PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ION EXCHANGE RESINS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed2001

Resin selection and single-step production and recovery of lactic acid from pretreated wood.

Four ion-exchange resins (Amberlite IRA 900, IRA 400, IRA 96, and IRA 67) were employed for lactic acid recovery from simultaneous saccharification and fermentation (SSF) media. The best resins (Amberlite IRA 900 and IRA 400) were assayed for capacity, regenerant consumption, percentage of lactic acid recovery, and product concentration. Almost quantitative lactic acid recoveries at constant capacities were achieved in four sequential loading/regeneration cycles. A strong-base resin (Amberlite IRA 400) was selected for intermittent lactic acid separation in a typical SSF process, in which pretreated wood was saccharified by cellulases in the presence of Lactobacillus delbrueckii. The dynamics of lactic acid generation and lactic acid recovery were established.

Biotechnology↗
PubMed1991

Throughfall below grassland canopies: a comparison of conventional and ion exchange methods.

Sampling of canopy fluxes (throughfall and stemflow) below low structured vegetation with a small-scale, intricate canopy architecture is difficult, and representative sampling with most methods is questionable. In the present study, two sampling methods for canopy fluxes below grassland vegetation are compared. Method I sampled canopy fluxes of moisture inefficiently, because stemflow volumes were not quantitatively included. Canopy fluxes of ions calculated with method I necessitated assumptions on equal concentrations in actually sampled throughfall and non-sampled stemflow. Method II sampled canopy fluxes of ions quantitatively, because the total volume of throughfall and stemflow percolated through a mixed bed of ion exchange resins below the canopy. Ion-specific differences between the two methods were observed. For ions with foliar leaching, such as K+ and Ca2+, higher canopy fluxes were recorded with method II than with method I. In contrast, for ions with foliar uptake, such as NH4+ and NO3-, canopy fluxes were found to be less with method II than with method I. Canopy fluxes of inorganic nitrogen below Mesobrometum grassland were 2.35 and 1.52 kmol(c) ha(-1) year(-1) for methods I and II, respectively, and 2.85 and 7.90 kmol(c) ha(-1) year(-1) for K+. It is argued that these differences result from under-estimated (foliar leaching) or over-estimated (foliar uptake) concentrations in stemflow by the first method. Canopy fluxes for SO4(2-) were not statistically different, indicating that canopy exchange of SOx was quantitatively unimportant, and that both methods estimated atmospheric input equally well.

Journal Article↗
PubMed2004

Ion exchange extraction of heavy metals from wastewater sludges.

Heavy metals are common contaminants of some industrial wastewater. They find their way to municipal wastewaters due to industrial discharges into the sewerage system or through household chemicals. The most common heavy metals found in wastewaters are lead, copper, nickel, cadmium, zinc, mercury, arsenic, and chromium. Such metals are toxic and pose serious threats to the environment and public health. In recent years, the ion exchange process has been increasingly used for the removal of heavy metals or the recovery of precious metals. It is a versatile separation process with the potential for broad applications in the water and wastewater treatment field. This article summarizes the results obtained from a laboratory study on the removal of heavy metals from municipal wastewater sludges obtained from Ardhiya plant in Kuwait. Data on heavy metal content of the wastewater and sludge samples collected from the plant are presented. The results obtained from laboratory experiments using a commercially available ion exchange resin to remove heavy metals from sludge were discussed. A technique was developed to solubilize such heavy metals from the sludge for subsequent treatment by the ion exchange process. The results showed high efficiency of extraction, almost 99.9%, of heavy metals in the concentration range bound in wastewater effluents and sludges. Selective removal of heavy metals from a contaminated wastewater/sludge combines the benefits of being economically prudent and providing the possibility of reuse/recycle of the treated wastewater effluents and sludges.

Industrial Waste↗
PubMed2000

Ion chromatographic determination of inositol in infant formulae and clinical products for enteral feeding.

An ion chromatographic method is described for the determination of inositol in infant formula and products for enteral feeding. A two-step procedure for hydrolysis and extraction of total inositol has been developed, involving alkaline hydrolysis with 3 M potassium hydroxide and enzymatic dephosphorylation. Substances having a long chromatographic retention time were removed with an ion-exchange resin. Inositol was separated on a high-resolution ion-exchange column and detected by pulsed amperometric detection. Phytic acid interferes only slightly in the analysis. This method can be used for determination of total inositol in infant formulae, and enteral feeding products. The analytical method gave an average recovery of 94% from infant formula samples spiked with inositol and a recovery of 86+/-3% from products spiked with lecithin.

Chromatography, Ion Exchange↗
PubMed2001

Towards functional group-specific detection in high-performance liquid chromatography using mid-infrared quantum cascade lasers.

A distributed feedback quantum cascade laser was applied for the first time as a powerful light source for mid-infrared (MIR) detection in liquid chromatography. Fructose and glucose in red wine were separated with an isocratic HPLC system, which was connected to a custom-made flow cell. This flow cell was constructed of two diamond windows with adjustable spacing and two hollow wave-guides for guiding the incoming and outgoing light. The HPLC column based on an ion-exchange resin with calcium(II) counter ion was run at 80 degrees C with 0.04% formic acid as the mobile phase. Under these conditions the carbohydrates could not be completely separated from the organic acids also present in wine. However, the emission of the laser at 1067 cm(-1) matches the absorption maximum of fructose and glucose, whereas the organic acids do not absorb appreciably at this wavenumber. Thus group-specific detection could be achieved. Additionally, the optical path length could be increased from 25 to 125 microm, which is very promising in gaining enhanced sensitivity compared to Fourier transform IR detection.

Calibration↗
PubMed2000

Controlled-release liquid suspensions based on ion-exchange particles entrapped within acrylic microcapsules.

Eudragit RS/RL polymers were used to prepare microcapsules containing terbutaline-loaded ion-exchange resins, with the final aim of formulating this anti-asthmatic drug in a controlled-release liquid form. Oil-in-oil (o/o) and oil-in-water (o/w) solvent evaporation procedures were conveniently modified in order to encapsulate the resin cores. The microcapsules were then suspended in a hydroxypropylmethylcellulose solution of adequate viscosity and palatability, and stored at 20 degrees C and ambient humidity conditions for a 6-month period. Stability studies of the dispersed microparticles were performed in order to evaluate the changes occurred in the diffusion of the drug to the suspending medium and in the dissolution behaviour during storage. The morphological alterations of the stored microcapsules were followed throughout the duration of the study by scanning electron microscopy. The polymer coatings of microcapsules prepared by the o/o method broke up on the first day of storage, while those made by the aqueous procedure remained intact during all the storage period. This agreed with the modification observed in the controlled-release profiles of terbutaline in the case of microcapsules prepared by the o/o method, which completely changed after the first week of storage. On the contrary, the microcapsules prepared by the aqueous method showed identical controlled-release profiles for all the stability study. The different behaviour of both types of microcapsules was attributed to the swelling suffered by the resin particles in contact with the aqueous suspending medium, which was higher in the microcapsules prepared by the o/o technique. In fact, in the anhydrous procedure, the microencapsulation was carried out on the shrunken resin particles, whereas in the o/w method, the presence of water during the microencapsulation process allowed the coating of the swollen particles, thus avoiding the further problem of rupture of the polymer coating.

Acrylic Resins↗
PubMed1982

Removal of total organic carbon from marine mammal pool water by polymeric resins.

Chlorinated organic compounds comprise a portion of the total organic carbon (TOC) of marine mammal pool water. The long-term effects of these substances on the health of captive marine mammals are unknown, but good husbandry practices should include maintaining TOC at low concentrations. Two polymeric resins (trade names XAD-2 and XAD-4) were tested for their capacity to adsorb TOC from the water of a saline, closed-system marine mammal pool. At a concentration of 588 mg of XAD-2/L, TOC was reduced by approximately 9% after 96 hours; 630 mg of XAD-4/L reduced TOC concentrations by approximately after 77 hours. Equilibrium was not approached in any of the experiments. The 2 materials tested are ineffective in this particular application, but ion exchange resins may perform better.

Adsorption↗
PubMed1989

[Polymeric sorbents for hemoperfusion].

Applications of various sorbents and ion-exchange resins to hemoperfusion are reviewed. With respect to the type of processes accompanying removal of toxines from blood, the fillings of hemoperfusion columns are classified into the group of: sorbents, iono-sorbents and ion-exchangers, immunoadsorbents. Possibilities of improving hemocompatibility of polymeric materials used in hemoperfusion columns by a sorptive or covalent covering their surfaces with natural materials-heparin and/or albumin are discussed.

Biocompatible Materials↗
PubMed1986

Isolation and partial characterization of a high molecular weight Cd/Zn-binding protein from the kidney of the scallop Placopecten magellanicus: preliminary studies.

Exposure of the scallop Placopecten magellanicus to 20 ppb Cd2+ in seawater for 7 weeks results in a 7-fold increase in the kidney cytosol content of Cd and 5-fold increase in Zn. Sephadex G-75 column chromatography of the kidney cytosol showed that most of the Cd and Zn were bound to a protein complex with an estimated molecular mass of 45,000 daltons. Further purification of this complex by DEAE A-25 column chromatography disclosed the presence of five peaks with varying degrees of affinity for the ion-exchange resin. One of these peaks (III) was successfully rechromatographed by ion-exchange chromatography and further purified by HPLC using a gel-permeation column. The resultant protein peak which was resistant to disaggregation by 20 mM dithiothreitol gave a preliminary amino acid composition with cysteine, glycine, alanine, and lysine as the major amino acids. The aromatic amino acid phenylalanine was also present. The ultraviolet absorption spectrum gave a 250/280 nm ratio of 2.5:1. Metal analysis of the purified protein showed that it contained Cd, Zn, and Cu in ratios of 1:1:1. Results of these studies indicate that scallop kidney produces a protein complex which appears to share both similarities with mammalian metallothionein with respect to the presence of both Cd and Zn but different with respect to apparent size, amino acid composition, and ultraviolet absorption spectrum.

Amino Acids↗
PubMed1986

Redox modification of sodium-calcium exchange activity in cardiac sarcolemmal vesicles.

Na-Ca exchange activity in bovine cardiac sarcolemmal vesicles was stimulated up to 10-fold by preincubating the vesicles with 1 microM FeSO4 plus 1 mM dithiothreitol (DTT) in a NaCl medium. The increase in activity was not reversed upon removing the Fe and DTT. Stimulation of exchange activity under these conditions was completely blocked by 0.1 mM EDTA or o-phenanthroline; this suggests that the production of reduced oxygen species (H2O2, O2-.,.OH) during Fecatalyzed DTT oxidation might be involved in stimulating exchange activity. In agreement with this hypothesis, the increase in exchange activity in the presence of Fe-DTT was inhibited 80% by anaerobiosis and 60% by catalase. H2O2 (0.1 mM) potentiated the stimulation of Na-Ca exchange by Fe-DTT under both aerobic and anaerobic conditions; H2O2 also produced an increase in activity in the presence of either FeSO4 (1 microM) or DTT (1 mM), but it had no effect on activity by itself. Superoxide dismutase did not block the effects of Fe-DTT on exchange activity; however, the generation of O2-. by xanthine oxidase in the presence of an oxidizable substrate stimulated activity more than 2-fold. Hydroxyl radical scavenging agents (mannitol, sodium formate, sodium benzoate) did not attenuate the stimulation of activity observed with Fe-H2O2. Exchange activity was also stimulated by the simultaneous presence of glutathione (GSH; 1-2 mM) and glutathione disulfide (GSSG; 1-2 mM). Neither GSH nor GSSG was effective by itself and either 0.1 mM EDTA or o-phenanthroline blocked the effects on transport activity of the combination of GSH + GSSG. Treatment of the GSH and GSSG solutions with Chelex ion-exchange resin to remove contaminating transition metal ions reduced (by 40%) the degree of stimulation observed with GSH + GSSG. Full stimulating activity was restored to the Chelex-treated GSH and GSSG solutions by the addition of 1 microM Fe2+; Cu2+ was less effective than Fe2+ whereas Co2+ and Mn2+ were without effect. In the presence of 1 microM Fe2+, GSH alone produced a slight increase in transport activity, but this was markedly enhanced by the addition of Chelex-treated GSSG. The results indicate that stimulation of exchange activity requires the presence of both a reducing agent (DTT, GSH, O-.2, or Fe2+) and an oxidizing agent (H2O2, GSSG, and perhaps O2) and that the effects of these agents are mediated by metal ions (e.g. Fe2+).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1976

Reconcentration of poliovirus from sewage.

Virus can be adsorbed from effluents of sewage treatment plants on large-surface membranes. Subsequent elution of virus requires large volumes, which in turn requires reconcentration of virus for assay. However, reconcentration of such viral eluates on small adsorbent surfaces is difficult because certain soluble sewage components are adsorbed along with the virus on the initial virus adsorbent and are removed along with the virus by the eluent. Upon acidification of the initial eluate to reconcentrate the virus on smaller membrane surfaces, flocs are formed that interfere with the reconcentration process. To circumvent this problem, the interfering sewage components can be removed by activated carbon and ion-exchange resins. The virus is then readily reconcentrated on small membranes.

Adsorption↗
PubMed1969

The effects of calcium and magnesium ions on the adenosine triphosphatase and inosine triphosphatase activities of myosin A.

1. The effects of Ca(2+) and Mg(2+) on the enzymic activity of myosin were studied with myosin preparations treated by the ion-exchange resin Chelex-100. A reaction mixture containing 0.05m-potassium chloride was chosen in which the effects of univalent ions such as K(+), Na(+) and Cl(-) do not change significantly with small variations in their concentrations. 2. The relationship between the rate of hydrolysis of ATP or ITP and the concentration of Ca(2+) suggests that a relatively weak binding of Ca(2+) either to myosin or to the substrate nucleotide is responsible for the activation of the enzymic activity. According to the experiments with an ultrafiltration technique, the binding of Ca(2+) to myosin proceeds in at least two steps, the first occurring at one site on every 500000 atomic mass units of myosin with an apparent association constant, K(app.), 1.3x10(6)m(-1), and the second seeming to be so weak that its binding parameters cannot be determined by the method used. The first type of Ca(2+) binding is not observable with N-ethylmaleimide-modified myosin, yet this modified myosin shows activation by Ca(2+) of its adenosine triphosphatase and inosine triphosphatase. 3. The inhibition by Mg(2+) can be related to a binding reaction of Mg(2+) with myosin having K(app.) approximately 10(6)m(-1). Mg(2+) replaces the Ca(2+) bound tightly to myosin. The K(app.) for Mg(2+)-myosin binding calculated by assuming a competition between Ca(2+) and Mg(2+) for the same site is 2.1x10(5)-3.0x10(5)m(-1). When myosin is modified with a thiol reagent (p-mercuribenzoate) at a certain ratio to myosin, the inhibition by Mg(2+) becomes unobservable. 4. The behaviour of the hydrolytic activity of myosin on ATP or ITP in the presence of both Ca(2+) and Mg(2+) is consistent with the explanation that the inhibition by Mg(2+) is due to the tight binding of Mg(2+) to myosin, whereas the activation by Ca(2+) is caused either by a weak binding of Ca(2+) to myosin or by CaATP(2-) or by both.

Adenosine Triphosphatases↗
PubMed1985

Separation of cephaloridine from the rat urine contaminated by feces and diet pellets in high-performance liquid chromatography. Pretreatment with strongly basic anion exchange resin following deproteinization.

In this study, a high-performance liquid chromatographic method including a treatment with ion exchange resin following a deproteinization treatment, was studied for determination of cephaloridine in the rat urine which was contaminated by pieces of feces and diet pellets. The solvent system used was 10% acetonitrile (v/v) in 0.1 M K2 HPO4-H3 PO4 buffer, pH 7.5, and this was isocratically eluted on a reversed-phase column of NOVA-PAK C18. The urine sample containing cephaloridine was deproteinized, treated with a strongly basic anion exchange resin of Dowex-1-Chloride, and then chromatographed. In comparison to the sample treated by the simple deproteinization, the residual substances after the deproteinization, which interfered the cephaloridine peak, were removed by the following treatment with Dowex-1-Chloride, as was confirmed using a three-dimensional computing spectrophotometric monitor. Thus, the present method is considered to be useful in determination of cephaloridine in such body fluids as urine in which many interfering substances are contained.

Animal Feed↗
PubMed2003

Mycorrhizal colonization mediated by species interactions in arctic tundra.

The Alaskan tussock tundra is a strongly nutrient-limited ecosystem, where almost all vascular plant species are mycorrhizal. We established a long-term removal experiment to document effects of arctic plant species on ecto- and ericoid mycorrhizal fungi and to investigate whether species interactions and/or nutrient availability affect mycorrhizal colonization. The treatments applied were removal of Betula nana ( Betulaceae, dominant deciduous shrub species), removal of Ledum palustre ( Ericaceae, dominant evergreen shrub species), control (no removal), and each of these three treatments with the addition of fertilizer. After 3 years of Ledum removal and fertilization, we found that overall ectomycorrhizal colonization in Betula was significantly reduced. Changes in ectomycorrhizal morphotype composition in removal and fertilized treatments were also observed. These results suggest that the effect of Ledum on Betula's mycorrhizal roots is due to sequestration of nutrients by Ledum, leading to reduced nutrient availability in the soil. In contrast, ericoid mycorrhizal colonization was not affected by fertilization, but the removal of Betula and to a lower degree of Ledum resulted in a reduction of ericoid mycorrhizal colonization suggesting a direct effect of these species on ericoid mycorrhizal colonization. Nutrient availability was only higher in fertilized treatments, but caution should be taken with the interpretation of these data as soil microbes may effectively compete with the ion exchange resins for the nutrients released by plant removal in these nutrient-limited soils.

Arctic Regions↗