Acid Cation Exchange Research Articles

Kinetics, mass transfer, and thermodynamic and statistical modeling study for esterification of valeric acid with n‐butanol: Homogeneous and heterogeneous catalysis

AbstractThe esterification of valeric acid with n‐butanol was studied with homogeneous and heterogeneous catalysts. The activity and performance of homogeneous p‐toluenesulfonic acid and heterogeneous cation exchange resin catalysts Amberlyst 36, Indion 190, and Amberlite IRC‐50 were evaluated. The pseudo‐homogeneous kinetic model was used to investigate the kinetic parameters of homogeneous‐ and heterogeneous‐catalyzed esterification. The UNIFAC (universal functional activity coefficient) approach was used to study the nonideality of the esterification reaction. The reaction was statistically modeled and optimized by the application of response surface methodology. The effects of independent variables such as reaction temperature, initial molar ratio, and catalyst loading on the conversion of valeric acid were investigated. The optimized conditions for the esterification reaction catalyzed by Amberlyst‐36 were found as temperature 360.4 K, initial molar ratio 3.8, and catalyst loading 6.7 wt%. The predicted conversion (89%) at these optimized conditions is in good agreement with the experimental conversion (87.3 ± 1.6%).

Selective separation of radium and actinium from bulk thorium target material on strong acid cation exchange resin from sulfate media

This work presents a complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material, in a process that may be applied in a separation scheme for the production of 225Ac by proton spallation on thorium. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Following rinsing steps to remove residual thorium, actinium and radium are recovered from the cation exchange resin using 5 M HNO3. Further separations of actinium via extraction chromatography with UTEVA and DGA resins yield actinium in >92% yield, while providing additional decontamination from thorium and other spallation byproducts. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity.

A biologically-derived 1,3-propanediol recovery from fermentation broth using preparative liquid chromatography

Abstract This work studies the process development for the purification of 1,3-propanediol by batch preparative chromatography. The strongly acidic cation exchangers in hydrogen and sodium form were used as the stationary phases. The equilibrium adsorption of 1,3-propanediol and glycerol onto two polymeric resins were investigated and the model parameters were experimentally determined to process simulation. The work has proven that 1,3-propanediol can be isolated from the fermentation broth with high efficiency. The obtained results show that the Equilibrium-Dispersive model can be applied to simulation experiments and scale-up designs of chromatographic processes.

In English

Weakly acidic cation exchange resin was modified with nanoparticles of zirconium hydrophosphate. The materials were investigated with methods of standard contact porosimetry and transmission electron microscopy. Both non-aggregated nanoparticles (4–15 nm) and larger formations (from 250 nm to several microns) have been found. Single particles in clusters and channels of the polymer depress dissociation of carboxylic groups due to counter-ions (H + ) in electric double layer around the particles. This causes transformation of porous structure of the polymer: the contribution of micropores to total porosity increases. These additional selective sites provide stronger interaction of Brilliant Green molecules with the surface in comparison with the pristine polymer. Removal of the dye from deionized water and Ni(II) ions from water containing also hardness ions was studied under dynamic conditions. The composite shows higher break-through capacity than that of the pristine resin. The modifier also facilitates regeneration of the weakly acidic ion-exchanger.

Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction.

Motivated by the proposed use of cationic protein-modified sand for water filtration in developing nations, this study concerns the adsorption of Moringa oleifera seed proteins to silica surfaces. These proteins were prepared in model waters of varying hardness and underwent different levels of fractionation, including fatty acid extraction and cation exchange chromatography. Adsorption isotherms were measured by ellipsometry, and the zeta potentials of the resulting protein-decorated surfaces were measured by the rotating disk streaming potential method. The results indicate that the presence of fatty acids has little effect on the M. oleifera cationic protein adsorption isotherm. Adsorption from the unfractionated extract was indistinguishable from that of the cationic protein isolates at low concentrations but yielded significantly greater extents of adsorption at high concentrations. Adsorption isotherms for samples prepared in model hard and soft fresh waters were indistinguishable from each other over the measured bulk solution concentration range, but adsorption from hard or soft water was more extensive than adsorption from deionized water at moderate protein concentrations. Streaming potential measurements showed that adsorption reversed the net sign of the zeta potential of silica from negative to positive for all protein fractions and water hardness conditions at protein bulk concentrations as low as 0.03 μg/mL. This suggests that sands can be effectively modified with M. oleifera proteins using small amounts of seed extract under various local water hardness conditions. Finally, ellipsometry indicated that M. oleifera proteins adsorb irreversibly with respect to rinsing in these model fresh waters, suggesting that the modified sand would be stable on repeated use for water filtration. These studies may aid in the design of a simple, effective, and sustainable water purification device for developing nations.

Efficiency estimation of cation-exchange recovery of heavy metals from solutions containing their mixtures

The object of research is the washing waste water of galvanic plants containing heavy metal cations. The most common reagent methods for purification of galvanic drains do not provide the required degree of water purification, are accompanied by the loss of valuable components and the formation of significant amounts of toxic sludge. Ion exchange is promising in development of wastewater treatment of galvanic productions. One of the most important problems of ion-exchange technology is the processes of regeneration of ion exchangers, and, in particular, the recycling of spent regeneration solutions. The most promising in the recovery of regeneration solutions is the electrochemical method. However, electroextraction of zinc and nickel is practically impossible from acidic solutions without separation of the electrode space by the membrane. In addition, effluents from the galvanic industry contain mixtures of heavy metal ions. This complicates the process of wastewater treatment and the return of valuable components to production. In the course of the study, a strongly acidic cation exchanger KU-2-8 in the Na + -form is used to study the processes of combined sorption of heavy metal ions. Regeneration of the cation exchanger is carried out with solutions of sulfuric and hydrochloric acids. Electroextraction of zinc and nickel from acid regeneration solutions is carried out in a two-cell electrolyzer with an anion-exchange membrane MA 41. The obtained results indicate that under conditions of the concentration of heavy metals on cation exchanger KU-2-8, efficient separation can’t be achieved. It is established that ions of heavy metals are sorbed individually and in mixtures with other ions of heavy metals are effectively desorbed by solutions of sulfuric and hydrochloric acids. The use of a two-cell electrolyzer, in contrast to carrying out electrolysis processes without separation of the electrode space, almost completely eliminates zinc and nickel ions from acidic regenerative rods. And to obtain a solution of sulfuric acid in the anode chamber at a concentration of 239–651 meq/dm 3 .

A simple and efficient headspace gas chromatographic method for the determination of carboxyl groups in nanofibrillated cellulose

This paper reports on a headspace gas chromatography method (HS-GC) for efficient determination of carboxyl groups in nanofibrillated cellulose (NFC). By pretreating the NFC suspension with a strong acid cation exchange resin for 30 min, the carboxyl groups in NFC were converted to the carboxyl acids. The pretreated suspension was added into a closed headspace sample vial containing bicarbonate solution. By HS-GC measuring the CO2 produced from the reaction between carboxyl acids and bicarbonate (10 min at 60 °C), the content of carboxyl groups in NFC can be determined. The results showed that the relative standard deviation of the method in the repeatability testing was < 3.7% and the limit of quantitation was about 0.1 mmol/g. Relative differences between the HS-GC and the reference (a conductometric titration) method were within 15.0%. The present method is simple and efficient, and suitable to be used for determining the content of carboxyl groups in NFC in the related applications.

Kinetics of solid acids catalysed nitration of toluene: Change in selectivity by triphase (liquid–liquid–solid) catalysis

AbstractNitrotoluenes are precursors to a variety of commercially important products such as dyes, pharmaceuticals, and plastics. The protonated form of Y, ZSM‐5, and mordenite zeolites as well as strongly acidic cation exchange resin (Amberlite IR‐120) were examined as triphase catalyst (liquid–liquid–solid) for the nitration of toluene to produce mainly mononitrotoluenes. Among the solid acid catalysts tested, zeolites were found to be more active than cation exchange resin with highest activity for H‐mordenite followed by HZSM‐5 and HY zeolites. The reaction was found to be free from external diffusional resistance. The effects of other parameters (temperature, catalyst loading, and nitric acid concentration) on the rate of toluene nitration over H‐mordenite catalyst were also investigated. The selectivity for p‐nitrotoluene increases with temperature but decreases with increase in nitric acid concentration. The acidity level of the catalyst determines the product distribution; the stronger the acidity, the lower the ortho/para ratio is in the product mixture. The triphasic nitration reaction is kinetically controlled with an activation energy of 24.24 kJ/mol. The catalyst could be reused for several cycles with negligible loss in activity.

Removal of impurities from scandium chloride solution using 732-type resin

The deep removal of Al, Fe(Ⅱ/Ⅲ), Ca, Zr, Ti and Si from scandium chloride solution was carried out by using 732-type strong acid cation exchange resin. The effects of pH value, contact time and complexing agents (EDTA) on the purification process are investigated. The results indicate that the 732-type resin have a good scandium selectivity and the adsorption order is Sc > Fe(Ⅲ)>Al > Ca > Zr > Ti > Si in the pH range of 1–3. The separation of Sc and Zr, Si, Ti can be directly carried out because the resin have a good adsorption effect on Sc, Al and Fe(Ⅲ) but poor adsorption effect on Zr, Si and Ti under the condition of pH = 2.5 and contact time 180 min. The Fe(Ⅱ), Ca and Al are selectively adsorbed on the resin by adding reducing agent ascorbic acid and EDTA into the solution for reducing Fe(Ⅲ) to Fe(Ⅱ) and complexing Sc. By using two-step ion exchange adsorption separation method, the removal rates of Fe(Ⅲ), Ti, Al, Ca, Zr and Si are 95.5%, 99.8%, 100%, 98.2%, 98.6% and 100%, respectively.

Photo-induced toxicity of tungsten oxide photochromic nanoparticles

We synthesised a new type of photochromic tungsten oxide nanoparticles, analysed their photocatalytic activity and carried out a thorough analysis of their effect on prokaryotic and eukaryotic organisms. Ultrasmall hydrated tungsten oxide nanoparticles were prepared by means of hydrothermal treatment of tungstic acid in the presence of polyvinylpyrrolidone as a template, stabiliser and growth regulator. Tungstic acid was synthesised through an ion-exchange method using sodium tungstate solution and a strongly acidic cation exchange resin.Upon illumination, photochromic nanoparticles of WO3 were shown to increase greatly their toxicity against both bacterial (both gram-positive and gram-negative – P. aeruginosa, E. coli and S. aureus) and mammalian cells (primary mouse embryonic fibroblasts); under the same conditions, fungi (C. albicans) were less sensitive to the action of tungsten oxide nanoparticles. UV irradiation of primary mouse fibroblasts in the presence of WO3 nanoparticles demonstrated a time- and dose-dependent toxic effect, the latter leading to a significant decrease in dehydrogenase activity and an increase in the number of dead cells. WO3 nanoparticles were photocatalytically active under both UV light and even diffused daylight filtered through a window glass, leading to indigo carmine organic dye discolouration.The obtained experimental data not only show good prospects for biomedical applications of tungsten trioxide, but also demonstrate the need for clear control of biosafety when it is used in various household materials and appliances.

Development of operator training simulator for isopropyl alcohol producing plant

In this study, an operator training simulator was developed for an isopropyl-alcohol producing plant. The main product of this plant is isopropyl alcohol — water azeotrope, by-product is diisopropyl ether which are formed by direct hydrolyzation of propylene via strong acid cation exchange resins. Firstly, the steady-state simulator of the plant was developed. The next step was to develop the dynamic simulator and the control system of the process. Reference data – main parameters of the equipments and streams – for this simulator was provided by the stationary simulator. The simulator contains the preheater and the reaction subsystems. Finally, an operator screen was developed and connected to the dynamic simulator via UniSim Excel Interface Tool.This operator training simulator can be used for analysis and optimization of the process. The OTS, which was tested by students, can be applied by chemical engineering students in different tasks – analysis, optimization and scenario – hence it can be used in education. By the use of this OTS the students may acquire adequate knowledge to control, optimize a process and handle malfunctions. This knowledge will be useful for them to operate the control system of a chemical plant.Honeywell’s UniSim® Design was used in the present simulation and further studies.

SORPTION OF RHENIUM FROM SULFURIC ACID SOLUTIONS BY IMPREGNATES CONTAINING TRIALKYLAMINES

The paper studies rhenium (VII) sorption from sulfuric acid solutions by impregnates based on macroporous polymer carriers (copolymers of styrene with divinylbenzene, weak acid cation exchange resion) containing commercial trialkylamine (ТAA). The study provides equilibrium and kinetic characteristics of rhenium recovery by the impregnate based on the macroporous weakly acidic cation exchange resin (K-TAA) having the best rhenium capacity. The maximum coefficient of rhenium distribution in the K-TAA impregnate is observed in sorption from pH = 2 solutions. The rhenium sorption isotherm is described by the Langmuir equation with the K = 29±2 ml/g constant. A limited solution volume method was used to obtain the integral kinetic curves of sorption with a half-reaction time value considered to calculate the effective coefficients of rhenium diffusion in the impregnate amounted to (3,8·10–11 (295 K) and 1,3·10–10 (308 K) m2/s). Kinetic results linearized by the equations of models (pseudo-first, pseudo-second order, Elovich and inner diffusion) showed that kinetic curves with the highest correlation degree are described by the pseudo-second order equation with the 0,00056 (295 K) and 0,00059 (308 K) g·mg–1·min–1 rate constants. The apparent activation energy of rhenium sorption (39±2 kJ/mol) was calculated using the Arrhenius equation. The K-TAA impregnate was tested for rhenium sorption from the eluate obtained by rhenium desorption from the Purolite A170, weak base anion exchange resin pre-saturated with rhenium from the complex pregnant solution for leaching of products derived from poor rhenium-containing copper sulfide raw materials processed.

Esterification of maleic acid and butanol using cationic exchange resin as catalyst

Dibutyl maleate is a perfumery ester used as an intermediate in the production of paints, adhesives, and copolymers. Esterification of maleic acid and butanol was studied in presence of acidic cation exchange resin as a catalyst. The objective of this work was to test the suitability and efficacy of heterogeneous catalysts such as Indion 225H and Amberlyst-15 in the synthesis of dibutyl maleate. Various parameters deciding the conversion of reaction such as mole ratio, catalyst loading, molecular sieves, speed of agitation and effect of temperature were optimized for the maximum rate and conversion. The activation energy was calculated as 71.5 kcal/mol. Diffusivity value $$\hbox {D}_{\mathrm{AB}}$$ (maleic acid in n-butanol) at $$80\,^{\circ }\hbox {C}$$ was calculated as $$5.08\times 10^{-10}~\hbox {m}^{2}/\hbox {s}$$ and effective diffusivity ( $$\hbox {D}_{{\text {e-A}}})$$ was calculated as $$5.08\times 10^{-11}\,\hbox {m}^{2}/\hbox {s}$$ . Solid–liquid mass transfer coefficient ( $$\hbox {k}_{{\text {sl-A}}}$$ ) was calculated as $$6.77\times 10^{-6}\,\hbox {m/s}$$ for the particle size of Amberlyst-15 as 0.5 mm. Synopsis. Synthesis of dibutyl maleate was carried out using ion exchange resin as a catalyst. Effect of various parameters on the conversion of reaction like mole ratio, catalyst loading, molecular sieves, the speed of agitation and effect of temperature was studied.

Selective removal and preconcentration of methylene blue from polluted water using cation exchange polymeric material

In this work, the selective adsorption and preconcentration of methylene blue dye from aqueous solution by using a strong acid cation exchanger (Purolite® SST60) was studied in a batch adsorption and column system. The removal of MB was found to be pH dependent and the highest adsorption capacity was observed at pH 8.5. The observed adsorption rate was relatively fast and the equilibrium was established within 30–60min. The obtained adsorption data were treated with the different adsorption isotherms. The maximum adsorption capacities obtained from the Langmuir model was 113mgg−1, 131mgg−1, 155mgg−1, 199mgg−1, 262mgg−1 at 288, 293, 298, 303 and 308K, respectively. Furthermore, the adsorption process was found to follow the pseudo-second-order kinetic model. The intraparticle diffusion study revealed that film diffusion might be involved in the present case. Thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of adsorption. The sorbents were successfully regenerated using 50:50 mixture of 2M HCl + 75% methanol mixture solutions.

Preparation and Evaluation of Taste Masking Iron Suspension: Taking Advantage of Weak Cationic Exchange Resin.

The objective of this study is to use weak acid cation exchange resin to mask the taste and eliminate the teeth staining problems of ferrous sulfate liquid preparations for use in pediatrics. Amberlite IPR64 was loaded by Fe(II). Then, different suspensions of the iron-resin complex were prepared using various polymers as the suspending agents, and sorbitol as well as sucrose as sweeteners. Physical stability, rheological assessment, kinetics of Fe(II) release, and taste evaluation of suspensions were studied. The results implied that the prepared iron suspension was more stable when xanthan gum is used as the suspending agent. It was also shown that iron release in 0.7% NaCl (similar to saliva) was very negligible compared to relatively quick release in acidic medium (resembled the stomach). Overall, the volunteers confirmed that the formulations were successful in iron taste masking. The pH-dependent process of ion exchange by weak cationic resins opens an attractive approach to access a taste-masked iron suspension for infants.

STUDY OF THE EFFICIENCY OF SORPTION TREATMENT WATER FROM AMMONIUM IONS ON NATURAL AND ARTIFICIAL SORBENTS

It was studied processes of ion-exchange water purification from ammonium ions from model solutions on cation exchangers and on zeolite. It was established dependencies ammonium sorption on the form of ion exchanger, the ratio of ammonium and calcium in water and the level of ion concentrations in solution. It was shown that the strongly acid cation exchanger KU-2-8 in Na+-form has a low selectivity for ammonium ions, in comparison with the H+-form. It was established that the sorption efficiency of ammonium ions on cation exchangers KU-2-8 and Dowex Mac-3 decreases in the presence of calcium ions. It was determined that regeneration of cation exchanger KU-2-8 was more effective when hydrochloric acid solutions were used. It was shown that ammonium sorption on zeolite from tap water goes in the same way as from model solutions. It was determined the boundary capacity of the zeolite for ammonium ions and it was amounted 40 mg/g. The regeneration of zeolite with a sodium chloride solution was investigated and it was established that the degree of regeneration reached 100 %. Bibl. 16, Fig. 6, Tab. 1.

Sorption Removal of Fluorine Ions, Incoming with the Recycling Zinc-Bearing Materials

&lt;p&gt;The possibility of using inorganic sorbent, iron oxyhydrate (IOH) to remove F&lt;sup&gt;-&lt;/sup&gt; ions from technological solutions of zinc production is considered in this article. The principal possibility of the use of ion-exchange resins as carriers modified by IOH is considered. The formation of the active substance on cation-exchange resins was studied. It was shown that the most durable composite sorbents were obtained using strong-acid cation-exchange resins with SO&lt;sup&gt;3-&lt;/sup&gt;- groups. A method for introducing IOH into the structure of carrier materials and obtaining composite sorbents is described. The strong acid cation exchanger KU-2×8 is recommended as the basis of the composite. &lt;/p&gt;

Regularities of copper(II) and nickel(II) distribution in an aqueous solution‒modified flax fiber heterophase system

The distribution of Cu2+ and Ni2+ ions in an aqueous solution — flax fiber heterophase system was investigated. The specific surface area of the sorbent and the average pore radius were determined. The sorption isotherms were processed in terms of the Langmuir and Freundlich models and the theory of volume filling of micropores. It was shown that the sorbent behaves as a weakly acidic cation exchanger with the α-hydroxycarboxyl groups as sorption sites. The modification of flax fiber with polyvinylpyrrolidone allows one to noticeably increase its sorption properties.

Synthesis of enantiomerically pure glycerol derivatives containing an organochalcogen unit: In vitro and in vivo antioxidant activity

We describe here the synthesis of enantiomerically pure chalcogenoethers obtained through the reaction of nucleophilic species of chalcogen (S, Se and Te), generated in situ from the respective diorganyl dichalcogenides, with (R)- and (S)-tosyl solketal. Furthermore, some of the chalcogenoethers were treated with acidic cation exchange resin Dowex-(H+) leading to the respective deprotected enantiomerically pure 3-phenylchalcogenyl-1,2-diols. In order to explore the biological potential of these molecules, the antioxidant activity of some organochalcogens was evaluated by several in vitro assays. Overall, the chalcogenoethers containing Te were better scavengers of DPPH and ABTS+ radicals, had higher ferric reducing capacity and prevented lipid peroxidation. To analyze the effects of these compounds in vivo, we used the alternative model Caenorhabditis elegans. Chalcogenoethers treatment, especially (S)- and (R)-2,2-dimethyl-4-(phenylselanylmethyl)-1,3-dioxolane, conferred protection against the mortality-induced by hydrogen peroxide. Accordingly, these chalcogenoethers were able to modulate the antioxidant enzyme catalase. Notably, the compounds did not present toxicity in worm’s reproduction. To sum up, our study demonstrated that Te- containing chalcogenoethers were promising in vitro scavengers, while Se molecules were more prone to protect against a stressor in vivo. In this sense, the antioxidant activity of chalcogenoethers, especially with Se and Te, indicates that these molecules may have biological application in an attempt to reduce the oxidative stress.

Removal of fluoride by effectively using spent cation exchange resin

Spent strongly acidic cation exchange resin was effectively used for the removal of trace concentration of fluoride ions. For this purpose, the spent resins were pulverized into fine powders to be used together with inorganic coagulation agent consisting of iron, aluminum, and calcium in batchwise operation. Prior to this operation, the pulverized resins were loaded with Zr(IV) ions to develop adsorption sites which effectively and selectively adsorb fluoride ions over other coexisting anionic species such as chloride and sulfate ions. The fluoride uptake capacity of the Zr(IV)-loaded resin powder was negligibly affected by the coagulation agent. This combined process of adsorption and coagulation was proven to be used for at least six repeated cycles of adsorption followed by desorption using dilute alkaline solution without lowering the uptake capacity for fluoride ion. Quantitative removal of trace concentration of fluoride was successfully achieved from actual waste plating solution by this process.