Macroporous Ion Exchange Resin Research Articles

EFFECTIVE DIFFUSION COEFFICIENTS OF COPPER IN MACROPOROUS CHELATING ION EXCHANGE RESIN D751

ABSTRACT Kinetic data on the macroporous chelating ion exchange resin D751 containing iminodiacetic acid as ligand are presented. The experimental systems are R-Na / Cu(N03)2, R2Cu/HNO3and R-(Na+H) / Cu(NO3)2. Sorption and desorption rates of copper were measured in batch experiments by using a three-necked flask as the reaction vessel. The effective diffusion coefficients of copper have been calculated.

Gas Chromatographic Determination of Linamarin in Bean Paste Products and Imported Beans

A gas chromatographic method for linamarin (LI) determination in raw/dried bean pastes was established.The sample was extracted with 80% (v/v) acetonitrile (final concentration) and cleaned up by the use of a macroporous ion-exchange resin column. LI was then converted into the trimethylsilyl derivative, which was determined by using a gas chromatograph with a flame ionization detector.The detection limit by this procedure was LI 0.2μg/g (as hydrogen cyanide) in bean paste. The recovery of LI added at the level of 10 to 100μg/g to a raw/dried sample was more than 91%, and the coefficient of variation was less than 2%.A survey of commercial bean paste by the use of the present method revealed levels of LI (as hydrogen cyanide) of 0.5-2.3μg/g in four of 14 samples.

The effects of the local concentration and distribution of sulfonic acid groups on 1-butene isomerization catalyzed by macroporous ion-exchange resin catalysts

The catalytic activities of sulfonated macroporous poly(styrene-divinylbenzene) beads in 1-butene isomerization were investigated through a model concerning the effects of the distribution and concentration of the sulfonic acid groups. The reaction rate constant increased nonlinearly with the sulfonic acid group concentration and the order of nonlinear power dependence was about 2.4. The values of effectiveness factors of the microparticles in the macroporous resin catalysts with 40 and 50% DVB ranged from 0.1 to 0.3. The diffusivities were 10 −13 and 10 −14cm 2/sec for 40 and 50% DVB, respectively. The result showed that the major reaction arena was the pore space between the microparticles.

Sulfonated latex particle as acid catalysts for the continuous inversion of sucrose

AbstractSulfonated polystyrene latex particles were used as acid catalysts in the continuous inversion of sucrose at 50–70°C. The particles (surface charge 168 μeq/g) were confined in a stirred reactor with a semipermeable membrane; sucrose solution was pumped in, and product solution was pumped out. The catalytic activity of the particles was unchanged after 20 days continuous use. Variation of particle size (0.13 and 0.42 μm) and stirring rate showed that internal and external mass transfer was not a controlling factor. The kinetics were pseudo‐first‐order; the rate constant at 70°C was 2.30/N min as compared with 0.07/N min for macroporous sulfonated ion‐exchange resin; the apparent activation energy was 111 kJ/mol as compared with 121 kJ/mol for the homogeneous acid‐catalyzed reaction. The faster rate was attributed to the very great surface area, high charge density, and lack of internal diffusional resistance of the latex particles. The proposed mechanism comprised adsorption of sucrose on the particle surface, followed by inversion and desorption of product.

Influence of water on the gas-phase decomposition of methyl tert.-Butyl ether catalysed by a macroporous ion-exchange resin

Sulphonic ion-exchange resins are very hygroscopic and readily adsorb water. As a result, the catalytic activity of this type of ion-exchange resin decreases substantially when water contaminates the reaction medium. The influence of water on the gas-phase decomposition of methyl tert.-butyl ether (MTBE) at 50.5°C catalysed by the macroporous ion-exchange resin Amberlyst 15 was studied. The results show that the addition of small amounts of water causes a very strong decrease in decomposition rate of MTBE. A set of Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic models are proposed. The statistical discrimination between them permits the selection of two models whose only difference lies in the adsorption model of MTBE: on two active centres with or without dissociation. The values of the parameters of these models (overall kinetic constant, kK IK M; MTBE adsorption constant, K E; and water adsorption constant, K W) obtained from the fit of data coincide, within the limits of experimental error, with those obtained from the fit of each of the curves r E vs. P E corresponding to different amounts of water in the feed. It is concluded that water reduces the rate of the MTBE decomposition reaction by occupying active centres in a competitive way with the ether. Finally, the values for K W in the literature agree fairly well with those determined in this work.

The concept of variable active centres in acid catalysis: Part I. Alkylation of benzene with olefins catalyzed by ion-exchange resins

The interaction of olefins with sulfonic acid macroporous ion-exchange resins in nonpolar medium has been investigated by measuring the acidity and the catalytic activity of the adsorbed olefin towards benzene. At low olefin concentrations a sharp maximum of reactivity was found, whereas the acidity continuously decreased with increasing olefin concentration. This substrate-inhibition has been described by the model of variable active centres: The homogeneously distributed accessible acid groups form clusters surrounding the adsorbed olefin. Increasing ratios of acid groups per adsorbed olefin operate to enhance the reactivity exponentially. In the case of more polar olefins, the maximum of reactivity is sharper and shifted to lower olefin concentrations.

Chromatographic Behavior of Aromatic Acids on Macroporous Ion-Exchange Resin

Abstract The chromatographic behaviour of aromatic acids on an anion exchange resin was examined in order to develop a high-speed separation procedure of urinary aromatic acids. The ion-exchange resin was a macro porous anion-exchange resin (5μm particle size). The eluent was a mixture of an ammonium acetate buffer, acetonitrile and octylsodium sulfate. The concentration effect of acetonitrile, ammonium acetate buffer, octylsodium sulfate and temperature effect were discussed. The application of the present chromatographic system to urine analysis was also described.

Vapour-phase dehydration of isopropanol on macroporous ion exchange resins

Vapour-phase dehydration of isopropanol on macroporous ion exchange resins

Selective separations by reactive ion exchange: Part 4. Preconcentration of cadmium and zinc by in situ precipitation as hexacyanoferrate(II) salts on gel and macroporous ion-exchange resins

The in situ precipitation of traces of cadmium(II) and zinc(II) ions as hexacyanoferrates from aqueous matrices was studied on conventional polystyrene gel and macroporous cation- and anion-exchange resins. Coprecipitation with each other or with copper(II) ions present in binary cation resins or in solution, and the influence of added nonprecipitating ions of the same charge type such as magnesium(II) were investigated. Microporous (gel) cation exchangers gave reasonable recoveries and macroporous cation exchangers gave very good recoveries; but macroporous anion exchangers performed best, suggesting macroporous hexacyanoferrate(II) resin as an ideal phase for collection/preconcentration of traces of Cu 2+, Cd 2+, Zn 2+, and possibly Co 2+, Ni 2+, and Pb 2+ from waters. As expected, very low yields were obtained with conventional anion exchange resin in the hexacyanoferrate form. Uniform distribution of Cu 2+, Zn 2+, and Cd 2+ over macroporous anion-exchange resin phases were established by means of electron probe scans and taken as evidence for the formation of a uniform, well-developed precipitate layer covering the entire resin particle surface.

A Study on the Condensation of Sorbose with Acetone: Catalysis by Macroporous Ion Exchange Resins

AbstractA study on the condensation of L‐sorbose with acetone to form 2,3‐4,6‐di‐o‐isopropylidene sorbose (diacetone sorbose, DAS) in the presence of various macroporous cationic exchange resins (sulfonic acid type based on styrene and divinyl benzene copolymers) has been carried out. The condensation rates were found to be dependent on the characteristics of the resins such as surface area and percent crosslinking. The formation of DAS was found to increase with increase in temperature and decrease with increase in particle size of the sorbose. On continuous use of the resins in the reaction the catalytic activity is found to decrease.

Features of porous structure of macroporous low-basicity anion-exchange resins based on ethylene diamine

A study was made of the porous structure of AN-221 type macroporous polyfunctional anion-exchange resins and it was found that in contrast with other macroporous ion-exchange resins, for AN-221 anion-exchange resins with a content of divinylbenzene (DVB) of ⩽ 15% wt.% as a result of further crosslinking at the stage amination the specific surface and overall pore volume are greater than for the initial copolymers. With a content of DVB ⩾ 30 wt.% for AN-221, as for other ion-exchange resins, specific surface and overall pore volume are lower than for the initial copolymer. Results are given which are typical of the porous structure of AN-221 industrial anion-exchange resin samples.

Pulsed NMR study of thermal hysteresis in the swollen macroreticular and gel-type resins

Pulsed NMR techniques have been applied to study the freezing of water in the macroporous ion exchange resins of different porosity and the gel-type resin of different crosslinking. The chemical composition of all of the resins studied was the same - namely it was the polystyrenesulphonic acid cross-linked with divinylbenzene.

Rigid Support Materials for the Immobilization of Enzymes

Abstract The purpose of the work presented here was to prepare a support material for enzymes and “affinity ligands” with the following characteristics: low cost, durability, rigidity, and high capacity. Our study encompassed conjugates of porous and nonporous silicas with organic polymers and macroporous ion-exchange resins. Poly-ethyleneimine (PEI), polyacrylic acid (PAA), poly (methyl vinyl ether/maleic anhydride) were attached to porous glass and silica in various combinations. The composite of silica beads with PEI and PAA is a good support for the enzyme trypsin as judged by the activity against N-α-benzoyl-L-arginine ethyl ester. Amberlyst (macroporous, sulfonated polystyrene) was activated by treatment with thionyl chloride; the resulting resin was either used directly or reacted with a diamine. The diamine derivative was used for enzyme coupling or transformed further to the succinyl or p-aminobenzoyl derivative. None of these derivatives were particularly good as supports for the enzyme trypsin....

Esterification of Palmitic Acid with Methanol in the Presence of Macroporous Ion Exchange Resin as Catalyst

The esterification of palmitic acid with methanol was studied in a batch reactor using macro porous ion exchange resin Amberlyst 15 as a catalyst. Methyl palmitate was produced from the reaction between palmitic acid and methanol in the presence of catalyst. The effects of processing parameters, molar ratio of alcohol to acid M, (4-10), catalyst loading (0-10 g cat/liter), water inhibition (0-2 mol/liter), agitator speed (200-800 rpm) and reaction temperature (343-373K) were studied. The experimental kinetic data were correlated using homogenous as well as heterogeneous models (based on single as well as dual site mechanisms). The activation energy of the reaction was 11.552 kJ/mol for forward reaction whilst 5.464 kJ/mol for backward reaction. The experimental data fitted well with the simulated data obtained from the kinetic models. Keywords: Palmitic Acid, Methanol, Esterification, Ion Exchange Resin, Kinetics.

Macroreticular ion-exchange resins: some analytical applications to petroleum products

Extraction and subsequent recovery, in four separate fractions, of naphthenic acids, alkylphenols, pyrrollic compounds and nitrogen bases can be made from petroleum products using macroporous ion-exchange resins. Distinctive features of the technique are the use of dissolved gases in polar solvents as eluants and the application of the carbonate form of anion-exchange resins. The transition metal form of a macroreticular cation exchanger is shown to extract ligands from non-aqueous systems and a specific application to petroleum analysis is given.