Acid Cation Exchange Research Articles

Adsorption studies of fluoride on weak base anion exchangers and surface modified strong acid cation exchangers in aqueous medium

Adsorption studies of fluoride on weak base anion exchangers and surface modified strong acid cation exchangers in aqueous medium

Selective Separation of Radium and Actinium from Bulk Thorium Target Material

A complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material will be presented. The process may be applicable to the production of 225Ac and 227Ac via proton spallation on thorium targets. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Targeting the minor components (Ac,Ra) allows use of much smaller chromatographic columns than traditional nitrate based systems which target the bulk thorium. Additionally, the primary separation is performed from 0.1M Th, 0.6M sulfate, pH 1-2 instead of the more corrosive 3-8M HNO3 typically employed in solvent extraction or anion exchange based thorium separations. Actinium and radium are recovered from the cation exchange resin in a small volume of 5M HNO3 and directly purified via extraction chromatography with UTEVA and DGA resins without feed adjustment or evaporation. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity. The flowsheet has been tested at the Canadian Nuclear Laboratory (CNL) on 25 gram solid thorium targets irradiated at Fermi Lab. -Bond, A.H., Horwitz, E.P., McAlister, D.R., 2006. A Multicolumn Selectivity Inversion Generator for the Production of High Purity Actinium-225 for Use in Therapeutic Nuclear Medicine, United States patent number 7,087,206. (Licensed to NorthStar Medical Radioisotopes) -D.R. McAlister, E.P. Horwitz, “Selective Separation of Radium and Actinium from Bulk Thorium Target Material on Strong Acid Cation Exchange Resin from Sulfate Media,” Applied Radiation and Isotopes, 140, 18-23 (2018).

Design, evaluation and optimization of taste masked clarithromycin powder.

Clarithromycin (CLA) is an extremely bitter macrolide antibiotic used to treat paediatric and adult infections. The bitter taste affects patient adherence and may compromise therapy. This research developed a taste masked CLA resinate using Indion® 234, a weak acidic cation exchange resin. The factors affecting formation of the CLA-resin complex were assessed. Design of experiments was used to optimize response while evaluating input variables such as temperature, CLA-resin ratio,stirring time and pH. CLA loading efficiency was determined spectrophotometrically and CLA release using USP Apparatus II. Differential Scanning Calorimetry (DSC), Scanning Electron Microscop (SEM), Fourier Transform Infrared (FT-IR) Spectroscopy and X-ray Diffraction (XRD) were used to confirm complex formation. A spectrophotometric method was used to assess taste evaluation. The optimum CLA-resin ratio, temperature, and stirring time were 1:4, 80 °C, 3 hours, respectively, at pH 8. Characterization techniques revealed that CLA was crystalline and the complex amorphous in nature. FT-IR spectra of resinate revealed the absence of resonance due to the tertiary amine functional group that is responsible for the bitter taste of CLA. CLA was stable in simulated salivary fluid and was released within 3 hours in gastric fluid. All CLAresin batches revealed complete taste masking. Taste analysis highlighted the improvement of taste masking properties of the resinate as the CLA to resin ratio, increased.

Erratum to: Sorption of Lanthanum(III) and Neodymium(III) from Concentrated Phosphoric Acid by Strongly Acidic Cation Exchange Resin (SQS-6)

Erratum to: Sorption of Lanthanum(III) and Neodymium(III) from Concentrated Phosphoric Acid by Strongly Acidic Cation Exchange Resin (SQS-6)

Sorption of Lanthanum(III) and Neodymium(III) from Concentrated Phosphoric Acid by Strongly Acidic Cation Exchange Resin (SQS-6)

The feasibility of using a macroporous strongly acidic cation exchange resin (SQS-6) as an adsorbent for lanthanum(III) and neodymium(III) from phosphoric acid medium, >4.0 M, was administered using batch and column techniques. Different parameters affecting the sorption of these metal ions such as v/m ratio, acid concentration and the metal ion concentration were separately investigated. The results indicated that the sorption process is relatively fast, reaching equilibrium state within 10 min. Influence of temperature on the equilibrium distribution values was also studied to evaluate the changes in standard thermodynamic quantities where the results indicated that the sorption is endothermic and the process is spontaneous associated with increasing the randomness of the system. The adsorption results of the studied metal ions were found to obey Langmuir isotherm model over the entire studied concentration range. The recovery of La(III) and Nd(III) from the loaded resin was performed with 1.0 M citric acid at pH 4.0. The breakthrough capacity of La(III) and Nd(III) was found to be 33.55 and 17.30 mg/g, respectively. The experimental data resulting from column technique were followed Thomas and Yoon-Nelson models.

Extraction of Cu2+, Zn2+ and Ni2+ cations from industrial wastewater by ionite KU-2-8

The object of the research is model solutions of wastewater and wash water from metal processing enterprises containing copper, nickel and zinc ions. One of the most problematic places is that the process of sorption of copper, nickel and zinc cations on the strongly acidic cation exchanger KU-2-8 at high metal concentrations is not well understood.The sorption and desorption processes of Cu2+, Zn2+ and Ni2+ ions on KU-2-8 cation exchanger in the H+ form are studied using model solutions of metal sulfate at high concentrations. The experiments were carried out in an ion-exchange column with a diameter of 2 cm 2 loaded with cation exchanger with a volume of 20 cm 3. During the research, the concentration of metals was measured by titrometric, photometric and instrumental methods (concentration of copper, zinc and nickel ions, acidity, alkalinity, pH). Model solutions of heavy metal ions Cu2+, Zn2+ and Ni2+ with a concentration of 10, 20, and 50 mg-Eq/dm3 were passed through KU-2-8 ion exchanger in the H+ form. During sorption of 0.01 n model solutions, the ion exchanger capacity on average reached 2073 mg-Eq/dm3, at 0.02 n – 2140 mg-Eq/dm3 and at 0.05 n – 2100 mg-Eq/dm3. After metal extraction from model solutions and complete saturation of the ion exchanger, the conditions for the regeneration of cation exchanger in the Cu2+, Zn2+ and Ni2+ form with solutions of 5, 8 and 10 % sulfuric acid were studied. The efficiency of desorption of divalent metal ions from an ion exchanger was almost 100 %.The scientific novelty of the work lies in the fact that metal ions were sorbed for the first time at concentrations of 10, 20, and 50 mg-Eq/dm3 in terms of metal and their desorption of 5, 8, and 10 % sulfuric acid from cation exchanger.After the experiments, a scheme for washing water treatment using ion exchange and electrolysis was proposed, which will allow the organization of environmentally friendly metal processing processes at galvanic enterprises.

Perfluorosulfonic Acid Membranes Thermally Treated and Modified by Dopants with Proton-Acceptor Properties for Asparaginate and Potassium Ions Determination in Pharmaceuticals.

The influence of incorporation of the dopants with proton-acceptor properties into perfluorosulfonic acid cation exchange membranes (MF-4SC and Nafion), and their treatment conditions on the characteristics of Donnan potential (DP)-sensors (analytical signal is the Donnan potential) in the aqueous solutions containing asparaginate and potassium ions in a wide pH range was investigated. A silica, surface modified by 3-aminopropyl and 3-(2-imidazolin-1-yl)-propyl groups, was used as the dopant. The membranes were subjected to mechanical deformation and thermal treatment at various relative humidities. The relationship between water uptake and diffusion permeability of membranes subjected to modification and treatment and the cross sensitivity of DP-sensors based on them to counter and co-ions was studied. The multisensory systems for the simultaneous determination of asparaginate and potassium ions in a concentration range from 1.0 × 10−4 to 1.0 × 10−2 M and pH range from 4 to 8 were developed. An array of cross-sensitive DP-sensors based on MF-4SC membranes containing 3 wt.% SiO2 modified by 10 mol.% 3-aminopropyl and 3-(2-imidazolin-1-yl)-propyl was used for the potassium asparaginate hemihydrate and magnesium asparaginate pentahydrate determination in Panangin® (with an error of 2 and 4%, respectively).

Superhigh adsorption of nickel from electroplating wastewater by raw and calcined electroplating sludge waste

Abstract Both the raw electroplating sludge (RES) waste and the calcined electroplating sludge (CES) were utilized to adsorb nickel from the real electroplating wastewater. The CES was obtained via calcination treatment at 500 °C, and the CES and RES were characterized by X-ray fluorescence (XRF), Fourier transform infrared spectrometer (FT-IR), X-ray powder diffraction (XRD). Adsorption isotherm results showed that the maximum adsorption capacities of Ni2+ on the CES and RES were 163.6 and 210.9 mg/g according to the Langmuir fitting, respectively. In the real nickel-containing wastewater treatment, the RES exhibited much higher adsorption capacity for Ni2+ than commonly used adsorbents including coal-based activated carbon (CAC), strong acid cation-exchange resin (D001), weak acid cation-exchange resin (D113) and amino carboxylic acid chelating resin (D463). The adsorption mechanisms of Ni2+ on the RES and CES mainly included ion exchange and surface complexation. The large amount of Ca2+ in the adsorbents played an important role in the adsorption of Ni2+ via cation exchange, and the hydroxyl and carboxyl groups on the adsorbent were also responsible for Ni2+ adsorption. Therefore, the electroplating sludge waste is an efficient adsorbent for Ni2+ removal from high concentrations of nickel-containing electroplating wastewater. This study provides a new method for the utilization of electroplating sludge as efficient adsorbents before being treated as hazardous waste, showing the feasible concept of disposal waste with waste.

Studies on active aromatic constituents from rhizomes of Sophora tonkinensis

Aromatic constituents from rhizomes of Sophora tonkinensis were purified by extensive chromatographic techniques including column chromatography over macroporous resin,MCI,silica gel,weak acid cation exchange resin,Sephadex LH-20,ODS,and semi-preparative HPLC. Twelve aromatic compounds were isolated and identified from the water aqueous extract of the rhizomes of S.tonkinensis. Their structures were elucidated as 4-( 3-hydroxypropyl) phenol( 1),( ±)-4-( 2-hydroxypropyl) phenol( 2),benzamide( 3),( ±)-3-( p-methoxyphenyl)-1,2-propanediol( 4),4-methoxybenzamide( 5),3-hydroxy-1-( 4-hydroxy-3-methoxyphenyl) propan-1-one( 6),tyrosol( 7),( ±)-2,3-dihydroxypropyl benzoate( 8),vanillin alcohol( 9),7,3'-dihydroxy-8,4'-dimethoxyisoflavone( 10),7,4'-dihydroxy-3'-methoxyisoflavone( 11),and 7,3'-dihydroxy-5'-methoxyisoflavone( 12). Compounds 1-9 were firstly isolated from the Sophora genus. Compounds 4,5,10 and 11 can remarkably protect Hep G2 cell against APAP-induced damage at the concentration of 10 μmol·L-1. Compounds 1-12 exhibited no significant activities on the assays of inhibition of LPS-induced NO production in RAW cell lines and NF-κB inhibition.

The Role of the Dependence of the Enthalpy of Ion Exchange on Temperature in Predicting the Behavior of Ion-Exchange Systems

The effect of temperature on the exchange of di- and monovalent ions on polymethacrylic and polyacrylic cation exchangers in the range from 298 to 413 K is studied. It is shown that the differential enthalpy and the equilibrium coefficient simultaneously increase with temperature. The dependences of the enthalpy on temperature are linear. The effect of temperature on the enthalpy of ion exchange observed for all studied ion exchangers is much more strong than in the systems described in the literature with sulfonic acid cation exchangers and highly basic anion exchangers. The problem of taking into account the dependence of enthalpy on temperature when predicting the behavior of ion-exchange systems is discussed.

FIBROUS ION EXCHANGERS FIBAN AS SORBENTS OF URANIUM(VI) COMPOUNDS PRESENT IN SULFATE SOLUTIONS

Some regularities of Uranium(VI) compounds sorption recovery from model sulfate solutions by fibrous ion exchangers FIBAN C-1 (strongly acidic cation exchanger with -SO3H groups), FIBAN AC-22V (polyampholyte with amino- and carboxyl groups) and FIBAN A-6 (anion exchanger with strongly basic and weakly basic aminogroups) under dynamic conditions were established. It was shown that effective recovery and concentration of Uranium(VI) are combined with a high rate of Uranium(VI) sorption. Quantitative characteristics of Uranium sorption under dynamic conditions such as dynamic exchange capacity, total dynamic exchange capacity, degree of Uranium recovery, Uranium content in the phase of the sorbent, sorption rate were calculated. It was established that the fibrous polyampholyte FIBAN АC-22V demonstrated the better indicators of Uranium(VI) sorption from sulfate solutions and concentration of these solutions (5.2 – 10.5 times) than other fibrous ion exchangers. It was shown that a 10-fold increase in the Uranium concentration in solutions leads to a considerable improvement of the sorption quantitative characteristics. It was found that the initial form of the fibrous ion exchangers can be completely restored by passing through the ion exchangers in Uranium form of a 0.5 M HCl or H2SO4 solutions. It was established that the fibrous polyampholyte FIBAN АC-22V advantageously be used for one cycle of Uranium(VI) sorption – desorption, and the fibrous cation exchanger FIBAN C-1 can be used during two cycles of Uranium(VI) sorption – desorption. The interaction mechanism of the Uranium(VI) compounds present in sulfate solutions (uranyl cations, neutral and negative sulfate complexes) with functional groups of studied sorbents was proposed.

Study on Methyl Esterification of Salicylic Acid Using an Intensified Fixed Bed Reactor

Abstract Methyl esterification of salicylic acid catalyzed by strong acidic cation exchange resin NKC-9 was carried out on an intensified fixed bed reactor (IFBR) to investigate the effects of different parameters and the results showed that the optimal conditions were as follows: circulation speed is 1.5 L· h−1, catalyst loading is 20 %, initial mole ratio of salicylic acid and methanol is 1:6 and reaction temperature is 343.15 K. The thermodynamics for the methyl esterification of salicylic acid have been studied to obtain the equilibrium constant from the experimental data at different temperature. PH, E-R and LHHW models were used to correlate the kinetic data in the temperature range from 328.15 to 348.15 K. The calculated value is in good agreement with experimental value, indicating that all the models can be used to accurately describe the process of the methyl esterification of salicylic acid.

Rapid Separation and Precise Determination of Strontium Isotopic from Geological Samples with High Rubidium/Strontium Ratios

Abstract In the isotopic measurement of strontium (Sr) of geological samples with high rubidium (Rb)/Sr ratios, it is difficult to completely remove the isobaric interference of Rb on Sr isotopic analysis by a single separation and purification using traditional strong acid cation exchange resin. Actually, one purification procedure performed twice is necessary to eliminate the interference of 87Rb on the testing of 87Sr/86Sr. Although the purification procedure can ensure a good effect on the separation and purification of Sr, the process is tedious and time-consuming, which is not suitable for simultaneous separation and purification of Sr from large quantity of geological samples with high Rb/Sr ratios. In this study, the conventional two-stage separation process was optimized, and an experimental method for rapid separation of Sr from geological samples with high Rb/Sr ratios was established. In this method, the Sr solution after purified by AG50 resin was directly added to a new AG50 resin to purify Rb and Sr again. The whole separation process would be accomplished quickly and efficiently. The method combined with highly sensitive thermal ionization mass spectrometer (TIMS) technique was completely satisfied in high precision determination of 87Sr/86Sr isotope ratio in the samples with high Rb/Sr ratios. Through the application of the novel separation method with a large number of geological samples with high Rb/Sr ratios, it was proved that the experimental process was stable and reliable and showed crucial application value.

An Isolated Method and Assignment for Critical Impurities in Semi-Synthetic Process of Arbekacin Sulfate.

Four potential process related impurities were detected during the impurity profiling study of a semi-synthetic aminoglycoside antibiotic, arbekacin. The current preparation process from 3',4'-didehydro-dibekacin easily generates the specific impurities with similar structures to arbekacin that makes hard to separate and identify the residues. HPLC-ELSD and column chromatography loading weakly acidic cation exchange resin were used for the detection and isolation of these process impurities. Based on the synthesis and spectral data (ESI-MS/MS, 1H NMR, 13C NMR and 2D-NMR), the structures of these impurities were characterized as dibekacin, 3-N-γ-aminohydroxybutyric (AHB)-dibekacin, 3''-N-AHB-dibekacin and 1,3-N,N-di-AHB-dibekacin. The characterization of these impurities is discussed in detail and our current efforts may help to develop a general strategy for isolation and identification of aminoglycoside products.

Каталитическое окисление катионита КУ-2×8 водным раствором пероксида водорода

During the operation of nuclear power plants, spent ion-exchange resins are formed, which are heterogeneous radioactive low-level waste in the form of particles from a cross-linked organic polymer. Such resins may not always be regenerated. Therefore, the disposal of spent ion exchange resins is currently one of the primary problems at nuclear power plants. Conventional technologies for the processing of waste resins are relatively expensive. In addition, there are difficulties with transportation and storage of waste, and the disposal of spent ion exchange resins is a complex process. In the present study, an attempt has been made to solve the problem of spent ion-exchange resins utilization on example of the sulfonic acid cation exchanger’s KU-2×8 oxidative degradation with the Fenton reaction. The decomposition of the cation exchanger was carried out with 20% hydrogen peroxide in the temperature range 323-353 K in the presence of a catalyst – low concentration copper(II) sulfate (0.001-0.009 mmol/l). The influence of process temperature and catalyst concentration on the reaction rate was estimated. When determining the rate of the cation exchanger KU-2×8 heterogeneous oxidation reaction with hydrogen peroxide in the presence of a catalytic additive, the spherical shape of the sorbent granules, the surface area of which changed during reaction, was taken into account. It was shown that with a reaction temperature increasing from 323 to 353 K, the rate constant of cation exchanger's oxidative decomposition have increased by a factor of 20-37. The activation energy values of the sulfonic acid cation exchanger's KU-2×8 decomposition with hydrogen peroxide in the presence of copper(II) sulfate are 89.7-115.2 kJ/mol, which indicates that the process is in the kinetic mode. It was established with electron-microscopic studies that the beads of the cation exchanger KU-2×8, when decomposed in H2O2 solution in the presence of a catalyst can stick together, change their shape and volume, and their surface becomes covered with cracks. The studies performed showed almost complete catalytic decomposition of cation exchanger KU-2×8 in a hydrogen peroxide solution at 323-353 K after 420-220 minutes, which allows accelerating the oxidation at relatively low temperatures.

Effectiveness of Ionic Polymer Soil Stabilizers on Warm Frozen Soil

Warm frozen soil has characteristics such as low shear strength and high compressibility. To improve its mechanical strength, the ionic polymer soil stabilizers (IPSS): named XRH stabilizer and acid cation exchange resin (CER) were adopted for reinforcing the warm frozen soil from the Beiluhe region of the Qinghai-Tibetan Plateau. To evaluate the effects of IPSS on warm frozen soil and analyze the mechanisms responsible, measurements were made of the physical, chemical and mechanical properties of warm frozen soil, both untreated and following treatment with IPSS. The addition of IPSS to the soil resulted in a significant decrease in the plasticity index, freezing temperature, and cation-exchange capacity of soil. The warm frozen soil were reinforced with XRH and CER, the cohesion increased by 87.9% and 43.1%, respectively, and the compressibility decreased by 44.5% and 41.1%, respectively. The trends of mechanical strength and unfrozen water content of reinforced warm frozen soil were the same, with extreme values being observed in response to treatment with an IPSS content of about 1% (optimal proportion). In addition, the curing mechanism of IPSS on warm frozen soil was analyzed. Overall, applying IPSS to the soil was an effective and feasible measure for reinforcing a warm frozen soil foundation.

Determination of morpholinium ionic liquid cations in environmental water samples: development of solid-phase extraction method and ion chromatography.

An ion chromatography and solid-phase extraction method has been applied for the separation and detection of morpholinium cations in environmental water samples. The water samples were purified and enriched by a UF-SCX sulfonic acid extraction column and eluted with 0.5molL-1 phosphoric acid/sodium dihydrogen phosphate buffer solution/55% methanol. The target compounds were separated on a carboxylic acid cation exchange column with 5.0mmolL-1 methane sulfonic acid/2% acetonitrile as the mobile phase and direct conductivity detection. The method has been successfully applied to extract morpholinium cations from spiked water samples of Songhua River, Hulan River, East Lake, and Mopanshan Reservoir in China with the recoveries ranging from 75.0% to 98.3%. The relative standard deviations of intraday precision and interday precision are 2.1% and 5.9% or less, respectively. Using this method it is possible to preconcentrate water samples to 0.01-0.04mgL-1. The results show that the method is applicable to detection of morpholinium ionic liquid cations in environmental water samples and provides a new approach for monitoring ionic liquids in environmental water. Graphical abstract The analysis procedure of morpholinium ionic liquids in environmental water samples.

Ion Transfer during the Electrochemical Reduction of Oxygen on Copper–Ion Exchange Nanocomposites

The electrochemical reduction of oxygen dissolved in water is studied using a thin granular layer of nanocomposites of copper–sulfonic acid cation exchanger in different ionic forms (H+, Na+). It is established there is considerable acceleration of oxygen absorption in the initial period under the simultaneous impact of electrical polarization and chemical activity of nanocomposites, especially in the H+-form. The rate of the process later slows and reaches a constant value regardless of the ionic form of the nanocomposite and without changing the pH or electrical conductivity of water. Products of the oxidation of metal nanoparticles form as insular nuclei distributed over the volume of nanocomposite granules; some grains are oxidized with the formation of sharp boundaries of oxide layers. A stationary mode of oxygen absorption is established due to the constant generation of hydrogen ions required for the reaction on anodes and the regeneration of copper nanoparticles on cathodes. It is concluded that these patterns are based on conjugate processes of ion transfer, electrochemical and chemical oxygen reduction, and the oxidation and reduction of copper nanoparticles.

Simple Synthesis and Characterization of Hexagonal and Ordered Al–MCM–41 from Natural Perlite

Silica reagents are expensive and toxic for use in the synthesis of mesoporous silica materials. It is imperative to take an interest in green silicon sources. In this paper, we report the synthesis of hexagonal and ordered aluminum-containing mesoporous silica materials (Al–MCM–41) from natural perlite mineral without addition of silica or aluminum reagents. A pretreatment process involving acid leaching, alkali leaching, and strongly acidic cation exchange resins treatment was critical to obtain silicon and aluminum sources from natural perlite mineral. The Al–MCM–41 material was synthesized via a hydrothermal reaction with hexadecyl trimethyl ammonium bromide (CTAB) as the template and subsequent calcination. The resulting mesophase had a hexagonal and ordered mesoporous structure, confirmed by small-angle X-ray diffraction (SAXRD) and transmission electron microscopy (TEM). Al–MCM–41 material had a high Brunauer–Emmet–Teller (BET) surface area of 1024 m2/g, pore volume of 0.72 cm3/g and an average pore diameter of 2.8 nm with a pore size distribution centered at 2.5 nm. The thermal behavior of the as-synthesized samples during calcination was investigated by thermogravimetry (TG) and differential thermogravimetry (DTG) analysis. The Al–MCM–41 material showed a negative surface charge in aqueous solution with the pH value ranging from 2 to 13. The variations of chemical structures from natural perlite to Al–MCM–41 were traced by wide-angle X-ray diffraction (WAXRD) and Fourier-transform infrared spectroscopy (FTIR). A proposed mechanism for the synthesis of hexagonal and ordered mesoporous silica materials from natural perlite is discussed.

URANIUM REMOVAL FROM NITRATE SOLUTION BY CATION EXCHANGE RESIN (AMBERLITE IR 120), ADSORPTION AND KINETIC CHARACTERISTICS

The present work aims to study the adsorption behavior of uranium ions from nitrate solutions usingthe strong acid cation exchange Amberlite IR120 resin. Batch shaking sorption experiments are carriedout to evaluate the performance of the studied resin in the uranium adsorption. The adsorption parametersincluding contact time, pH, initial uranium concentration and temperature have been optimized. Thephysical parameters including the adsorption kinetics, the isotherm models and the thermodynamic datahave also been determined to describe the nature of the uranium adsorption by the investigated resin.The modellated data has been found to agree with both the exothermic pseudo first order reaction and theLangmuir isotherm. The applied procedure was used for uranium ions removal from scrub and raffinateliquors.