Cation-exchange Resin Beads Research Articles

Numerical analysis of the porous structure of spherical activated carbons obtained from ion-exchange resins

This paper presents the results of an analysis of the porous structure of spherical activated carbons obtained from cation-exchange resin beads subjected to ion exchange prior to activation. The study investigated the effects of the type of cation exchange resin, the concentration of potassium cations in the resin beads and the temperature of the activation process on the adsorption properties of the resulting spherical activated carbons. The numerical clustering-based adsorption analysis method and the quenched solid density functional theory were used to analyse the porous structure of spherical activated carbons. Based on original calculations and unique analyses, complex relationships between preparation conditions and the porous structure properties of the obtained spherical activated carbons were demonstrated. The results of the study indicated the need for simultaneous analyses using advanced methods for the analysis of porous structures, i.e., the numerical clustering-based adsorption analysis method and the quenched solid density functional theory. This approach allows a reliable and precise determination of the adsorption properties of the materials analysed, including, among other things, surface heterogeneities, and thus an appropriate selection of production conditions to obtain materials with the expected adsorption properties required for a given industrial process.

Switching between Two Oscillatory States Depending on the Electrical Potential

Various spatiotemporal patterns were created on the surface or in the body of cation-exchange resin beads which were loaded with the catalyst of the Belousov-Zhabotinsky (BZ) reaction. Either global oscillations (GO) or traveling waves (TW) and the switching between them were observed in the previous papers, but it was not clear how chemicals contribute to the reaction inside/around the BZ bead. In this paper, we scanned the electrical potential, E, from +1 to -1 V (negative scan) and then turned from -1 to +1 V (positive scan) to control the switching between GO and TW. We found that the electrical switching potential from TW to GO, ETG, and from GO to TW, EGT, depended on the scanning direction of E and the diameter of the bead, d. The present study suggests that the electrode-induced increase of the inhibitor, Br-, and the activator, HBrO2, around the BZ bead plays an important role in determining ETG and EGT.

Oxidative dissolution of cation ion exchange resin by the Fenton process using a fluidized bed reactor

Wet oxidation processes such as Fenton and Fenton-like have been considered to treat radioactive ion exchange resins. This investigation demonstrates the oxidative dissolution of cation exchange resin beads by using a fluidized bed Fenton process. The cation exchange resin beads were firstly saturated with catalyst (Fe(II)) in the tubular reactor with a temperature control jacket, and then initiated the oxidation with injecting the H2O2 into the fluidized bed reactor. By means of adjusting a suitable amount of ferrous ions saturated on the cation IER, the reaction can be aimed on the IER destruction rather than homogeneous oxidation. The conversion of resins to gas and soluble fragments reached 91.6% under conditions of solid loading = 117.6 g/L, 25 mL H2O2 dosage (50 wt%), FeSO4 = 10 mM at 75 °C. The fluidized bed Fenton process is efficient and ready to control for the oxidation of cation exchange resin beads in heterogeneous catalysis.

Coupling of Two Microbeads Exhibiting Different Features of Oscillations in the Belousov-Zhabotinsky Reaction

We analyzed the coupling of chemical oscillations between cation-exchange resin beads loaded with a metal catalyst for the Belousov-Zhabotinsky (BZ) reaction. We observed two different oscillatory behaviors, i.e. global oscillations (GO) and traveling waves (TW). We noted that the features of synchronization between the two coupled beads under the initial conditions for GO are different from those under the initial conditions for TW.

Kinetics study on esterification of acrylic acid and ethanol over acidic cation-exchange resin beads Amberlyst 35

Abstract The heterogeneous kinetics and adsorption behavior for the esterification of acrylic acid and ethanol were studied by using a fixed-bed reactor over an acidic cation-exchange resin beads, Amberlyst 35. The reaction experiments were conducted at 318.15 K–348.15 K under atmospheric pressure. The influences of molar ratios of ethanol to acrylic acid in the feed (θBo) and the mass transfer resistances on the kinetic behavior were also investigated. The experimental results show that the equilibrium conversion of acrylic acid increases with increasing reaction temperature and θBo. Moreover, the adsorption experiments were also made to determine the relative adsorption strengths among the reacting species. The results reveal that the magnitude of adsorption strengths obeyed the sequence of water > acrylic acid > ethanol > ethyl acrylate. The kinetic data obtained from the present study were correlated with the ideal-quasi-homogeneous (IQH), the non-ideal-quasi-homogeneous (NIQH), the Langmuir-Hinshelwood-Hougen-Waston (LHHW), the Eley-Rideal (ER) models, the modified LHHW (M-LHHW) and the modified ER (M-ER). The best-fitted values of the kinetic parameters were reported. The correlated results indicated that the M-LHHW model provides the best representation for this reaction system.

Intensification of sonochemical reactions in solid-liquid systems under fully suspended condition

Process intensification of sonochemical reactions due to the addition of solids is studied using very high solids concentrations (up to 0.5 (v/v)). The impacts of particle size, surface roughness, and solids concentration on sonochemical yields were studied experimentally by measuring the concentration of I3− formed in the cavitation of potassium iodide solution in an agitated baffled tank fitted with an ultrasonic generator (20kHz, 131W). Solids used were cation exchange resin (625μm), sand (303μm), and spherical glass beads (207, 551 and 1290μm). It was found that, due to the net effect of wave attenuation and increased number of nucleation sites available, cavitation level initially decreases with increasing solids concentration up to 0.1 (v/v), then increases up to 0.4 (v/v), followed by a further decrease. Cavitation activity increases with increasing particle diameter due to the reduction in the liquid tensile strength in the presence of larger particles, which decrease the cavitation threshold. The cavitation level is found to be enhanced due to an increase in the surface roughness. The results imply that particle size, concentration, and surface roughness all play important roles in the formation and subsequent collapse of cavities, which cumulatively influence sonochemical reaction yields.

Surface ion engineering for tuning dual emission of ZnxCd1−xS nanocrystals

Oleate capped Zn doped CdS (ZnxCd1−xS) colloidal nanocrystal exhibited dual emission, which was tunable by selective removal of the cations, over its surface and in its immediate vicinity, using cation exchange resin beads (CB). The near band gap emission disappeared more rapidly in comparison to deep level emission, the peak wavelength of which shifted by as much as 25 nm, while both exhibited increasingly faster decay.

Surface Ion Engineering of Mn2+-Doped ZnS Quantum Dots Using Ion-Exchange Resins

We report the engineering of surface ions present as defects in doped quantum dots (Qdots) following their synthesis. This was achieved by treating the Qdots with cation-exchange resin beads (CB). An aqueous dispersion of Mn(2+)-doped ZnS Qdots, when treated with different amounts of CB, resulted in two kinds of changes in the emission due to Mn(2+) ions. First, the intensity increased in the presence of a smaller amount of CB, to the extent of a doubled quantum yield. With increased CB as well as incubation time, the emission intensity decreased systematically, accompanied by an increasing blue shift of the peak emission wavelength. Electron spin resonance results indicated the removal of clusters of Mn(2+) present in the Qdots by the CB, which has been attributed to changes in the emission characteristics. Transmission electron microscopy studies revealed that for smaller amounts of CB there was no change in the particle size, whereas for greater amounts the particle size decreased. The results have been explained on the basis of the removal of Mn(2+) (and also Zn(2+)) ions present on the surfaces of Qdots in the form of clusters as well as individual ions.

Kinetics of heterogeneous esterification of glutaric acid with methanol over Amberlyst 35

The kinetic behavior of heterogeneous esterification of glutaric acid with methanol over acidic cation-exchange resin beads, Amberlyst 35, was investigated through a packed-bed reactor. The experiments were conducted at temperatures from 313.2 K to 333.2 K and the molar ratios of feed (methanol to glutaric acid) at 15 and 20. The reaction rate was found to increase with increasing temperature, but the equilibrium conversions of glutaric acid were almost identical over the entire temperature range; that is, the heat effect of this reaction system was minor. It was also found that the equilibrium conversion of glutaric acid increases slightly as the molar ratio of feed increases from 15 to 20. The experimental results showed that the mass-transfer resistance could be neglected over the range of experimental conditions. The kinetic data were correlated with two quasi-homogeneous models. The model parameters were determined and their applicability was discussed.

Esterification of adipic acid with methanol over Amberlyst 35

The kinetic behavior of heterogeneous esterification of adipic acid with methanol over acidic cation-exchange resin beads, Amberlyst 35, was investigated through a packed-bed reactor. The experiments were conducted at temperatures from 313.2 K to 343.2 K and the molar ratios of feed (methanol to acid) at 15 and 20. The reaction rate was found to increase with increasing temperature, but the equilibrium conversions of adipic acid were almost identical over the entire temperature range; that is, the heat effect of this reaction system was minor. It was also found that the equilibrium conversion of adipic acid increases slightly as the molar ratio of feed increasing from 15 to 20. The experimental results showed that the mass-transfer resistance could be neglected over the range of experimental conditions. The kinetic data were correlated with two quasi-homogeneous models. The model parameters were determined and their applicability was discussed.

On-chip type cation-exchange chromatography with ferrocene-labeled anti-hemoglobin antibody and electrochemical detector for determination of hemoglobin A 1c level

An on-chip type cation-exchange chromatography system with electrochemical detection of HbA 1c, which is one of the most important diabetes marker protein, was developed using ferrocene-conjugated anti-human hemoglobin (Hb) monoclonal antibody (FcAb). The FcAb was used as an electrochemical probe for the detection of each Hb. The system contains syringe pump, on-chip type cation-exchange column consisted of PDMS and cation-exchange resin beads, and a three-electrode flow-cell system. The separation conditions of HbA 1c in blood calibrator samples from other Hbs, e.g. HbA 0, HbA 1a or HbA 1b, were optimized using the on-chip type system. The electrochemical oxidation current from FcAb reacting with each Hb was measured at 350 mV (vs. Ag/AgCl). Hbs including HbA 1a and HbA 1b, HbA 1c and HbA 0 fractions were eluted in this order. A linear relationship between HbA 1c levels and electrochemical oxidation currents was obtained in the range from 4.0% to 12.6% HbA 1c. All procedure including antigen–antibody reaction was completed in 15 min. Furthermore, a good correlation was obtained between KO500 method (HPLC) and our proposed method. These results indicate that the on-chip type system with electrochemical detection can be applied to a novel POCT device for rapid and precise detection of HbA 1c.

SU-FF-T-288: Measurement of MRI Image Degradation in Three-Dimensional Dosimeter Made of Ion Exchange Resin Beads Labeled with Ferrous Ions

Purpose: To investigate the rate of MRIimage degradation in a three‐dimensional dosimeter made of ion exchange resin beads labeled with ferrous ions and to compare the rate to MRIimage degradation in a three‐dimensional ferrous‐gel dosimeter. Method and Materials: A three‐dimensional dosimeter material was made by labeling cation exchange resin beads with ferrous ions. After hydration, the beads contain a low pH solution. Adding ferrous ions makes each bead a self‐contained Fricke chemical dosimeter. A container packed with these beads forms a tissue equivalent three‐dimensional dosimeter. Dosimeter samples exposed to 6 MV x‐rays and evaluated using MRI show a linear R1 versus dose response of 0.10 to 0.09 sec−1 Gy−1 similar to a ferrous‐gel dosimeter. Diffusion of ferric ions is problematic for ferrous‐gel dosimeters, as diffusion results in rapid blurring of dose distribution information. For comparison, two sample vials were prepared, each consisting of a layer of unlabeled beads interfaced to a layer of either ferrous or ferric ion labeled beads. MRI scans of R2, which is proportional to ferrous and ferric ion concentration, versus distance from the bead layer interface were made of the vials when constructed and six days later. To evaluate chemical diffusion, scan results were fit to the error function complement and changes between initial and final scans were used to calculate the diffusion constants. Results:Diffusion constants for ferrous and ferric ions in the ion exchange resin bead dosimeter were 1.5 × 10−5 and 2.5 × 10−6 cm2/hr, respectively. These are significantly less than the ferric ion diffusion constant in ferrous‐gel dosimeters, which is 1.5 × 10−2 cm2/hr. Conclusion: In comparison to the image blurring of a ferrous‐gel dosimeter, blurring of dose distribution information due to diffusion does not appear to be a problem with the ion exchange resin bead dosimeter material.

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).

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.

Au Nanoparticles and Polyaniline Coated Resin Beads for Simultaneous Catalytic Oxidation of Glucose and Colorimetric Detection of the Product

In this letter, we report the synthesis of Au nanoparticles (NPs) and polyaniline (PANI) on the same cation-exchange resin beads and demonstrate their use in catalyzing the oxidation of glucose to gluconic acid by Au NPs and simultaneously in detecting the formation of the acid by the color change of PANI. The synthesis was carried out by exchanging the cations of the resins with HAuCl4 and anilinuium chloride and then reducing the metal ions by NaBH4 to produce Au NPs followed by polymerization of aniline using H2O2. The green emeraldine salt form of PANI thus obtained was treated with NaOH to be converted to blue emeraldine base before use. The deposition of Au NPs was confirmed by a change in color of the bead, visible spectroscopy, X-ray diffraction, and scanning electron microscopic measurements. On the other hand, the presence of PANI was confirmed by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopy. The formation of gluconic acid from glucose was confirmed by FTIR spectroscopy. We could detect the presence of glucose of a minimum 1.0 mM concentration in water, using the present method. Our experimental observations demonstrate the possibility of the incorporation of multifunctional components on the surfaces of resins for carrying out a chemical reaction as well as detection of the product.

Meso/macroporous AlPO-5 spherical macrostructures tailored by resin templating

A multi-step procedure for the preparation of meso/macroporous AlPO-5 spherical macrostructures using cation exchange resin beads as macrotemplates is presented. Firstly, aluminum species were introduced into the resin beads by ion exchange resulting in a resin-aluminum composite. Thereafter, the resin-aluminum composite was mixed with TEAOH, H 3PO 4 and distilled water and hydrothermally treated at 150 °C to yield resin-AlPO-5 composite. Finally, the resin was removed by calcination leaving behind self-bonded AlPO-5 spheres. The product AlPO-5 macrostructures were thoroughly characterized by SEM, XRD, nitrogen adsorption measurements, 31P and 27Al solid state NMR spectroscopy. The influence of various components of the synthesis mixture on the crystallinity, phase purity and stability of the AlPO-5 spheres was systematically studied. Samples prepared for different treatment times using the initial synthesis composition that gives spheres of the highest quality were used to study the crystallization process within the resin.

Coupling sequential injection on-line preconcentration by means of a renewable microcolumn with ion-exchange beads with detection by electrothermal atomic absorption spectrometry: Comparing the performance of eluting the loaded beads with transporting them directly into the graphite tube, as demonstrated for the determination of nickel in environmental and biological samples

The design of a flow injection/sequential injection (FIA/SIA) on-line preconcentration system incorporating a renewable microcolumn with ion-exchange beads and interfaced with an electrothermal atomic absorption spectrometry (ETAAS) detector is described, and its practical applicability is demonstrated for the determination of trace level concentrations of nickel. The column is loaded with a defined volume of SP Sephadex C-25 cation-exchange resin beads and subsequently exposed to a metered volume of sample solution. The analyte loaded beads are afterwards eluted with 30 μl of diluted nitric acid, and the eluate transported via air segmentation into the graphite tube. The used beads are then discarded. The ETAAS determination is performed in parallel with the preconcentration process of the ensuing sample. An improved precision of R.S.D. 1.5% is obtained as compared to the 3.4% for the procedure in which the loaded beads are transported directly to the graphite furnace for pyrolysis and atomization, and even improved in comparison to the traditional unidirectional and bidirectional repetitive elution procedures which under comparable conditions yield R.S.D.-values of 5.8 and 4.9%, respectively. The tolerance limits for cations such as Pb(II), Zn(II), Co(II) and Mn(II) were improved up to 10–50-folds, and the linear calibration range extended to comprise 0.02–1.20 μg l −1. Because of lower operating temperature, the life time of the graphite tube is extended. An enrichment factor of 71.1 and a detection limit of 10.2 ng l −1 along with a sampling frequency of 12 h −1 were obtained, which are at the same levels as those for the previously described procedure without elution. The present approach was validated by determination of the nickel contents in two certified reference materials, an industrial waste water sample and a human urine sample.

The Use of a Co-matrix for Improved Analysis of Oligonucleotides by Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

Cation adduction to oligonucleotides and nucleic acids during mass spectrometric analysis is a recurrent problem. We have found that the use of organic base solutions of high gas-phase proton affinity, as used previously in electrospray ionization mass spectrometry, can significantly reduce the cation adduction problem during matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. A comparison of the utility of adding imidazole or triethylamine as a co-matrix versus the standard addition of cation exchange resin beads was made. The co-matrices studied were found to be more effective than the cation exchange resin beads at reducing cation adducts from samples containing a high level of salt. The use of co-matrices also appears to improve the gas-phase stability of larger oligonucleotides. MALDI-time-of-flight analysis of a binary mixture of oligoribonucleotide 27-mers with a co-matrix exhibited less metastable decomposition than the same analysis using cation exchange resin beads. The use of co-matrices may be a viable strategy for the mass spectrometric characterization of larger oligonucleotides obtained from media containing a high salt content such as polymerase chain reaction products. © 1997 John Wiley & Sons, Ltd.

Refraction, Reflection, and Frequency Change of Chemical Waves Propagating in a Nonuniform Belousov−Zhabotinsky Reaction Medium

Propagation of chemical waves in the Belousov−Zhabotinsky reaction in a thin layer of ferroin-loaded cation-exchange resin beads is investigated. Dispersion relations are obtained for waves propagating in layers of resin beads. The relations in layers of resin beads are different both in the trigger wave velocity and the refractory period, when mesh size and/or percentages of cross-linkage of resin beads are different. A system with a sharp boundary between two layers with different wave velocities is made using two different resin beads exhibiting different dispersion relations. Incident waves at any angle from the high-velocity layer are refracted at the boundary. Waves from the low-velocity layer also exhibit refraction when the angle of incidence is smaller than a critical value. Refraction obeys Snell's law. Incident waves from the low-velocity layer at angles larger than the critical value are reflected. The angle of reflection is equal to the critical angle and does not depend on the incident angle. When the period of incident waves from the high-velocity layer is shorter than the refractory period in the low-velocity layer, wave propagation across the boundary causes the change of frequency.

Membrane-based solid-phase extraction as a sample clean-up technique for anion analysis by capillary electrophoresis

The use of membrane-based solid-phase extraction disks as a sample clean-up technique for anion analysis by capillary electrophoresis is discussed. The polytetrafluoroethylene membrane is impregnated with high-purity polystyrene-divinylbenzene sulfonated cation-exchange resin beads. Three different chemistries are used to remove various interfering components from the sample. The applications of this technique for the analysis of various anions in difficult samples are demonstrated.