Effect of ultraviolet irradiation on the selective transport of alkali metal ions 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 alkali metal ions against their concentration gradient through the membranes was investigated by using the system which contains HCl (left side) and alkali metal solution including two kinds of alkali hydroxides (right side). The effect of ultraviolet (UV) irradiation on the selective transport of alkali metal ions through the ETMA–MAc copolymer membranes was investigated. The membranes were irradiated with a 6-W low pressure mercury lamp at a distance of 10 cm at room temperature in air. The transport selectivity could be increased by using UV-irradiated membranes and the selectivity increased with increasing irradiation time up to 2–3 h, although the transport rate of alkali metal ions decreased with increasing time of UV irradiation. The maximum selectivity of K⁺/Na⁺, Na⁺/Li⁺, and K⁺/Li⁺ were 1.7, 2.0, and 4.2, respectively. In order to explain this phenomena, the effect of UV irradiation on the properties of the membranes was studied. It was concluded that the increase of the selectivity is attributed to the formation of the dense membrane by photocrosslinking of the membrane by UV irradiation.     

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.     

Behaviors of polyelectrolyte AAm/AMPS/bentonite composite hydrogels in uptake of uranyl ions from aqueous solutions

Uranyl ion (UO₂²⁺) sorption properties of polyelectrolyte composite hydrogels made by the polymerization of acrylamide (AAm) with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) and clay such as bentonite (Bent) were investigated as a function of composition to find materials with swelling and uranyl ion sorption properties. Highly swollen AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with AMPS as co‐monomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. Finally, adsorption capacity (the amount of sorbed uranyl ion per gram of dry hydrogel) (q) was calculated to be 0.67 × 10⁻³–2.11 × 10⁻³ mol uranyl ion per gram for the hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio (K_d) of uranyl ions was calculated to be 0.10–0.43 for AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Rate of Adsorption of Uranium from Seawater with a Calix[6]arene Adsorbent

Abstract

The rate of complex formation between calix[6]arene-p-hexasulfonate and uranyl ion is studied over a wide range of carbonate ion concentrations. The presence of carbonate ion decreases the complexation rate. The distribution of various uranyl species is calculated from a set of mass balances of participating ions with their stability constants. UO₂(CO₃)₃ ^4? has the highest concentration, followed by UO₂(OH)₃ ^? and UO₂(CO₃)₂ ^2?. Other uranyl species are negligible. The complexation rate is proportional to the 0.27–1.0 power of the total concentration of uranyl species other than UO₂(CO₃)₃ ^4?. This implies that the rate-determining step of the complexation is the reaction between calix[6]arene-p-hexasulfonate and UO₂(OH)₃ ^? or UO₂(CO₃)₂ ^2?.     

Uranyl ion adsorptivity of N-vinyl 2-pyrrolidone/acrylonitrile copolymeric hydrogels containing amidoxime groups

Summary N-vinyl 2-pyrrolidone (VP) / Acrylonitrile (AN) copolymeric hydrogels were synthesized by using γ-radiation and amidoximated for the purpose of uranyl ion adsorption. Optimum amidoximation time was determined by following the uranyl ion, UO₂ ²⁺, adsorption capacity. The adsorption of amidoximated copolymers was studied from different uranyl ion solutions (1000–1850 ppm). The results of all adsorption studies showed that the interaction between UO₂ ²⁺ and amidoxime groups comply with Langmuir type isotherm. The adsorption capacity was found as 0.54 g UO₂ ²⁺ /g dry amidoximated copolymeric hydrogels. From the stoichiometric calculations, it was found that the bonding between UO₂ ²⁺ and amidoxime groups is 1 to 4. Received: 7 September 1999/Revised version: 21 February 2000/Accepted: 18 March 2000     

Behaviors of Chemically Crosslinked CAAMPS Hydrogels in Uptake of Uranyl Ions from Aqueous Solutions

Uranyl ion adsorption from aqueous solutions has been investigated by chemically crosslinked (C) polyelectrolyte acrylamide/2-acrylamido-2-methyl-1-propanesulfonic acid (CAAMPS) hydrogels. CAAMPS hydrogels with various compositions were prepared from ternary mixtures of acrylamide (A), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), and water by free radical polymerization in an aqueous solution using multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). The swelling equilibrium of polyelectrolyte copolymer gels containing of CAAMPS hydrogels has been studied as a function of copolymer composition. Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. The weight-swelling ratio of CAAMPS hydrogels was increased up to 127.03 (for 300 mg AMPS and crosslinked by EGDMA) and 93.32 (for 300 mg AMPS and crosslinked by BDMA), while acrylamide hydrogels swelled up to 10.27 (crosslinked by EGDMA) and 10.06 (crosslinked by BDMA). Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. In the experiments of the sorption, L type sorption in the Giles classification system was found. Finally, the amount of sorbed uranyl ion per gram of dry hydrogel (q) was calculated to be 0.67 × 10^?3–2.11 × 10^?3 mol uranyl ion per gram for CAAMPS hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio, (K _d ) of uranyl ions was calculated to be 0.10–0.43 for CAAMPS hydrogels.     

Removal of concentrated heavy metal ions from aqueous solutions using polymers with enriched amidoxime groups

Particulate and fibrous adsorbents with enriched amidoxime groups were synthesized by using a novel monomer N,N′‐dipropionitrile acrylamide. The adsorption properties of amidoximated poly(N,N′‐dipropionitrile acrylamide) [poly(DPAAm)] particles and a nonwoven fabric grafted with the same for UO₂²⁺, Pb²⁺, Cu²⁺, and Co²⁺ at high concentrations were investigated by batch process. Metal ion adsorption studies were conducted from metal ion solutions with different initial concentrations (100–1500 ppm). It was shown that particulated amidoximated poly(DPAAm) has higher adsorption capacity than amidoximated nonwoven fabrics for all metal ions, especially for uranyl ions. The results of the adsorption studies showed that the interaction between UO₂²⁺ and amidoximated groups agree with the Langmuir‐type isotherm. From the Langmuir equation, the adsorption capacities were found as 400 mg UO₂²⁺/g dry amidoximated poly(DPAAm) and 250 mg UO₂²⁺/g dry amidoximated graft polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1705–1710, 2004     

Removal of heavy metals from model wastewater by using carboxymehyl cellulose/2‐acrylamido‐2‐methyl propane sulfonic acid hydrogels

A series of functional copolymer hydrogels composed of carboxymethyl cellulose (CMC) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) were synthesized using γ‐radiations‐induced copolymerization and crosslinking. Preparation conditions were optimized, and the swelling characteristics were investigated. The ability of the prepared hydrogels to recover some toxic metal ions from their aqueous solutions was studied. The prepared hydrogel showed a great capability to recover metal ions such as: Mn⁺², Co⁺², Cu⁺², and Fe⁺³ from their solutions. The data revealed that the chelating ability of the prepared hydrogels is mainly dependent on their internal composition, in addition to the physical properties of the metal ion solution such as pH and metal ion concentration. The data show that the chelating ability of the prepared hydrogels increases by increasing the AMPS content in the hydrogel as well as the increment in the pH of the solution and the metal ion concentration. The prepared CMC/AMPS copolymer hydrogels are chemically stable enough to be reused for at least five times with the same efficiency. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The Mechanism of a Selective Permeation of Ions through “Solvent Polymeric Membranes”

Abstract

The mechanism of diffusion of uranyl nitrate in “solvent polymeric membranes” was investigated. It is suggested that a “carrier” transport mechanism is responsible for the selective permeation of ions or ion pairs through such membranes. The fluidity of the membranes was investigated by proton magnetic resonance and by the “fluorescent probe” technique. Radioactive labeling was used in order to determine the self-diffusion coefficient of dicresylbutylphosphate (DCBP) which serves both as plasticizer and as complexing agent in such membranes. Comparison of its value (～10^?7 cm²/sec) with the limiting value of the diffusion coefficient of uranyl nitrate in such membranes (3.3 × 10^?8 cm²/sec) indicates that the latter diffuses as a (DCBP)₂UO₂(NO₃)₂ complex. It is also suggested that the study of the “solvent polymeric membranes” may help to understand certain properties of biological membranes.     

Enhancement of uranyl ion uptake by prestructuring of acrylamide–maleic acid hydrogels

Acrylamide–maleic acid (AAm–MA) hydrogels were prepared by gamma‐irradiation of their aqueous solutions. UO₂⁺² ion uptake on P(AAm–MA) hydrogels was investigated using two types of gel systems prepared by a simple irradiation method and a prestructured reaction. It has been observed that gels prestructured with UO₂⁺² ions adsorbed approximately 15–20% more UO₂⁺² ions than gels prepared in pure water (the usual method). It was also found that the uranyl ion adsorption capacity of hydrogels increased with an increasing amount of maleic acid in the gel system and an increasing concentration of uranyl ion in the solution. A possible interaction mechanism between the groups in the copolymeric gels and UO₂⁺² ion has been proposed based on the stoichiometry and the spectroscopic evidence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 284–289, 2000     

Synthesis and heavy metal ion adsorptivity of macroreticular chelating resins containing phosphono and carboxylic acid groups

Macroreticular copolymer beads were prepared by suspension polymerization of 4-vinylbenzyl chloride (VBC), divinylbenzene (DVB) and monomers with carboxylic ester groups like dibutyl maleate (DBM), dibutyl fumarate (DBF) and dibutyl itaconate (DBI) in the presence of toluene as diluent. The copolymer beads were phosphorylated at the chloromethylated phenyl rings with triethyl phosphite and hydrolyzed by an aqueous sodium hydroxide solution; the hydrolysis on the bead surface converted carboxylic ester/phosphonate groups into carboxylic acid/phosphono groups, respectively. The investigations on the metal ion chelation characteristics of the H-form copolymer beads revealed that they have good adsorptivity toward heavy metal ions like Pb²⁺, Cd²⁺ and Cu²⁺, and poor adsorptivity toward ions like Hg²⁺ and UO₂²⁺. The adsorptivity caused by the three carboxylic ester monomer derivatives was in the order DBM > DBI > DBF. Especially, the Na-form copolymer beads neutralized by alkali treatment were very available for the adsorption of all the metal ions under investigation.     

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.     

Aqueous Biphase Systems for Liquid/Liquid Extraction of f-Elements Utilizing Polyethylene Glycols

Abstract

Aqueous biphasic systems formed by adding a H₂O soluble polymer (polyethylene glycol) to an aqueous salt solution ((NH₄)₂SO₄ or K₂CO₃) have been investigated for use in extracting aqueous Am³⁺, Pu⁴⁺, UO₂ ²⁺, and Th⁴⁺ ions into the polymer-rich phase. Extraction occurs only in the presence of complexing dyes which preferentially partition to the polymer-rich phase. Three such dyes, arsenazo III, alizarin complexone, and xylenol orange were investigated. Arsenazo III extracts all four metal ions from SO₄ ^2- media but not from CO₃ ^2- solutions. Alizarin complexone quantitatively extracts Th⁴⁺ and Pu⁴⁺ from SO₄ ^2- media, while Am³⁺ is the best extracted ion in CO₃ ^2- solution. Xylenol orange extracts only Am³⁺ from CO₃ ^2- media. In SO₄ ^2- solutions low concentrations of xylenol orange extract Th⁴⁺ and Pu⁴⁺, while Am³⁺ and UO₂ ²⁺ are extracted at higher concentrations of xylenol orange. H₂SO₄ can be used to strip the metal ions, while NH₄OH often but not always enhances the extraction.     

Uranyl ion-selective optical test strip

A novel, optical sensor, test strip has been developed for the spectrophotometric determination of trace amounts of uranyl ions, UO₂²⁺, based on immobilization of C.I. Mordant Blue 29 (Chromazurol S)/cetyl N,N,N-trimethyl ammonium bromide ion pair on a triacetyl cellulose membrane. Optimization of the sensor for the detection of low levels of uranyl ion is described. The test strip responded linearly to uranyl ions between 3.0 × 10^?7 and 6.0 × 10^?5 mol L^?1; the reproducibility of the sensor at a medium level of UO₂²⁺ activity was ±0.55%. The optical sensor can be regenerated using 0.01 mol L^?1 HCl or 0.01 mol L^?1 NaF solution after 10 min. The developed test strip was used in the determination of UO₂²⁺ in ground water samples.     

Kinetic Behavior of Lightly Crosslinked Chelating Resins Containing Amidoxime Groups for Batchwise Adsorption of UO2 2+

Abstract

Lightly crosslinked poly(acrylonitrile-co-divinylbenzene) beads (RN-5) have been synthesized by suspension polymerization. The use of dichloroethane and chloroform as a porogen produced lightly crosslinked copolymer beads having highly porous structures. The chelating resins containing amidoxime groups (RNH-5) have been prepared by the reaction of copolymer beads with NH₂OH in MeOH. The resulting chelating resins have been used in the batchwise adsorption of UO₂ ²⁺ from nitrate solutions containing 0.01 mol·dm^?3 UO₂ ²⁺ at pH 3.25. In order to get some measure of the relative performance of each resin in kinetic terms, the extraction of UO₂ ²⁺ was monitored with time and some adsorption profiles were obtained. An increase in porogen content resulted in a marked increase in the batchwise adsorption of UO₂ ²⁺. Alkaline treatment allowed a high swelling and hence rapid accessibility of UO₂ ²⁺ to the ligands. Even after 30 minutes, the alkali-treated resins were 50% loaded.     

Uranium membrane separation from binary aqueous solutions of UO22+-K+ and UO22+-Ca2+ by the nanofiltration process

The performance of the nanofiltration process was investigated for uranium separation from binary aqueous solutions of UO₂²⁺-K⁺ and UO₂²⁺-Ca²⁺ containing uranium in high concentration ranges. Rejection coefficient, permeate flux, and membrane selectivity of PES-2, NF-1, and NF-2 membranes under various operational conditions of pH, pressure, and concentration of interfering cation were evaluated. In most cases, the order of metal rejections with these membranes was UO₂²⁺ > Ca²⁺ > K⁺. According to the obtained results, the nanofiltration process could be effectively used for selective uranium separation from aqueous solutions containing uranium and other monovalent and divalent cations.     

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     

Development of novel adsorbent materials for recovery and enrichment of uranium from aqueous media

A new polymeric adsorbent bearing both hydrophilic groups providing swelling in water and amidoxime groups for chelating with uranyl ions (UO₂²⁺), has been developed and its adsorptive ability for recovering uranium from aqueous media has been investigated. The polymers obtained by irradiating the solution of polyethylene glycol (PEG) in acrylonitrile (AN) are defined as interpenetrating polymer networks (IPNs) and the adsorbent has been obtained by applying the amidoximation reaction to the IPNs with a conversion ratio of ∼ 60%. Kinetics of the conversion reaction of the cyano (CN) group to the amidoxime (HONCNH₂) group has been studied by reacting with hydroxylamine (NH₂OH) solution at a molar ratio of NH₂OH/CN = 1.25 in aqueous media at three different temperatures, 30, 40, and 50°C, for 3–4 days. The degree of amidoximation ratio was determined by UO₂²⁺ ion adsorption and FTIR spectrometry and the UO₂²⁺ ion adsorption values were found by both UV and gamma spectrometry and also by gravimetry. It was found that the polymeric adsorbent has a very high adsorption ability for uranium and quite a good stability in aqueous media. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2475–2480, 1997     

Removal of hazardous by radiation‐synthesized copolymer hydrogels based on 2‐acrylamido‐2‐methylpropanesulfonic acid and 2‐dimethyaminoethyl methacrylate monomers

Superabsorbent copolymer hydrogels were prepared by gamma irradiation of aqueous solutions of 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) and 2‐dimethyaminoethyl methacrylate (DEMA) monomers mixtures. The thermal stability of hydrogels was evaluated by thermogravimetric analysis. The ability to adsorb Cu²⁺ ions and dyes by the prepared hydrogels from aqueous solutions was investigated. The swelling study, in water, showed that the hydrogels based on pure AMPS monomer and AMPS/DEMA copolymers reached the equilibrium state after 6 h. However, the hydrogel based on pure AMPS monomer showed higher swelling than the copolymer hydrogels based on AMPS/DEMA. It was found that the copolymer hydrogels based on different compositions showed affinity to absorb Cu²⁺ metal ions as well as basic and acid dyes; however, this affinity was found to decrease with increasing the ratio of DEMA in the initial feeding solutions. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium): Synthesis,characterization, and its potential application for the removal of metal ions from aqueous solution

In the current study, poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium), poly(VP‐co‐AMPS), was prepared and used for the removal of Cu²⁺, Cd²⁺, and Ni²⁺ ions via a polymer‐enhanced ultrafiltration (PEUF) technique. The copolymer was synthesized by radical polymerization in an aqueous medium with a comonomer feed composition of 50:50 mol %. The molecular structure of the copolymer was elucidated by ATR‐FTIR and ¹H NMR spectroscopy, and the average molecular weight was obtained by GPC. The copolymer composition was determined to be 0.42 for VP and 0.58 for AMPS by ¹H NMR spectroscopy. The copolymer and homopolymers exhibited different retention properties for the metal ions. PAMPS exhibited a high retention capacity for all of the metal ions at both pH values studied. PVP exhibited selectivity for nickel ions. Poly(VP‐co‐AMPS) exhibited a lower retention capacity compared to PAMPS. However, for poly(VP‐co‐AMPS), selectivity for nickel ions was observed, and the retention of copper and cadmium ions increased compared to PVP. The homopolymer mixture containing PAMPS and PVP was inefficient for the retention of the studied metal ions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41272.