Ion-exchange Studies Research Articles

Synthesis, characterization and analytical applications of sodium dodecyl sulphate cerium (IV) phosphate: A new Pb (II) selective, surfactant-based intercalated fibrous ion exchanger

Sodium dodecyl sulphate-based cerium (IV) phosphate (SDS-CeP), a new Pb (II) selective intercalated fibrous ion exchanger, has been synthesized. It has been characterized on the basis of X-ray diffraction analysis, IR, thermo-gravimetric and differential thermal analysis, scanning electron microscopy (SEM) and ion exchange studies. The adsorption studies have also been carried out for some alkaline earths and heavy metal ions in different acidic media, showing a marked selectivity towards Pb (II), a toxic metal ion. Hence, its analytical utility has been established by achieving some binary separations on its column. The prepared material has shown good ion exchange capacity (2.92 meq/dry g basis), thermal stability and adsorption behaviour. The ion exchanger may play an explicit role in environmental studies.

Thermal, ion-exchange, catalytic and antimicrobial aspects of synthetic oligomer and its polychelates with 4f-block elements

Acetophenone based oligomer was synthesized by condensation of 2-hydroxy-4-ethoxyacetophenone with 1,3-propane diol in the presence of polyphosphoric acid as a catalyst at 145 °C for 10 h. The synthesized oligomer was used to study its ion exchange efficiency and to synthesize its polychelates with 4f-block elements. The oligomer and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, FTIR, NMR and Thermogravimetric analyses. The Number Average Molecular Weight ( $$\overline M n$$ ) was determined using Vapor Pressure Osmometry (VPO) method. Ion-exchange studies at different electrolyte concentrations, pH and rate have been carried out for 4f-block elements. Antimicrobial activity of polychelates against Escherichia coli, Bacillus subtilis, Staphylococcus aureus (bacteria) and Saccharomyces cerevisiae (yeast) were measured Catalytic activity of only selected polychelates was examined for organic synthesis. It is observed that, oligomer can be used as an ion – exchanger and polychelates act as an efficient catalysts and antimicrobial agents.

Na2[VB3P2O12(OH)]·2.92H2O: A New Open-Framework Vanadium Borophosphate Containing Extra-Large 16-Ring Pore Openings and 128166 Super Cavities Synthesized by Using the Boric Acid Flux Method

A new three-dimensional (3-D) open-framework vanadium (IV) borophosphate, Na2[VB3P2O12(OH)]·2.92H2O (denoted as VBPO-CJ27), has been synthesized by using boric acid flux method. Single-crystal structure analysis reveals that its structure is constructed by the connection of VO6 octahedra, PO4 and BO4 tetrahedra, and BO2(OH) trigonal planes to form a 3-D anionic framework containing intersecting 8-, 12-, and 16-ring channels. Charge neutrality is achieved by Na+ ions, and the guest water molecules locate in the void space of the open framework. To the best of our knowledge, it is the first borophosphate with extra-large 16-ring openings. Interestingly, its structure features unprecedented 128166 super cavities. The compound is further characterized by SEM, powder XRD, ICP, TGA, and IR analyses. Its magnetic property and ion-exchange capacity are also studied. The magnetic measurement reveals that VBPO-CJ27 is paramagnetic. Ion-exchange studies show that Na+ ions can be partially exchanged by NH4+ ions.

Synthesis, charecterization and chelation ion-exchange studies of a resin copolymer derived from 8-hydroxyquinoline-formaldehyde-catechol

A chelating ion exchange resin was synthesized from 8-hydroxyquinoline and catechol using formaldehyde as a cross linking agent at 120 ± 2 °C in DMF solution. The resin was characterized by FTIR and elemental analysis. The morphology of the synthesized resin was studied by optical photograph and scanning electron microscopy (SEM). Various kinetic parameters such as energy of activation (Ea), enthalpy of activation (H‡), entropy of activation (S‡), free energy of activation (G‡), order of reaction (n) and pre-exponential factor (A) of various steps of thermal decomposition have been calculated from thermogravimertic results. The physico-chemical properties of the resin have been studied. The total cation exchange capacity was measured and effect of pH and metal ion concentration on ion exchange capacity were studied. The rate of cation exchange reactions and distribution coefficient values in tartaric acid media at different pH were also studied using batch equilibration method.

A study of ion exchange at the poly(butyl viologen)-electrolyte interface by SECM

In this work, the ion exchange characteristics of poly(butyl viologen) (PBV) thin films on a platinum electrode has been investigated by cyclic voltammetric (CV) scans. Since ferrocyanide anions (Fe(CN) 6 4−) were added during the polymerization of the PBV thin-film for its stability, Fe(CN) 6 4− could form charge transfer complex with monomer and co-deposited with polymer. Scanning electrochemical microscopy (SECM) was used to probe the released Fe(CN) 6 4− ions from PBV film with Os(bpy) 3Cl 2 as a mediator for the approaching process in 0.5 M KCl medium. Mass changes during the redox process of the film were also monitored in-situ by electrochemical quartz crystal microbalance (EQCM). The ion exchange and transport behavior was observed during CV cycling of the film of the SECM and EQCM. The insertion and extraction of anions were found to be potential-dependence. Moreover, the decrease in tip current of released Fe(CN) 6 4− with increasing cycle number accounted for the ion exchange between Fe(CN) 6 4− and Cl − in the KCl electrolyte. However, the Fe(CN) 6 4−/Fe(CN) 6 3− redox couple was found to be highly stable between 0.0 and 0.5 V (vs. Ag/AgCl/saturated KCl) in the phosphate buffer solution. Therefore, the electrochemical property of Fe(CN) 6 4−/Fe(CN) 6 3− redox couple was studied at different scan rates using CV technique. The peak currents were directly proportional to the scan rate as predicted for a surface confined diffusionless system. The surface coverage ( Γ) and the concentration of Fe(CN) 6 4− were determined to be 1.88 × 10 −8 mol/cm 2 and 0.641 mol/dm 3, respectively. By neglecting cations incorporation during redox reaction of the PBV film and also based on the results obtained from energy-dispersive X-ray spectroscopy for the films of as-deposited, reduced and oxidized states, an ion exchange mechanism was proposed.

Synthesis, characterization, ion-exchange and antimicrobial study of poly[(2-hydroxy-4-butoxy benzophenone)ethylene] resin and its polychelates with lanthanides

The polymeric ligand (resin) was prepared from 2-hydroxy-4-butoxy benzophenone with ethane diol with polyphosphoric acid as catalyst on constant heating at 160°C for 13 h. The poly[(2-hydroxy-4-butoxy benzophenone)ethylene] (HBBP-ED) forms 1 : 2 metal : ligand polychelates with La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III). The polymeric ligand and its polychelates were characterized by elemental analyses, electronic spectra, magnetic susceptibilities, IR-spectroscopy, NMR and thermogravimetric analyses. The molecular weight was determined using number average molecular weight (M n) by a vapor pressure osmometry (VPO) method. All the polychelates are paramagnetic except La(III). Ion-exchange studies at different electrolyte concentrations, pH and rate have been carried out for the lanthanide ions. The resin can be used as an ion-exchanger and antimicrobial agent.

La (III) polychelates of phenolic resin: synthesis, characterization and ion-exchange study

The polymeric ligand, specially resins are proved very effective, active and satisfy specific requirements. The formation of polychelates with polymeric resin behave as an excellent catalysts, ion-exchanger, heat resistant surface coatings, antifouling paints and antimicrobial agents. This is due to the presence of organic and inorganic materials because these two are the prime factors to establish the effective and desire change in their physical and chemical properties. Therefore, an attempt has been made to synthesis and characterizes polymeric ligand (resin) and its polychelates, to study ion-exchange property of resin. The polymeric ligand [(2-hydroxy-4-methoxy benzophenone)1,4-butylene (HMBP-1,4-BD)] was synthesized by polycondensation of 2-hydroxy-4 -methoxy benzophenone with 1,4-butane diol in presence of polyphosphoric acid as a catalyst at 160 °C for 13 h. La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III) metal ions were selected for the synthesis of polychelates. HMBP-1,4-BD possess good selectivity for the lanthanides (III). The use of resin, as an ion-exchanger has been studies, and it has been found that resin can be used as an ion-exchanger.

Triton X-100 based cerium(IV) phosphate as a new Hg(II) selective, surfactant based fibrous ion exchanger: Synthesis, characterization and adsorption behaviour

Triton X-100 based cerium(IV) phosphate (TX-100CeP) has been synthesized as a new phase of fibrous ion exchanger. It has been characterized using IR, X-ray, SEM, TGA/DTA and elemental analysis in addition to its ion exchange studies such as ion exchange capacity, elution, concentration and thermal behaviour. Its adsorption behaviour has also been studied for some alkaline earths and heavy metal ions in different acidic media. On this basis, the material has been found to be selective for Hg(II), a toxic heavy metal ion. Hence, some binary separations of Hg(II) from other metal ions have been performed on its column, exploring its potential in environmental studies.

Cesium exchange reaction on natural and modified clinoptilolite zeolites

Cesium cation exchange reaction with K, Na, Ca and Mg ions on natural and modified clinoptilolite has been studied. Batch cation-exchange experiments were performed by placing 0.5 g of clinoptilolite into 10 ml or 20 ml of 1·10−3M CsCl solution for differing times. Two type deposits of clinoptilolite zeolites from, Nižný Hrabovec (NH), Slovakia and Metaxades (MX), Greece were used for ion-exchange study. The distribution coefficient (Kd) and sorption capacity (Γ) were evaluated. For the determination of K, Na, Ca and Mg isotachophoresis method, the most common cations in exchange reaction was used. Cesium sorption was studied using 137Cs tracer and measured by γ-spectrometry.

Exchange and reduction of Cu 2+ ions in clinoptilolite

The ion-exchange and reduction processes for Cu 2+ ions in clinoptilolite from the Caimanes deposit (Moa, Cuba) were studied at different temperatures. The ion-exchange studies were done to determine the kinetic parameters of Cu 2+ removal from solution by this clinoptilolite modified previously to NH + 4 form, and thermodynamic parameters of Cu 2+ elution from zeolite using NH 4Cl solution. The results show that temperature increase favors the exchange and that it is a reversible process. The external diffusion rate appreciably increases with temperature, while, the internal diffusion coefficient rises relatively little. This means that besides ion exchange other processes (such as precipitation of the low-solubility phase and/or salt adsorption) occur, which cause copper removal from solution and affect the intracrystalline diffusion of the ions. For steric reasons the exchange of [Cu(H 2O) 6] 2+ ions from a solution must occur with a number of water molecules n smaller than 6 ( 6 > n ⩾ 0 ) . Cu 2+ reduction by hydrogen and the formation of Cu-particles in the clinoptilolite were verified. The Cu 2+ reduction mechanism is complex, indirect, and sensitive to reduction temperature; consequently, Cu + n states intermediate between Cu 2+ and Cu 0 should be present in the reduced samples.

Mixed-Valence Iron(II, III) Trimesates with Open Frameworks Modulated by Solvents

Solvothermal reactions with different solvents produced two iron trimesates [Fe2(H2O)2(BTC)4/3]Cl x 4.5(DMF) (1) and [Fe4Cl(BTC)8/3]Cl2 x H2O x 2.5(DEF) (2) (BTC = 1,3,5-benzenetricarboxylate, DMF = N,N'-dimethylformamide, DEF = N,N'-diethylformamide). The framework of 1 is a (3,4)-connected net constructed from mixed-valence paddlewheel Fe2(II, III) units and BTC linkers, while the framework of 2 is a (3,8)-connected net built from mixed-valence square-planar Fe4(III, III, III, II) units and BTC linkers. The large volume inside the framework of 1 (or 2) is occupied by disordered Cl- anions and guest DMF (or DEF) molecules. The mixed-valence character of the frameworks of 1 and 2 was confirmed by Mössbauer spectroscopy studies. The active electronic property of iron cations may be the origin of the variability of the iron-organic frameworks, which are readily affected by some synthetic factors, such as solvents. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the Fe atoms in 1 and 2. Ion-exchange studies for 1 show that the Cl- anions inside the framework of 1 can be exchanged by CNS- anions.

Ion-exchange studies of 110mAg(I) using synthetic inorganic ion-exchanger

In the present investigation, the selective adsorption of silver on synthetic inorganic ion exchanger, zinc(II) ferrocyanide, has been established by batch method, under specific conditions, using 110mAg as a tracer. The efficiency of adsorption has been determined by γ-ray spectrometry and was found to be greater than 96%. The Ag(I) uptake by the exchanger has also been evaluated. The selectivity of the method was checked by studying the adsorption of Ag(I) in the presence of a number of foreign ions using their corresponding tracers. The interfering ions were removed by washing the ion-exchanger with appropriate reagents, so that it could be applied for the determination of trace amount of Ag(I) in complex matrices, containing trace amount of other metal ions.

Synthesis of swelling micas with stoichiometric amount of fluorine, characterization and ion exchange studies

A stoichiometric fluorine content method for synthesizing high charge density swelling micas is developed by keeping the fluorine content stoichiometric in the precursors. Hydrated mica phase was obtained in all cases. The synthetic mica samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and magic angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. Using the stoichiometric amount of fluorine has yielded micas of small particle size (<2 μm) as revealed by SEM. Distribution coefficient, Kd values were obtained for the micas by conducting ion exchange studies with solutions containing Sr2+ and Ba2+ cations separately and these studies show high selectivity for the above metal cations. The present studies show that swelling micas could be obtained without using excessive fluorine in the synthesis procedure, there by minimizing processing steps and perhaps reducing but not eliminating the release of fluorides in to the environment. The confirmation of high selectivity for cations such as Sr2+ makes these micas potential remediation agents for cleanup of nuclear waste contaminated sites.

Synthesis, characterization, ion-exchange and antimicrobial study of poly[(2-hydroxy-4-methoxy benzophenone) ethylene] resin and its polychelates with lanthanides(III)

The polymeric ligand (resin) was prepared from 2-hydroxy-4-methoxybenzophenone with Ethane Diol in the presence of polyphosphoric acid as a catalyst on constant heating at 160 °C constant heating for 13 h. The poly[(2-hydroxy-4-methoxybenzophenone) ethylene] (HMBP-ED) form 1:2 metal:ligand polychelates with La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III). The polymeric ligand and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, IR-spectroscopy, NMR and thermogravimetric analyses. The molecular weight was determined using number average molecular weight ( M ¯ n ) by a vapour pressure osmometry (VPO) method. All the polychelates are paramagnetic in nature except La(III). Ion-exchange studies at different electrolyte concentrations, pH and rate have been carried out for lanthanides(III) metal ions.

Acoustic Recognition of Counterions in Ion-Exchange Resins

In a coupled acoustic-gravity field, particles are aggregated at a particular position determined by their acoustic properties, such as density and compressibility. The observation of the aggregation of cation-exchange resin particles in this field has confirmed that the types of countercations strongly affect the behavior of the particles. Detailed analyses have revealed that the different behavior comes not from the density of the resins but from their compressibility as far as H+- and NBu4+-form cation-exchange resins are concerned. Since these resins are aggregated at the different positions, we can gain information of counterions from aggregation coordinates. Counterions can thus be recognized through the observation of the aggregation behavior of resin particles in the field without chemical analyses routinely employed in ion-exchange studies.

Chloride, Gluconate, Sulfate, and Short-Chain Fatty Acids Affect Calcium Flux Rates Across the Sheep Forestomach Epithelium

In ruminants, more than 50% of overall gastrointestinal Ca absorption can occur preintestinally, and the anions of orally applied Ca salts are thought to play an important role in stimulating ruminal Ca absorption. This assumption is based mainly on ion-exchange studies that have used gluconate as the control anion, which may bind Ca2+ ions and interfere with treatment effects. In the present study, we investigated the distinct effects of different anions on Ca absorption across the sheep rumen and on the concentration of free Ca2+ ions ([Ca2+]ion). We showed that gluconate, sulfate, and short-chain fatty acids (SCFA) remarkably reduced [Ca2+]ion in buffer solutions. Nevertheless, increasing the Cl or SCFA concentration by 60mM stimulated net ruminal Ca absorption 5- to 7-fold, but these effects could be antagonized by gluconate. Therefore, ion-exchange experiments must be (re)evaluated very carefully, because changes in [Ca2+]ion in the presence of gluconate, sulfate, or SCFA not only might entail an underestimation of Ca flux rates, but also might have effects on other cellular pathways that are Ca2+ dependent. Concerning the optimal Ca supply for dairy cows, the present study suggests that CaCl2 formulations and Ca salts of the SCFA stimulate Ca absorption across the rumen wall and are beneficial in preventing or correcting a Ca deficiency.

Synthesis, Characterization, and Ion-Exchange Study of Benzophenone Based Resin and Its Polychelates with Lanthanides(III)

The polymeric ligand (resin) was prepared from 2-hydroxy-4-methoxybenzophenone and 1,3-Butanediol in presence of polyphosphoric acid as a catalyst at 160°C for 13 h. The poly[(2-hydroxy-4-methoxybenzophenone) 1,3-butylene] (HMBP-1,3-BD) form 1:2 metal:ligand chelates with La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), and Dy(III). The polymeric ligand and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, IR-spectroscopy, NMR, and thermogravimetric analyses. The Number Average Molecular Weight () was determined by a Vapour Pressure Osmometry (VPO) method. All the polychelates are paramagnetic in nature except La(III), which is diamagnetic in nature. Ion-exchange studies at different electrolyte concentrations, pH and rate have been carried out for lanthanides(III) metal ions.

Ion exchange studies for the removal of plutonium and americium from organic liquid scintillator waste solution

Removal of radioactive nuclides from effluents is important for the safe disposal of the radioactive waste. In the present work ion exchange studies were carried out using simulated alpha active organic liquid scintillator and ethyl alcohol waste solutions containing Pu and Am using different resins. The time of equilibration and batch data were obtained under different conditions for individual resins as well as their mixtures. The indigenously developed Macroporous bifunctional phosphinic acid (MPBPA) resin was found to be suitable for the removal of alpha activity mainly due to Pu and Amberlite IR-120 and Biorad 50W × 8 for removal of Am. The results indicated that the presence of alcohol in the scintillator solution helps in increasing the distribution ratio. Experiments were carried out with column containing either MPBPA resin alone or with additional resin bed of Amberlite IR-120 using active organic liquid scintillator waste (with and without dilution with alcohol). Studies were also carried out on alcoholic waste generated in the laboratory during the washing of the used liquid scintillator vials. The alcohol after removal of activity either could be reused or could be disposed off directly as a ‘potentially’ active waste.

Study of lithium ion exchange by two synthetic zeolites: Kinetics and equilibrium

We examined the exchange of univalent cations (Na + and H +) retained on two commercially available synthetic zeolites with Li + ions present in aqueous solutions in contact with the solids with a view to preparing effective controlled–release pharmaceutical forms. The studied zeolites were manufactured by Merck and featured channel diameters of 0.5 (Zeolite 5A, Ref. 1.05705.250, designated Z-05 in this work) and 1.0 nm (Zeolite 13X, Ref. 1.05703.250, designated Z-10 here). The XRD technique revealed that Z-05 possesses an LTA structure derived from that of sodalite and Z-10 a faujasite-type structure. Their exchange capacities were found to be 2.72 and 3.54 meq/g. The Z-Na + Li +/Z-Li + Na + and Z-H + Li +/Z-Li + H + ion-exchange processes were found to be reversible and their kinetic laws to obey the equation ( − d C / d t ) = k a ⋅ C n ⋅ ( 1 − θ ) − ( k d ⋅ θ ) , with n = 1 for Z-10 and n = 2 for Z-05. Based on the equilibrium results, the overall processes involve one (with Z-05) or two single ion-exchange processes (with Z-10). In both cases, the equations that govern equilibrium are direct results of the kinetic laws. Thus, the first process—the one with only Z-05—involves the retention of Li + cations at anionic sites on the outer surface of the solid and their access to the larger pores; the second process—which occurs with Z-10 only—involves the retention of lithium(I) cations within the zeolite channels. In both systems, the exchange with Li + (from the aqueous solution) is easier than that with H +; this is consistent with our kinetic, equilibrium, and thermodynamic results.

Effect of aging on the water sorption and ion exchange studies on Nafion and Dowex resins: Transition metal ions-proton exchange systems

Transition metal ion-H + exchanges on Nafion 117 membrane (pre-treated differently prior to use), Dowex 50W × 4 and Dowex 50W × 8 resins have been studied. The water sorption isotherms of these exchangers in different ionic forms generated over the entire range of water activity have been analyzed by the D’Arcy and Watt equation (DWE). The results show that the physical structure of the exchangers change due to long-storage or aging, and the amount of water sorbed becomes low. As a result, the counter-ions in the exchangers are not hydrated, resulting in discrepancies in the ion exchange studies. In the absence of any hydration of the transition metal ions in the resin phase, the driving force for the ion exchange reaction is the electrostatic interaction between the sulphonato group and transition metal ions. Pre-treatment of Nafion 117 membrane with boiling acid/water modifies the membrane structure and arrangement of the ionogenic groups. These modifications influence the state of water present in the Nafion 117 membrane and the ion exchange equilibria. The results obtained in the present study indicate that the ion exchangers lose their elasticity or swelling characteristics and therefore show poor water sorption characteristics.