Polymeric Ion-exchange Resins Research Articles

Utilization of Electrodeionization for Lithium Removal.

In this work, usage of a hybrid polymeric ion exchange resin and a polymeric ion exchange membrane in the same unit to remove Li+ from aqueous solutions was reported. The effects of the applied potential difference to the electrodes, the flow rate of the Li-containing solution, the presence of coexisting ions (Na+, K+, Ca2+, Ba2+, and Mg2+), and the influence of the electrolyte concentration in the anode and cathode chambers on Li+ removal were investigated. At 20 V, 99% of Li+ was removed from the Li-containing solution. In addition, a decrease in the flow rate of the Li-containing solution from 2 to 1 L/h resulted in a decrease in the removal rate from 99 to 94%. Similar results were obtained when the concentration of Na2SO4 was decreased from 0.01 to 0.005 M. The selectivity test showed that the simultaneous presence of monovalent ions such as Na+ and K+ did not change the removal rate of Li+. However, the presence of divalent ions, Ca2+, Mg2+, and Ba2+, reduced the removal rate of Li+. Under optimal conditions, the mass transport coefficient of Li+ was found as 5.39 × 10-4 m/s, and the specific energy consumption was found as 106.2 W h/g LiCl. Electrodeionization provided stable performance in terms of the removal rate and transport of Li+ from the central compartment to the cathode compartment.

Etherification of olefins from catalytic cracking gasoline to increase its octane number

This study explores the etherification of the olefins in the Fluid Catalytic Cracking (FCC) gasoline, without previous separation of isoamylenes fraction. The bench- scale experiment demonstrated that etherification performed with Purolite CT-275, a macroporous polymeric ion-exchange resin, and different alcohols (methanol, bioethanol, isopropanol and 1-butanol) produces significant conversion of olefins, even for the heavier C6-C9, so that overall conversion of olefins reaches 70% in reaction with ethanol and 83% with isopropanol. As a result, the Motor Octane Number of the gasoline increases by up to two valuable units. The optimization of the reactive distillation parameters was performed by simulation in CHEMCAD 8 and a process flow was suggested for the etherification sequence, in the FCC unit.

Recovery of Rare Earth Elements from acidic mine waters by integration of a selective chelating ion-exchanger and a solvent impregnated resin

A polymeric ion-exchange resin, incorporating methyl-amino-phosphonic (TP260) functionalities, and a solvent impregnated resin (SIR) incorporating tri-methylpentylphosphinic acid (TP272), were evaluated for the selective separation of Rare Earth Elements (REE) from Transition (TE), post -Transition (PTE), and Alkaline Earth (AE) Elements in acidic mine waters (AMW). The influence of the functional groups nature and the acidity dependence were studied and their effects on efficiencies for REE removal and separation from TE/PTE were analysed Both resins provided good separation factors of REE from TE/PTE by acidity control of the treated effluent once Fe(III), the major component in AMW, had been removed by precipitation. The TP272 resin, containing tri-methylpentylphosphinic acid (Cyanex 272) onto the polymeric network, showed higher affinity towards Heavy REE (HRRE) than for Light REE (LRRE) by acidity control (pH>4).Higher pre-concentration factors were achieved for TP272 impregnated resin (e.g., 20–30) in comparison with the TP260 phosphonic resin (2−5), as the pH extraction window is in the moderate pH region (1−5). The integration in series of both resins could be used to separate and recover HREE and LREE from TE/PTE from AMW generated concentrates could be used to recover REE as secondary resources for the clean energy technology industry.

Polymeric ion exchanger supported ferric oxide nanoparticles as adsorbents for toxic metal ions from aqueous solutions and acid mine drainage.

Acid mine drainage (AMD) is a worldwide industrial pollution of grave concern. AMD pollutes both water sources and the environment at large with dissolved toxic metals which are detrimental to human health. This paper reports on the preparation of polymeric ion exchange resins decorated with hydrated iron oxides and their application for the ecological removal of toxic metals ions from AMD. The hydrated iron oxide particles were incorporated within commercial chelating ion exchange resins using the precipitation method. The synthesised hybrid resins were then characterized using appropriate spectroscopic and solid-state techniques. The metal ion levels were measured using the inductively coupled plasma-optical emission spectrometer (ICP-OES). The optimization of contact time, pH, and adsorbent dosage were conducted to enhance the efficiency of adsorption of toxic metals onto the hybrid organic/inorganic nanosorbents. Kinetics and adsorption isotherms were constructed to study the adsorption mechanisms of the adsorbents. The results showed that the dispersed Fe-O is hydrated and amorphous within the hybrid materials. The adsorption kinetics followed the pseudo-second-order shown by the high R2 values. The hybrid adsorbents were finally tested on environmental AMD samples and were able to remove toxic metals Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn at various removal degrees. Solution pH played a crucial role in the adsorption of toxic metals on hybrid iron oxide adsorbents. The hybrid TP-260 HFO had higher affinity for toxic metals than other prepared adsorbents thus has a potential for acidic mine water pollution remediation. The adsorbed Al(III) can be recovered using NaCl-NaOH binary solution from the loaded resins.

Selective separation of lactic acid after fermentation process using novel polymeric ion-exchange resin

Selective separation of lactic acid after fermentation process using novel polymeric ion-exchange resin

Towards Cleaner Methods for the Production of Mo-99 Using Refractory Ceramics and its Relevance to Actinide Partitioning and Transmutation

Mo-99 is the most utilized isotope in nuclear medicine accounting for over 30 million medical diagnostic procedures annually worldwide. The process for the production of Mo-99 through fission of U-235 normally involves the irradiation of UAlx dispersion plate fuel in a research reactor, the subsequent dissolution of the fuel plate, the selective separation of the Mo-99 from all of the other fission products and possibly also the recovery of U-235 for future reuse. Compared to the amount of product recovered, copious radioactive waste is generated during the Mo-99 production process. Gaseous wastes are produced at the head-end during the plate dissolution and several liquid wastes are produced during the recovering of Mo-99 using solid extractants, typically polymeric ion exchange resins, which themselves constitute an additional waste stream. It would be extremely advantageous to devise a new process that generates little or no waste. We have been working on a new strategy for the production of fission Mo-99 that involves replacing the dispersion plate targets that are used in the traditional process with inert or active matrix fuel particles that do not need to be dissolved. In one embodiment of the strategy the preparation of new highly porous ZrCx and graphite-ZrCx composite target kernels are used that are prepared through polymer templating. The surface properties of these porous materials have been studied and are such that they can be easily loaded with uranium, or for that matter, with any other actinide. In our work we are exploring the possibility of selectively extracting the Mo-99 from the irradiated target kernels by either solution or gas-phase methods and then easily recover the uranium. The fission product-containing kernels can be oxidized in air to generate ZrO2 that can act as a stable host material either alone or as part of a multiphase ceramic matrix or possibly even as an actinide transmutation host. At the conceptual level, this Mo-99 production strategy could be applicable to the recycling of actinides within the context of advanced fuel cycles and it could indeed act as a useful test-bed.

Elicitation and in situ adsorption enhanced secondary metabolites production of Tripterygium wilfordii Hook. f. adventitious root fragment liquid cultures in shake flask and a modified bubble column bioreactor

The experiments of elicitation and in situ adsorption were conducted in shake flasks and then tested in a modified bubble column bioreactor for enhancing the productions of three active metabolites in Tripterygium wilfordii Hook. f., triptolide, wilforgine and wilforine. Methyl jasmonate was screened out as the elicitor and the non-ionic polymeric ion-exchange resin of Amberlite(®) XAD-7 was used for in situ product removal and protecting the alkaloids from degradation in the medium. In shake flask experiments, 3.55-fold, 49.11-fold, and 10.40-fold of triptolide, wilforgine, and wilforine, respectively, could be recovered from the medium and XAD-7 resin by elicitation and in situ product removal, compared with the control. The modified 10L bubble column bioreactor had similar productions of the three active metabolites but needed a further optimization of parameters for better growth of adventitious roots.

Hepatoprotective activity of extracted anthocyanins fraction of red radish (<i>Raphanus sativus</i> L) on albino rats

Objective: We investigated hepatoprotective and antioxidant activity of extracted anthocyanins fraction of red radish for the first time. Methods: Anthocyanins fraction of red radish (Raphanus sativus; AFRS) was selectively extracted by employment of polymeric ion-exchange resin. AFRS was evaluated for antioxidant and hepatoprotective activity against carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. The animals were divided into seven groups of six animals each. Group I (control) received vehicle. Group II (drug control) received AFRS. Group III (toxicant) received CCl4. Group IV, V and VI received AFRS at doses of 50, 100 and 150 mg/kg po, respectively. Group VII (standard) received silymarin. Various biochemical parameters like alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TB) and direct bilirubin (DB) levels in serum as well as the glutathione (GSH) and malondialdehyde (MDA) levels in the liver were determined. Histopathological changes in the liver were also studied. The activity of AFRS was compared with the reference drug silymarin. Results: The yield of AFRS was found to be 0.084% (w/w). AFRS treated group did not show any significant change in the activity of serum ALT, AST, ALP, TB, DB, MDA and GSH level compared to control group. CCl4 significantly raised the serum level of all biochemical parameters (except GSH) in the toxicant group. The pre-treatment of AFRS for seven days had reversed the alteration of biochemical parameters towards normal, and the effects were comparable to standard drug (silymarin 100 mg/kg). The animals received pre-treatment of AFRS showed amelioration in necrotic zones and hepatocellular degeneration. Conclusion: This study demonstrates the antioxidant and hepatoprotective activity of anthocyanins fraction isolated from Raphanus sativus and thus scientifically supports the usage of it as food colorant and also justifies the use of the crude extracts of radish to treat various liver ailments in Indian folk medicine.

Evaluation of a Primary Amine-Functionalized Ion-Exchange Resin for CO2 Capture

A primary amine-functionalized polymeric ion-exchange resin (Lewatit VP OC 1065, Lanxess) was evaluated for use in CO2 capture applications. The polymeric resin was characterized by SEM, DRIFTS-IR, N2 adsorption isotherms, and packed bed sorption measurements to determine some of the characteristic properties of the resin. Capture capacities ranging from 1.85 to 1.15 mol CO2/kg sorbent were obtained in a packed bed reactor exposed to 10 vol % CO2 in N2 at adsorption temperatures ranging from 30 to 70 °C. The capture capacity of the resin was stable over 18 adsorption/regeneration cycles. The resin was evaluated through thermogravimetric analysis to have a low moisture adsorption (1.5 mol H2O/kg sorbent). It is possible to completely regenerate the resin under 1 atm of CO2 at 200 °C.

A convenient access to 1,3-disubstituted furo[3,4-b]indoles by acid ion-exchange resin-catalyzed furan formation

Efficient synthesis of furo[3,4-b]indoles starting from the corresponding indole is reported. The first route involves derivatization, protection, and deprotection steps, which stretch the syntheses. The second method provides a shorter and more efficient strategy to accessing the furoindole. The innovation starts with alkylation at C-2 of the indole presenting at the C-3 position a ketone-acetal, followed by the cycloaromatization catalyzed by polymeric ion-exchange resins. The second route represents a significant improvement over other methods previously described.

Photocatalytic degradation of hydroquinone using HFO supported polymeric material

Photocatalytic degradation of hydroquinone (HQ) has been investigated using polystyrene-divinyl benzene polymeric hybrid ion exchange (HIX) resin. The polymeric material was modified with iron cations and thermally treated at 60°C to produce nano FeOOH species (HFO) supported on the HIX polymer and denoted as Fe-HIX. The obtained material was characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). The data obtained for the degradation of HQ indicate that the addition of Fe-HIX material to the degraded HQ solution greatly enhance the rate of degradation in the presence of H2O2. Since the rate of degradation was found to be governed by the adsorption mechanism, so the adsorption isotherms were established in dark at different pH values and different doses from resin correlated with the obtained data of degradation.

Kinetics of esterification of propionic acid with n-amyl alcohol in the presence of cation exchange resins

Esterifications of n-amyl alcohol with propionic acid catalyzed by macroporous (Amberlyst-15) and microporous (Dowex 50 W and Amberlite IR-120) polymeric ion-exchange resins were carried out between 333–348 K. When these catalysts were used as commercially available, Amberlyst-15 was observed to be the most effective catalyst with respect to rate constants, but after drying it became the less effective one. The reaction rate increased with increase in catalyst concentration and reaction temperature. Stirrer speed and different mesh sizes had virtually no effect on the rate under the experimental conditions. The effect of divinylbenzene content was examined for the microporous resin Dowex 50W, and the results showed that the propionic acid conversion decreased as the divinylbenzene content was increased. The rate data were correlated with a second-order homogeneous reaction model. The apparent activation energies, reaction enthalpies and entropy values were calculated for each catalyst. Reaction monitoring is simple and fast by volumetric method and the reproducibility of this method was the order of ± %2.54.

Volumetric, Chromatographic, Refractometric Studies on the Esterification of Methanol with Acetic Acid in the Presence of Cation-Exchange Resins

Summary Esterification of methyl alcohol with acetic acid catalysed by commercially available polymeric ion-exchange resins Amberlyst-15, Dowex 50W and Amberlite IR-120 was carried out in the temperature ranging between 323–338K. Mesh sizes and divinylbenzene contents had virtually no effect on the rate the data of which were correlated with a second-order homogeneous reaction. The samples were analysed with gas chromatography, refractometry and volumetry. The reproducibilities were the order of ±2.89%, ±5.07% and the order of ±6.58% respectively for the volumetric, chromatographic and refractometric methods.

Uranium recovery from industrial effluent by ion exchange—column experiments

The recovery of uranium from nuclear industrial effluent has been studied using laboratory column and polymeric ion exchange resin. The industrial effluent, at pH around 10, contains uranium (40 mg/L), ammonium (80 g/L) and carbonate (170 g/L) and cannot be discharged without previous treatment. Uranium is in the form of uranyl quadrivalent complex anions [UO 2(CO 3) 3] 4−. The resin IRA 910 U was employed for its specific application for uranium extraction. Adsorption was carried out at flow rate of 1.0, 2.0, and 5.0 mL/min, which corresponds to a retention time of 10, 5.0 and 2.5 min, respectively. The use of ion the exchange technique makes the recovery of more than 98% of the uranium possible. Elution was carried out with ammonium carbonate solutions and also with the diluted effluent. The eluate contained uranium ranging from 2.4 to 2.7 g/L. The solution eluate might be recycled back into the process with the advantage of saving this valuable metal.

Characterisation of the surface of oxidised carbon adsorbents

The surface reactivity and functional group content of a series of oxidised active carbons has been assessed by elemental analysis, electrophoretic mobility measurements and potentiometric titrations. Oxidation of carbons with hot air resulted in a greater proportion of relatively weak acidic surface functional groups (i.e., phenolic), whereas nitric acid modification produced a greater amount of carboxylic groups. Electrophoretic mobility measurements suggest that the carbon surface is negatively charged within the range of the pH values studied. pH titration results indicate that the surface acidity of active carbons is stronger than that of a commercial polymeric carboxylic acid ion exchange resin. Possible mechanisms of carbon surface oxidation are discussed.

Solid acid catalysis using ion-exchange resins

In this review article, we describe the use of commercially available polymeric ion-exchange resins for a range of industrially important transformations. Recent developments both on the materials design and applications will be described. Examples of high catalytic activity will be described in areas ranging from alkylation, transalkylation, isomerization, oligomerization, acylation, esterification and nitration. The two main classes of ion-exchange resins are based upon styrene-based sulfonic acids (Amberlyst ® and Dow type resins), which show very high activity in the areas of esterification and etherification, to the perfluorosulfonic acid-based catalysts including the recently developed Nafion ® resin/silica nanocomposites. These show very high activity in the area of linear alkyl benzene formation, isomerization, and some select acylation type chemistries. These new types of catalysts (which have been used commercially) are adding to the ever-growing portfolio of highly active solid acid catalysts, which couple both economic and environmental drivers to improve organic transformations within the chemical industry.

Adsorption of acetic acid on ion-exchange resins in non-aqueous conditions

Sorption of acetic acid from ethyl acetate and ethanol (95%) has been investigated using polymeric ion-exchange resins with a view for being possibly applied to the removal of acetic acid impurities from organic solvents. The resins have tertiary or quaternary amino functional groups on a styrene–divinyl benzene copolymer matrix. The equilibrium adsorption studies show very selective adsorption with a high loading capacity for acetic acid. The uptake of the acid from the organic solutions is by sorption reinforced by specific interaction with the functional groups on the polymer matrix. The specific interaction takes place by a hydrogen bonded complex formation between the acidic proton and the lone pair of electrons on the amino group. An efficient application of ion-exchange resins is indicated in purification of ethyl acetate by selective sorption of acetic acid.

Removal of some dyes from industrial effluents by polymeric materials and gamma-irradiation

The radiolysis of two basic dyes (Astrazon Red 6B and Astrazon Blue BG-200%), was investigated as a function of dye concentration, pH, irradiation dose and dose rate. It was found that the Astrazon Red 6B dye showed more radiation degradation than the Astrazon Blue BG-200% dye. Combining irradiation with the conventional treatment enhanced the degree of degradation. Addition of oxygen or hydrogen peroxide showed this enhancement, while nitrogen showed no change. A pH drop was observed and may be attributed to the degradation of the dye molecules to lower molecular weight compounds such as organic acids. Experiments on the adsorption or exchange the dyes onto GAC, some polymeric ion exchange resins and polymeric membranes were carried out showing that GAC had the highest adsorption capacity. By combined treatment of irradiation and adsorption, the total removal of these toxic dyes was achieved.

Studies on thio-substituted polyurethane foam (T-PUF) as a new efficient separation medium for the removal of inorganic/organic mercury from industrial effluents and solid wastes

Novel thio-substituted flexible polyurethane foam (T-PUF) was synthesised by addition polymerisation of mercaptan with the precursors of an open-cell polyurethane foam, which can be used as a highly selective sorbent for inorganic and organic mercury from complex matrices. The percentage extraction of inorganic mercury was studied at different flow-rates, over a wide pH range at different concentrations ranging from 1 ppm, to 100 ppm. The break-through capacity and total capacity of unmodified and thio-foams were determined for inorganic and organic mercurials. The absorption efficiency of thio-foam was far superior to other sorbent media, such as activated carbon, polymeric ion-exchange resins and reagent-loaded polyurethane foams. It was observed that even at the 1000 ppm level, divalent ions like Cu, Mg, Ca, Zn do not appreciably influence the per cent extraction of inorganic mercury at the 10 ppm level. These matrix levels are the most concentrated ones which are likely to occur, both in local sewage and effluent waters. Further, the efficiency of this foam was sufficiently high at 10–100 ppm levels of Hg, even from 5–10 litres of effluent volumes using 50 g of thio-foam packed into different columns in series. Thio-foams were found to possess excellent abilities to remove and recover mercury even at low levels from industrial effluents and brine mud of chlor-alkali industry after pre-acid extraction. This makes it a highly efficient sorbent for possible application in effluent treatment. Model schemes for the removal and recovery of mercury from industrial effluents and municipal sewage (100–1000 litre) by a dynamic method are proposed and the costs incurred in a full-scale application method are indicated to show that the use of thio-foam could be commercially attractive.

Examination of ion-exchange resins by derivatography

The possibility of observing the thermal behaviour of polymeric ion-exchange resins by means of a derivatographic method is considered. The thermal processes that take place during thermal decomposition are discussed and their nature is elucidated. Information has been obtained on the process of thermal decomposition of the most frequently used Hungarian ion-exchange resins, and relationships are established between the thermal characteristics, the ionic form of the resin and its divinylbenzene content.