Acid Cation Exchange Research Articles

Extraction and derivatization of chemical weapons convention relevant aminoalcohols on magnetic cation-exchange resins

Analysis and identification of nitrogen containing aminoalcohols is an integral part of the verification analysis of chemical weapons convention (CWC). This study was aimed to develop extraction and derivatization of aminoalcohols of CWC relevance by using magnetic dispersive solid-phase extraction (MDSPE) in combination with on-resin derivatization (ORD). For this purpose, sulfonated magnetic cation-exchange resins (SMRs) were prepared using magnetite nanoparticles as core, styrene and divinylbenzene as polymer coat and sulfonic acid as acidic cation exchanger. SMRs were successfully employed as extractant for targeted basic analytes. Adsorbed analytes were derivatized with hexamethyldisilazane (HMDS) on the surface of extractant. Derivatized (silylated) compounds were analyzed by GC–MS in SIM and full scan mode. The linearity of the method ranged from 5 to 200ngmL−1. The LOD and LOQ ranged from 2 to 6ngmL−1 and 5 to 19ngmL−1 respectively. The relative standard deviation for intra-day repeatability and inter-day intermediate precision ranged from 5.1% to 6.6% and 0.2% to 7.6% respectively. Recoveries of analytes from spiked water samples from different sources varied from 28.4% to 89.3%.

Bipolar membrane modified by cation/anion exchange nanofibers containing copper phthalocyanine derivatives with different substituents

Carboxymethyl cellulose (CMC)-polyvinyl alcohol (PVA) and chitosan (CS)-polyvinyl alcohol were cross-linked by Fe3+ and glutaraldehyde respectively to prepare the cation exchange membrane layer and the anion exchange membrane layer, polyvinyl alcohol-sodium alginate (SA)-copper phthalocyanine tetrasulfonic acid (CuTsPc, or copper tetracarboxy phthalocyanine: CuTcPc) cation exchange nanofibers or polyvinyl alcohol-chitosan-copper tetraaminophthalocyanine (CuTAPc) anion exchange nanofibers prepared by electrospinning technique were introduced into the interlayer to obtain the modified bipolar membrane (BPM). The experimental results showed that in comparison with the BPM without the cation/anion exchange nanofibers interlayer, the water splitting efficiency of the modified BPM was obviously increased, and its membrane impedance decreased. When the concentration of CuTsPc in the PVA-SA-CuTsPc nanofibers was 3.0 %, the transmembrane voltage drop (IR drop) of the CMC-PVA/PVA-SA-CuTsPc/CS-PVA BPM was as low as 0.5 V at a high current density of 90 mA·cm−2.

無機-有機複合型強酸性陽イオン交換体による汚染水からの核種分離に関する研究

無機-有機複合型強酸性陽イオン交換体による汚染水からの核種分離に関する研究

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.

Radiation stable graft copolymers based on petroleum asphaltite

A new type of the latent reactivity of petroleum asphaltites, which manifested itself under the action of γ-radiation, was determined. γ-Radiation facilitates the conversion of the asphaltites into macromolecular initiators onto which the macromolecular chains of styrene, methyl methacrylate, and acrylic acid are grafted. Based on this new type of reactivity, phosphoric acid cation exchangers and multifunctional cation exchangers were synthesized using the most environmentally appropriate non-power-consuming wasteless method.

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.

Preparation of high-purity 68Ga solutions by ion exchange in mixed acetone-hydrochloric acid medium

Ion-exchange behavior of 68Ga in the mixed HCl-acetone medium on cation and anion exchangers was studied. The equilibrium gravimetric distribution coefficients of 68Ga on Dowex AG 50W×8 strongly acidic cation exchanger in the H+ form and on Dowex AG 1×8 strongly basic anion exchanger in the Cl− form in mixed HCl-acetone solutions at HCl concentrations in the range 0.1–3 M and acetone volume fractions in the range 0–90% were determined. The dynamic characteristics of the 68Ga ion exchange in mixed HCl-acetone solutions were studied. A process based on the data obtained was developed for preparing 68Ga solutions in 0.1 MHCl of high chemical and radiochemical purity, suitable for producing 68Ga radiopharmaceuticals of required quality (radiochemical purity 98.1 ± 1.4%).

Preparation and High Reusability of a Novel Acid-Resistant Magnetic Weak Acid Resin for Ni2+ Removal

A novel magnetic weak acid resin (MWA06) was successfully synthesized and characterized. To enhance the acid resistance and lipophilicity of the γ-Fe2O3 particles, a titanate coupling agent (TCA) was employed to modify the particle surface. Afterward, the resultant resin was obtained through copolymerization and hydrolysis reactions, with a specific saturation magnetization of 10.9 emu/g and weak acid cation exchange capacity of 8.44 mmol/g. Leaching tests in acid showed that the magnetic resin was stable at pH 2. The presence of Ca2+ in the solution had an obviously negative impact on the adsorption of Ni2+, whereas Na+ did not influence the adsorption process. The adsorption of Ni2+ was pH-dependent as the uptake capacity increased from 0.06 to 2.81 mmol/g with the pH rising from 2 to 6. The desorption efficiency was nearly 100% by using 0.01 M HCl solution as desorption agent. Moreover, MWA06 could maintain high adsorption capacities for at least 10 regeneration cycles, indicative of a good reusability.

Влияние полиакрилатных ингибиторов на слабокислотный катионит в установках обработки продувочной воды оборотных систем охлаждения

Влияние полиакрилатных ингибиторов на слабокислотный катионит в установках обработки продувочной воды оборотных систем охлаждения

Acid–base properties, FT-IR, FT-Raman spectroscopy and computational study of 1-(pyrid-4-yl)piperazine

We report the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy for 1-(pyrid-4-yl)piperazine (PyPi). Single crystals of PyPi suitable for X-ray structural analysis were obtained. The acid–base properties are also reported. PyPi supported on a weak acid cation-exchanger in the single protonated form and this system can be used efficiently as the solid supported analogue of 4-N,N-dimethyl-aminopyridine. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule and with the molecular electrostatic potential map was applied for the reactivity assessment of PyPi molecule toward proton, electrophiles and nucleopholes as well. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated first hyperpolarizability of PyPi is 17.46 times that of urea.

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.

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.

EFFECTS OF DIFFERENT REACTION CONDITIONS ON THE SYNTHESIS OF BENZYL ACETATE

Effects of different reaction conditions such as different water carrying agents, the amount of water carrying agent, the calcination temperature, the calcination time and the amount of catalysts, the reaction time, the molar ratio of acetic acid to benzyl alcohol, the reaction temperature, the amount and type of catalyst (tris(trimethylsilylmethyl)tin chloride, S 2 O 8 2- - Fe 2 O 3 – CoO, N-methylpyrrolidone hydrosulfate, FeCl 3 (<46 %)/carbon, SO 4 2- - ZrO 2 - Nd 2 O 3 and strong acid cation exchange resin loaded Fe 3+ ) on the synthesis of benzyl acetate from benzyl alcohol and acetic acid are discussed.

Nickel removal from electroplating waste water using stand-alone and electrically assisted ion exchange processes

Wastewater discharged from metal-finishing processes usually contains nickel, a hazardous substance that is used extensively in the surface finishing industry. In the present study, an acidic solution containing nickel was treated using strong acid cation exchange resin. A continuous lab-scale cation exchange arrangement permitting the assessment of electric current as an enhancement mechanism was designed and utilized at different flow rates successfully. Applying the electrical potential enhanced the nickel removal by 12.7 % at flow rate 240 ml/h, and 2.5 % at flow rate 500 ml/h. Nickel recovery has been also investigated using hydrochloric acid as an eluent with and without electric current enhancement.

Pre-Concentration of Traces of Cadmium, Cobalt, Nickel and Lead in Natural Honeys by Solid Phase Extraction Followed by Their Determination Using Flame Atomic Absorption Spectrometry

A simple and fast sample preparation procedure for the determination of traces of Cd, Co, Ni and Pb in honeys was proposed. It included the preparation of acidified sample solutions of honeys, the retention of elements of interest on resin beds of a strongly acidic gel cation exchanger Dowex 50W×8-400, and their elution with a 3.0 mol L-1 HCl solution prior to measurements by flame atomic absorption spectrometry (FAAS). The method provided the precision and the accuracy better than 4.5% and detection limits of 0.005 µg g-1 (Cd), 0.015 µg g-1 (Co, Ni) and 0.073 µg g-1 (Pb). The reliability of results obtained with the developed procedure and FAAS was validated by the recovery test and the comparison with results achieved using the wet digestion and inductively coupled plasma optical emission spectrometry. The method was applied for the analysis of sixty nine samples of honeys originated from the Lower Silesia region (southeast Poland). It was found that Cd, Co and Pb were under detection limits, while Ni was determined in nine honeys at the level of 0.19-0.93 µg g-1.