Mixed-bed Ion-exchange Resin Research Articles

Iron hydrolysis and lithium uptake on mixed-bed ion exchange resin at alkaline pH

The use of ion exchange resins to remove ionic impurities from solution is prevalent in industrial process systems, including in the primary heat transport system (PHTS) purification circuit of nuclear power plants. Despite its extensive use in the nuclear industry, our general understanding of ion exchange cannot fully explain the complex chemistry in ion exchange beds, particularly when operated at or near their saturation limit. This work investigates the behaviour of mixed-bed ion exchange resin, saturated with species representative of corrosion products in a CANDU (Canadian Deuterium Uranium) reactor PHTS, particularly with respect to iron chemistry in the resin bed and the removal of lithium ions from solution. Experiments were performed under deaerated conditions, analogous to normal PHTS operation. The results show interesting iron chemistry, suggesting the hydrolysis of cation resin bound ferrous species and the subsequent formation of either a solid hydrolysis product or the soluble, anionic Fe(OH)3-.

Identification of Polysaccharides From Dipsacus asperoides and Their Effects on Osteoblast Proliferation and Differentiation in a High-Glucose Environment.

Polysaccharides (DAI-1 and DAI-2) from Dipsacus asperoides (D. asperoides) were obtained using mixed-bed ion exchange resin and Sephadex G-50 column chromatography following which their properties, structures, and activities were investigated. The results showed that DAI-1 and DAI-2 were homogeneous in nature, with glucose the only constituent, and had molecular masses of 17 and 4 kDa, respectively. Methylation analysis indicated that the backbones of DAI-1 and DAI-2 were mainly composed of (1→6)-linked glucose residues. DAI-1 possessed a small number of side chains and a branch point of (1→3, 6)-glucose, while DAI-2 lacked branching. Activity assays demonstrated that exposing osteoblasts to different DAI-1 concentrations (25, 50, or 100 μg/mL) in a high-glucose environment induced cell proliferation and led to a significant increase in bone morphogenetic protein 2 (BMP-2) and runt-related transcription factor 2 (Runx2) expressions at both the mRNA and protein levels. Moreover, DAI-1 treatment significantly increased alkaline phosphatase (ALP) and osteocalcin (OCN) activities in osteoblasts. Combined, our results suggested that DAI-1 may promote osteoblast proliferation and differentiation in a high-glucose environment.

Opportunities for coupled electrochemical and ion-exchange technologies to remove recalcitrant micropollutants in water

Micropollutants are found in many waters at concentrations that are concerning for living and environmental systems. They are usually characterised as being persistent and are generally difficult to remove from the water using traditional techniques. In this work, we investigate a treatment technology that couples electrooxidation of micropollutants with subsequent absorption of charged products and remaining compounds through a mixed strong acid and strong base ion exchange resin. The results clearly show that carbon fibre is a promising electrode material. Electrooxidation of the drug Ibuprofen using carbon fibre in a coulombic efficiency of 13 mC/ppm removed 71% of the compound after two hours (down to 29 ppm). The addition of sodium chloride led to a near doubling of the pseudo-first order reaction rate from 1.7 to 3.0 10−4 s−1. A mix of Ibuprofen and the pesticide Diuron showed similarly promising results and while the overall oxidation decreased the positive effect of sodium chloride was present. Strikingly, coupling electrooxidation with a mixed bed ion exchange resin removed both compounds, decreasing levels of Diuron to below the limit of detection (18 ppb) and Ibuprofen down to 0.8 ppm. The approach shows potential as a treatment technology for the removal of complex pollutants in water.

A deep desalination and anti-scaling electrodeionization (EDI) process for high purity water preparation

Electrodeionization (EDI) is a composite desalination process that combines ion exchange and electrodialysis to achieve continuous deionization. However, the current EDI technology has demanding requirements for the feed water, and fouling in the stack often exists in practical industrial applications. For the above-mentioned issue, a novel deep desalination and anti-scaling EDI stack configuration was proposed. Different from previous configuration, a cation exchange membrane was added to the right side of the reverse anode exchange membrane to form a protective chamber, in which mixed bed ion exchange resin was filled with a certain proportion, Meanwhile, the influent of concentrated stream was supplied by dilute stream. Aiming at no fouling and maximum dilute water resistivity, the effect of operating conditions on the EDI process for the preparation of high purity water were studied. All the results demonstrated that for the feed water with a hardness of 7.9 mg·L−1 (calculated as CaCO3), with the proposed EDI stack configuration and a membrane stack voltage of 8 V, a concentrated flux of 6 L/h, a dilute flux of 32 L/h, the membrane stack can run stably for 400 h without fouling, and the dilute water resistivity can reach 16.1 MΩ·cm−1, the total desalination rate was 99.8%, the hardness ion removal rate was close to 100%, the energy consumption could be maintained at <0.03 KWh·m3. These results indicate that the proposed EDI stack configuration can broaden the limits of EDI feed water conditions and it is of great practical significance to realize the industrial application of the deep desalination and anti-scaling EDI model.

Critical point analysis and biocide treatment in a microbiologically contaminated water purification system of a power plant

Many industries use ultrapure water (UPW) for their operation. In spite of purification efforts, microbial contaminations are the major cause of manufacturing problems in these systems. In our experiments, the water purification system of a power plant was investigated: the microbiologically critical points of the ultrapure water purification system were located by checking the number and diversity of bacteria to determine the optimum operational unit for chemical intervention: the most contaminated site was the mixed-bed ion-exchange resin containing unit. Biocides were tested against bacteria previously isolated from the same system; effect of biocides was checked also in laboratory model systems, and based on the results, a biocide treatment was carried out in the mixed-bed ion-exchange resin columns of the working power plant. Kathon WT was the most effective from the studied chemicals, being effective already in low concentration against most studied microorganisms. In case of the handling of the mixed-bed ion-exchange resin, 8-h treatment with 25 ppm biocide concentration was effective. Following the treatment, the quality of the produced UPW met the standards (specific electric conductivity was < 1.0 × 10−3 µS cm−1 at 25 °C) and water production capacity increased; moreover, the run-down time of the mixed-bed ion-exchange resin significantly grew.

Recovery of citric acid from fermented liquid by bipolar membrane electrodialysis

The process of recovering citric acid from fermented liquid by bipolar membrane electrodialysis (BMED) was studied. Two bipolar membranes and one cation exchange membrane were stacked to form a two-compartment BMED stack configuration. The effects of the current density, initial concentration of sodium citrate, and structure of the acid compartment (AC) and base compartment (BC) on the performance of the BMED process were investigated. Filling mixed-bed ion exchange resins in BC could decrease the compartment resistance and led to a pure base solution for reuse. The highest acid recovery of 97.1% was achieved with 3.3% initial sodium citrate under a current density of 40 mA cm−1. Additionally, a decrease of voltage across AC by filling cation exchange resins restricted the migration of H+ ions from AC to BC. A higher initial concentration of sodium citrate has an adverse effect on the recovery of citric acid. BC with a bipolar membrane (BPM) exhibited lower energy consumption and a higher recovery rate of citric acid. BMED appears to be a promising technology for recovering citric acid from fermented liquid.

Separation and purification of hemicellulose-derived saccharides from wood hydrolysate by combined process

Prehydrolysis of wood biomass prior to kraft cooking provides a stream containing hemicellulose-derived saccharides (HDSs) but also undesired non-saccharide compounds (NSCs) that were resulted from lignin depolymerization and carbohydrate degradation. In this study, a combined process consisting of lime treatment, resin adsorption, and gel filtration was developed to separate HDSs from NSCs. The macro-lignin impurities that accounted for 32.2% of NSCs were removed by lime treatment at 1.2% dosage with negligible HDSs loss. The majority of NSCs, lignin-derived phenolics, were eliminated by mixed bed ion exchange resin, elevating NSCs removal to 94.0%. The remaining NSCs, furfural and hydroxymethylfurfural, were excluded from HDSs by gel filtration. Chemical composition analysis showed that xylooligosaccharides (XOS) with the degree of depolymerization from 2 to 6 accounted for 28% of the total purified HDSs.

Experimental design approach for identification of the factors influencing the γ-radiolysis of ion exchange resins

Gamma radiolysis was investigated on a nuclear grade mixed bed ion exchange resin and its pure components under different irradiation conditions. Screening designs were performed to identify the factors influencing gas production after their γ-radiolysis and to compare their γ-degradation stability. Only hydrogen and trimethylamine quantities were considered as the response in the experimental designs. The other detected gases and water-soluble products were used to improve the resins degradation. Aerobic irradiation atmosphere decreased the H2g production of AmbOH, MB400, and amines. The water presence increased the H2g quantities for AmbH and decreased those for MB400 resin. Liquid water had no effect on H2g production from AmbOH but was favorable to increased amine production. The H2g production of AmbH increased with the absorbed dose that had little effect on the AmbOH resin. No impact of dose on the H2g production was detected for MB400 that appeared to be less degraded.

Comparison of Mass Transfer Coefficient Approach and Nernst–Planck Formulation in the Reactive Transport Modeling of Co, Ni, and Ag Removal by Mixed-Bed Ion-Exchange Resins

Experiments performed under chemical and flow conditions representative of pressurized water reactors (PWR) primary fluid purification by ion exchange resins (Amberlite IRN9882) are modeled with the OPTIPUR code, considering 1D reactive transport in the mixed-bed column with convective/dispersive transport between beads and electrodiffusive transport within the boundary film around the beads. The effectiveness of the purification in these dilute conditions is highly related to film mass transfer restrictions, which are accounted for by adjustment of a common mass transfer coefficient (MTC) on the experimental initial leakage or modeling of species diffusion through the bead film by the Nernst–Planck equation. A detailed analysis of the modeling against experimental data shows that the Nernst–Planck approach with no adjustable parameters performs as well as, or better than, the MTC approach, particularly to simulate the chromatographic elution of silver by nickel and the subsequent enrichment of the solution in the former metal.

Optimization of large gel 2D electrophoresis for proteomic studies of skeletal muscle

We describe improved methods for large format, two-dimensional gel electrophoresis (2DE) that improve protein solubility and recovery, minimize proteolysis, and reduce the loss of resolution due to contaminants and manipulations of the gels, and thus enhance quantitative analysis of protein spots. Key modifications are: (i) the use of 7 M urea and 2 M thiourea, instead of 9 M urea, in sample preparation and in the tops of the gel tubes; (ii) standardized deionization of all solutions containing urea with a mixed bed ion exchange resin and removal of urea from the electrode solutions; and (iii) use of a new gel tank and cooling device that eliminate the need to run two separating gels in the SDS dimension. These changes make 2DE analysis more reproducible and sensitive, with minimal artifacts. Application of this method to the soluble fraction of muscle tissues reliably resolves ~1800 protein spots in adult human skeletal muscle and over 2800 spots in myotubes.

Microbiological investigation of an industrial ultra pure supply water plant using cultivation-based and cultivation-independent methods

Ultra pure waters (UPW), characterized by extremely low salt and nutrient concentrations, can suffer from microbial contamination which causes biofouling and biocorrosion, possibly leading to reduced lifetime and increased operational costs. Samples were taken from an ultra pure supply water producing plant of a power plant. Scanning electron microscopic examination was carried out on the biofilms formed in the system. Biofilm, ion exchange resin, and water samples were characterized by culture-based methods and molecular fingerprinting (terminal restriction fragment length polymorphism [T-RFLP] analysis and molecular cloning). Identification of bacteria was based on 16S rDNA sequence comparison. A complex microbial community structure was revealed. Nearly 46% of the clones were related to as yet uncultured bacteria. The community profiles of the water samples were the most diverse and most of bacteria were recruited from bacterial communities of tube surface and ion exchange resin biofilms. Microbiota of different layers of the mixed bed ion exchange resin showed the highest similarity. Most of the identified taxa (dominated by β-Proteobacteria) could take part in microbially influenced corrosion.

Separation of Oleic Acid from Soybean Oil Using Mixed-Bed Resins

Two mixed bed ion-exchange resins (Dowex Monosphere MR-450 UPW and Amberlite MB-150) were investigated for their ability to remove oleic acid from a laboratory-prepared 5 % (w/w) oleic acid/soybean oil mixture. The performance of the heterogeneous mixed-bed resins to remove oleic acid from the mixture was investigated for resin loading and reaction duration while the mixing rate, reaction temperature, and initial oleic acid composition of the mixture were kept constant. Both resins removed > 93 % of the oleic acid in the sample within 4 h with a 20 % (w/w) resin loading in a nonpressurized batch reactor system at 50 °C. The maximum adsorption capacity for Amberlite MB-150 and Dowex Monosphere MR-450 UPW was determined to be 0.27 g·g−1 (oleic acid/wet resin) and 0.26 g·g−1 (oleic acid/wet resin), respectively. Ion-exchange of oleic acid onto the quaternary ammonium site of the mixed-bed resin was determined to be the mechanism of oleic acid removal. The presented research has promising application in the a...

Currents: Ambient thermal dissociation generates fragments outside the mass spectrometer | Tag for improved limits of detection with ESI MS | Mixed-bed ion-exchange resin for enhanced MudPIT | Quantitative proteomics method for fast events | A feedback strategy leads to high proteome coverage | Potential biomarkers for Sjögren’s syndrome | Dinosaur and mastodon fossils yield evidence of collagen with proteomics

Currents: Ambient thermal dissociation generates fragments outside the mass spectrometer | Tag for improved limits of detection with ESI MS | Mixed-bed ion-exchange resin for enhanced MudPIT | Quantitative proteomics method for fast events | A feedback strategy leads to high proteome coverage | Potential biomarkers for Sjögren’s syndrome | Dinosaur and mastodon fossils yield evidence of collagen with proteomics

Anion and Cation Mixed-Bed Ion Exchange for Enhanced Multidimensional Separations of Peptides and Phosphopeptides

Shotgun proteomics typically uses multidimensional LC/MS/MS analysis of enzymatically digested proteins, where strong cation-exchange (SCX) and reversed-phase (RP) separations are coupled to increase the separation power and dynamic range of analysis. Here we report an on-line multidimensional LC method using an anion- and cation-exchange mixed bed for the first separation dimension. The mixed-bed ion-exchange resin improved peptide recovery over SCX resins alone and showed better orthogonality to RP separations in two-dimensional separations. The Donnan effect, which was enhanced by the introduction of fixed opposite charges in one column, is proposed as the mechanism responsible for improved peptide recovery by producing higher fluxes of salt cations and lower populations of salt anions proximal to the SCX phase. An increase in orthogonality was achieved by a combination of increased retention for acidic peptides and moderately reduced retention of neutral to basic peptides by the added anion-exchange resin. The combination of these effects led to approximately 100% increase in the number of identified peptides from an analysis of a tryptic digest of a yeast whole cell lysate. The application of the method to phosphopeptide-enriched samples increased by 94% phosphopeptide identifications over SCX alone. The lower pKa of phosphopeptides led to specific enrichment in a single salt step resolving acidic phosphopeptides from other phospho- and non-phosphopeptides. Unlike previous methods that use anion exchange to alter selectivity or enrich phosphopeptides, the proposed format is unique in that it works with typical acidic buffer systems used in electrospray ionization, making it feasible for online multidimensional LC/MS/MS applications.

The production of high purity water by continuous electrodeionization with bipolar membranes: Influence of the anion-exchange membrane permselectivity

Continuous electrodeionization is used widely today for the production of high purity water. The conventional electrodeionization process using mixed-bed ion-exchange resins has several shortcomings, such as incomplete removal of weak acids and diluate conductivity above that of completely deionized water. In this study, the performance of a modified continuous electrodeionization stack using separated beds of cation- and anion-exchange resins and a bipolar membrane as source of regenerating protons and hydroxide ions is considered. Two modifications of this design, one with and one without a so-called protection compartment are compared with each other. The role of the co-ion transport through an anion-exchange membrane of incomplete permselectivity on the process performance is discussed theoretically and shown experimentally as function of the current density, the hydrostatic pressure and the flow velocity in the concentrate compartment, as well as the nature of the protection compartment rinse water. Using the protection compartment, the co-ion transport into the diluate could be eliminated and a specific conductivity of the product water of less than 0.056 μS/cm was achieved.

Analysis of polyols in urine by liquid chromatography–tandem mass spectrometry: A useful tool for recognition of inborn errors affecting polyol metabolism

Several inborn errors of metabolism with abnormal polyol concentrations in body fluids are known to date. Most of these defects can be diagnosed by the assessment of urinary concentrations of polyols. We present two methods using tandem mass spectrometry for screening for inborn errors affecting polyol metabolism. Urine samples supplemented with internal standards ([13C4]erythritol, [13C2]arabitol and [2H3]sorbitol) were desalted by a mixed-bed ion-exchange resin. Separation was achieved by two different columns. Sugar isomers could not be separated using a Prevail Carbohydrate ES 54 column (method 1), whereas with the other column (Aminex HPX-87C) separation of the isomers was achieved (method 2). Multiple reaction monitoring polyol detection was achieved by tandem mass spectrometry with an electron ion-spray source operating in the negative mode. Age-related reference ranges of polyols (erythritol, treitol, arabitol, ribitol, xylitol, galactitol, mannitol, sorbitol, sedoheptitol and perseitol) in urine were established. The applicability of the method was demonstrated by the abnormal polyol concentrations observed in patients with transaldolase deficiency, ribose-5-phosphate isomerase deficiency and classical galactosaemia. This paper describes two methods for the analysis of urinary polyols by liquid chromatography-tandem mass spectrometry. Method 1 is a fast screening method with the quantification of total isomers and method 2 is a more selective method with the separate quantification of the polyols. Both methods can be used for diagnosing inborn errors of metabolism affecting polyol metabolism.

Colloidal crystals of core–shell-type spheres in deionized aqueous suspension

The structure, crystal growth kinetics and rigidity of colloidal crystals of core–shell-type latex spheres (diameters 280–330 nm) with differences in shell rigidity have been studied in aqueous suspension, mainly by reflection spectroscopy. The suspensions were deionized exhaustively for more than 2 years using mixed-bed ion-exchange resins. The five kinds of core–shell spheres examined form colloidal crystals, where the critical sphere concentrations, ϕ c, of crystallization (or melting) are high and range from 0.01 to 0.06 in volume fraction. Nearest-neighbor intersphere distances in the crystal lattice agree satisfactorily with values calculated from the sphere diameter and concentration. The crystal growth rates are between 0.1 and 0.3 s−1 and decrease slightly as the sphere concentration increases, indicating that the crystal growth rates are from the secondary process in the colloidal crystallization mechanism, corresponding to reorientation from metastable crystals formed in the primary process and/or Ostwald-ripening process. The rigidities of the crystals range from 2 to 200 Pa, and increase sharply as the sphere concentration increases. The g factor, the parameter for crystal stability, is around 0.02 irrespective of the sphere concentration and/or the kind of core–shell sphere. There are no distinct differences in the structural, kinetic and elastic properties among the colloidal crystals of the different core–shell-type spheres, showing that the internal sphere structure does not affect the properties of the colloidal crystals. The results show that colloidal crystals form in a closed container owing to long-range repulsive forces and the Brownian movement of colloidal spheres surrounded by extended electrical double layers and that their formation is not influenced by the rigidity and internal structure of the spheres.

A study on stack configuration of continuous electrodeionization for removal of heavy metal ions from the primary coolant of a nuclear power plant

This study investigated the production of high-purity water in the primary coolant of a nuclear power plant via the continuous electrodeionization (CEDI) process, using ion exchange resins as ion-conducting media between ion exchange membranes. The effectiveness of this method was examined with respect to the removal of heavy metals. The study was carried out on a laboratory scale with an effective area of 20 cm 2. The CEDI system was operated with a layered bed of cation exchange resins, anion exchange resins, and mixed-bed ion exchange resins. The stack configuration was designed to prevent a reaction between metal ions and hydroxide ions. The CEDI operation with the layered bed removed more than 99% of the ions at 30% of the current efficiency. The results showed that, with an inlet conductivity of 40 μS cm −1, a linear velocity of 4.17 cm s −1, and an applied current density of 17 mA cm −2, the CEDI process yielded an outlet conductivity of 0.5 μS cm −1, thereby preventing the precipitation of metal ions. This study therefore successfully demonstrated the feasibility of the CEDI operation for the removal of heavy metals at a very low concentration.

Adsorption and Recovery of Dissolved Organic Phosphorus and Nitrogen by Mixed-Bed Ion-Exchange Resin

A laboratory study was conducted to investigate the efficacy of using various mixed-bed anion-cation exchange resins in absorbing dissolved organic and inorganic N (DON and DIN) and P (DOP and DIP). Leachate from foliage of aspen (Populus grandidentata) was passed through columns containing three brands of mixed-bed resin contained in nylon bags, with and without pretreatment of the resins by rinsing with KCI. After leaching, the resins were extracted with either 2 M KCI or 2 M HCl, and recoveries of DIN, DON, DIP, and DOP were calculated. The results showed that all brands of resin adsorbed more DIP (91-98.5%) than DOP (55-70%) and more NO, (87-100%) than NH, (0-14%) and DON (18-49%). In general, pretreating the resin significantly decreased absorption. The recovery of DIP and DOP was influenced by the pretreatment and the extracting solution whereas the recovery of DIN and DON was problematic because of the release of amine groups. Overall, the use of mixed-bed resin seems adequate for P studies but not for N studies on a short-time scale. Longer exposure periods are needed for studies of N so that the signal/noise (blank) ratio is higher than in this study.

Adsorption and Recovery of Dissolved Organic Phosphorus and Nitrogen by Mixed-Bed Ion-Exchange Resin

Adsorption and Recovery of Dissolved Organic Phosphorus and Nitrogen by Mixed-Bed Ion-Exchange Resin