Ion exchange of Cs ion in acid solution with potassium cobalt hexacyanoferrate

Potassium cobalt hexacyanoferrate (KCoFC) was synthesized for removal of Cs ions in acid waste solution. The synthesized KCoFC. was stable in nitric acid solution of pH= 1 and showed high selectivity for Cs ion over Sr and Na ions. The K_d,cs for 0.01 N Cs ion solution at pH=2 was about 3.6x 10³ mL/g in the presence of the same concentrations of Sr and Na ions, respectively. In the binary ion exchange system, both the Dubinin-Polanyi model and Langmuir model fit the experimental data, although the Dubinin-Polanyi model fit more correctly than the Langmuir model. However, in the multi-component system, only the modified Dubinin-Polanyi model, which is a semiempirical equation, fit the experimental data accurately. The ion exchange capacity of KCoFC. for Cs ion obtained by the Dubinin-Polanyi equation was 1.72 meq/g.     

Multi-component ion exchange kinetics with PAN-KCoFC composite ion exchanger

An ion exchange kinetic study was performed using PAN-KCoFC for removal of cesium ion from mixed solution of Cs, Sr, Ni and Ba ions. Uptake curves were obtained for a multi-component ion exchange system as well as binary system. A PAN-KCoFC composite ion exchanger showed higher selectivity for Cs ion over the Sr, Ba, Ni ions. A homogeneous model could predict accurately the uptake curve for both the binary and multi-component systems. Solid phase effective pore diffusivities obtained by modeling ranged between 10⁻⁵ cm₂/min and 10⁻⁶ cm₂/min.     

The Extraction of 137Cs and 89Sr from Waste Simulants Using Pillared Montmorillonite

ABSTRACT

Two samples of a silica-pillared montmorillonite produced using 3-aminopropyltrimethoxy silane and an alumina-pillared montmorillonite were evaluated for the removal of ¹³⁷Cs and ⁸⁹Sr from a simulated nuclear waste solution and a simulated groundwater, and the results were compared to the parent montmorillonite and two zeolites, AW500 (chabazite) and clinoptilolite. The parent and pillared clays were characterized using x-ray powder diffraction and surface area analysis by nitrogen adsorption/desorption studies. The pillared clays exhibited d-spacings of between 173 and 182 A after calcination, and surface areas ranging from 71 to 264 m²g^-1. Both of the silica-pillared clays and the alumina-pillared clay exhibited excellent K_dsfor ¹³⁷Cs from simulated groundwater with values of 23,650, 23,260 and 144,570 mL/g, respectively. These were far better than the K_ds obtained by clinoptilolite and AW500 which had K_ds of only 14,560 and 9650 mL/g, respectively. None of the pillared clays showed a high selectivity for ⁸⁹Sr from groundwater or ^l37Cs from simulated alkaline tank waste. They did, however, show a slight selectivity for ⁸⁹Sr in the simulated Hanford tank wastes, but this is thought to be due to a precipitation mechanism rather than to ion exchange.     

Uptake of cesium and strontium cations by potassium-depleted phlogopite

Phlogopite mica was equilibrated with 1.0 N sodium chloride (NaCl)–0.2 N sodium tetraphenylborate (NaTPB)–0.01 M disodium ethylenediaminetetraacetic acid (EDTA) solution at room temperature resulting in an almost complete removal (92%) of the mica's interlayer K. X-ray powder diffraction analysis provides additional evidence that hydrated Na⁺ ions had almost completely replaced the interlayer K⁺. Following equilibration, the c-axis spacing of the mica increased from 10.0 Å to approximately 12.2 Å. Cesium and Sr ion exchange isotherms indicate that K-depleted phlogopite is highly selective for both elements, the Cs⁺ exchange capacity is 1.26 meq/g or 65% of the theoretical cation exchange capacity and the Sr²⁺ exchange capacity is 1.94 meq/g or 100% of the theoretical exchange capacity of the mica. Kielland plots indicated that the mica was selective for Cs⁺ when the equivalent exchange capacity of Cs⁺ in the exchanger phase (X¯_Cs) was < 0.66 and selective for Sr²⁺ when X¯_Sr < 0.41. At equivalent fractions greater than these levels, layer collapse and/or steric effects limit the diffusion of these ions into the interlayers of the mica. Analysis of the Cs⁺ equilibrated mica utilizing XRD indicated that a collapse of the c-axis spacing had occurred. Based on the high selectivity of < 45-μm K-depleted phlogopite for Sr²⁺ and Cs⁺, this material may prove useful as an inorganic ion exchanger for these radioactive isotopes.     

A thermally regenerable composite sorbent of crosslinked poly(acrylic acid) and ethoxylated polyethyleneimine for water desalination by Sirotherm process

Crosslinked poly(acrylic acid) (XPAA) made by copolymerization of acrylic acid and ethylene glycol dimethacrylate in bulk was further reacted with 80% ethoxylated polyethyleneimine, and the latter insolubilized by treatment with glutaraldehyde. The resulting composite sorbent, XPAA(EPEI.XG), containing carboxylic acid groups and weakly basic tertiary amine groups in close proximity in the same resin bead exhibited thermally regenerable desalination property, simulating the well‐known Sirotherm? resins. For NaCl and MgCl₂, the sorbent has saturation capacities of 0.796 and 0.839 meq/g (dry) sorbent, respectively, at 30°C but less than 0.1 meq/g (dry) sorbent at 80–90°C. The equilibrium sorption data at 30°C fit well to both Langmuir and Freundlich isotherms for single‐component sorption and to Butler‐Ockrent and Jain‐Snoeyink models for bicomponent sorption. Although the sorption of NaCl exhibits a plateau in the pH range of 4–5, that of MgCl₂ increases sharply above pH 4 because of additional sorption by cation exchange at the ionic sites formed at higher pH. The sorption rate data show characteristics of particle‐diffusion controlled ion‐exchange process, yielding diffusivity values of 1.0–1.3 × 10^?6 cm²/s for NaCl and 3.0–3.5 × 10^?7 cm²/s for MgCl₂, in the initial period at 30°C, with the diffusivity falling abruptly in both cases at higher conversions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Simultaneous removal and recovery of cadmium and cyanide ions in synthetic wastewater by ion exchange

Simultaneous removal and recovery of cyanide and cadmium ions using a strong-base anion exchange resin was studied on the basis of formation of Cd-CN complexes at high pH in synthetic wastewater containing cyanide and cadmium ions. Strong-base anion exchange resin particles, of Dowex1X8-50, were contacted with synthetic aqueous solutions. For different molar ratios between cyanide and cadmium, ion exchange characteristics of cadmium-cyanide complexes were studied experimentally in a batch reactor. Treatment efficiencies of packed and fluidized beds were compared under various conditions. Several regenerants, NaSCN, NaCN, and NaOH, were used to regenerate the exhausted resin. The rates of regeneration and recovery for the various regenerants were estimated and discussed. The resin used in this work, Dowex1X8-50, can exchange about 6.6 CIST meq./g resin and 3.2 Cd²⁺ meq./g resin of cyanide and cadmium ions as complexes, respectively. Free cyanide ion has a lower selectivity than Cd-CN complexes on the anion exchange resin. The degree of treatment efficiency applied in this study was greater in the fluidized bed than packed bed. NaSCN was the best regenerant among regenerants used for regeneration of resin saturated with Cd-CN complexes.     

Synthesis and characterization of fluorescent PEG-polyurethane with free carboxyl groups

An innovative spherical poly(vinyl alcohol)(PVA)/peat/clay porous composite bead was prepared and shown to be suitable for use as an adsorbent. The mass transport process for the adsorption of metal ions onto this composite bead in an aqueous system was investigated. In the external mass transport process, the diffusion coefficient (D₁) of Cu⁺² and Zn⁺² ions increased with increasing initial metal ion concentration and the increasing effect was more pronounced in the initial metal ion concentrations range of 18?×?10^-3 to 22?×?10^-3?M. The diffusion rate of Zn⁺² ions was faster than that of Cu⁺² ions. In the intraparticle diffusion process, the diffusion coefficient (D₂) decreased with increasing initial metal ion concentration in the initial concentration range of 1?×?10^-3 to 4?×?10^-3?M, and the value of D₂ maintained an almost constant value in the initial concentration range of 8?×?10^-3 to 22?×?10^-3?M. The rate of ion diffusion within the adsorbent for Cu⁺² ions was faster than that for Zn⁺² ions. The adsorption mechanism was controlled by the intraparticle diffusion process. The adsorption followed the Langmuir adsorption isotherm model. The maximum amount of adsorbed metal ions for Cu⁺² and Zn⁺² ions were 22.57 and 13.62?mg/g composite bead, respectively.     

Preparation and Adsorption Properties of λ-MnO2-Cellulose Hybrid-Type lon-Exchanger for Lithium Ion. Application to the Enrichment of Lithium Ion from Seawater

Abstract

spherical beads of a hybrid-type ion-exchanger (HIE) have been prepared by dispersing microcrystalline λ-MnO2 in macroporous cellulose gel beads. The beads were 0.1 to 0.3 mm in diameter and contained 0.71 g λ-MnO2/g dry HIE. The ion-exchange behaviors of HIE for lithium and sodium ions were investigated by batch and column methods. The uptakes for lithium and sodium ions were 2.8 and 0.1 mmol/g dry HIE, respectively, at pH 12.3 by the batch method and 1.0 and 0.1 mmol/g dry HIE at pH 11.6-11.8, respectively, by the column method. When 1.52 L seawater was passed through a column containing 0.05g wet HIE at a flow rate of 0.3 mL/min, 2.0 mg lithium/g dry HIE was recovered, indicating that the enrichment ratio for lithium ion was 1.3 × 10⁴ mL/g and the enrichment factors for lithium ion to sodium, potassium, calcium, and magnesium ions were 7.1 × 10⁴, 1.7 × 10³, 1.0 × 10³, and 6.9 × 10³, respectively.     

COMPARISON OF ION EXCHANGE AND DONNAN EQUILIBRIUM MODELS FOR THE PH-DEPENDENT ADSORPTION OF SODIUM AND CALCIUM IONS ONTO KRAFT WOOD PULP FIBERS

ABSTRACT

Management of nonprocess element (NPE) accumulation in pulp washing operations requires equilibrium models that predict the distribution of metals between the wash liquor and the pulp fibers. The overall goal of this study was to assess models for predicting the multi-component adsorption of hydrogen ions (H⁺), sodium ions (Na⁺), and calcium ions (Ca⁺²) onto bleached and unbleached kraft pulp fibers over a pH range of 2.7–11. As part of this study, binary equilibrium constants for hydrogen and metal ion exchange on carboxylate sites in bleached pulp (0.041 meq/g dry pulp) were measured at 25°C, with log K ^Na/Ca = ?1.604 ± 0.119, log K ^H/Ca = 0.633 ± 0.087, and intrinsic dissociation constant pK _io of 3.64 ± 0.46. Ion exchange and Donnan equilibrium models adequately predicted the multi-component equilibrium data for competitive adsorption of H⁺, Na⁺, and Ca⁺² onto bleached kraft wood pulp fibers. The ion exchange model was fully predictive, whereas the Donnan model required that the solution pH be known. At pH 2.7–6, the Donnan model predicted the adsorption of Na⁺ and Ca⁺² onto both bleached and unbleached wood pulp fibers better than the ion exchange model. The ion exchange model assumed that residual carboxylate in the pulp served as the only site for the competitive binding of hydrogen and metal ions. In contrast, the Donnan model assumed a non site-specific distribution of metal ions between charged fiber and external solution phases and a carboxylate site specific adsorption of hydrogen ions. Above pH 6, both models failed to predict that the calcium adsorption on unbleached brownstock pulp increased beyond the carboxylate site capacity, suggesting that other functional groups within the brownstock pulp with intrinsic dissociation constant values higher than carboxylate were providing additional binding sites for calcium.     

Ion Exchange in Selected Low Rank Coals. Part I: Equilibrium

ABSTRACT

The ion exchange behavior of 4 low rank coals has been investigated. Their total carboxyl group contents ranged from 1.52 meq/g for a subbituminous coal to 2.78 meq/g for a lignite. The coverage of the carboxyl groups by metal cations varied from 30% to 60% (on an equivalent basis) for the raw coals. For all raw coals, Ca²⁺was the predominant metal cation. The equilibrium ion exchange behavior of metal cations for H⁺was found to be a linear function of pH regardless of the cation concentration in solution. Thus, the extent of exchange is a function of available hydrogen ions. From equilibrium ion exchange measurements, the following cation exchange selectivity pattern for a subbituminous coal was determined:

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while that for a lignite was:

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Novel organic–inorganic composite material as a cation exchanger from a triterpenoidal system of dammar gum: synthesis,characterization and application

A pioneer study has been conducted to synthesize novel hydrogel starting from a non-cellulosic raw material, gum dammar-a triterpenoidal system, and then converting this hydrogel into an organic–inorganic composite zirconium-based ion exchanger. Gum dammar was cross-linked with polyacrylamide zirconium (IV) iodo-oxalate [Gd-cl-poly(AAm)-Zr (IV) iodo-oxalate] by incorporating inorganic precipitates into the polymeric mixture. The polymeric mixture was synthesized using gum dammar (Gd), acrylamide (AAm), N, N′-methylene-bis-acrylamide (MBA) and potassium persulphate (KPS). The reaction conditions for synthesis of hydrogel and ion exchanger such as time (120 min), temperature (70 °C), solvent (4 mL), concentration of monomer (12.97 × 10^?3 mol/L), initiator (1.48 × 10^?4 mol/L), cross-linker (4.22 × 10^?4 mol/L) and ratio of zirconium oxychloride (0.1 M), potassium iodate (0.1 M) and oxalic acid (0.1 M) in ratio 2:3:2 were optimized to obtain maximum ion exchange capacity (2.02 meq/g). The morphology and structure of hydrogel and ion exchanger were studied using FTIR, SEM, XRD and TGA/DTA/DTG. The SEM study was followed by energy dispersive spectroscopy for elemental analysis. The ion exchanger was quite stable in various acids and bases at low concentration but it completely dissolved in acids and bases at high concentrations. Distribution studies showed that the synthesized ion exchanger had high selectivity for Pb²⁺ ions. Thus, the polymeric-inorganic hybrid material showed integration of both inorganic and organic characteristics within the composite material.     

Synthesis of single‐walled carbon nanotubes cerium(IV) phosphate composite cation exchnager: Ion exchange studies and its application as ion‐selective membrane electrode for determination of Cd(II) ions

Single‐walled carbon nanotubes cerium(IV) phosphate composite cation exchanger was synthesized using sol−gel method. The ion‐exchange properties such as elution concentration, elution behavior and effect of temperature on ion exchange capacity were studied. The composite cation exchange material showed an ion‐exchange capacity (IEC) of 1.64 meq dry g⁻¹ of ion exchanger. The distribution studies revealed that the composite cation‐exchanger is highly selective for Cd(II) ions. The material was used as an electroactive component for the construction of a cadmium ion‐selective membrane electrode. The membrane electrode showed a Nernstian response for Cd(II) ions over a wide concentration range of 1 × 10⁻⁷−1 × 10⁻¹ M with a sub‐Nernstian slope of 27.429 mV per decade change in concentration of cadmium ions. The limit of detection was found to be 1 × 10⁻⁷ M. It possessed a fast response time 10 s and can be utilized for 130 days without any considerable divergence in response potential. The practical utility of membrane electrode was demonstrated by employing as an indicator electrode for the potentiometric titration of Cd(II) with ethylenediamine tetra acetic acid, disodium salt (EDTA). POLYM. COMPOS., 38:1005–1013, 2017. © 2015 Society of Plastics Engineers     

Ion exchange properties of sulfonated polycarbonate and polyimide track etch membranes

Heterogeneous sulfonation was successfully utilized to convert the surfaces of PC and PI track etched membranes with 20 nm pores into ion exchange membranes. Short sulfonation times of 1-5 min using gaseous sulfuric trioxide were sufficient to achieve good coverage of ion exchange sites on the membrane surface yet minimal structural damage to the bulk material. Consequently, the ion exchange capacities were relatively low, up to 0.015 meq/g, compared to literature. Electroselectivity typical of ion exchange materials was observed for these membranes and metal uptake of higher valences was preferred Eu³⁺ > Co²⁺ > Cs⁺. Clear differences in metal uptake properties were measured between the sulfonated PC and PI membranes with different ions. As a consequence of relatively high metal uptake and certain experiment set up also Donnan exclusion was determined to play a role in the overall ion exchange process.     

TRANSFER RATE AND SEPARATION OF Sr2+ and Cs+ BY SUPPORTED LIQUID MEMBRANES UTILIZING SYNERGIZED CROWN ETHER CARRIERS

ABSTRACT

The rate of the isotopic exchange of Na? and Cs? between hydrous silicon-titanium(IV) oxide in the relevant ionic form and aqueous solution was determined radiochemically. The rate was controlled by the diffusion of the ions in the exchanger particles. The diffusion coefficients at 5 °C are (3.9±0. 1)×10^?11m² s^?1 and (2.4± 0. 1)×10^?11 m² s^?1respectively, for Na? and Cs? in the exchanger equilibrated with solutions at pH 6. The activation energies are 31±5 kJ mol^?1 and 20±5 kJ mol^?1 for Na? and Cs? diffusion, respectively. The diffusion coefficients of the ions decreases with increasing pH of the solutions equilibrated with the exchanger, whereas their activation energy is independent of pH. The results were interpreted in terms of the strength of the electrostatic interaction between the counter ions and the ion-exchange sites.     

Multiple Ion Exchange Column Tests for Cesium (CS+) Removal from Hanford Site Tank 241‐AW‐101 with SuperLig® 644 Resin

Abstract

Six cycles of loading, elution, and regeneration were performed to remove cesium (Cs⁺) from a Hanford Site tank waste sample using SuperLig^® 644 resin. The sample, which was retrieved from Tank 241‐AW‐101, was diluted to 5.09 M Na⁺ and processed through dual ion exchange columns to remove ¹³⁷Cs. Each column had an inside diameter of 1.45 cm and a height of 30 cm; and contained 15 mL of wet resin in the sodium form. The columns, designated as primary (lead) and polishing (lag), were connected in series during loading, but they were separated during elution and regeneration. The cesium loading on the primary column during the six cycles ranged from 160 to 225 bed volumes (BV) at <50% breakthrough. A gradual decline of the resin loading performances was observed as a function of number of loading cycles. For all cycles, the percent removal of cesium (¹³⁷Cs) was greater than 99.99% and the decontamination factors (DFs) achieved were higher than 1.0 × 10⁴. Elution of the resin with 0.5 M nitric acid at 25 ± 2°C was effective. Approximately 99% of the ¹³⁷Cs bound on the resin was eluted with less than 15 BV of the eluent (0.5 M nitric acid). The cumulative dose absorbed by the resin in the primary column was 1.99 × 10⁷ rad with a 20% loss of ion exchange capacity was at 50% breakthrough after completing six loading cycles.     

Ion separation of binary metallic aqueous solutions at acidic Langmuir monolayer surfaces

We focused on analyzing the capability of the acidic monolayer surfaces for separation of toxic metal ions out of house-prepared binary inorganic ionic solutions such as calcium-lead, calcium-chromium, calcium-copper, and calcium-zinc aqueous systems. The affinities of the films to toxic metal ions were analyzed by using Fourier transform infrared spectroscopy. A model considering both the electrochemical and thermodynamic aspects was also applied to quantify the surface ion affinities. It is noted that surface ion binding capability for binary ionic solutions can be much different from that for pure ionic solutions. As a result, surface binding constants were found to be 4.5 × 10⁶ for lead ions, 1.5 × 10⁶ for chromium ions, 5.5×10⁵ for copper ions, and 6 ×10⁴ for zinc ions, respectively, at pH=5.5. For the separation experiments done at pH=5.5, lead, copper, zinc ions were separated more efficiently from the mixed ionic solutions by the factors of ca. 30,000, 10,000, 3,700, and 400, respectively, compared to calcium ions of which binding constant is 1.5 × 10². Interestingly, when compared to corresponding pure ionic systems, copper and lead ions were separated as much, while chromium and zinc ions were less by the factor of 500 and 50, respectively. Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University.     

Ion Exchange of Selected Group II Metals and Lead by Crystalline Silicotitanate and Competition for Cs Exchange Sites

ABSTRACT

A series of batch contact tests were conducted to evaluate the exchange behavior of Ba, Ca, Pb, and Sr onto crystalline silicotitanate (CST) in support of an expedited Cs removal and pretreatment system at the Hanford site. Binary Na/M²⁺ and ternary Na/Cs/M²⁺ isotherms were generated to understand selectivity, capacity, and competitive impact of each analyte on Cs uptake from a simple 1 M NaOH/4.6 M NaNO₃ simulant. Analyte loading from a 0.1 M NaOH/5.5 M NaNO₃ simulant was assessed to determine the effect of hydroxide concentration on binary Na/M²⁺ isotherms. Results from binary and ternary isotherms indicated that Group II metals Ca, Sr, and Ba (and Pb) do not impact CST performance toward Cs removal at concentrations expected in Hanford tank-waste supernate.     

Monoclinic-celsian ceramics formation: Through thermal treatment of ion-exchanged 3D printing geopolymer precursor

Based on conventional ion exchange method from zeolite materials, we herein report a facile synthetic procedure to prepare monoclinic celsian ceramics through thermal treatment of ion-exchanged 3D printing geopolymer precursors. In this contribution, both ion exchange process and thermal evolution of celsian precursors were systematically investigated. The results proved 3D printing Na- and K- based geopolymer were ideal precursors with low residual Na⁺ content (0.10 meq/g) and K⁺ content (0.05 meq/g) and translated into monoclinic celsian after being heated at 1400 °C. With increasing Sr²⁺ doping concentration from 20% (mole ratio) to 30% (mole ratio), more significant phase transition results (hexagonal → monoclinic) were observed. All 3D printing geopolymer precursors kept fine integrity and stable 3D structure upon ion exchange process and heating, indicating the combination of geopolymer technique and 3D printing opens up a versatile and robust way to yield monoclinic celsian ceramics and related components of complex shapes.     

EDTA-stannic(IV)iodate: preparation, characterization and its analytical applications for metal content determination in real and synthetic samples

A new organic–inorganic cation exchanger EDTA-stannic(IV)iodate was synthesized. The materials possess good chemical and thermal stability. The exchanger was characterized on the basis of X-ray, TGA, FTIR, UV–Visible spectrophotometery and SEM studies. ion exchange capacity, pH titration, elution and distribution studies were also carried out to determine the primary ion exchange properties of the material. The SEM study confirms the fibrous nature of the material. The exchanger behaves as a monofunctional cation exchanger with ion exchange capacity of 1.30 meq/g for Na⁺ ions. The material can perform well upto the temperature of 500 °C and retains the 76.4% of ion exchange capacity. The material is fairly stable in dilute solutions of some common mineral acids, bases and organic solvents. The differential selectivity of metal ions on EDTA-stannic(IV)iodate has been utilized to perform analytically and industrially important binary separations.     

Lysine Adsorption on Cation Exchange Resin. IV. Temperature Effects on Equilibrium and Kinetics in Batch and Column Systems

Abstract

Ion exchange equilibria and kinetics are determined for lysine adsorption on the strong acid cation exchanger DIAION SK‐1B at temperatures of 25, 40, and 60°C. The ion exchange equilibrium is found to be independent of temperature. Conversely, the kinetics of ion exchange increases dramatically as the temperature is increased. Average ion exchange selectivity coefficients of 6.0 g/cm³ and 0.52 are obtained for the ion exchange of divalent and monovalent cationic lysine with hydrogen ion, respectively. Resin phase diffusivities are determined by fitting batch binary ion‐exchange data with a mass transfer model based on the Nernst‐Planck equations. As the temperature is increased from 25 to 60°C, the resin phase diffusivity increases from 0.04×10^?6 to 0.14×10^?6 cm²/s for divalent lysine and from 0.16×10^?6 to 0.55×10^?6 cm²/s for monovalent lysine. The combination of temperature‐independent ion exchange equilibria and faster mass transfer at higher temperatures results in higher dynamic binding capacity and more efficient desorption of lysine when ion exchange is operated at an elevated temperature. This behavior is confirmed by means of column adsorption/desorption experiments whose results are found to be in agreement with a model incorporating the equilibrium and mass transfer data obtained in this work.