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Results for “ION EXCHANGE RESINS”

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At least 343 records · Page 19Linked to original sources

PubMed1983

Evidence that Na+ in a sulfonate ion exchange resin exists in an adsorbed state. Its significance for the interpretation of NMR data in resins and cells.

The concentrations of total Na+ and of free Na+ were measured in solutions of Na+ polystyrene sulfonate (NaPSS). Free Na+ was determined using a Na+-sensitive glass electrode having a high degree of specificity for Na+. In a 5% PSS solution, 80% or more of the Na+ was not detected by the glass electrode and was adsorbed specifically onto the anionic sulfonate groups. The degree of adsorption increased with an increase in the concentration of PSS. These results were discussed in regard to the interpretation of NMR studies of Na+ in the cross-linked PSS resins (Dowex 50) and in living cells. The results show that the quadrupolar splitting of the Na+ NMR signal is caused by specific ionic adsorption onto fixed anionic sites and not by a diffuse charge gradient extending over large distances.

Adsorption↗

PubMed2005

Cellulose acetate butyrate microcapsules containing dextran ion-exchange resins as self-propelled drug release system.

Sulfopropylated dextran microspheres (SP-Ms), (Dm = 80 microm) loaded with a water soluble drug (Tetracycline HCl), were included in cellulose acetate butyrate (CAB) microcapsules. Spherical CAB microcapsules were obtained by oil in water (o/w) solvent evaporation method in the presence of an inert solvent as cyclohexane (CyH) or n-hexane (N-Hex), and different excipients (Phospholipon, Tween, Span, Eudragit RS 100). Chloroform was found to be the best solvent for the preparation of the microcapsules. Also, the sphericity as well as the porosity of the microcapsules was controlled by the presence of an inert solvent. The final concentration of the drug in CAB microparticles was up to 25% (w/w). The key factors for the successful preparation were also the viscosity of the polymer, while the wettability of the resulted microcapsules, the temperature of the preparation, and the porosity have modulated the release of the drug. The higher is the amount of encapsulated microspheres the thinner is the CAB wall between the compartments created by their incorporation. When these microspheres come in contact with the release medium, the pressure created by their swelling breaks the polymer film and the drug starts to be released. The more drug is released in phosphate buffer the higher is the swelling degree of the encapsulated ion exchange resins and the force created by their supplementary swelling will break the more resistants walls. In this way a self-propelled drug release is achieved, until almost all drug was eliberated.

Anti-Bacterial Agents↗

PubMed2006

Modified procedure for improved synthesis of some octameric silsesquioxanes via hydrolytic polycondenzation in the presence of Amberlite ion-exchange resins.

Practical alternative procedures are described for the syntheses of octavinylsilsesquioxane 1, octaphenylsilesquioxane and octabenzylsilsesquioxane. The hydrolytic polycondensation of RSiX3 (R = CH2=CH-, C6H5- or C6H5CH2-; X = Cl, OCH3, or OC2H5) in the presence of solid acid or base Amberlite ion-exchange resin gave improved yields of the corresponding octameric oligosilsesquioxanes. Repetitive usage of the Amberlite resin as the hydrolysis reagent was tested during synthesis of 1. The results indicate that it could be used many times in the same solvent making the procedure a more economically viable technique.

Journal Article↗

PubMed1956