Transport of alkali metal ions against its concentration gradient through 2,3-epithiopropyl methacrylate–methacrylic acid copolymer membrane

Cationic exchange membranes were prepared with 2,3-epithiopropyl methacrylate (ETMA)–methacrylic acid (MAc) copolymer. Transport of Li⁺ against its concentration gradient through the membranes was investigated by using the system containing HCl and LiCl (left side) and LiOH (right side). The rate of transport of Li⁺ increased with increasing MAc content in the membranes with less than 56.3 mol % MAc. The rate of transport and transport fraction of Li⁺ could be increased by using the copolymer membranes irradiated with ultraviolet light, because the physical and chemical structure of the membrane made of ETMA–MAc copolymer can be easily changed by irradiation with ultraviolet light. The transport in this system, where one side of the membrane in a cell was acidic and the other alkaline, was influenced significantly by the initial H⁺ concentration on the acidic side.     

Uphill and selective transport of uranyl ions through 2,3-epithiopropyl methacrylate–2-acrylamide-2-methyl propane sulfonic acid copolymer membranes

Cation exchange membranes were prepared with 2,3-epithiopropyl methacrylate (ETMA)-2-acrylamide-2-methylpropane sulfonic acid (AMPS) copolymers. Transport of uranyl ion against its concentration gradient through the membranes was investigated by using a system containing carbonate solution (left side) and uranyl ion (and other metal ion) solution (right side). ETMA–AMPS copolymer membranes transported UO²⁺₂ against its concentration gradient. Na₂CO₃ solution was most effective as receiving solution for the uphill transport of UO²⁺₂. The transport was greatly affected by the composition of the copolymer membranes. Highly selective transport of UO²⁺₂ from the solution containing UO²⁺₂ and other metal ions was observed by using Na₂CO₃ solution in the left side. The main driving force for this transport of UO²⁺₂ is the high complex-formation ability of UO²⁺₂ with CO^2?₃.     

Preparation of unsaturated polyester–styrene beads using gamma irradiation and chemical polymerization routes for use in the recovery of some alkali metal ions

Suspension polymerization of unsaturated polyester–styrene was carried out in different media using different routes of polymerization. The effects of matrix type and concentration hold up, viscosity, irradiation dose, and the agitation speed on the resultant polymer characteristics were examined. The formed beads were physically identified using scanning electron microscopy, hardness, and particle size analysis techniques. They were smooth having typical spherical surfaces; the beads diameters were in the range of about 5–200 μm. The size of the resin beads was found to decrease with increase in the concentration and viscosity of the dispersant and impeller speed. The resultant beads were applied in the recovery of Li⁺, Na⁺, K⁺, and Cs⁺ ions from acidic media. The distribution coefficients of the alkali metal ions were calculated; the order of selectivity was Li⁺ > Na⁺ > K⁺ > Cs⁺ in case of the chemically processed resin beads, while the selectivity lies in the order of Li⁺ < Na⁺ < K⁺ < Cs⁺ in case irradiation processed ones. Finally, the economics of production of the unsaturated polyester–styrene resins using different methodologies was studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1149–1160, 2007     

Alkali metal tungsten bronze-doped energy-saving glasses for near-infrared shielding applications

Tungsten bronze has attracted global attention for its applications in near-infrared (NIR)-shielding windows. Here, alkali metal tungsten bronze (M_xWO₃, M = one or two types of Li, Na, and K)-doped glasses are prepared by a simple melt-quenching method. Their structure and properties were characterized by XRD, Raman spectroscopy, XPS and UV–Vis–NIR spectrophotometry. The effects of M on their structure and the NIR shielding performance are investigated. The LiF sample has the best NIR shielding performance, but its visible transmittance is sacrificed due to its low quality. The glasses containing mixed Li⁺ and K⁺ cooperate to form a high-quality Li⁺/K⁺-codoped tungsten bronze, while the glasses containing mixed Li⁺ and Na⁺ compete for limited tungsten resources to form Li⁺- and Na⁺-doped tungsten bronzes separately. The research here is helpful for understanding the role of different alkali metal ions in bulk energy-saving glass and is hugely significant for the guidance of the future applications of energy-saving glass without films.     

Diffusion and Selective Transport of Alkali Cations on Cation-Exchange Membrane

Abstract

The diffusion coefficients and selective transport for alkali metal cations through a charged polysulfonated ICE-450 ion-exchange membrane were measured as a function of pH at 25°C. The permeability and diffusion coefficients were found to increase in the sequence Cs⁺ ≥ K⁺ > Na⁺ > Li⁺. The relationship between the permeability and the diffusion coefficients, and the hydrated radii of cations in the membrane were shown. This sequence was also explained by considering the hydration of ions in the membrane. The selectivity transport of K—Na and K—Li binary systems at various pH gradients through the membrane were also investigated under various conditions. In the selective transport of metal ions, the selectivity depended on both the hydrated ionic size and the interaction between the fixed groups in the membrane and the metal ions.     

Ion-Exchange Properties of lon-Sieve-Type Manganese Oxides Prepared by Using Different Kinds of Introducing Ions

Abstract

Three ion-sieve-type manganese oxides, HMnO(Li), HMnO(Na), and HMnO(K), were prepared by acid treatments of Li⁺-, Na⁺-, and K⁺-introduced manganese oxides, respectively. Three oxides were obtained from γ-MnO² and the corresponding alkali metal hydroxides by heating at 600°C. The ion-exchange properties of the adsorbents were investigated by pH titration, K_d measurements, and the adsorption of metal ions from seawater. The selectivity sequences of alkali metal ions were Na⁺ < Cs⁺ < Rb⁺ < K⁺ < Li⁺ for HMnO(Li) and Li⁺ Na⁺ < Cs⁺ < K⁺ < Rb⁺ for HMnO(Na) and HMnO(K). The high selectivity of Li⁺ on HMnO(Li) can be ascribed to an ion-sieve effect of spinel-type manganese oxide which was produced from LiMn₂O₄ Since HMnO(Na) and HMnO(K) had [2 × 2] tunnels of edge-shared [MnO₆] octahedra, the high selectivities of K⁺ and Rb⁺ on these samples were used to explain that the sizes of the [2 × 2] tunnels were suitable for filling ions of about 1.4 Å in radius in a stable configuration. The order of metal-ion uptake from seawater was Sr²⁺ < K⁺ < Mg²⁺ < Ca²⁺ < Na⁺ < Li⁺ for HMnO(Li), Li⁺ < Sr²⁺ < Mg²⁺ < Ca²⁺ < Na⁺ < K⁺ for HMnO(Na), and Li⁺ < Sr²⁺ < Ca²⁺ < Mg²⁺ < K⁺ < Na⁺ for HMnO(K).     

Pervaporation separation of water–ethanol mixtures using metal‐ion‐exchanged poly(vinyl alcohol) (PVA)/sulfosuccinic acid (SSA) membranes

Poly(vinyl alcohol)/sulfosuccinic acid (PVA/SSA) membranes in the hydrogen form were converted to monovalent metal ion forms Li⁺, Na⁺, and K⁺. The effect of exchange with metal ions was investigated by measuring the swelling of water–ethanol (10/90) mixtures at 30 °C and by the pervaporative dehydration performance test for aqueous ethanol solutions with various ethanol concentrations at 30, 40, and 50 °C. In addition, electron spectroscopy for chemical analysis (ESCA) analysis was carried out to study the quantity of metal ions in membranes. From the ESCA analysis, the lithium ion quantity in the resulting membranes is greater than that of any other metal ions in question because of the easy diffusion of a smaller metal ion into the membrane matrix. The swelling ratio was in the following order: PVA/SSA‐Li⁺ > PVA/SSA‐Na⁺ > PVA/SSA‐K⁺ membranes. For pervaporation, the PVA/SSA‐Na⁺ membrane showed the lowest flux and highest separation factor for all aqueous ethanol solutions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1867–1873, 2002     

Selective Transport of Alkali and Alkaline Earth Metallic Ions through a Supported Liquid Membrane Containing Tripentyl Phosphate as a Carrier

Abstract

A selective transport system for alkali and alkaline earth metallic ions with a perchlorate ion as a pairing ion species through a supported liquid membrane (SLM) containing tripentyl phosphate (TPP) as a carrier is described. The SLM used is a porous polypropylene membrane impregnated with TPP solution in o-nitrophenyloctylether. The effects of the pairing ion species, the initial perchlorate concentration, and the TPP concentration on metallic ion transportability are examined under various experimental conditions. The permeation velocities of the metallic ions in the transport system followed the sequence Li⁺?Na⁺>K⁺>Mg²⁺; that is, a highly selective transport for Li⁺ ion was observed. Compared with the transport rates of alkali metallic ions, those of transition metallic ions such as Cu²⁺ and Fe³⁺ ions are very low. The permeation velocities of alkali and alkaline earth metallic ions through an SLM are dependent on the concentrations of perchlorate and TPP. Equations for the permeation velocities of Li⁺, Na⁺, K⁺, and Mg²⁺ ions through an SLM, based on two concentrations of perchlorate and TPP, are proposed.     

Proton-Ionizable Crown Compounds: Transport of Alkali and Alkaline Earth Cations Using Proton-Ionizable Triazolo Macrocycles

Abstract

The macrocycle-mediated flaxes of the alkali and alkaline earth metal cations have been determined in a H₂O-CH₂Cl₂-H₂O bulk liquid membrane system. Water-insoluble proton-ionizable macrocycles of the triazolo type were used. The proton-ionizable feature allows the coupling of cation transport to reverse H⁺ transport. This feature offers promise for the effective separation and/or concentration of alkali metal ions with the metal transport being driven by a pH gradient. A counter anion in the source phase is not co-transported. Transport of the alkali cations only occurred when the source phase pH was greater than the aqueous pK_a value for the carriers. Transport increased regularly with increasing source phase pH. Transport of alkaline earth cations from neutral pH source phases was minimal. The alkali cation selectivity order was K⁺ > Rb⁺ > Cs⁺ > Na⁺ > Li⁺ for the l8-crown-6 sized macrocycles, while little selectivity was observed with the 15-crown-5 sized macro-cycle.     

SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS. XXXXI. ION EXCHANGE EQUILIBRIA OF ALKALI METAL IONS/HYDROGEN IONS ON TIN(IV) ANTIMONATE

Ion exchange equilibria of alkali metal ions (Li⁺, Na⁺, K⁺,, Rb⁺, and Cs⁺)H⁺, systems have been studied in MNO-j-HNOj media with ionic strength of 0.1 at 30, 45 and 60 °C on tin(IV) antimonate as a cation exchanger. The ion exchange isotherms have been measured for both forward and backward reactions by the batch technique. The isotherms showed S-shaped curves for all exchange systems studied. The selectivity coefficients (logarithmic scale) vary with the equivalent fraction X_M of alkali metal ions in the exchanger and give two linear functions of X_M with a break point (X_M= 0.14, except 0.04 for Li⁺, /H⁺) indicating two different exchanging sites. The selectivity sequence, Na⁺, ? K⁺, ? Rb⁺, ? Cs⁺, ? ? Li, holds in the range of Xu= (0 - 0.04) and the sequence, Cs < Rb ⁺, ? K ⁺, ? Na ⁺, < Li ⁺, applies when X_M is higher than 0.14.

Hypothetical thermodynamic data on “zero loading” of the ion exchange reaction was evaluated.     

Synthetic ionophores for the separation of Li, Na, K, Ca, Mg metal ions using liquid membrane technology

Carrier-assisted transport through liquid membranes is one of the important applications of supramolecular chemistry. This work investigates the use of synthetic carrier (ionophore) for the separation of metal ions. We have tested the effect of structure of ionophore on the separation of metal ions. For this purpose, we have used a new series of non-cyclic ionophores having different end groups and chain length (R₁–R₅). 1,5 bis (2-naphthyloxy)-3-oxapentane (R₁), 1,8 bis (2-naphthyloxy)-3,6-di-oxaoctane (R₂), 1,11 bis (2-naphthyloxy)-3,6,9-tri-oxaundecane (R₃) 1,11-(dianthraquinonyloxy) 3,6,9-trioxaundecane (R₄), 1,8 (dianthraquinonyloxy) 3, 6-dioxaoctane (R₅) have been used in extraction, bulk liquid membrane (BLM) and supported liquid membrane (SLM) transport of alkali (Li⁺, Na⁺, K⁺) and alkaline earth metal cations (Ca²⁺, Mg²⁺). The supported liquid membrane consisted of a porous cellulose nitrate and and an onion membrane support impregnated with ionophore using chloroform as a solvent. The results reveal that ionophores R₁, R₂ and R₃ are better extractants for K⁺ while R₄ and R₅ are better extractants for Ca²⁺. Among these ionophores R₃ and R₄ are best extractants for K⁺ and Ca²⁺ ions. The results of BLM reveal that ionophores R₁, R₂ and R₃ transport Na⁺ at a greater extent, while R₄ and R₅ transport Ca²⁺ and K⁺ at a greater extent. In SLM experiments using a cellulose nitrate membrane support, it was observed that naphthyl end group bearing ionophores (R₁–R₃) transports Na⁺ > K⁺, and anthraquinone bearing ionophores (R₄ and R₅) transport K⁺ > Na⁺ > Ca²⁺ respectively. In the onion membrane support R₄ transports Ca²⁺ and Na⁺ equally and R₅ transports K⁺ selectively. On comparing the membrane support, the cellulose nitrate membrane is found better support for the transport of metal ions. The results suggest that due to the presence of different end groups and chain lengths the selectivity of non-cyclic ionophores towards metal ions is enhanced. Thus selectivity of ionophores may have fruitful application in ion selective electrodes and separation of metal ions.     

SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS. XLVIII. ION-EXCHANGE REACTION OF ALKALI METAL IONS/H+ ON MONOCLINIC ANTIMONIC ACID

The pH titration curves of monoclinic antimonic acid (M-SbA) showed apparently monobasic acid for the systems of alkali metal ions/H⁺. The uptake order of the metal ions were K⁺ < Rb⁺ < Cs⁺ < Na⁺ < Li⁺ throughout the pH range studied. The low uptakes of K⁺, Rb⁺, Na⁺ and Cs⁺ at high pH might be due to steric or ion sieve effects for large unhydrated cations on M-SbA. Thermodynamic data were derived for Li⁺/H⁺ exchange on M-SbA from pH titration curve.     

ION EXCHANGE SELECTIVITY OF A RESORCINOL-FQRMALDEHYDE POLYCONDENSATE RESIN FOR CESIUM IN RELATION TO OTHER ALKALI METAL IONS

ABSTRACT

Ion exchange isotherms for the ion-pairs Li⁺ -Cs⁺, Na⁺ -Cs⁺ and K⁺ -Cs⁺ have been measured for a cesium selective resorcinol—formaldehyde polycondensate resin synthesized in the laboratory- The equilibrium data have been used to calculate the thermodynami c equilibrium constants as well as standard free energies of ion ex change and thus arrive at a selectivity series for the above ions- The high selectivity towards cesium as compared to other alkali metal ions has been discussed in the 1ight of existing theories and models of ion ex change phenomena.     

The Influence of Counter-Ions on the Properties of a Polyethylene Phosphonic Acid Membrane

Permselective polyethylene-phosphonate membranes have been prepared from polyethylene, both by topochemical reaction and by casting from solution. At capacities around 1–2 meq/g these membranes change their electric resistance by more than four orders of magnitude and deswell in acid solutions. The jump in resistance values takes place at different pH according to capacity and cross-linking of the membrane. The influence of different alkali ions and some tetraalkyl-ammonium ions on conductivity, swelling and hysteresis of these membranes has been determined. The Li⁺ ion deswells the membrane and increases its resistance nearly as much as the H⁺ ion while swelling and conductivity increase in hydroxide solutions with increasing atomic weight of the alkali metals. In non-alkaline solutions the K⁺ form has lower conductivity than the Na⁺ form. Physiological implications of the findings are discussed.     

Interactions of Some Hofmeister Cations with Sodium Dodecyl Sulfate in Aqueous Solution

In this work, we have investigated the influence of some alkali metal ions on the Krafft temperature (T_K) and critical micelle concentration (CMC) of a classical ionic surfactant, sodium dodecyl sulfate (SDS), over a wide range of temperature. The alkali metal cations such as Li⁺, Na⁺, Cs⁺, and K⁺ are found to affect the solubility and hence the T_K of the surfactant. It was observed that kosmotropic Li⁺ lowers the T_K of the surfactant. Due to the common ion effect, the solubility of SDS decreases in the presence of Na⁺, resulting in an increase in the T_K. On the other hand, chaotropic K⁺ and Cs⁺, capable of forming contact ion pairs with the chaotropic dodecyl sulfate ion, lower the solubility and hence elevate the T_K. In terms of decreasing the T_K, the ions follow the trend: Li⁺ > Na⁺ > Cs⁺ > K⁺ except for 0.0025 M CsCl. The added cations screen the charge of the micelle surface and facilitate closer packing of the surfactant with a consequent decrease in the CMC. In terms of the effectiveness in lowering the CMC, the ions follow the order: Cs⁺ > K⁺ > Na⁺ > Li⁺. In the presence of added electrolytes, the γ_CMC values are found to be lower than the corresponding values in pure water. The thermodynamic parameters (Gibbs free energy, enthalpy, and entropy changes) of micellization were calculated to gain insights into the mechanism of the process.     

Development of thin‐film composite membranes for carbon dioxide and methane separation using sulfonated poly(phenylene oxide)

Novel membranes based on sulfonated poly (phenylene oxide) (SPPO) was developed. SPPO membranes in the hydrogen form were converted to metal ion forms. The effect of exchange with metal ions including monovalent (Li⁺, Na⁺, K⁺), divalent (Mg²⁺, Ba²⁺, Ca²⁺) and trivalent (Al³⁺) ions was investigated in terms of permeation rate and permeation rate ratios for CO₂ and CH₄ gases. Both dense homogeneous membranes and thin‐film composite (TFC) membranes were studied for their gas separation characteristics. The effect of membrane preparation conditions and operating parameters on the membrane performance were also investigated. The selectivity of the TFC membrane increased as the cationic charge density increased as a result of electrostatic cross‐linking. TFC membrane of very high selectivity was achieved by coating a thin layer of SPPO‐Mg on a PES substrate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 735–742, 2000     

SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS XXX III. SELECTIVITIES OF ALKALI METAL IONS ON TIN(IV) ANTIMONATE CATION-EXCHANGER PREPARED AT DIFFERENT CONDITIONS

ABSTRACT

A tin(IV) antimonate(SnSbA) cation exchanger has been synthesized under different conditions; changes in the concentration, the molar ratio of Sb/Sn in the starting solution, and hydrolysis temperature. The products obtained were characterized by powdered X-ray diffraction and thermal analysis, and infrared spectra. The pH titration curves on SnSbA showed apparently mono-basic acid, but can be expected to the presence of the number of the functional groups with overlapping different pKa values. The increased acidities were observed with increasing the molar ratio (Sb/Sn) in the exchanger. The equilibrium distribution coefficients were determined at micro-amount of alkali metal ions in the hydrochloric acid solution. The SnSbA showed an unusual selectivity for alkali metal ions compared to cation exchange resins and other inorganic ion-exchangers.

The selectivity sequence shows; Na⁺ < K⁺ < Rb⁺ < Cs⁺ < Li⁺

An extremely high selectivity of lithium ions was found on the SnSbA hydrolyzed at relatively high temperature and with high Sb/Sn molar ratio     

THE MECHANISM OF DIFFUSION AND IONIC TRANSPORT OF Li+, Na+ AND K+ ON SEMICRYSTALLINE NIOBIUM PHOSPHATE

A computer simulation technique has been applied to solve the Nernst-Planck equations for the kinetics of exchange of alkali metal ions (Li⁺, Na⁺ and K⁺). Activation energy and the self diffusion coefficient were found to be linear functions of hydration energies and the ionic radii of these ions, respectively. It has been proposed, on the basis of kinetic parameters, that the exchange of alkali metal ions occurs in the unhydrated form. They shed most of their water of hydration at the surface of the beads and then again get hydrated after being exchanged. The exchanger appears to have a zeolite type structure.     

Pervaporation separation of dimethyl carbonate/methanol mixtures with regenerated perfluoro‐ion‐exchange membranes in chlor‐alkali industry

The waste perfluoro‐ion‐exchange membranes (PFIEMs) in chlor‐alkali industry were regenerated and used to the separation of dimethyl carbonate (DMC)/methanol (MeOH) mixtures by pervaporation process. The energy‐dispersive spectrum (EDS) demonstrates that the impurities on the surfaces of waste PFIEMs can be effectively cleared by the regeneration process. The degree of swelling, sorption, and pervaporation properties of the regenerated PFIEMs with different counter ions were investigated. The results indicate that the counter ions of PFIEMs conspicuously influence the degree of swelling, sorption, and pervaporation properties for DMC/MeOH mixtures. The degree of swelling and solubility selectivity both decreases with the alkali metal counter ions in the sequence: Li⁺ > Na⁺ > K⁺ > Cs⁺. The degree of swelling increases with MeOH concentration increasing in feed liquid. The pervaporation measurements illustrate that the permeation flux decreases and the separation factor increases with the rising in ion radius of counter ions. The increase of feed concentration (MeOH) and feed temperature is advantageous to improve permeation flux while at the cost of separation factor decreasing. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of Additives on the Activity and Enantioselectivity of Candida rugosa Lipase in a Biphasic Medium

The effects of Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺ ions on the activity and enantioselectivity of Candida rugosa lipase (CRL) were investigated in a biphasic medium composed of phosphate buffer solution (containing a metal ion within a 50–500 mM concentration range) and isooctane. The hydrolytic activities of CRL towards p‐nitrophenyl acetate were measured after incubation of the enzyme in the presence of metal ions for 24 h, and they were compared to that obtained after incubation in the absence of any metal ion. The CRL activity was stimulated by the chloride salts of Li⁺, K⁺ and Mg²⁺ for all concentrations considered and the highest enhancement was achieved by Li⁺ with a 1.24–1.75 fold increase observed. The effects of metal ions on the enantioselectivity of CRL were investigated by performing the hydrolysis of racemic Naproxen methyl ester in the same biphasic medium containing Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺ ions. The addition of metal ions increased the hydrolysis rate by ca. 1.31–1.45 fold relative to the control, whereas the enantiomeric excess of product increased slightly in the presence of the metal ions. The effect of Triton X‐100 on the activity and enantioselectivity of the CRL was also investigated by employing 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 mM concentrations of it in phosphate buffer solution of the biphasic medium. High concentrations of Triton X‐100 stimulated the enzyme activity up to 1.66 fold after 24 h incubation. Triton X‐100 increased the hydrolysis rate almost independently of the concentration.