Studies on syntheses and permeabilities of special polymer membranes. 62. Active transport of alkali metal ions through poly(vinyl alcohol) membranes crosslinked with glutaraldehyde

The transport of alkali metal ion through poly(vinyl alcohol) crosslinked with glutaraldehyde without dissociating groups in a diaphragm cell, at one side being an alkaline and at the other an acidic solution, was investigated under various conditions. The active transport fraction of alkali metal ions from the alkaline side to the acidic side was significantly influenced by the degree of crosslinking of the membrane, size of anion species, initial pH on the acidic side, and the electric potential difference across the membrane.     

Studies of synthesis and permeabilities of special polymer membranes. LI. Active transport of halogen ions through chitosan membranes

Anion exchange membranes containing amino groups, insoluble in acidic and alkaline aqueous solutions, were prepared from chitosan, poly(vinyl alcohol), and glutaraldehyde. Using the membrane in a diaphragm cell, one side being adjusted to be acidic and the other alkaline, it was possible to transport actively halogen ions through the membrane from the acidic side to the alkaline side against the concentration gradient between both sides of the membrane. The active transport of halogen ions through the membrane was significantly influenced by the pH difference and electric potential difference between both sides of the membrane.     

pH‐controlled uphill transport of boric acid through a poly(vinyl alcohol) (PVA) membrane

The uphill transport of boric acid in aqueous solutions through a thermal‐crosslinked poly(vinyl alcohol) (PVA) membrane was investigated. A normal permeation caused by the concentration difference of the boron along the PVA membrane was observed for equal pH conditions at both sides of the membrane, and higher flux was observed under an acidic condition at pH = 5.0 than under a basic condition at pH = 10.0. When the pH of one side is kept pH = 5.0 (acid side) and the other side was kept at pH = 10.0 (base side), uphill transport of boric acid from the acid side to the base side was observed under an equal initial concentration of both sides. Such an uphill transport was also observed against the concentration difference under the condition in which the initial concentration of the base side was higher than that of the acid side. The uphill transport could be explained by the difference in the permeation rates through the PVA membrane between B(OH)₃, the dominant form under lower pH, and B(OH)₄^?, the dominant form under higher pH, which makes a complex with diols in PVA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1451–1455, 2007     

Studies on syntheses and permeabilities of special polymer membranes

Summary An ion exchange membrane containing carboxyl groups, insoluble in acidic and alkaline aqueous solutions, was prepared from poly(isobutylene-alternating co-maleic anhydride) and poly(vinyl alcohol). Using the membrane in a diaphragm cell, one side being adjusted to be acidic and the other alkaline, it was possible to transport actively and selectively alkali metal ions through the membrane from the alkaline side to the acidic side.     

Studies on syntheses and permeabilities of special polymer membranes: 50. Transport of metal ions against their concentration gradient through water-insoluble poly(styrene sulphonic acid) membrane

Water-insoluble cation exchange membranes were prepared by heat treating membranes made of poly(styrene sulphonic acid) and poly(vinyl alcohol). Transport of metal ions through the above cation exchange membrane against their concentration gradient was investigated under various conditions. The transport in this system, where one side of the membrane in a diaphragm cell was acidic and the other alkaline, was influenced significantly by the initial H⁺ ion concentration on the acidic side. The selectivity of metal ions in diffusive transport depended on the size of their hydrated ions and that in transport against their concentration gradient was due to the affinity between the metal ions and the carrier fixed to the membrane.     

Studies on syntheses and permeabilities of special polymer membranes. XLVII. Active transport and selective transport of metal ions through membranes from poly(isobutylene-alternative co-maleic anhydride) and poly(vinyl alcohol)

When a cation exchange membrane having carboxyl groups, made of poly(isobutylene-alternative co-maleic anhydride) and poly(vinyl alcohol), was set in a diaphragm type cell, in which one side of the solution was adjusted to be acidic and the other side alkaline, metal ions were actively transported from the alkaline side to the acidic side across the membrane against the concentration gradient of metal ions between both sides. The driving force of the transport of metal ions was the difference in H⁺ ion concentration between both sides. It was presumed that the active transport was carried out chemically and physically. In the selective transport of metal ions, the selectivity was dependent on both the hydrated ionic radius for the metal ions and the affinity between the carrier fixed to the membrane, the carboxyl group, and the metal ions.     

Studies on Syntheses and Permeabilities of Special Polymer Membranes. 59. Active Transport of Organic Ions through Crosslinked Chitosan Membrane

Abstract

Active transport of organic ions such as benzenesulfonate and benzoate ions and amino acids was studied through a chitosan–PVA membrane under various conditions. The organic anions of benzenesulfonate and benzoate ions were actively transported through the chitosan–PVA membrane from the acidic side to the alkaline side, but the active transport of amino acid occurred from the alkaline side to the acidic side. These active transports were significantly dependent on a pH difference and electric potential difference between the two sides of the membrane     

Active transport membrane for chlorine ion

A specific functional group that could interact with ions was introduced in a synthetic membrane to achieve an active transport of ions. One way to synthesize the active transport membrane was to introduce a functional group which has a tautomerism upon pH changes in an aqueous solution. A polymer having pendent N-hydroxyethyl amide groups was synthesized to form a membrane, and the membrane was fixed in a cell as a partition film, in which one side of the solution was adjusted to be acidic and the other side basic. It was then possible to transport chlorine ion through the membrane owing to the carrier functions caused by tautomerism of the N-hydroxyethyl amide group from the acidic to the basic sides. The transport of the chlorine ion was not dependent on diffusion control.     

Studies on syntheses and permeabilities of special polymer membranes

Summary An active transport of alkali metal ion through cation exchange membranes was studied under various conditions. This active transport was facilitated by using a greater anion species on an acidic side in a diaphragm cell, in which one side of the solution was adjusted to be acidic and the other side alkaline across the membrane. An active transport fraction of alkali metal ion was in order poly(styrenesulfonate)>benzenesulfonate>Cl^– >I^–>Br^– of anion species on the acidic side. A rate, fraction and period of the active transport of metal ion were significantly influenced by an electric potential gradient in the membrane.     

Permeability control of poly(methacrylic acid)–poly(ethylenimine) complex capsule membrane responding to external pH

Previously, permeability of partly crosslinked poly(acrylic acid)–poly(ethylenimine) complex capsule membranes has been shown to be controlled responding to external pH [K. Kono, F. Tabata, and T. Takagishi, J. Membr. Sci., 76 , 233 (1993)]. In order to improve pH-dependent permeation behavior of the polyelectrolyte complex capsule membranes, poly(methacrylic acid), which has hydrophobic side groups, was used as a polyanion component instead of poly(acrylic acid). The polyelectrolyte complex capsules composed of poly(methacrylic acid)–poly(ethylenimine) with a diameter of 5.2 mm were prepared. Permeation of phenylethylene glycol, which was used as a permeant, through the capsule membrane was quite limited at pH between 4 and 8. The permeation of the permeant across the capsule membrane in these pH regions was much less than that of poly(acrylic acid)–poly(ethylenimine) complex capsule membrane. However, the permeability constant was drastically increased in the order of 1 or 2 above pH 8 and below pH 4, depending on temperature. The Arrhenius plot for the permeation of phenylethylene glycol through the capsule membrane showed that the activation energy for the permeation is almost constant in the pH region between 4.5 and 8, but greatly decreases below pH 4 and above pH 8.8, suggesting occurrence of a significant change of the capsule membrane structure near these pH regions due to dissociation of polyelectrolyte complex. When environmental pH of the capsule was changed, release rate of phenylethylene glycol from the capsule was altered quickly and reversibly under acidic condition. © 1995 John Wiley & Sons, Inc.     

Selective Transport of Bismuth Ions through Supported Liquid Membrane

A new supported liquid membrane (SLM) system was prepared for the selective transport of bismuth ions from the aqueous feed into the aqueous permeate phase. The support of the SLM was a thin porous polypropylene or polyvinylidene fluoride membrane impregnated with diisooctyldithiophosphinic acid (Cyanex 301) as mobile carrier in 4‐chloroacetophenon as organic solvent. Cyanex 301 acts as a highly selective carrier for the uphill transport of bismuth ions through the SLM. In the presence of HNO₃ as a metal ion acceptor in the strip solution, the transport of bismuth ions into the strip side reached 70 % of the initial feed concentration after 3.5 hours. The selectivity and efficiency of bismuth transport from aqueous solutions containing different mixtures of cations were investigated. In the presence of P₂O₇^2– ions as suitable masking agent in the feed solution, the interfering effects of other cations were completely eliminated. The selective transport of bismuth through SLM is superior to liquid‐liquid extraction or through bulk liquid membranes. This is due to the high efficiency. The SLM reduces the solvent requirements, combines extraction and stripping operations in a single process and allows the use of highly selective extractants. The system may be applied to samples containing very low bismuth concentrations.     

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.     

Effect of Magnesium Ions on the Adsorption of Poly(acrylic acid) onto Alumina

The adsorption isotherms of poly(acrylic acid) (PAA) onto alumina powder have been determined as a function of pH, ionic strength, and magnesium-ion concentration. The adsorption of PAA is strongly enhanced by magnesium ions in alkaline media but less affected under acidic conditions. The adsorption isotherms display a maximum when PAA is fully complexed with magnesium ions in the solution, corresponding to a ratio of 0.25 ± 0.05 [Mg²⁺]/[acrylic acid monomer]. The decrease in adsorbed amount with an increase in PAA concentration at constant magnesium-ion concentration is related to a decrease in the complexation ratio.     

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.     

Modeling of facilitated transport of Cr(III) using (RNH3+HSO4−) ionic liquid and pseudo-emulsion hollow fiber strip dispersion (PEHFSD) technology

The permeation of chromium (III) using PEHFSD technology and the ionic liquid (RNH₃⁺HSO₄^?), formed by reaction of the primary amine PRIMENE JMT and sulphuric acid, dissolved in n-decane as mobile carrier has been investigated. The alkaline feed solution containing Cr(III) was passed through the tube side, and pseudo-emulsions of the ionic liquid + n-decane + n-decanol and sulphuric acid were passed through the shell side in counter-current mode and using a single hollow fiber module for extraction and stripping. In this advanced membrane technology, the aqueous acidic strip solution is dispersed in the organic membrane solution in a tank with an impeller stirrer to form a strip dispersion. The pseudo-emulsion phase is circulated from the tank to the membrane module to provide a constant supply of the organic solution to the membrane micropores. Factors affecting chromium permeability, such as hydrodynamic conditions, carrier concentration in the organic phase, metal and NaOH concentrations in the feed phase, have been analyzed. A model is reported describing the transport mechanism, whereas the experimental data are quantitatively explained by mathematical equations describing the rate of transport. Different rate-controlling processes take place as long as the metal transport occurs.     

Transport of nickel and copper against a concentration gradient through a carboxylic membrane,based on poly(vinyl chloride)/poly(methyl methacrylate-co-divinylbenzene)

Carboxylic exchange membranes were prepared from poly(vinyl chloride)/poly(methyl methacrylate-co-divinylbenzene) (PVC) [poly(MMA-co-DVB]. Transport of nickel and copper against a concentration gradient through the membrane was investigated by using a system containing NiCl₂ or CuCl₂ aqueous solution on the left side (L) and mixed solution of NiCl₂ (or CuCl₂) and HCl on the right side (R) of the membrane. It was found that nickel and copper were actively transported through the membrane from the L to the R side during the first 5 h of the experiments. The rate of transport of the ions increased with increasing H⁺ ion concentration on the R side and the initial concentration of the metals ions on both sides. The highest rate of transport was observed when 0.1 mol/L MeCl₂ on the L side and 0.1 mol/L MeCl₂-0.5 mol/L HCl on the R side were used. The nickel and copper transport fractions were 34 and 24%, respectively. © 1996 John Wiley & Sons, Inc.     

High Diffusion Permeability of Anion-Exchange Membranes for Ammonium Chloride: Experiment and Modeling

It is known that ammonium has a higher permeability through anion exchange and bipolar membranes compared to K⁺ cation that has the same mobility in water. However, the mechanism of this high permeability is not clear enough. In this study, we develop a mathematical model based on the Nernst–Planck and Poisson’s equations for the diffusion of ammonium chloride through an anion-exchange membrane; proton-exchange reactions between ammonium, water and ammonia are taken into account. It is assumed that ammonium, chloride and OH⁻ ions can only pass through membrane hydrophilic pores, while ammonia can also dissolve in membrane matrix fragments not containing water and diffuse through these fragments. It is found that due to the Donnan exclusion of H⁺ ions as coions, the pH in the membrane internal solution increases when approaching the membrane side facing distilled water. Consequently, there is a change in the principal nitrogen-atom carrier in the membrane: in the part close to the side facing the feed NH₄Cl solution (pH < 8.8), it is the NH₄⁺ cation, and in the part close to distilled water, NH₃ molecules. The concentration of NH₄⁺ reaches almost zero at a point close to the middle of the membrane cross-section, which approximately halves the effective thickness of the diffusion layer for the transport of this ion. When NH₃ takes over the nitrogen transport, it only needs to pass through the other half of the membrane. Leaving the membrane, it captures an H+ ion from water, and the released OH⁻ moves towards the membrane side facing the feed solution to meet the NH₄⁺ ions. The comparison of the simulation with experiment shows a satisfactory agreement.     

Selective separation of some heavy metals by poly(vinyl alcohol)‐grafted membranes

A poly(vinyl alcohol) membrane (PVA) was modified by radiation graft copolymerization of acrylic acid/styrene (AAc/Sty) comonomers. The Cu and Fe ion‐transport properties of these membranes were investigated using a diaphragm dialysis cell. In the feed solution containing CuCl₂ or a mixture of CuCl₂ and FeCl₃, the PVA‐g‐P(AAc/Sty) membranes showed high degrees of permselectivity toward Cu²⁺ rather than toward Fe³⁺. The permeation of Cu²⁺ ions through the membranes was found to increase with decrease in the grafting yield. However, as the content of Cu²⁺ ions in the Cu/Fe binary mixture feed solutions decreased, the rate and the amount of transported Cu²⁺ through the grafted membrane decreased, with no appreciable permselectivity toward Fe³⁺. When Fe²⁺ ions were used instead of Fe³⁺ ions in the feed solution containing Cu²⁺, the transport of both Cu²⁺ and Fe²⁺ through the membrane was observed. The rate of transport of Fe²⁺ was higher than that of Cu²⁺. In addition, it was found that the selective transport of ions was significantly influenced by the pH difference between both sides of the membranes. As the pH of the feed or the received solution decreased, both Cu²⁺ and Fe³⁺ passed through the membrane and were transported to the received solution. The role of carboxylic acid and the hydroxyl groups of the grafted membranes in the transportation process of ions is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 125–132, 2000     

固体酸催化合成肉桂酸乙酯进展

评述了对甲苯磺酸、氨基磺酸、强酸性阳离子交换树脂、六水三氯化铁、聚氯乙烯三氯化铁树脂、五水四氯化锡十二水合硫酸铁铵、一水硫酸氢钠,固体超强酸和固载杂多酸催化合成肉桂酸乙酯的方法。     

Water-soluble polymers by interaction of sulfonic polyelectrolytes with dipolar aprotic solvents

The solution of the strongly acidic polyelectrolyte poly(2-acrylamido-2-methylpropanesulfonic acid) in N,N-dimethylformamide or N,N-dimethylacetamide is accompanied by a simultaneous reaction of amidation of the sulfonic acid to the corresponding sulfonamide groups. Various compositions of binary copolymers poly[(2-acrylamido-2-methylpropanesulfonic acid)-co-(2-acrylamido-2-methylpropane-N,N-dimethylsulfonamide)] up to high amidation conversions of 98–99% were synthesized and characterized. The amidation of the sulfonic acid groups appears to be a common reaction for different copolymers having 2-acrylamido-2-methylpropanesulfonic acid moieties but fails with the free monomer.