Strong Cation Exchange Resin Research Articles

Radiolytic and Chemical Degradation of Strong Acidic Ion-Exchange Resins: Study of the Ligands Formed

The formation of water-soluble organic ligands by radiolytic and chemical degradation of several strong acidic ion-exchange resins was investigated under conditions close to those of the near field of a cementitious repository. The most important degradation products were studied and their complexing properties evaluated.Irradiation of strong acidic cation exchange resins (Powdex PCH and Lewatite S-100) resulted in the formation of mainly sulfate and dissolved organic carbon. High-performance liquid chromatography analysis indicated the presence of oxalate, contributing to 10 to 20% of the organic carbon. The identity of the remainder is unknown. The presence of oxalate as a complexant is consistent with results from earlier work. Complexation studies with Cu2+ and Ni2+ showed the presence of two ligands: oxalate and ligand X. Although ligand X could not be identified, it could be characterized by its concentration ([X]T ~ 10-5 to 10-6 M), a deprotonation constant (pKH ~ 7.4 at I = 0.1 M), and a complexation constant for the NiX complex (log KNiX ~ 7.0 at I = 0.1 M).In the absence of irradiation, no evidence for the formation of ligands was found.

Quantitative analysis of clenbuterol in meat products using liquid chromatography–electrospray ionisation tandem mass spectrometry

A method is presented that allows quantitation of clenbuterol in meat and liver products at the ng/kg level by liquid chromatography–electrospray ionisation tandem mass spectrometry (LC–ESIMS–MS) using a stable isotopically labeled internal standard. The practical procedure involves acid extraction followed by two solid-phase clean-up steps with C 18 and strong cation-exchange (SCX) resins. The typical recovery of the analyte spiked at 0.4 μg/kg in meat and liver samples was at 63±7%. Mass spectral acquisition was done in multiple reaction monitoring (MRM) to provide a high degree of sensitivity, achieving a limit of detection and quantitation at 10 and 15 ng/kg, respectively. Two precursor ions at m/z 277 and 279, corresponding to the characteristic isotopic cluster of the two chlorine atoms of clenbuterol, were monitored by LC–ESIMS–MS to provide unambiguous identity of the analyte. Samples of meat and liver of various origins with either incurred residues or spiked with known amounts of clenbuterol were used to validate the method.

Binary and Ternary Cation Exchange on Strong Acid Cation Exchange Resin Involving Na, Mg, and Zn in Single and Binary Backgrounds of Chloride, Perchlorate, and Sulfate

A systematic study with the negatively charged cation-exchange resin Amberlite 200 was performed to investigate the influence of anion type on cation exchange. A comprehensive data set was obtained for binary and ternary cation exchanges involving Na, Mg, and Zn on a strongly acidic, sulfonate cation-exchange resin in electrolyte systems with the single anions chloride, perchlorate, and sulfate, and with 1:1 mixtures of them at two total cation concentrations of 0.05 and 0.2 N. The binary and ternary cation exchange data exhibited internal consistency in that Mg and Zn were selected over Na to a comparable degree. The binary and ternary cation exchange data also indicated clearly an effect of anion type, with reduction in selectivity of Mg and Zn relative to Na in the presence of more strongly complexing anions such as sulfate. The effects of anions in cation exchange may be ascribed in part to their association with cations in solution, as demonstrated by application of conventional mass action models fo...

Spectrophotometric determination of copper(II) at low μg l −1 levels using cation-exchange microcolumn in flow-injection

A simple spectrophotometric flow-injection method is reported for the highly sensitive and fast determination of copper(II). The method is based on the formation of coloured Cu(II)-(4-methylpiperidinedithiocarbamate) 2 complex when the copper solutions are introduced into a tertiary reagent stream containing 4-methylpiperidinedithiocarbamate. The coloured complex is then selectively monitored at 435 nm. To increase interactions between copper(II) and colour forming reagent and preconcentrate of copper(II), a microcolumn containing strong cation exchange resins was placed between injection manifold and spectrophotometer. The system required no mixing chamber and allowed a sample throughput >60 sample h −1. The calibration graph was linear in the range 5–100 μg l −1. The detection limit was <0.5 μg l −1 for 20 μl injection volume of copper(II) ion solution. The developed method was applied to environmental, copper processing water, and ore samples.

Isolation and characterization of two distinct forms of liver fatty acid binding protein from the rat

Liver fatty acid binding protein (L-FABP) appears to contain several different forms that may result from post-translational modification or bound ligand. To further assess this possibility, L-FABP was purified from rat liver homogenate and two putative isoforms separated using a sulfonyl column, a strong cation exchange resin. Fraction I eluted at 0.2 M NaCl, had a p I of 7.59, and following a final size exclusion step contained >98% L-FABP. Fraction II eluted at 1.0 M NaCl, had a p I of 7.59, and following a final size exclusion step contained >99% L-FABP. Both fractions contained approx. 0.15 moles of endogenous bound fatty acid per mole of protein, while L-FABP not subjected to the cation exchange step contained 0.75 moles of fatty acid per mole of protein. Fractions I and II had a greater proportion of saturated and monounsaturated fatty acids with a large reduction in polyunsaturated fatty acids compared to L-FABP not fractionated by cation exchange. Mass spectral analysis indicated the molecular mass of Fraction I was 14 315.02±0.35 Da and Fraction II was 14 315.86±0.34 Da. The peptide map for each fraction was determined by limited digestion of each fraction with either trypsin, Asp-N, or chymotrypsin to yield overlapping peptide fragments. Mass spectral analysis of these digests indicated the two proteins had identical amino acid fragments and that Cys 69 was reduced and there were no Asn to Asp exchanges. Hence, these two forms of L-FABP were not isoforms and were not the result of differences in bound fatty acid. It is proposed that these two distinct forms of rat L-FABP were structural conformers based on two alternative folding pathways.

Synthesis, Crystal Structure and Complexing Properties of Phosphinic Analogues of Glycylglycine

The phosphinic dipeptides of the general formula H2NCH2CONHCH2P(R)(O)(OH) where R˭Me, Ph and t-Bu has been synthetized from the free phosphinic acids and N-hydroxnunimide esters of the N-protected glycine. The deprotected dipeptida were purified by combination of the column chromato graphy on strong and week cation exchange resins by elution with diluted aqueous ammonia (0.1–3%)

Modelling of Ion Exchange Step of L-Lysine Purification Process

ABSTRACTIon-exchange purification of L-lysine from culture broth on strong acid cation exchange resin (Amberlite IR 120) was investigated. Culture broth was obtained from L-lysine fermentation process with beet molasses as a main carbon source. Processes of amino acid recovery from this multicomponent system were carried out at the dynamic conditions in a column packed with the ion-exchange resin. The behaviour of the experimental data is described through mathematical models which take into account the relationship between L-lysine concentration and pH of the culture broth, temperature, flow rate, etc. Regression and time series analyses were applied for investigation of specific behaviours of the discussed process. The adequacy of the proposed time series models was confirmed by simulation researches.

Studies in the Reaction–Separation Method for the Preparation of Barium Chloride from Barite Using Ion Exchange

We report the application of an ion-exchange process as a reaction-separation strategy for the preparation of barium chloride from barite ore and sodium chloride. Experimental studies were carried out to evaluate the process efficiency and purity/yield of barium chloride using a strong acid cation-exchange resin, Tulsion T-42. The effects of various process parameters such as concentration of barium sulfide and concentration of sodium chloride were investigated, and optimization of the experimental variables was attempted. The results indicate the developed strategy to be attractive and an alternative route to existing processes. The methodology developed has large potential for the inorganic chemical process industry in general.

On-line cation exchange for suppression of adduct formation in negative-ion electrospray mass spectrometry of nucleic acids.

One major difficulty in the analysis of nucleic acids by electrospray mass spectrometry is represented by the affinity of the polyanionic sugar-phosphate backbone for nonvolatile cations, especially ubiquitous sodium and potassium ions. A simple on-line sample preparation system comprising a microflow pumping system and 45 x 0.8-mm-i.d. microcolumns packed with weak or strong cation-exchange resins is described for the efficient removal of cations from nucleic acid samples. Samples were analyzed by flow injection analysis at a 3-5 microL/min flow of 10 mM triethylamine in 50% water-50% acetonitrile. After on-line desalting, mass spectra of oligonucleotides revealed no significant sodium adduct peaks. Moreover, signal-to-noise ratios were greatly enhanced compared to direct injection of the samples. Electrospray mass spectrometry with on-line sample preparation allowed accurate molecular mass determinations of picomole amounts of crude oligonucleotide preparations ranging in size from 8 to 80 nucleotides within a few minutes. The good linearity of the calibration plot (R2 = 0.9988) over at least 2 orders of magnitude and a relative standard deviation in peak areas of less than 9% permitted the sensitive quantitative measurement of oligonucleotides in a concentration range of 0.2-20 microM with selected-ion monitoring. Finally, the on-line sample preparation system was evaluated for the mass spectrometric analysis of complex oligonucleotide mixtures.

Removal and recovery of heavy metal ions in fixed and semi-fluidized beds

Uptakes of heavy metal ions such as Pb2+ and Ni2+ were studied experimentally in fixed and semifluidized beds packed with a strong cation exchange resin, Amberlite 200. Single and binary aqueous solutions of lead and nickel ions were passed through ion exchange columns, and the exit concentrations were measured to get the breakthrough behavior of the ions. From the exit concentration profiles, the breakthrough time and the ion exchange capacity were evaluated. After removal of heavy metal ions from binary solution of lead and nickel ions until the breakthrough time, two metal ions were recovered by precipitation and resolubilization of lead. In this paper, the recovery yield and separation efficiency are rigorously discussed.

Effect of cation-exchange pretreatment of aqueous soil extracts on the gas chromatographic–mass spectrometric determination of nerve agent hydrolysis products after tert.-butyldimethylsilylation

The efficency of pretreatment of aqueous soil extracts using a cation-exchange resin has been investigated by gas chromatographic–mass spectrometric (GC–MS) determination of nerve agent hydrolysis products after tert.-butyldimethylsilyl (TBDMS) derivatization. An aqueous solution containing methylphosphonic acid (MPA) and its monoalkyl esters, ethyl methylphosphonic acid, isopropyl methylphosphonic acid and pinacolyl methylphosphonic acid, was dried, and these phosphonic acids were derivatized with N-methyl- N-( tert.-butyldimethylsilyl)trifluoro-acetamide and analyzed by GC–MS. The yields of TBDMS derivatives were significantly decreased by the addition of calcium and magnesium ions to an aqueous solution (≈0.5 m M) before derivatization. The extent of lowered yields was related to the hydrophilicity of phosphonic acids. MPA and its monoalkyl esters were spiked into soil samples (sand, alluvial soil and volcanic ash soil), extracted with distilled water, dried, silylated and applied to GC–MS. The yields of TBDMS derivatives of monoalkyl esters from soil samples were low (3–42%) and MPA derivative was scarcely detected (yield: <0.7%). By desalting the aqueous soil extract by passage through a strong cation-exchange resin, the yields of TBDMS derivatives of monoalkyl esters were significantly improved (12–69%) and MPA derivative was detected (yield: 2–36%). The extent of improved yields was related to the concentrations of divalent metal cations in aqueous soil extracts. In combination with desalting by the cation-exchange resin, GC–MS after TBDMS derivatization enables detection of nerve agent hydrolysis products in soils at sub-ppm (0.2 μg/g) concentrations.

Removal of copper ions by a cation-exchange resin in a semifluidized bed

The removal of copper ions was studied experimentally in a semifluidized bed charged with a strong cation-exchange resin, Amberlite 200C. The semifluidized bed system was formed by inserting a retaining grid in a packed bed and increasing the fluid velocity above Umf. In this arrangement, the bed is separated into two sections; the upper packed bed section and the lower fluidized bed section. As the fluid velocity increases, the portion of the packed bed section becomes larger. As expected, the breakthrough curve obtained from the semifluidized bed lies between those from packed and fluidized beds. The breakthrough curves of copper ions were predicted reasonably well by using an axial dispersion model. In this paper, the effects of the liquid flowrate and the retaining grid height on the breakthrough behavior are extensively discussed.

Clean Ion-Exchange Technologies. I. Synthesis of Chlorine-Free Potassium Fertilizers by an Ion-Exchange Isothermal Supersaturation Technique

This paper reports the results of studying ion-exchange synthesis of chlorine-free potassium sulfate from KCl and Na2SO4 on strong acid cation-exchange and strong base anion-exchange resins using an ion-exchange isothermal supersaturation (IXISS) effect. This effect is observed for a number of ion-exchange systems, where the ion-exchange process is accompanied by the formation of a stable supersaturated solution of slightly or sparingly soluble substances in the interstitial space of ion-exchange columns. The formation of stable K2SO4 solutions in the columns has been observed by the displacement of either K+ or SO42- ions from a cation or anion exchanger with concentrated Na2SO4 or KCl solutions, respectively. After leaving the column, a supersaturated solution crystallizes spontaneously, which allows for the design of a practically ideal ion-exchange process where a crystalline chlorine-free potassium sulfate is obtained right after the ion-exchange conversion cycle. The process is practically wasteless...

Retention behavior of carboyxlic acids on highly cross-linked poly(styrene-divinylbenzene)-based and silica-based cation exchangers

A highly cross-linked porous poly(styrene-divinylbenzene) resin was reacted with sulfuric acid to give strong cation-exchange resins with capacities from 0.2 to 1.9 mequiv./g. The retention behavior of mono- and dicar☐ylic acids on these resins was compared with results obtained from silica-based cation exchangers functionalized with alkylsulfonic acid or phenylsulfonic acid groups. The contribution of different retention mechanisms like ion exclusion, hydrophobic interaction and adsorption to the separation of the analytes on these chromatographic supports was discussed. Additionally the applicability of silica-based cation exchangers was tested in the field of silage analysis.

Uptake of hydrophobic amino acids and sodium chloride by a strong cation exchanger: Application to desalting and separation by preparative liquid chromatography

The uptake of sodium chloride, leucine and phenylalanine by a strong cation-exchange resin in the sodium form have been compared.

Manufacturing High Purity Maltose and Maltotetraose from Starch by a Novel and Efficient Procedure Named "Reducing End Modification Method".

A novel and efficient procedure named "reducing end modification method" was developed for manufacturing high purity maltooligosaccharides. By the method, high purity maltose and maltotetraose were prepared from starch. Starch was liquefied, debranched, and oxidized with sodium hypochlorite at the reducing end. The reaction mixture was treated with β-amylase or maltotetraose-forming amylase from Pseudomonas stutzeri IFO-3773, resulting in the production of high purity maltose or maltotetraose, oxidized maltooligosaccharides, and oxidized undigested dextrin. High purity maltose (maltose content, 99.9%) or maltotetraose (maltotetraose content, 95%) was obtained very effectively from the reaction mixture by chromatography on a strong acid cation exchange resin (Na (+)).

Application of a three-dimensional ion-exchange electrolyte in the deoxygenation of low-conductivity water

A solid ion-exchange electrolyte has successfully been used in the electrochemical deoxygenation of low-conductivity water. A packed bed three-dimensional cathode was mixed with ion-exchange resin. Oxygen-rich low-conductivity water was passed through the three-dimensional cathode and the dissolved oxygen was reduced to water. A sufficient ionic conductivity in the three-dimensional electrode was obtained for both distilled water and tap water by small-size strong cation exchange resins in the H+ and Ca2+ forms, respectively. Deoxygenation efficiencies of over 99.9% were achieved.

Kinetics of ion exchange accompanied by neutralization reaction

In a variety of applications involving ion-exchange resins, the process of ion exchange is accompanied by an instantaneous chemical reaction such as neutralization, association, or complex formation. Helfferich (1965) has classified these reactions into four categories viz. Type I to Type IV. In this work, we have modeled the Type I ion-exchange process represented by neutralization of metal hydroxide (MOH) on a strong acid cation exchange resin in H-form. The model presented is an extension of a model on an ordinary ion-exchange process (Hasnat and Juvekar, 1996)

Disinfection of viable Pseudomonas stutzeri in ultrapure water with ion exchange resins

This study describes the disinfection of gram-negative bacteria, Pseudomonas stutzeri, isolated from ultrapure water (total organic carbon 5 ppb; effluent resistivity, > 18 MΩ cm at 25°C) with ion exchange resins using a batchwise procedure. A single bed of strong base anion exchange resin (SBAER) in OH − form shows disinfection ability; however, a bed of strong acid cation exchange resin (SACER) in H + form does not. Adsorption of bacteria on SBAERs occurs mainly due to the electrostatic attraction between positively charged SBAERs and negatively charged bacteria. In addition, hydrophilic interactions between SBAERs and bacteria are considered based on the results of adsorption isotherms. Since the positively charged SBAERs in Cl − form have no bactericidal effect, OH − ions are utilized for disinfection. Acrylic SBAERs in OH − form were more effective at disinfection than styrenic SBAERs. A mixed bed of SBAERs in OH − form and SACERs in H + form also disinfects bacteria more effectively.

Studies on ion exchange equilibria and kinetics VI. Prediction of ion exchange equilibria of UO 2 2+ −Na+−H+ ternary system

Experimental data are reported for the ion exchange equilibria of the binary systems UO 2 2+ −H+, UO 2 2+ −Na+ and Na+−H+, and of the ternary system UO 2 2+ −Na+−H+ on a strong acid cation exchange resin 001X7 at 25 °C. It is found that the equilibria for any pairs of ions are essentially the same in binary and ternary mixtures and that the prediction method proposed by our laboratory for SO 2 2− −Cl−−NO 3 − -201X7 strong base anion exchange resin system is also applicable to the ternary system studied in this paper. The predictions of the ternary system UO 2 2+ −Na+−H+ based solely on the binary data without using resin phase activity coefficients are consistent with the experimental data.