Acidic Cation-exchange Resin Research Articles

Catalysts, Kinetics, and Reactive Distillation for Methyl Acetate Synthesis

Two novel acidic cation-exchange resins, namely, NKC-9 and D072, were first developed to catalyze the esterification of acetic acid with methanol. Kinetics of methyl acetate synthesis are determined by the experiments in a batch reactor at temperatures from 45 to 60 degrees C under atmospheric pressure, with molar ratio of reactants (theta(Bo) = n(methanol):n(acetic acid)) from 0.8 to 1.3. The kinetic data are correlated with the Q-H, E-R, and LHHW and pseudohomogeneous (P-H) models. Then, the reactive distillation process for methyl acetate synthesis is simulated by the Aspen Plus process simulator. Lifetime evaluation of NKC-9 was carried out to study the conversion rate of acetic acid and selectivity of methyl acetate during the long-period running in the fixed-bed reactor. Finally, a series of characterizations such as Fourier transform infrared spectroscopy, X-ray diffraction, and polarizing microscopy were performed to investigate the structure and properties of NKC-9.

Study on Treatment of Heavy Metal Lons of Chemical Wastewater by Ion Exchange Resin

This paper used the ion exchange resin method to treat the heavy metal ion Cu2+ of a chemical wastewater and studied the flow velocity, pH and the temperature’s effect on Cu2+ removal effect by macroporous strongly acidic styrene type cation exchange resin D001. The results shown that: when the flow velocity was 1.5 mL/min, pH was 6.0 and the temperature was 30°C, the removal rate of Cu2+ by D001 reached 99.8%. The chemical wastewater could achieve the wastewater’s discharge standard.

Dissolved and colloidal organic nitrogen removal from wastewater treatment plants effluents and reject waters using physical-chemical processes.

Four physical-chemical processes were compared in terms of the efficiencies of dissolved and colloidal organic nitrogen (DON and CON) removal from the secondary effluents (SE) and reject water from full-scale biological nutrient removal activated sludge systems. Adsorption on activated carbon was most efficient and allowed removal from the SE of up to 80% and 100% of DON and CON, respectively. High efficiencies of DON removal from SE (up to 55%) were also obtained when using coagulation with iron(III) chloride and calcium hydroxide at final pH = 11.0-11.5. The efficiency of DON removal from thickening waste activated sludge (TWAS) reject water, obtained using coagulation with iron(III) chloride, was comparable with the efficiency for the SE. The efficiency of this process with regard to the sludge digester liquors (SDL) was significantly higher, i.e., 65-70% for both DON and CON. The ion exchange process with strongly acidic cation exchange resin (without pH correction) resulted in a relatively small efficiency of DON removal (<15%), and negligible efficiency of CON removal (<10%). Furthermore, ultrafiltration (0.015 μm) of SE and TWAS reject water resulted in a relatively low efficiency of DON removal (10-13% and 10-20% respectively). Ultrafiltration was found to be more effective for DON removal from SDL (41-68%).

Hydroarylation of Styrenes with Electron-Rich Arenes Over Acidic Ion-Exchange Resins

A series of acidic cation-exchange resins were used for the hydroarylation of resorcinol with styrene, in which resin D072 exhibited the excellent catalytic performance in this reaction with 99% conversion of styrene and 90% selectivity of 4-(1-phenylethyl)resorcinol. It was applied to the hydroarylation of various electron-rich arenes with styrenes, and the hydroarylated products were quantitatively obtained. This catalyst could be used for four consecutive runs with slight decrease in activity. The hydroarylation of resorcinol with styrene over resin D072 in a fixed bed was completed effectively with 94% selectivity and 99% conversion, and this green continuous process is potentially applicable to large-scale productions.

Isolation and structure characterization of related impurities in etimicin intermediate P1 by LC/ESI–MSn and NMR

Etimicin intermediate 3,2″,6″-N,N,N-triacetyl gentamicin C1a (P1), is a key intermediate of etimicin, which is a semi-synthetic aminoglycoside antibiotic effective to both gram-positive and gram-negative bacteria infections. Four major related impurities of P1 were detected by HPLC–ELSD and ESI–MSn methods. Weakly acidic cation exchange resin, CM-sephadex and silica gel column chromatography were used for the isolation and purification of four major impurities. By means of ESI–MSn and NMR analysis, related impurities were characterized as 3,2″-N,N-diacetyl gentamicin C1a (1), 3,2″,6″-N,N,N-triacetyl gentamicin C2b (2), 2″-N-acetyl gentamicin C1a (3), and 2″,6″-N,N-diacetyl gentamicin C1a (4). Impurities 1, 2, 4 are novel compounds and the NMR data of these isolates were first reported in this paper. The possible mechanism for the formation of these impurities is also discussed.

Combination of aqueous two-phase extraction and cation-exchange chromatography: New strategies for separation and purification of alliin from garlic powder

In this study, a two-step process combining aqueous two-phase extraction (ATPE) with chromatography was developed for extraction and purification of alliin from garlic powder. The partition coefficient and yield value of alliin in different types of aqueous two-phase system (ATPS) were compared and response surface methodology (RSM) was used for analyzing and optimizing the extraction process. The optimal extraction conditions of 19% (w/w) (NH4)2SO4, 20% (w/w) 1-prpanol, at 30°C, pH 2.35 with 8.54% (w/w) NaCl was chosen based on the higher yield. Compared to the results obtained with the conventional extraction method, this method had an evident advantage on yield (20.4mg/g versus the original yield of 15.0mg/g) and the concentration of alliin in extract solution by ATPE was close to three times of that with conventional extraction. The purification of alliin was carried out with the ammonium form of sulfonic acid cation-exchange resins 001×7. Sample solution with alliin concentration of 1mg/mL was passed through resins and the desorption of alliin was accomplished by water at the flow velocity of 0.5mL/min, 1.5mL/min, respectively. The purity and recovery of alliin after purification were 80% and 76%, respectively.

Removal of Hardness of Earth Alkaline Metals from Aqueous Solutions by Ion Exchange Method

An ion exchange process was introduced as an approach for softening of artificial hard water solutions. A strong acid cation exchange resin, Amberlite IR 120 [Na+], was used to reduce the hardness of water with the matrix of styrene-divinylbenzene copolymer having functional group as sulfonate. The ion exchange behavior of the ions of calcium and magnesium in synthetic solutions of hard water was investigated with the variables depending on pH, stirrer speed of the solutions and amount of the resin as a function of contact time between resin phase and hard water solution. The maximum ion exchange capacity was found to be 68 mg/g for Ca(II) and 12 mg/g for Mg(II) at pH 3.0. The method is a simple and efficient one to remove calcium and magnesium hardness from hard water solutions with the resin having more selectivity for calcium.

Production of citric acid using its extraction wastewater treated by anaerobic digestion and ion exchange in an integrated citric acid-methane fermentation process

In order to solve the problem of extraction wastewater pollution in citric acid industry, an integrated citric acid-methane fermentation process is proposed in this study. Extraction wastewater was treated by mesophilic anaerobic digestion and then used to make mash for the next batch of citric acid fermentation. The recycling process was done for seven batches. Citric acid production (82.4 g/L on average) decreased by 34.1 % in the recycling batches (2nd-7th) compared with the first batch. And the residual reducing sugar exceeded 40 g/L on average in the recycling batches. Pigment substances, acetic acid, ammonium, and metal ions in anaerobic digestion effluent (ADE) were considered to be the inhibitors, and their effects on the fermentation were studied. Results indicated that ammonium, Na(+) and K(+) in the ADE significantly inhibited citric acid fermentation. Therefore, the ADE was treated by acidic cation exchange resin prior to reuse to make mash for citric acid fermentation. The recycling process was performed for ten batches, and citric acid productions in the recycling batches were 126.6 g/L on average, increasing by 1.7 % compared with the first batch. This process could eliminate extraction wastewater discharge and reduce water resource consumption.

ION-EXCHANGE RESIN–CATALYZED SYNTHESIS OF POLYOXYMETHYLENE DIMETHYL ETHERS: A PRACTICAL AND ENVIRONMENTALLY FRIENDLY WAY TO DIESEL ADDITIVE

Polyoxymethylene dimethyl ethers (PODEn) were synthesized via the reaction between dimethoxymethane (DMM) and trioxymethylene catalyzed by CT175, a macroporous strongly acidic cation-exchange resin. The influences of reaction conditions such as catalyst types, reaction temperature, time, pressure, catalyst dosage, and mass ratio of DMM to trioxymethylene were also investigated. Under the optimized conditions of m(dimethoxymethane):m(trioxymethylene) = 2.5:1, CT175 (7.5 wt.%), 90°C, 0.5 h, and 1.5 MPa, the conversion of trioxymethylene and the selectivity to PODE3-8 was obtained as high as 89.0% and 64.2%, respectively. Moreover, the resin catalyst can be reused up to 20 times without obvious change in its activity. The 100% atom efficiency, green reaction process, mild reaction conditions, as well as easy workup make the protocol advantageous and acceptable.

Reaction Kinetics of Catalytic Esterification of Nonanoic Acid with Ethanol over Amberlyst 15

AbstractThe kinetic behaviour of heterogeneous esterification of nonanoic acid with ethanol over an acidic cation exchange resin, Amberlyst 15, was investigated in a batch reactor and effect of various parameters such as catalyst loading, molar ratio and reaction temperature on degree of fractional conversion has been studied. Internal and external diffusions were found to be negligible in this study. Nonideality of the liquid phase was taken into account by using activities instead of concentrations. The activity coefficients were estimated using UNIFAC group contribution method. Eley–Rideal (ER) kinetic model was used to interpret the obtained kinetic data. The temperature-dependent initial reaction rate constants and the adsorption coefficients for ethanol and water were determined from the observed experimental data obtained at different initial concentration of acid, alcohol and water. Activation energy and pre-exponential factor of the reaction were found to be 53.7 kJ mol−1and 1.51×105l2g−1mol−1h−1respectively.

Removal of Boron from the Bittern Solution of Lake Qarun Water by Electrically Assisted Ion Exchange

In this study, we investigated the use of ion exchange processes using a chelating resin, Diaion CRB02 for the removal of boron from the bittern solution left after the extraction of sodium sulfate and sodium chloride from the water of Lake Qarun, located in Egypt. The effects of parameters such as the initial boron concentration and the pH value on the breakthrough volume were studied using boric acid as the synthetic simulant of the bittern solution. The breakthrough capacity was shown to be directly proportional to the height of the resin bed and inversely proportional to the initial boron concentration and the feed flow rate. In addition, the optimum pH for boron removal was found to be 10. An electrically assisted process, which had been found to be effective for a strongly acidic cation exchange resin, was also applied to the ion exchange by taking the electric current as a parameter. However, no remarkable effect was observed, which may result from the difference in the function group between an ion exchange resin using electrostatic attractive force and a chelating resin using complex formation.

Degradation of Ion Exchange Resin by Vanadium-Containing Water

Irreversible swelling of strongly acidic cation exchange resins (SAC) had been observed when ground water in a volcanic zone was used as raw water for ion-exchange pure water production facilities. Vanadium has been presumed to act as an oxidative substance to the SAC resin, with the analysis of the ground water. It was confirmed that hydroxyl radicals were generated when the metavanadate anions were present in strong a sulfuric acidic solution, and the amount of generated radicals changed with the molar ratio of metavanadate to sulfuric acid. When an ammonium vanadate solution was passed through a resin layer of normal cross-linked type SAC, eluted polystyrene sulfonic acids were detected in the treated water. However, highly cross-linked SAC resin is resistive to oxidative degradation in vanadate containing water.

Separation of toxic Pb2+ metal from aqueous solution using strongly acidic cation-exchange resin: analytical applications for the removal of metal ions from pharmaceutical formulation

A strongly acidic cation-exchange resin Amberlite IR-120 was successfully used for the separation of toxic metal ions. The distribution coefficient values for various metal ions were performed in different acidic mediums using Amberlite IR-120 resin columns. On the basis of distribution coefficient values, Amberlite IR-120 was found to be selective for Pb2+ ion. A number of important quantitative binary separations of metal ions viz. Cd2+– Pb2+, Hg2+– Pb2+, Cu2+– Pb2+, Zn2+– Pb2+, Cd2+– Al3+, and Mg2+– Al3+ were achieved on the columns of this resin. In order to demonstrate the practical utility of these separations, Mg2+ and Al3+ were determined in commercially available pharmaceutical preparation namely digene using Amberlite IR-120 resin columns. The regeneration studies were carried out which demonstrated a decrease in the recovery of Pb2+ from 88 to 74% after five consecutive cycles.

Selective elution of nickel and cobalt from iminodiacetic acid cation exchange resin using ammoniacal solutions

Nickel and cobalt were eluted from iminodiacetic acid functionalized ion exchange resin by ammoniacal eluents. The highest recovery of nickel and cobalt was achieved using a mixture of aqueous ammonia, ammonium sulphate, and magnesium sulphate. The use of ammonium sulphate yielded a higher extent of nickel desorption than the use of ammonium carbonate. The presence of a divalent metal salt such as magnesium sulphate, calcium sulphate, or manganese sulphate was found to increase the extent of nickel desorption. Magnesium was found to be most suitable for this purpose. Nickel and cobalt on the resin are displaced by magnesium during this process. The selectivity of this elution process varies by metal. Aluminium and iron show little or no affinity for ammoniacal elution. Calcium and manganese desorb to a limited extent. The kinetics of nickel desorption in aqueous ammonia–ammonium sulphate–magnesium sulphate solution are slower than that of sulphuric acid elution. When resin loaded with magnesium is contacted with aqueous nickel sulphate, nickel sulphate will displace magnesium on the resin. This reaction occurs on a similar time scale as that of protonated resin.

Concentration of ammonium from municipal wastewater using ion exchange process

The scope of this study is concentration of ammonium from municipal wastewater using ion exchange process. Four types of ion exchange materials were tested in packed bed columns, namely strong and weak acid cation exchange resins and natural and synthetic zeolites. In total 23 runs of saturation and regeneration were done using synthetic wastewaters of different kinds and pretreated municipal wastewater. Due to its high exchange capacity and fast regeneration strong acid cation exchange resin was found to be the most suitable for ammonium concentration under condition that selectivity of ammonium removal is not of a main concern and it allows concentrating ammonium from 27 to 580mg NH4-N/L. If selective ammonium removal is required, natural zeolite should be used instead. Regeneration with 0.17M HCl and 0.17–0.51M NaCl was tested and suitability of different regenerants for different technologies of spent regenerant treatment was discussed. It was shown that electric conductivity measurements can be used for detection of breakthrough and estimation of ammonium concentration in outflow from an ion exchange column. Breakthrough curve fitting with Thomas and Adams–Bohart models was performed which gave information about the maximum exchange capacity of materials and kinetics of ion exchange.

Acarbose Isolation with Gel Type Strong Acid Cation Exchange Resin: Equilibrium, Kinetic and Thermodynamic Studies

Acarbose, a potent α-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001×4 was applied to isolate acarbose from fermentation broth. It was demonstrated that cation exchanger 001×4 displayed a large adsorption capacity and quick exchange rate for acarbose. The static adsorption equilibrium data were well fitted to the Langmuir equation. Column adsorption experiments demonstrated that high dynamic adsorption capacity was reached at bed height of 104.4 mm, feed flow rate of 1.0 ml·min−1 and acarbose concentration of 4.0 mg·ml−1. Under the optimized conditions, the column chromatography packed with cation exchanger 001×4 recovered 74.3% (by mass) of acarbose from Actinoplanes utahensis ZJB-08196 fermentation broth with purity of 80.1% (by mass), demonstrating great potential in the practical applications in acarbose separation.

Polymer Ion-Exchangers Modified with Zirconium Hydrophosphate for Removal of Cd2+ Ions from Diluted Solutions

Hybrid ion-exchangers have been synthesized by modification of strongly acidic cation-exchange resin with zirconium hydrophosphate. The samples were investigated with scanning and transmission electron microscopy and standard contact porosimetry. Single nanoparticles and their aggregates have been found in the polymer. The nanoparticles in transport pores increase the electrical conductivity of ion-exchanger from 0.21 to 0.65 Ohm−1 m−1. The diffusion coefficient of Cd2+ ions reaches 2.43 × 10−11 m2 s−1 for initial resin and (2.50–4.34) × 10−11 m2 s−1 for nanocomposites. The inorganic constituent improves Cd2+ recovery from a solution, which contains also Ca2+ and Mg2+. The degree of Cd2+ removal is 18% for non-modified resin and 99% for the sample containing 38 mass% zirconium phosphate.

INVESTIGATE THE ADSORPTION KINETICS AND ISOTHERM MODELS OF Pb(II) IONSREMOVAL BY RESINEXTMK-8 STRONG ACID CATION EXCHANGE RESIN.

In the present study we investigated the adsorption kinetics and isotherm models of Pb(II) removal by ResinexTM K-8 strong acid cation exchange resin at different temperatures. Adsorption kinetics is investigated to develop an understanding of controlling reaction pathways (e.g. chemisorptions versus physisorption) and the mechanisms (e.g. surface versus intraparticle diffusion) of adsorption reactions. Kinetic data can be used to predict the rate at which the target contaminant is removed from aqueous (pure water) and aqueous-organic solutions (formic, acetic, propionic) and equilibrium adsorption isotherms are used to quantify the adsorptive capacity of an adsorbent. The results can be used to assess the utility of the adsorbent for the heavy metal removal, in particular Pb(II) ions adsorption, in the field scale. Thermodynamic parameters, the Gibbs free energy change (∆G), enthalpy change (∆H), and entropy change (∆S), were calculated and show that adsorption of Pb(II) ions is spontaneous and endothermic in nature.

Removal of Tetramethylammonium Hydroxide From Solution Using Ion Exchange

Ion exchange is used to remove tetramethylammonium hydroxide from an aqueous solution. Both strong acid cation (SAC) and weak acid cation (WAC) exchange resins show excellent uptake of the TMA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ion. The pseudo-second-order kinetic model fits the data of uptake rate well. When using an SAC exchange resin, the pH does not affect the uptake efficiency, while that of the WAC exchange resin is strongly affected by the pH. Regeneration experiments show excellent performance of resins after five cycles. The selectivity coefficient of TMA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> over H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> for SAC is calculated as 5.16, while for WAC, in the bulk solution, the selectivity coefficient is notably lower (6.45×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ). The presence of competing ions interfere with the TMA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> uptake, of which Mg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> has the most notable effect. The ion exchange model is applied to obtain resin selectivity over the TMA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ion as well.

Development of a Modified Ion Exchange Resin Column for Removal of Gadolinium From the Moderator System of PHWRs

Gadolinium is used as neutron poison in Pressurized Heavy Water Reactors (PHWR) at 15 ppm concentration during emergency shut down and at 2 ppm during start up of the reactor. The pHa range of 5–5.5 is recommended based on the acidity requirement for maintaining gadolinium in the solution and to minimize corrosion of moderator system structural materials and radiolysis. Gadolinium has to be progressively removed as the reactor goes to power. It has been observed that gadolinium precipitates in the purification system consisting of ion exchange columns. Experimental investigations were carried out to understand the phenomenon of precipitation of gadolinium in the weak base ion exchange resin. Attempts were made to selectively cap the strong base groups in weak base resin with nitrate to prevent precipitation of gadolinium. Based on studies carried out on gadolinium pick-up and radiation decomposition of weak base anion exchange resins, a simple mixed resin column consisting of nitrate treated poly acrylic based macroporous weak base resin and a strong acid cation exchange resin has been recommended for the removal of gadolinium. It does not precipitate gadolinium and gives optimum chemistry parameters in the outlet.