an synthetischen Natriumpolysilicaten mit Schichtstruktur

Ion Exchange of Monovalent Cations in Synthetic Sodium Polysilicates with Layer Structure Cation-exchange equilibria of synthetic sodium polysilicates Ilerit (Na₂O · 8.3SiO₂ 8.9 H₂O) and Magadiite (Na₂O · 13 SiO₂ · 6.8 H₂O) with H⁺, Li⁺ and K⁺ Ions were investigated with respect to their selectivity behaviour. The range of ion selectivity is: H⁺ > Na⁺ > Li⁺ > K⁺. Thermodynamic data ΔG, ΔH, and ΔS were determined by means of the integral thermodynamic equilibria constants K_th of the ion-exchange reactions.     

Cerium (IV) oxidation rate of p-chloromandelic acid in perchlorate and sulfate media

The rate of the cerium (IV) oxidation of p-chloromandelic acid has been studied in perchlorate media at an ionic strength of 1.50 mol/dm³ by the stopped-flow technique and in H₂SO₄? MHSO₄ (M⁺ = Li⁺, Na⁺, K⁺) and H₂SO₄? MClO₄ (M⁺ = H⁺, Li⁺, Na⁺) mixtures at constant total electrolyte concentrations of 1.00 and 2.00 mol/dm³ using the conventional spectrophotometric method. In perchlorate media the kinetic data indicate the formation of two intermediate complexes between cerium (IV) and the organic substrate, but only one is significantly involved in the intramolecular electron-transfer process. The oxidation rate is markedly lower in sulfate media, where two reaction paths have been found to contribute to the overall redox reaction. The univalent cations examined exhibit negative specific effects upon the overall oxidation rate increasing in the order H⁺ < Li⁺ < Na⁺ < K⁺. Activation parameters have been also estimated.     

Core—Core interaction potentials by alkali diatomic molecular ions. Heteronuclear case

Core—core interaction potentials of alkali diatomic molecular ions are calculated for all the heteronuclear combinations of H⁺, Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺. The Thomas—Fermi—Dirac statistical model is employed to calculate the short-range repulsive interaction potential. The interaction due to core polarization is estimated.     

Kinetics of cerium (IV) oxidation of mandelic acid. Ionic strength and specific cation effects

The kinetics of the redox reaction between mandelic acid (MA) and ceric sulfate have been studied in aqueous sulfuric acid solutions and in H₂SO₄? MClO₄ (M⁺ = H⁺, Li⁺, Na⁺) and H₂SO₄? MHSO₄ (M⁺ = Li⁺, Na⁺, K⁺) mixtures under various experimental conditions of total electrolyte concentration (that is, ionic strength) and temperature. The oxidation reaction has been found to occur via two paths according to the following rate law: rate = k[MA] [Ce(IV)], where k = k₁ + k₂/(1 + a)²[HSO₄^?]² = k₁ + k₂/(1 + 1/a)²[SO₄^2?]², a being a constant. The cations considered exhibit negative specific effects upon the overall oxidation rate following the order H⁺ ? Li⁺ < Na⁺ < K⁺. The observed negative cation effects on the rate constant k₁ are in the order Na⁺ < Li⁺ < H⁺, whereas the order is in reverse for k₂, namely, H⁺ ? Li⁺ < Na⁺. Lithium and hydrogen ions exhibit similar medium effects only when relatively small amounts of electrolytes are replaced. The type of the cation used does not affect significantly the activation parameters.     

Kinetics of ion-exchange on montmorillonite clays

The kinetics for the exchange of Li⁺, K⁺, Rb⁺, and Cs⁺ for Na⁺ as the exchangeable cation on bentonite and montmorillonite K10 and KSF have been studied using conductimetric stoppedflow. Dilute aqueous suspensions of the clays, of particle sizes of a few micrometers, were used, so that diffusion was fast and the rate-determining step was the substitution of one cation by another on the lattice surface. The kinetics were treated in terms of relaxation from equilibrium. Relaxation times ranged from 100 to 250 ms, and forward rate constants from 30 to 500 M^?1 s^?1. The reactions had very low activation enthalpies (7–25 kJ mol^?1) and were only slow enough to be studied by the stopped-flow technique because of the large negative entropies of activation (?120 to ?170 J K^?1 mol^?1). © 1993 John Wiley & Sons, Inc.     

协同萃取液膜体系从Li+、Na+、K+混合溶液中提取Li+

从卤水、海水中提取Li是目前较为活跃的研究课题。用液膜法从Li~+、Na~+、K~+混合溶液中分离Li~+的报道很少。协同效应在乳状液型液膜中的应用还未见报道。本文采用噻吩甲酰三氟丙酮(HTTA)和磷酸三丁酯(TBP)作为混合载体的液膜体系,快速、高效地从Li~+、Na~+、K~+的混合溶液中分离、浓缩Li~+,为从卤水、海水中提取Li~+提供了重要的依据。     

Monohydration selectivity mechanism of alkali cations in the potassium channel of excitable biomembranes

Nonempirical quantum chemical method Hartree–Fock–Roothan LCAO SCF MO in a two-exponent Dunning basis with the use of an extended set of Gaussian functions by Huzinaga–Dunning with consideration of electron correlation according to the Meller–Plesset theory of excitations of the second order was used to study monohydrates of Li⁺, Na⁺, K⁺, and HCOO^? ions. The indicated basis was supplemented with polarization functions of d-type on the O atom and of p-type on the hydrogen atom as well as with diffusion functions of p-type on the oxygen atom. It has been found that binding energies of the water molecule with Li⁺, Na⁺ appeared to be higher and with K⁺ lower than with HCOO^? · H₂O. Potential curve shapes of K⁺ + H₂O and HCOO^? + H₂O reactions are shown to be similar. The molecular mechanism of K⁺ channel selectivity of an excitable membrane is explained on the basis of the obtained calculations.     

Cover Feature: Are the Accompanying Cations of Doping Anions Influential in Conducting Organic Polymers? The Case of the Popular PEDOT (Chem. Eur. J. 63/2019)

Conducting organic polymers (COPs) are made of a conjugated polymer backbone supporting a certain degree of oxidation. These positive charges are compensated by the doping anions that are introduced into the polymer synthesis along with their accompanying cations. In this work, the influence of these cations on the stoichiometry and physicochemical properties of the resulting COPs have been investigated, something that has previously been overlooked, but, as here proven, is highly relevant. As the doping anion, metallacarborane [Co(C₂B₉H₁₁)₂]⁻ was chosen, which acts as a thistle. This anion binds to the accompanying cation with a distinct strength. If the binding strength is weak, the doping anion is more prone to compensate the positive charge of the polymer, and the opposite is also true. Thus, the ability of the doping anion to compensate the positive charges of the polymer can be tuned, and this determines the stoichiometry of the polymer. As the polymer, PEDOT was studied, whereas Cs⁺, Na⁺, K⁺, Li⁺, and H⁺ as cations. Notably, with the [Co(C₂B₉H₁₁)₂]⁻ anions, these cations are grouped into two sets, Cs⁺ and H⁺ in one and Na⁺, K⁺, and Li⁺ in the second, according to the stoichiometry of the COPs: 2:1 EDOT/[Co(C₂B₉H₁₁)₂]⁻ for Cs⁺ and H⁺, and 3:1 EDOT/[Co(C₂B₉H₁₁)₂]⁻ for Na⁺, K⁺, and Li⁺. The distinct stoichiometries are manifested in the physicochemical properties of the COPs, namely in the electrochemical response, electronic conductivity, ionic conductivity, and capacitance.