Strong Acid Cation Exchange Resin Research Articles

In-situ Investigation of Sucrose Hydrolysis � Successful Link between Design of Experiment, RC1 and ReactIR System

The reaction was catalyzed by strong acidic cation-exchange resin Amberlite IR-120 in H+ form. Four process parameters, including reaction temperature (J), sucrose mass concentration (gS), catalyst mass concentration (gC) and the rotational frequency of the stirrer (fm) at four levels were considered in this study. Relative contributions of the proposed influencing process parameters on hydrolysis time were estimated by analysis of the variance (ANOVA). The results showed that J had a substantial effect on the reaction time (78,3 %), the fm and gC had a smaller ones (7,9 % and 6,4 %, respectively), meanwhile the remain fraction to 100 % represents error (7,4 %). The optimum conditions, where the time required for complete sucrose hydrolysis would be the shortest, are: J= 79 �C, gC = 180 g/L, gS = 50 g/L and fm = 180 min�1. Although the presented results refer strictly to the selected case study and are specific within the observed ranges of selected process parameters, the proposed procedure shows their potential usage in general process design.

Selective Conversion of D-Fructose to 5-Hydroxymethylfurfural by Ion-Exchange Resin in Acetone/Dimethyl sulfoxide Solvent Mixtures

Catalytic dehydration of D-fructose to 5-Hydroxymethylfurfural (5-HMF) in acetone/dimethyl sulfoxide solvent mixtures was studied in the presence of a strong acidic cation-exchange resin catalyst (DOWEX 50WX8−100) by microwave heating. The addition of acetone to the dimethyl sulfoxide (DMSO) solvent promoted the formation of 5-HMF from D-fructose. For a D-fructose conversion of 97.9%, the 5-HMF selectivity was 91.7% for a 20-min reaction time in 70:30 (w/w) acetone/DMSO solvent mixtures. Concentrations as high as 10 wt % D-fructose were studied, for which it was found that 5-HMF yields of 82.1% for a reaction time of 10 min could be obtained. The stability of the ion-exchange resin used as the catalyst was confirmed. Compared to pure DMSO solvent, the combination of low-boiling-point acetone with DMSO used as the reaction medium not only gives highly selective 5-HMF formation, but also improves the separation efficiency and reduces environmental risk.

An empirical kinetic model for calcium removal from calcium impurity-containing saturated boric acid solution by ion exchange technology using Amberlite IR–120 resin

Abstract In this study, the use of Amberlite IR–120, a strong acidic cation exchange resin, was investigated to remove calcium impurity from saturated boric acid solutions. Calcium impurity arised from high calcium content of colemanite ore is a very important problem as it increases impurity on the boric acid crystals. Ion exchange experiments were carried out in batch mode as a function of solution pH, resin-to-solution ratio, temperature, and resin contact time. Optimum operation conditions were determined as pH 1.5, resin-to-solution ratio 6.174 g/250 mL, temperature 303 (K), contact time 20 min and, in those conditions maximum calcium removal was about 99%. Also, data calculated by a mass balance equation were employed with the pseudo-first-order and the pseudo-second-order equations. It was determined that the pseudo-second-order equation was the best fitting kinetic equation with a correlation range of 0.991–1. Furthermore, an empirical kinetic model was developed to predict operational conditions of the batch process in the following form; t / q t = 6.1452 × ( S / L ) 0.8903 × [H + ] −0.00094 × exp(−31.2181/ T ) × [ C 0 ] −0.7319 × t 0.9567 .

Investigation into the presence of Monatin in related plant species

Monatin, comprising the 4 isomers of (indol-3-yl)-2-amino-4-carboxy-4-hydroxypentanoic acid, is a high intensity sweetener isolated from the bark of the roots of Schlerochiton ilicifolius, a spiny-leafed hardwood shrub growing in the rocky hills of the Limpopo Province in South Africa. The original isolation of natural monatin from the plant involved the extensive fractionation of an aqueous extract of the root bark of S. ilicifolius using AG50WX8 strong acid cation exchange resin followed by successive gel filtration procedures using Biogel P2 and Sephadex G10 [1]. Recent work conducted by the CSIR analyzed aqueous extract of minimally processed plant material. Using an an HPLC-mass spectrometry method with Marfey's Reagent as a chiral derivitizing agent, both the (2S,4S) and (2R,4R) monatin enantiomers were found to be present in the root and root bark of plant samples collected from several locations. These data confirmed the natural occurrence of the 2R,4R isomer in S ilicifolius, in addition to the 2S,4S configuration that was reported in the original work. The latter determination was based on comparison of the specific optical rotation of the purified monatin with those of related 4-hydroxy-4-methylglutamic acids.

Uptake of Iodine and Bromine by Ion-Exchange Resins in Aqueous Solution

The uptakes of molecular iodine and bromine by both strong acid cation (Dowex 50W-X4 and X8) and strong base anion (Dowex 1-X4 and X8) exchange resins have been studied in aqueous solutions at 25 degrees C. An empirical formula for the amount of solute taken up by the resin in mmol per gram of dry resin, Q, as a function of the solute concentration in M (mol dm(-3)), C, was derived. Direct proportional relationships between Q and C have been found, except for the bromine-anion exchanger system. In contrast to the cation-exchange resin, the anion exchanger exhibits extremely high affinity for I(2) and Br(2).

Liquid-phase esterification of acetic acid with isobutanol catalyzed by ion-exchange resins

Esterification of carboxylic acids with alcohols represents well-known liquid-phase reactions of considerable industrial interest due to the importance of organic ester products. These ester products include environmentally friendly solvents, flavors, pharmaceuticals, plasticizers, and cosmetics. In this study, the esterification kinetics of acetic acid with isobutanol in 1,4-dioxan as a solvent without adding a catalyst and catalyzed by ion-exchange resins are carried out using a batch reactor. The effect of catalyst type, stirrer speed, the effects of reaction temperature and catalyst loading on the initial reaction rate, the effect of speed of agitation and the conversion of acetic acid versus time were investigated. The kinetics of heterogeneous catalyzed esterification of acetic acid with isobutanol was correlated by a kinetic model based on pseudo-homogeneous catalysis. The strong acidic cation exchange resins were used as solid catalysts, Dowex 50 Wx2, Amberlite IR-120, respectively. As a result, it was found that the weight-based activity of the heterogeneous catalysts increases in the following order: Dowex 50 Wx2 > Amberlite IR-120 and these catalysts were effectively for the synthesis of isobutyl acetate under these experimental conditions.

Coupling on-line preconcentration by ion-exchange with microwave plasma torch-atomic emission spectrometry for the determination of cobalt and nickel

In the present work, a simple and sensitive preconcentration-microwave plasma torch-atomic emission spectrometric procedure was carried out for the determination of cobalt and nickel. The method was based upon a flow-injection system with on-line preconcentration of the metal ions on a minicolumn of a strong acid cation-exchange resin. The operation parameters including sample acidity, flow rate, loading time, and eluent concentration, flow rate were studied and optimized. Under the optimal experimental conditions the enrichment factors were calculated as 13.58 and 17.65 for cobalt and nickel, respectively. The relative standard deviations, 3.73% for cobalt and 4.23% for nickel ( n = 7), and a sample throughput of 40 h − 1 were obtained. Furthermore, the limits of detection were shown to be 1.28 and 1.80 μg·L − 1 for cobalt and nickel, respectively. The method was applied to the determination of cobalt and nickel in tea samples and the accuracy was assessed through recovery experiments.

Uptake of Benzene and Alkylbenzenes by Cation- and Anion-Exchange Resins from Aqueous Solutions

Uptakes of benzene and 12 alkylbenzenes (from toluene to n-pentylbenzene including xylene and trimethylbenzene isomers) by both strong acid cation (Dowex 50W-X4 and X8) and strong base anion (Dowex 1-X4 and X8) exchange resins have been studied in aqueous solutions at 25 degrees C; their distribution constants (K) have been determined. The relationship between the octanol-water partition coefficient (K(ow)) and the resin affinity for solutes has been analyzed. The K values of benzene and alkylbenzenes were larger than the K values of aliphatic hydrocarbons expected from the K(ow) values. While the K value was increased with the alkyl chain length, no further increase in the K value was observed for n-butylbenzene and n-pentylbenzene.

Influence of shaped and modified Hβ zeolite on etherification of FCC light gasoline

Oxygenated compounds such as ethers produced by the reaction of methanol and tert-olefins have good potential for use as performance and environmental enhancing additives for transportation fuels. Catalytic etherification of tert-olefins with methanol has been carried out over a series of solid-acid catalysts such as Hβ (Si/Al = 25), HM OR(Si/Al = 50), HZSM-5 (Si/Al = 50) and strong acidic cation exchange resin D005 using a flow fix-bed reactor. Hβ zeolite shows higher conversion and catalytic stability than other catalysts for the production of tert-amyl methyl ether (TAME). In the shaping process, the catalytic activity of extruding zeolite Hβ before impregnating two oxides on it is higher than the reverse order. The best extruding condition is that pore-enlarging agent is PEG-4000 (10%), the dosage of binder (α-AlOOH) is 20% and the dosage of peptizer (HNO 3) is 10%. The regeneration of Hβ zeolite is much better than other catalysts. At the optimal reaction condition 70 °C, 1 h −1, 0.8 MPa and a 1.05:1 molar ratio of methanol to tert-olefins, the highest conversion of tert-olefins could reach 62.93%, the yield of TAME is high too and the technology can be applied to commercial industry well.

Ferrous–Ferric Ion exchange dosemeter

In this work a three-dimensional ferrous-ferric ion exchange dosemeter is proposed and the dose response measured. The dosemeter consists of strong acid cation exchange resin beads in the H form in water. Amberlyst 15 Wet beads with a harmonic mean diameter of 0.600-0.850 mm were prepared by soaking them in an aqueous solution of ferrous ammonium sulphate to exchange ferrous ions for H(+) ions. The beads were rinsed with distilled water and packed in glass vials. Sets of samples with ferrous ion concentrations of 0.5 and 1.0 mM were dosed with 6 MV X rays from a Varian 2100C linac. The spin-lattice relaxation time constants (T1) for the samples were measured using an Apollo spectrometer (Tecmag, Houston, TX) interfaced to a 1.5 T magnet (Magnex, Abingdon, UK). Each sample had two T1 values; a long T1 at 1200 ms that did not significantly change with dose and a short T1 that ranged from 56 ms at 0 Gy to 36 ms at 100 Gy. The R1 vs. dose responses were linear with slopes of 0.066 and 0.079 s(-1) Gy(-1).

Uptake of Cycloalkanes and Bicyclic Aromatic Compounds by Ion-Exchange Resins from Aqueous Solutions

The uptakes of cycloalkanes (C5 - C8) and bicyclic aromatic compounds (naphthalene, biphenyl, and azulene) by both strong acid cation (Dowex 50W-X4 and X8) and strong base anion (Dowex 1-X4 and X8) exchange resins have been studied in aqueous solutions at 25 degrees C; their distribution constants (K) have been determined. The relationship between the octanol-water partition coefficient and the resin affinity for solutes has been analyzed. The K values of three aromatic compounds were found to be much higher than expected from the octanol-water partition coefficients. This is probably due to the pi interaction of aromatic rings with the resin matrix. Microscopic observations revealed that azulene molecules are uniformly distributed inside a resin particle.

SU-FF-T-236: Dose Response of Ion Exchange Resin Beads

Purpose: To investigate the x-ray dose versus 1H NMR spin lattice relaxation (T1) response of ion exchange resin beads, with and without ferrous ions. Method and Materials: Strong acid cation exchange resin beads (Rohm and Haas, Amberlyst 15 Wet) were rinsed in distilled water and packed in plastic vials. Similar beads were treated to produce a 1 mM ferrous ion concentration inside the beads, then rinsed with distilled water, and finally packed in plastic vials. Sample vials were placed in a water phantom and exposed to 6 MV x-rays from 0 to 100 Gy. The T1 for each sample was measured in a 1.5 Tesla MRI unit. Beads from two manufacturing lots, Lot 1 and 2, were tested. Density of the bead samples was 1.10 g/cm3. Results: Vials with beads containing ferrous ions exhibited a linear dose versus R1 (i.e., 1/T1) response with slopes of 0.102 and 0.093 sec −1 Gy−1 for respectively Lot 1 and Lot 2 beads. Vials of Lot 1 beads containing no ferrous ions exhibited a linear dose versus R1 response with a slope of 0.083 sec−1 Gy−1. Vials of Lot 2 beads containing no ferrous ions showed an exponential increase in R1 of 2.4 sec−1 from 0 to 50 Gy with minimal increase in R1 from 50 to 100 Gy. Conclusion: For both bead lots, the beads containing ferrous ions exhibited similar linear dose versus R1 responses. Beads containing no ferrous ions exhibited significant, but different dose versus R1 responses. When the ferrous ions are present in the beads, a ferrous oxidation reaction appears to dominate the dose response. The results support the concept of using strong acid cation exchange resin beads containing ferrous ions to create a three dimensional dosimeter which can be evaluated using MRI.

Destruction of Cyanide in Water Using N-Chlorinated Secondary Sulfonamide-Substituted Macroporous Poly(styrene-co-divinylbenzene)

Cyanide ion in water is converted to cyanate ion by use of macroporous poly(styrene-co-divinylbenzene) bearing regenerable N-chlorinated N-alkylsulfonamide functional groups. Cyanide is converted first to cyanogen chloride that is then rapidly hydrolyzed to cyanate ion, which is stable at high pH. Cyanate ion can be further oxidized by active chlorine supplied by the resin to nitrogen and carbonates under weakly basic conditions or more rapidly hydrolyzed to ammonium ion and carbon dioxide by passage through a bed of a strong acid cation-exchange resin in the H+ form without use of additional active chlorine. Much of the active chlorine that escapes the reactor can be recaptured by unchlorinated polymer for subsequent use.

A new cation-exchange method for accurate field speciation of hexavalent chromium

A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 μg l −1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg l −1 and Fe(III) concentrations up to 10 mg l −1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

Uptake of alkanes and alcohols by ion-exchange resins in aqueous solution.

Uptake of alkane (C5-C9) and alcohol (C4-C7) solutes by both strong acid cation exchange resins and strong base anion exchange resins in aqueous medium has been studied. The amount of solute taken up by resins is directly proportional to the solute concentration equilibrium with resins. Hydrophobic interaction between the solute and the resin matrix appears to play an important role in the uptake phenomenon.

The effect of corrosion particles present in water solutions on the behavior of strong acid cation-exchange resins during the process of cobalt removal

The effect of the presence of corrosion particles on the behavior of different structure types of cation-exchange resins during the adsorption process of 60Co from water solutions was studied. Comparative valuation of sorption behavior and capacity of polyreticular and monoreticular structure type cation-exchangers was carried out. It was found that the ion-exchange filtration efficieny depends upon the presence of corrosion particles on the surface of ion-exchange beads and in their pore structure. The cation-exchange process of 60Co is affected differently by different structure type ion-exchange resins. The fouling phenomenon caused by iron-corrosion particles during the water clean-up process at a RWCU system in BWR and by CVSE demineralizers in PWR dose not affect negative phenomenon for ion-exchange behavior of ion-exchange resins to remove polyvalent ions from the water. The polyreticular cation exchanger Amberlite 200C can better remove 60Co cations from water solutions than the monoreticular (gel type) cation-exchanger Amberlite IR 120. Evidently this is due to the true porous macroreticular structure of the cation-exchange beads. In parallel with the ion-exchange processes, the sorption process of the corrosion products situated on the larger surface area of the true physical pore structure of Amberlite 200C also plays an important role. The information obtained will be very useful to the technological service of nuclear power stations.

MEASURING SURFACE CHEMICAL PROPERTIES OF SOIL USING FLOW CALORIMETRY 1

Flow calorimetry, which is ideally suited for measuring reactions occurring at the liquid/solid interface, has been used to study the surface chemistry of many types of solids, but little use of it has been made in the study of surface reactions of soils. The purpose of this study was to demonstrate the application of flow calorimetry to the study of two fundamental soil chemical processes, namely cation exchange and phosphate sorption. Surface horizon samples of a Typic Acrorthox and a Typic Tropohumult from Puerto Rico, a strong acid cation exchange resin (Dowex 50W-8), and an amorphous Al(OH)3 were used. Heats for K/Ca exchange on the Dowex resin and the Oxisol, and K/Na exchange on the Ultisol, were consistent with literature values that were obtained using conventional batch calorimetry or derived from the temperature dependence of the exchange constant. Although peak areas associated with a given pair of exchange reactions were equal, peak shapes were generally not equivalent, indicating differences in the rate at which the two reactions occurred. For example, Ca displacing exchangeable K occurred more rapidly than the reverse reaction on the Dowex resin. The reaction of phosphate with the Ultisol and amorphous Al(OH)3 was exothermic. Exposure of the soil to several cycles of phosphate was sufficient to saturate the sorption sites, as evidenced by the loss of a detectable heat signal. However, phosphate reactive sites were regenerated by flushing the column with a salt solution at pH 10. Precipitation of Al-phosphate was shown to be endothermic, confirming that precipitation was not the primary mechanism for phosphate sorption in this study. The results of this study show that flow calorimetry can provide valuable information about surface chemical reactions in soils that cannot be obtained readily by other methods.

Reaction kinetics studies on catalytic dehydration of 1,4-butanediol using cation exchange resin

In the present work, we report kinetics of dehydration of 1,4-butanediol to tetrahydrofuran (THF) using a strong acid cation exchange resin as catalyst. Effects of various parameters such as temperature, catalyst concentration, substrate concentration, initial water concentration, speed of agitation and also effect of solvent have been investigated in detail. The initial rate varies linearly with reaction temperature. Also, we observed a strong dependence of rate on catalyst loading; this also followed a linear relationship. The rate data showed exponential dependence on initial substrate concentration. Water was found to inhibit the reaction due to the strong adsorption of water on active acid sites of resin. A mechanism has been proposed to explain the reaction behaviour. Contributions of film diffusion and intraparticle diffusion were found to be negligible in the range of parameters studied in this work. Reactor performance under integral conditions was predicted successfully using the proposed rate model.

Parametric studies on the performance of cation exchange for the ammonium removal

Ion exchange performance to remove ammonium in drinking water was studied experimentally in batch and continuous operation systems under the various conditions. Data were collected using commercially available strongacid cationexchange resins of Na+ and H+ types. The performance was evaluated using equilibrium concentrations for the batch system or the effluent concentration histories for the continuous column system as a function of time or the solution volume passed through the experimental column until resins were exhausted. With high temperature or low initial feed concentration, ammonium removal characteristics of the batch system increase. At the solution concentrations of 0.5, 1.0, and 2.0 mg/L of NH4+-N and the temperatures of 15, 25, and 35 ‡C, the selectivity coefficients of resin were determined between 1.38 and 1.43 for Na+ type resin, and 3.22 and 3.47 for H+ type resin. The selectivity coefficient was correlated as a function of temperature using Kraus-Raridon equation. The breakthrough curves obtained from the continuous column operation give some results; i) with small column diameter or large column height, ii) with low initial feed concentration, iii) with low volumetric flow rate, or iv) with high solution temperature, the ammonium removal for the typical macroporous type resin increase. The results of this study could be scaled up and used as a design tool for the waterpurification systems of the drinking water treatment processes.

Automatic semi-microcolumn liquid chromatographic determination of catecholamines in rat plasma utilizing peroxyoxalate chemiluminescence reaction.

A fully automated and highly sensitive method with a semi-microcolumn liquid chromatography system for the determination of rat plasma catecholamines (CAs) was developed. Automated on-line extraction of CAs in diluted plasma using a precolumn packed with strong acidic cation exchange resin was coupled with separation of CAs on a semi-microcolumn (250 x 1.5 mm id). fluorogenic derivatization with ethylenediamine and finally postcolumn peroxyoxalate chemiluminescence detection utilizing bis[2-(3,6,9-trioxadecanyloxycarbonyl)-4-nitrophenyl]oxalate (TDPO) and hydrogen peroxide. The detection limits were 0.91, 0.36 and 1.1 fmol for norepinephrine (noradrenaline), epinephrine (adrenaline) and dopamine, respectively, at a signal-to-noise ratio of 3. A good linearity of the calibration curve for each CA was observed in the range of 5.0 to 500 fmol for each CA using N-methyldopamine (N-MeDA) as an internal standard. The RSD for the proposed method (n = 5) were 3.7-9.5% for the intra-day assay and 6.6-10.0% for the inter-day assay. The volume of rat plasma required for the determination of CAs was 10 microliters.