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At least 127 records · Page 7Linked to original sources
PubMed2000

Comparison of chromatographic ion-exchange resins. I. Strong anion-exchange resins.

A comparative study has been undertaken on various strong anion-exchangers to investigate the pH dependence, titration curves, efficiency, binding strength, and dynamic capacity of the chromatographic resins. The resins tested included: Macro-Prep 25Q, TSK-Gel Q-5PW-HR, Poros QE/M, Q Sepharose FF, Q HyperD 20, Q Zirconia, Source 30Q, Fractogel EMD TMAE 650s, and Express-Ion Q. Testing was performed with five different proteins: Anti-FVII Mab (IgG), aprotinin, BSA, lipolase, and myoglobin. The dependence of pH on retention varies from generally low to very high for proteins with low pI. No direct link between pH dependence on retention and titration curves of the different resins was observed. Efficiency results show the expected trend of lower dependence of the plate height with increasing flow-rate of resins for medium and high pressure operation compared to the soft resins. Binding to the anion-exchange resins as a function of ionic strength may vary depending on the specific protein. Generally, binding and elution at a high salt concentration may be performed with Poros QE/M or Macro-Prep 25Q, while binding and elution at low salt concentration may be done with TSK-Gel Q-5PW. Dynamic capacities are strongly dependent on the specific protein employed and for some resins dependent on the flow-rate. A general good agreement was obtained between this study and data obtained by suppliers for the dynamic capacity. The results of this study may be used for selection of resins for testing in process development, however, the data does not tell anything about specific selectivity differences or resolution between a target protein and a given impurity. None of the resins studied here should be regarded as good or bad, but more or less suitable for a specific purpose, and only testing for the specific application will determine which one is the optimal resin.

Anion Exchange Resins↗
PubMed2005

Preparation and characterization of a novel pH-sensitive ion exchange resin.

Methylacrylic acid/styrene cross-linked with divinylbenzene is a novel pH-sensitive ion exchange resin. Microspheres of this resin were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The microspheres showed a pulsatile swelling behavior when the pH of the media changed. The pH-sensitive microspheres were loaded with salbutamol sulfate and the drug-release characteristics were studied under both simulated gastric and intestinal pH conditions. The results obtained showed that the drug release also depended on the pH of the release media.

Hydrogen-Ion Concentration↗
PubMed2006

Biodiesel production using anionic ion-exchange resin as heterogeneous catalyst.

The transesterification reactions of triolein with ethanol using various ion-exchange resin catalysts were conducted to produce ethyl oleate as a biodiesel. The anion-exchange resins exhibited much higher catalytic activities than the cation-exchange resin. The anion-exchange resin with a lower cross-linking density and a smaller particle size gave a high reaction rate as well as a high conversion. By combining the three-step regeneration method, the resin could be repeatedly used for the batch transesterification without any loss in the catalytic activity. A continuous transesterification reaction was carried out using an expanded bed reactor packed with the most active resin. The reactor system permitted the continuous production of ethyl oleate with a high conversion.

Anions↗
PubMed1975

The mechanism for the exclusion of sugars from the water in a model of the liveing cell: the ion-exchange resin: pore size or water structure?

The equilibrium distribution coefficients (p-value) of D-arabinose between the water in sulfonate ion-exchange resin and the external aqueous solution vary with the nature of the five alkali metal counterions studied. The strongest exclusion (lowest p-value) is found in the Li+ resin and the least exclusion (highest p-value) in the Cs+ resin. The p-value decreases with the increasing atomic weights for the alkali-metal ions: pCs+ greater than or equal to pRb+ greater than or equal to pRb+ greater than or equal to pK+ greater than pNa+ greater than pLi+. The water contents of these resins, on the other hand, vary in the opposite direction, being highest for the Li+ resin and lowest for the Cs+ resin. These data disprove the pore size theory but fully substantiate the predictions of the association-induction hypothesis.

Arabinose↗
PubMed1975

The removal of organic matter with a weakly basic macroreticular ion-exchange resin. A case history.

Natural waters containing organic pollutants have a strong tendency to foul anionic exchange resins irremediably. The use of various types of scavenging resins is discussed and results are given on trials carried out at a chemical plant. The conclusion is drawn that a proper analysis of organic matter present in water cannot be made and that consequently it is difficult to determine which types of scavengers are the most suitable. The paper suggests a principle of calculating weakly basic macroreticular resins into the flow system so as to function both as a scavenger and a weakly basic ion-exchange resin.

Industrial Waste↗
PubMed2001

Removal of chromium from water and wastewater by ion exchange resins.

Removal of chromium from water and wastewater is obligatory in order to avoid water pollution. Batch shaking adsorption experiments were carried out to evaluate the performance of IRN77 and SKN1 cation exchange resins in the removal of chromium from aqueous solutions. The percentage removal of chromium was examined by varying experimental conditions viz., dosage of adsorbent, pH of the solution and contact time. It was found that more than 95% removal was achieved under optimal conditions. The adsorption capacity (k) for chromium calculated from the Freundlich adsorption isotherm was found to be 35.38 and 46.34 mg/g for IRN77 and SKN1 resins, respectively. The adsorption of chromium on these cation exchange resins follows the first-order reversible kinetics. The ion exchange resins investigated in this study showed reversible uptake of chromium and, thus, have good application potential for the removal/recovery of chromium from aqueous solutions.

Adsorption↗
PubMed2026

Sulfonic Ion-Exchange Resins as Versatile Tools for the Oxidative Degradation of Chemical and Biological Hazardous Agents.

Commercial sulfonic styrene-divinylbenzene ion-exchange resins are activated with aqueous H2O2 to generate metal-free decontamination systems that combine strong Brønsted acidity with immobilized oxidizing capability. Among five tested materials, Amberlyst 15 dry showed the best performance in terms of oxidant immobilization capacity and promoting the oxidative degradation of the sulfur mustard simulant (2-chloroethyl)ethyl sulfide, CEES, and the organophosphorus pesticide malathion under very mild conditions. Control experiments with K2CO3-exchanged resin demonstrate that efficient decontamination requires the synergy between surface acidity and peroxide functionality. The activated resins also display rapid biocidal activity, strongly reducing viable Escherichia coli and Staphylococcus aureus and completely suppressing the infectivity of HSV-1 and SARS-CoV-2 within min. These findings identify peroxide-activated sulfonic resins as simple, sustainable, regenerable, and versatile tools for efficient combined hazardous chemical and biological decontamination.

Oxidation-Reduction↗
PubMed1995

Intragastric distribution of ion-exchange resins: a drug delivery system for the topical treatment of the gastric mucosa.

Previous studies by this group on freeze-dried oral dosage forms containing finely-divided ion-exchange resins revealed prolonged gastric residence and uniform distribution within the stomach. The present study was carried out to ascertain whether this was due to freeze-drying, properties of the radiolabelled ionic exchange resin, or the small dosing volume used. 99mTc-labelled cholestyramine resin was administered in two dosage forms, a freeze-dried tablet which dissolved in the oral cavity (orally dissolving tablet; ODT) and a 1.5 mL aqueous suspension. Two resin particle sizes (20-40 and 90-125 microns) were studied. Oesophageal transit and intragastric distribution and residence were followed by gamma scintigraphy. In a second study, in six subjects, gastric emptying of the water-soluble fraction of the ODT and 1.5 mL of water, was measured using 99mTc diethylenetriaminepentaacetic acid. Oesophageal transit of a water-soluble marker and resin in suspension was rapid, but the transit of the resin in the ODTs was significantly prolonged. Regardless of particle size or dosage form, the resin was evenly distributed throughout the stomach with 20-25% remaining for 5.5 h. In contrast, the water-soluble marker cleared from the stomach rapidly from both dosage forms. We suggest that oral dose forms containing finely-divided ion-exchange resins may form a useful system for topical treatment of the gastric mucosa, for example in targeting to Helicobacter pylori infection.

Adult↗