Macroreticular Ion Exchange Research Articles

Efficient solid dielectric electrochemical polishing with minimal electrolyte consumption and reusable conductive media

Electrochemical polishing finds wide application across various industries, including manufacturing, biomedicine, and semiconductors. However, this technology requires substantial water usage and results in environmental pollution due to the generation of waste electrolytes containing highly corrosive acids and heavy metal ions. Herein, we propose an electrochemical polishing method (SDEP) that employs solid dielectrics consisting of macroreticular ion exchange resin (MIER) solid particles and phosphoric acid electrolyte as an alternative to traditional liquid conductive media. Maintaining a polishing current of 0.4–0.5 A requires only an electrolyte consumption of 10–20 mL/h, leading to a more than 65% reduction in electrolyte usage compared to liquid electrochemical polishing. Meanwhile, this method can be applied to polish additively manufactured metal parts with an initial roughness Ra>10 μm. The achievable surface finish features Ra = 0.778 ± 0.078 μm, Rq = 0.960 ± 0.121 μm, and Rz = 4.175 ± 1.111 μm after 1-h polishing, with a material removal rate of 0.15–0.19 mm3/min. The improvement of Ra, Rq, and Rz are 92.3%, 92.1%, and 92.0%, respectively. With the EDS and XPS analysis, rod-shaped by-products adhering to the surface of MIER particles generated during the SDEP process are confirmed as Fe3+, PO43−, and PO3−. Furthermore, the MIER particles can be reused after cleaning, exhibiting polishing performance comparable to fresh MIER. This method reduces the use of electrolytes at the source of electropolishing, and MIER particles can be recycled, pointing towards the development of eco-friendly electrochemical polishing.

Macro-Reticular Ion Exchange Resins for Recovery of Direct Dyes from Spent Dyeing and Soaping Liquors.

Dyes are a major class of organic pollutants that are well-known for their harmful impact on aquatic life and humans. Several new strategies for removing colours from industrial and residential effluents have recently emerged, with adsorption being the best option. The current study looked at the recovery of direct dyes from aqueous streams for reuse using macro-reticular ion exchange resins (IERs). The investigation includes dyeing single jersey cotton grey textiles with direct dyes from the Isma dye Company in Kafr El Dawar, Egypt. After centrifuging and separating the supernatant liquid, solutions from thirteen different dyes, produced at an average concentration between the wasted and soaping liquor concentrations, were calculated spectrophotometrically from the first dyeing trials. Kinetic data were well fitted with pseudo-second-order rate kinetics. The amounts of dye retained by the anion exchangers increased with a rise in temperature in the case of Strong Base Resin (SBR) and vice versa for Weak Base Resin (WBR). Batch adsorption experiments with SBR and WBR were conducted for each dye, and both Freundlich and Langmuir isotherms were constructed. It was found that adsorption obeyed both isotherms, that monolayer adsorption took place, and that the dye molecular weight, structure, and solubility, as well as the type of anionic resin used, had varying effects on the extent of absorption. The monolayer sorption capacities Q0 determined from the Langmuir isotherm model for the strongly and weakly basic anion exchangers were found to be 537.6 and 692 mg/g for Direct Yellow RL, respectively. As a result, Yellow RL exhibited the greatest adsorption on both SBR and WBR. Orange GRLL, Blue 3B, and Congo Red, on the other hand, were the poorest colours absorbed by the IERs, whereas Blue RL demonstrated good adsorption by SBR and accelerated adsorption by WBR. Most of the dyes may be recovered and reused in this manner.

Amino Acid Modified Macroreticular Anion Exchange Resins for CO<sub>2</sub> Adsorption

Amino acids were used to modify macroreticular ion exchange resin for the adsorptive capture of CO2. Adsorption isotherms, adsorption rate curves, heats of adsorption, and gas separation performance were determined. It is found that the adsorption capacity of the resin increases significantly after the loading of amino acids. The adsorption progresses rapidly and reaches equilibrium within 3 min. The adsorption capacity decreases with the increasing temperature, and room temperature is a suitable condition that enables high adsorption of CO2. The adsorbent can be promoted by water vapor in removing CO2 effectively from gas mixtures. Ten continuous adsorption–desorption cycles was performed, showing that the adsorbent is of good regeneration performance and the adsorption capacity keeps at about 0.9 mmol/g after regeneration.

Kinetic study of methyl-butenes dimerization and trimerization in liquid-phase over a macroreticular acid resin

A kinetic study of the dimerization and the trimerization of isoamylenes (2-methyl-1-butene and 2-methyl-2-butene) in liquid-phase catalyzed by the acidic macroreticular ion exchange resin Amberlyst™ 15 was performed in a continuous-stirred tank reactor in the temperature range 323–393K using n-hexane as a solvent. Reaction rate data were obtained free of internal and external mass transfer resistance effects. The best kinetic models that fit the experimental results were based on the LHHW–ER formalisms. They included the participation of isoamylene, dimer and n-hexane in the adsorption term. The number of active sites or clusters implied in the surface reaction was one for dimerization and three for trimerization. It was also inferred that trimers were formed via dimers. Finally, the obtained apparent activation energies for dimerization and trimerization were 37±2 and 89±3kJ/mol, respectively, being the dimerization activation energy value in agreement with literature data.

Condensation of phenol and acetone on a modified macroreticular ion exchange resin catalyst

Macroreticular ion exchange resin catalysts were prepared by suspension polymerization, and then modified by alkylmercaptoamines. The modified catalysts were characterized by N2 adsorption/desorption measurements, scanning electron microscopy and differential scanning calorimetry. Key factors such as the mercaptan content, the degree of crosslinking and the structures of the promoters were investigated for the synthesis of Bisphenol A (BPA). At optimal conditions, the macroreticular ion exchange resin catalysts modified by alkylmercaptoamines showed high catalytic activity and selectivity for BPA synthesis.

Effect of macroreticular acidic ion-exchange resins on 2-methyl-1-butene and 2-methyl-2-butene mixture oligomerization

A screening of macroreticular ion exchange resins has been carried out in order to select the most suitable catalysts for liquid-phase oligomerization of an isoamylene mixture. The reaction was performed at mild temperature (343K) to promote the dimerization and trimerization, and at higher temperature (383K) to evaluate side reactions like cracking and copolymerization. No compounds higher than trimers were significantly detected at studied conditions. By plotting product yields versus conversion at 343K, it was showed no significant differences between all catalysts tested. However, at 383K, the ion exchange resins which mainly work in the external zone were more selective to dimerization and less to cracking and trimerization products, which suggests that trimerization and cracking mainly took place inside the gel-phase of the macroreticular resins.The most active catalysts were the oversulfonated resins with high cross-linking degree and high acid capacity. A heterogeneous Eley-Rideal kinetic model showed better fitting of dimerization rates than two pseudo-homogeneous models.

Working-state morphologies of ion exchange catalysts and their influence on reaction kinetics

The esterification of fatty acids is an important pretreatment step in the production of biodiesel from low-cost raw materials. It was thus used as a model reaction in a study of the influence of concentration variations of the polar component (methanol) in a reaction mixture on the morphology and functioning of ion exchange catalysts. For a gel-type ion exchange catalyst, a decrease in the methanol concentration proved to have unambiguously negative effects, as it induced de-swelling of the polymer matrix and diminished the accessibility of the active centers. For macroreticular ion exchange catalysts, on the other hand, the drop in methanol concentration had a positive influence on the efficiency of the catalytic action mechanism of the acidic centers. This was due to the existence of some swelling-independent porosity, causing a shift from a general to a specific catalysis-like mechanism.

CR(III) removal by macroreticular chelating ion exchange resins

The poly(styrene-co-divinylbenzene) beads were synthesized by suspension polymerization using benzoylperoxide as an initiator and i -octane as a diluent. The copolymer beads with a particle size range of 32-60 mesh were selected. Chloromethylation was performed with chloromethylether at 0°C using tetrachloroethane as swelling agent and AlCl 3 as catalyst. The phosphorylation of copolymer beads (RS) and its chloromethylated derivative (RCS) was carried out using a mixture of PCl 3 and AlCl 3 under the reflux. The phosphorylated resins (RSP) were further oxidized using concentrated HNO 3 to obtain the oxidized form of RSP resins (RSPO). The removal of Cr(III) by the resins RSP, RSPO, and RCSP containing phosphinic, phosphonic, and methylenephosphonic groups, respectively, was investigated by batch and column methods. The results were compared with that of Diaion CRP-200 resin having methylenephosphonic functional groups. These resins exhibited a high affinity for Cr(III). The percent removal of Cr(III) reached a plateau with almost a 100% of removal at pH range between 2 and 2.5. The breakthrough capacity decreased in the order RCSP>RSPO>Diaion CRP-200>RSP.

Amberlyst-15 mediated decomposition of α-diazo carbonyl compounds

An efficient heterogeneous catalytic method for the synthesis of α-hydroxy ketones from α-diazo carbonyl compounds 1, 3 and 6 in the presence of Amberlyst-15, a macro reticular ion exchange resin, is reported. The desired products were obtained at room temperature or by ultrasonication in good yield. Interestingly, novel fused 3-furanones and bicycloalkane-1,3-diones were obtained as unusual products in the case of alicyclic α-diazo carbonyl compounds.

Characterisation of surface modified polystyrene particles by microcalorimetry and liquid sorption

Different types of polystyrene particles were investigated by titration microcalorimetry and selective liquid sorption from 1-propanol(1)–water(2) mixtures. The first type of polymer particles is related to sulfonated polystyrene macrobeads of different surface charge. The other types are colloidal polystyrene particles: One of these is type-3-latices prepared by emulsion copolymerisation of styrene and sodium styrene sulfonate with potassium peroxodisulfate as the initiator. The second type of colloidal polystyrene particles is formed by a ground macroreticular ion exchange resin (Amberlyst 15). The adsorption measurements were performed in 1-propanol–water mixtures and were documented by composite isotherms. The composite isotherms found for all three types of polystyrene particles are S-shaped in character. Water is preferentially sorbed up to water mole fractions x 2 ≈ 0.80. The mole fraction of the adsorbed layer ( x s 2) was calculated from the surface excess and equilibrium diagrams ( x s 2/ x 2) are presented. The enthalpy effect accompanying the solvent exchange was determined by titration microcalorimetry. Changes in the conformation of the macromolecular frame were found to be an endothermic effect which is overlapped by the exothermic process of water displacement. The enthalpy of displacement isotherms fairly well reveal differences in the swelling ability of the particles surfaces. The change in free enthalpy was calculated from adsorption data from which entropy functions for the exchange process can be calculated. In view of the thermodynamic potential functions structural changes in the adsorption layer and formation of alcohol water clusters on the surfaces of the colloidal polystyrene particles may play an important role in the dispersion stability.

ION EXCHANGE EQUILIBRIUM OF POTASSIUM ON STRONG ACID RESINS IN POLYOL MEDIA

ABSTRACT The uptake equilibrium of potassium from impure polyols was obtained experimentally on two different H-form ion exchangers: Dowex XZS-1, a homogeneous gel resin and Amberlite 252, a macroreticular ion exchange resin. The equilibrium isotherms are highly favourable for both types of resins and an acid'base neutralization reaction is proposed to explain the behaviour of the system. It was observed that these resins are not able to exchange their full potential capacity in pure potyol media. Based on the main properties of the resin matrix and the potyol, an explanation about this lack of capacity is proposed. Equilibrium isotherms of potassium from ternary mixtures polyol-methanol-water over Amberlite 252 were also obtained. A different mechanism for ion exchange of potassium was proposed for this kind of system, explaining the improvements inresin capacity.

Diffusion and catalytic zero-order reaction in a macroreticular ion exchange resin

The behavior of macroreticular ion exchange resins as catalysts is analyzed for the case of isothermal zero-order reactions. The particle is viewed as an ensemble of microspheres (gel phase) with a given fraction of active sites and macropores between those microspheres, where the remainder fraction of active sites is located. This study displays different situations concerning the annulment and nonannulment of reactant concentrations in the pores and/or inside the microspheres for different values of the governing parameters: pore and microsphere Thiele modulii and fraction of active sites on the pore walls. The overall effectiveness factor for the various situations is calculated once the micro and macroeffectiveness factors are known.

Development and start‐up of a fixed bed reaction column for manufacturing antiknock enhancer MTBE

AbstractA laboratory fixed‐bed reaction column is presented, in which a heterogeneouslyl catalyzed reversible fluid‐phase reaction and the separation of the reaction product from unreacted or inert components by distillation are performed simultaneously. The rection studied, the formation of methyl tertiary butyl ether (MTBE) from methanol and isobutylene, is catalyzed by strongly acidic macroreticular ion exchange resins. Packing elements are Raschig rings, manufactured for the first time from the above‐mentioned ion exchange resins. This in‐house made catalyst shows practically the same ion exchange capacity as the commercial products. The control system installed in the equipment is capable of correcting strong disturbances os the steady state. As shown by expwrimental results, the superimposed distillation process occurs in such a way that the chemical equilibrium of the MTBE synthesis does not limit isobutylene conversion.

Kinetics and mechanism of ethyl tert-butyl ether liquid-phase synthesis

This paper presents the results of an experimental investigation on ethyl tert-butyl ether (ETBE) liquid-phase synthesis from isobutene (IB) and ethanol (EtOH), catalyzed by an acidic macroreticular ion exchange resin, Amberlyst 15 (A15). The experiments were carried out batchwise in a Parr reactor in the range 323–363 K at 2 MPa for different initial EtOH/IB mole ratios and amounts of catalyst. Data collected at equilibrium gave thermodynamic information which was compared with theoretical calculations using the UNIFAC method. The kinetic results were used to develop a reaction mechanism and a kinetic model. The resin's affinity for polar substances and the strong nonideality of the liquid phase lead to a complex kinetic expression, which is valid both in the presence of high and low alcohol concentrations. Simulations performed with this kinetic model agree satisfactorily with the experimental results.

Alkylation of benzene with 1dodecene by macroreticular resin catalysts

The alkylation of benzene with 1-dodecene was performed in a batch reactor by two types of macroreticular ion exchange resin catalysts, i.e., Amberlyst 15 and Amberlyst XN-1010. The external mass transfer resistance and the macropore diffusion resistance could well be neglected since the stirring speed and the resin particle size had little effect on the reaction rate. The experimental data on the initial reaction rates have been correlated fairly well with the Rideal kinetics, from which the reaction rate constant, the distribution coefficient and the adsorption equilibrium constant were estimated. The activation energy of alkylation was about 7 Kcal/g mole. It is believed that the isomerization occurs prior to the final attachment of the phenyl group to the alkyl chain. This was explained by the isomer distribution of phenyldodecane, which was not influenced very much by the reaction time, the temperature, and the feed composition.

Resin hemoperfusion for unconjugated bilirubin removal.

The application of an anionic macroreticular ion exchange resin, coated with a thin cross-linked albumin layer, as a hemoperfusion device for the removal of unconjugated bilirubin from the blood of hyperbilirubinemic newborn babies is reviewed. In vivo hemoperfusion runs with hyperbilirubinemic animal models - either by a choledocho-suprarenal vein shunt or by direct infusion of bilirubin into the vein - showed that a 40-ml resin column can remove some 20 mg bilirubin in 3 h. Hemoperfusion of female 8-14 kg baboons showed no significant effect of the column on blood chemistry and coagulation factors and repeated runs had no ill effects.

In vivo Hemoperfusion Studies of Bilirubin Removal from Jaundiced Dogs

Removal of bilirubin by hemoperfusion (HP) on a macroreticular ion-exchange resin is suggested as a novel clinical procedure for the treatment of jaundiced newborn babies. The efficiency and biocompatibility of the proposed macroreticular (MR) ion exchange column was tested in vivo with jaundiced dogs. An animal model with a choledocho-suprarenal vein shunting allowed to test the column capacity for the adsorption of conjugated and unconjugated bilirubin. A second animal model, based on infusing unconjugated bilirubin directly into the blood stream, enabled to test the column operation at desired unconjugated bilirubin concentrations. The results of the in vivo hemoperfusion tests are very encouraging and compare favorably with bilirubin removal from babies by exchange transfusion (ET). Operating a column containing 10 ml resin per kg body weight for 3 hours removed over 1.7 times the initial unconjugated bilirubin content. Furthermore, the animals seemed to be unaffected by the HP procedure; the changes due to hemoperfusion on blood chemistry, hematology and some hormone levels were practically insignificant.

Bilirubin Removal from an Hepatic Failure Patient by Resin Hemoperfusion

An hemoperfusion (HP) column, packed with beads of a macroreticular MR ion exchange resin which were made biocompatible by coating with a fine layer of cross-linked human albumin, was applied to the removal of bilirubin (BIL) from a jaundiced 69-year old man with hepatic failure. The column was found most suitable for BIL removal. However, the high volumetric mass transfer coefficient of the unconjugated (UC) BIL indicates that this column could best be used for BIL removal from babies suffering from unconjugated hyperbilirubinemia.

Esterification Catalyzed by Macroreticular Ion Exchange Resin in Strong Acid Form

The esterification of n-fatty acids with 1- and 2-butanols catalyzed by macroreticular sulfonated ion exchange resin has been studied in a batch reactor. The reaction was first-order in concentration of fatty acid over the range of experimental conditions.From the results summarized in Figs.-2 and 3, it was determined that neither bulk diffusion nor pore diffusion is a limiting step in the reaction.The results of Fig.-4 show that in the esterification with 1-butanol catalyzed by the ion exchange resin the carbon number of fatty acid influences significantly the reaction rate, in other words the ion exchange resin as catalyst has selectivity. However, as may be seen in Fig.-5, in the esterification with 2-butanol the selectivity of the catalyst was not recognized. The above results are explained by introducing the assumption that the reaction with 1-butanol is catalyzed by the hydrophobic proton and the matrix-bound -SO3H groups, the reaction with 2-butanol is catalyzed by the hydrophobic proton and hydrated proton in the resin matrix.

Immobilization of glucose oxidase on macroreticular ion exchange resins

Immobilization of glucose oxidase on macroreticular ion exchange resins