Ion-exchange Studies Research Articles

Preparation and Properties of Novel Quaternized Metal–Polymer Matrix Nanocomposites

A new class of PANI/Sn(II)SiO3/FCNTs nanocomposite was synthesized by mixing polyaniline into the gel of Sn(II)SiO3 followed by FCNTs (Polyaniline/Sn(II)SiO3/Functionalized Carbon nanotubes). The physico-chemical characterization was carried out by scanning electron microscope, XRD (X-ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), ultraviolet–visible spectroscopy, and simultaneous thermogravimetric analysis studies. The ion-exchange capacity (1.2 meq/g) and distribution studies were also determined to understand the ion-exchange capabilities. The DC electrical conductivity studies revile it in the range of 3–5 × 10−3 S/cm. On the basis of distribution studies, ion-selective membrane electrode was designed for Hg(II). The analytical utility of this membrane was established by using it as an indicator electrode in electrometric titrations.

Ion Pair-π Interactions.

We report that anion-π and cation-π interactions can occur on the same aromatic surface. Interactions of this type are referred to as ion pair-π interactions. Their existence, nature, and significance are elaborated in the context of spectral tuning, ion binding in solution, and activation of cell-penetrating peptides. The origin of spectral tuning by ion pair-π interactions is unraveled with energy-minimized excited-state structures: The solvent- and pH-independent red shift of absorption and emission of push-pull fluorophores originates from antiparallel ion pair-π attraction to their polarized excited state. In contrast, the complementary parallel ion pair-π repulsion is spectroscopically irrelevant, in part because of charge neutralization by intriguing proton and electron transfers on excited push-pull surfaces. With time-resolved fluorescence measurements, very important differences between antiparallel and parallel ion pair-π interactions are identified and quantitatively dissected from interference by aggregation and ion pair dissociation. Contributions from hydrogen bonding, proton transfer, π-π interactions, chromophore twisting, ion pairing, and self-assembly are systematically addressed and eliminated by concise structural modifications. Ion-exchange studies in solution, activation of cell-penetrating peptides in vesicles, and computational analysis all imply that the situation in the ground state is complementary to spectral tuning in the excited state; i.e., parallel rather than antiparallel ion pair-π interactions are preferred, despite repulsion from the push-pull dipole. The overall quite complete picture of ion pair-π interactions provided by these remarkably coherent yet complex results is expected to attract attention throughout the multiple disciplines of chemistry involved.

Synthesis of single‐walled carbon nanotubes cerium(IV) phosphate composite cation exchnager: Ion exchange studies and its application as ion‐selective membrane electrode for determination of Cd(II) ions

Single‐walled carbon nanotubes cerium(IV) phosphate composite cation exchanger was synthesized using sol−gel method. The ion‐exchange properties such as elution concentration, elution behavior and effect of temperature on ion exchange capacity were studied. The composite cation exchange material showed an ion‐exchange capacity (IEC) of 1.64 meq dry g−1 of ion exchanger. The distribution studies revealed that the composite cation‐exchanger is highly selective for Cd(II) ions. The material was used as an electroactive component for the construction of a cadmium ion‐selective membrane electrode. The membrane electrode showed a Nernstian response for Cd(II) ions over a wide concentration range of 1 × 10−7−1 × 10−1 M with a sub‐Nernstian slope of 27.429 mV per decade change in concentration of cadmium ions. The limit of detection was found to be 1 × 10−7 M. It possessed a fast response time 10 s and can be utilized for 130 days without any considerable divergence in response potential. The practical utility of membrane electrode was demonstrated by employing as an indicator electrode for the potentiometric titration of Cd(II) with ethylenediamine tetra acetic acid, disodium salt (EDTA). POLYM. COMPOS., 38:1005–1013, 2017. © 2015 Society of Plastics Engineers

Preparation, characterization and kinetics of ion exchange studies of Ni2+ selective polyaniline–Zr(IV)molybdophosphate nanocomposite cation exchanger

Polyaniline–Zr(IV)molybdophosphate (PAZMP) was synthesized by sol–gel mixing of polyaniline (PANI) into the inorganic precipitate Zr(IV)molybdophosphate (ZMP). The physico-chemical properties of the material were characterized by using XRD, TGA, FTIR, SEM and TEM. Distribution studies for various metal ions revealed that the composite is highly selective for Ni2+. Its selectivity was examined by achieving some important binary separations of metal cations which indicates its utility in environmental pollution control. Ion-exchange kinetics for few divalent metal ions was evaluated by particle diffusion-controlled ion-exchange phenomenon at different temperatures. Some physical parameters like D0, Ea and ΔS0 have been evaluated under favoring a particle diffusion-controlled mechanism.

Synthesis and modification by ion exchange of the composite Core-Shell

Zeolites are a large family of inorganic compounds with particular properties that have resulted in several important industrial applications; ion exchange has the first industrial application in the field of water treatment. The exchange by aqueous route is the most used method in the case of this type of micro-porous materials and it is that technique which will be used in the present work, this study aims to “Purification”. The objective of this work is to find performance materials for recovery and the incorporation of heavy metals such as lead and cadmium. The study is to compare the ion exchange properties of different zeolite Na-X and Na-A, their physical mixture and a composite called LTA/FAU formed by zeolites A (LTA) and zeolite X (FAU). Indeed, several syntheses of different zeolites X and A were performed, then a coreshell model was designed to form the composite LTA/FAU. Finally, the study of ion exchange on the different zeolite materials formed are thus achieved. The cations are exclusively tested for lead and cadmium, toxic elements harmful to health and to the environment as well.

Synthesis and properties of the metallo-supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]·AgNO3: Ag+/Cu2+ ion exchange and effective antibacterial activity.

The commercial polymeric anhydride poly(methyl vinyl ether-alt-maleic anhydride) (PVM/MA) is converted by reaction with NaOH to give poly(methyl vinyl ether-alt-mono-sodium maleate) (PVM/Na-MA). By addition of AgNO3-solution, the formation of the silver(i) supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]·AgNO3 is reported. Freeze-dried samples of the hydrogel show a mesoporous network of polycarboxylate ligands that are crosslinked by silver(i) cations. In the intact hydrogel, ion-exchange studies are reported and it is shown that Ag+ ions can be exchanged by copper(ii) cations without disintegration of the hydrogel. The silver(i) hydrogel shows effective antibacterial activity and potential application as burn wound dressing.

Removal of Toxic Metal Ions from Water Using Chelating Terpolymer Resin as a Function of Different Concentration Time and pH

Terpolymer resin 4-ASAUF was synthesized by the condensation of 4-aminosalicylic acid (4-ASA) and urea (U) with formaldehyde (F) in the presence of 2 N hydrochloric acid. The structure of the resin was characterized by various spectral techniques like infrared (FTIR) and nuclear magnetic resonance (1H and 13C-NMR) spectroscopy. The empirical formula and empirical weight of the resin were determined by elemental analysis. The physiochemical properties of terpolymer resin were determined. The morphological feature of the 4-ASAUF terpolymer resin was studied by scanning electron microscopy (SEM). The chelating ion-exchange property of this copolymer was studied for eight metal ions, namely, Fe3+, Cu2+, Ni2+, Co2+, Hg2+, Zn2+, Cd2+, and Pb2+ ions by using batch equilibrium method. The chelating ion-exchange study was carried out over a wide pH range at different time intervals using different electrolyte of various ionic strengths.

Equilibrium ion exchange studies of Ni2+ on homoionic forms of clinoptilolite

A natural zeolite (clinoptilolite) that is mined in KwaZulu-Natal, South Africa, was evaluated for the removal of Ni2+ from wastewater. In particular, the effect of zeolite modification on Ni2+ removal from synthetic wastewater was investigated. The natural clinoptilolite was pretreated with 2 M metal chlorides for 24 h to yield near homoionic Na+, K+ and Ca2+ forms. A comparison of the isotherms for the Na+-Ni2+, K+-Ni2+, Ca2+-Ni2+ and natural-Ni2+ systems gave insight into how the displaced ion affects the selectivity of the clinoptilolite for Ni2+. The Na+, K+ and natural forms show highly selective convex isotherms whereas the Ca2+ form has a concave graph suggesting that the selectivity series is Ca2+> Ni2+> (Na+, K+, natural). Thermodynamic properties revealed that the Ni2+ sorption capacity increases as the values of the equilibrium constant and Gibbs free energy increase with increasing temperature from 298.15 K to 348.15 K. The enthalpy change was positive for all forms of clinoptilolite; values of 26.00 kJ/mol, 18.72 kJ/mol and 42.05 kJ/mol were obtained for exchange of Ni2+ into Na+, K+ and Ca2+ forms, respectively. The positive changes in enthalpy provide an indication that the sorption reaction is endothermic for Ni(II). The Gibbs free energy values were all negative except for Ca2+-exchanged clinoptilolite at 298.15 K and 308.15 K, for which the values were positive 3.10 kJ/mol and 0.53 kJ/mol, respectively. The entropy values for Ni2+ sorption were also positive; values of 0.12 kJ/mol.K, 0.08 kJ/mol.K and 0.14 kJ/mol.K were obtained for the Na+, K+ and Ca2+ forms, respectively. As expected, the enthalpy obtained from the Van’t Hoff plot is dependent not only on the metal ion being adsorbed, but also on the ion being displaced. Pretreatment of the zeolite enhances the removal efficiency provided that monovalent ions are used for the pretreatment. Thus clinoptilolite is an effective low-cost absorbent for the removal of Ni2+ from aqueous solutions.

Synthesis, Characterization and Chelation Ion-Exchange Studies of a Resin Copolymer Derived From 8-Hydroxyquinoline-Formaldehyde-Pyrogallol

An ion exchange resin chelator was synthesized from 8-hydroxyquinoline and pyrogallol using formaldehyde as a crosslinking agent to 120°C in a solution of DMF. The resin was characterized by elemental analysis and FTIR. The morphology of the synthesis resin was examined by optical photograph and scanning electron microscopy (SEM). The physicochemical properties of the resin were studied. The cation exchange capacity was measured and the effect of pH and metal ion concentration on the ability of the ion exchange were studied. The ratio of cation exchange reaction and the distribution coefficient in tartaric acid medium at different pH were also studied using the method of batch equilibration.

Ion-exchange Studies of Copolymer Derived from 4,4′-Biphenol

A novel copolymer resin (4,4′-BP-4,4′-ODA-F-II) has been synthesized by condensation polymerization reaction of 4,4′-biphenol and 4,4′-oxydianiline using the linkage of formaldehyde in presence of acid catalyst. The resin composition was determined on the basis of elemental analysis. Solution viscosity measurements in dimethylformamide were carried out to ascertain the characteristic functions and constants. The number average molecular weight was determined by conductometric titration in non-aqueous medium. The copolymer resin was further characterized by UV-Visible, Infra-red and Nuclear magnetic resonance spectroscopy to confine the most probable structure of synthesized copolymer. Thermal analysis was carried out for studying the thermal degradation behavior and kinetic parameters. Thermal degradation curve depicts four decomposition steps after a loss of water molecule and has been discussed with minute details by applying Freeman-Carroll, Sharp-Wentworth and Coat-Redfern equations to evaluate the kinetic parameters i.e., activation energy (Ea), order of reaction (n) and frequency factor (z). The data from Freeman-Carroll method has been used to determine various thermodynamic parameters i.e., entropy change (ΔS), free energy change (ΔF) and apparent entropy (S*). This copolymer is proved to be a selective chelating ion exchanger for certain metal ions such as Fe3+, Cu2+, Hg+2, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+. A batch equilibrium method was employed in the study of selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the copolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range, shaking time and in media of various ionic strengths.

Applied poly(2-methoxy aniline) Sn(II)silicate carbon nanotubes composite: Synthesis, characterization, structure–property relationships and applications

A new class hybrid poly(2-methoxy aniline) Sn(II)silicate carbon nanotubes composite was synthesized by sol–gel method. The physico-chemical characterization was carried out by Scanning Electron micrograph, X-ray Diffraction, Fourier Transform Infrared, Ultraviolet–Visible Spectroscopy and simultaneous Thermo Gravimetric Analysis. The ion-exchange studies were also carried out to understand the ion-exchange capabilities. The dc electrical conductivity studies reviles its highly conducting nature in the range of 2–3−2Scm−1. On the basis of distribution studies it was found highly selective for Hg2+. Due to selectivity of the composite, ion selective membrane was prepared and employed it as an indicator electrode in potentiometric titrations.

Studies on Ion-Exchange Properties of Polyaniline Zr(IV) Tungstoiodophosphate Nanocomposite Ion Exchanger

Organic-inorganic hybrid materials prepared by sol-gel approach have attracted a great deal of attention in material science. Organic polymeric part of the composite provides mechanical and chemical stability whereas the inorganic part supports the ion-exchange behaviour and thermal stability and also increases the electrical conductivity. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening. Polyaniline zirconium(IV) tungstoiodophosphate nanocomposite ion exchanger is prepared by sol-gel method. Polyaniline zirconium(IV) tungstoiodophosphate nanocomposite ion exchanger is synthesized and characterized by Fourier transform-infrared spectra, ultraviolet-visible spectra, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, ion exchange, conductivity, and antimicrobial studies. A mechanism for the formation of the polyaniline zirconium(IV) tungstoiodophosphate nanocomposite ion exchanger was discussed. The route reported here may be used for the preparation of other nanocomposite ion exchangers.

Application of the BDST model for nickel removal from effluents by ion exchange

The effect of pH on the equilibrium ion exchange capacity of nickel using an imino diacetate ion exchange resin has been studied to determine the pH for optimum metal uptake. A series of fixed bed ion exchange studies have been carried out using the resin to remove nickel from water and the effect of a number of process variables, including initial nickel ion concentration, resin particle size and effluent solution flowrate, have been studied. The Bed Depth Service Time (BDST) model has been applied to the experimental date with only limited predictive success and subsequently a modified “BDST” model has been successfully applied to the data to model the system.

Syntheses and Structures of Uranyl Ethylenediphosphonates: From Layers to Elliptical Nanochannels

A family of uranium diphosphonates have been hydrothermally synthesized through the reaction of ethylenediphosphonic acid (EDP, H4L) and uranyl nitrate/zinc uranyl acetate in the presence of organic templates, such as tetraethyl ammonium (NEt4(+)), 4,4'-bipyridine (bipy), and 1,10-phenanthroline (phen). The UO2(2+) in UO2(H2O)(H2L)(EDP-U1) is equatorially five-coordinated by four phosphonate groups and one aqua ligand, forming a pentagonal bipyramid. Each EDP ligand is doubly protonated and chelates three UO2(2+), resulting in a layered structure. Compounds (NEt4)2(UO2)3(HL)2(H2L)·4H2O (EDP-U2) and (H2bipy)UO2L (EDP-U3) have the same layered structure in which NEt4(+) and protonated bipy fill in the uranyl-phosphonate interlayers, respectively, and play a role to balance the negative charges. Different from that in EDP-U1, the UO2(2+) exists in the form of a UO6 tetragonal bipyramid and is surrounded by four different EDP ligands in EDP-U2 and EDP-U3. (Hphen)2(UO2)2(H2L)3 (EDP-U4) features a three-dimensional framework structure with large elliptical channels along the c axis (1.3 × 1.1 nm(2)). Monoprotonated phen molecules fill in these channels and hold together through strong π···π interactions. All of the four compounds have been characterized by IR and photoluminescent spectroscopy. Their characteristic emissions have been attributed as transition properties of uranyl cations. The ion-exchange study indicates that [Co(en)3](3+) could partially replace the protonated phen molecules.

Structure and Ion Exchange Behavior of Zirconium Antimonates for Strontium

Zirconium antimonates with initial Sb:Zr mole ratios of 1.0, 1.5, 4.0, and 9.0 were synthesized by co-precipitation to remove strontium ions from acidic solutions. The characterization of materials was investigated by X-ray diffraction (XRD), Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX), X-ray fluoresence (XRF), and zeta potential analyses. Ion exchange studies of the synthesized materials towards strontium were conducted as a function of contact time and initial pH. Preliminary results reveal that as the antimony ratio increases the surface of the materials become more acidic and thus, strontium exchange is more favorable in a pH range of 2-6.

Comprehensive ion-exchange and adsorption study of the distribution of exchanging inorganic cations over the interlayer gaps of vermiculite

The exchange of Co2+ ions on Na-vermiculite has been comprehensively studied by the ionexchange, adsorption, and X-ray diffraction methods. It has been shown that vermiculite is distinguished by high selectivity to Co2+ cations and Kielland dependence log \(\tilde K_m (\theta )\) increasing with filling of ion-exchange sites with sorbed cations rather than a decreasing one that is observed for common systems. It has been established that the ion exchange is accompanied by segregation of Na+ and Co2+ cations in separate interlayer gaps of vermiculite with the final formation of a disordered layered “cake” composed of separate silicate layers and interlayer gaps enriched with Na+ and Co2+ ions.

A thalium-doped sodium iodide well counter for radioactive tracer applications with naturally-abundant 40K

The use of a thallium-doped sodium-iodide well-type scintillation detector for the assay of the low-activity radioisotope 40K, in open-source potassium chloride aqueous solutions, is described. The hazards, safety concerns and radiowaste generation associated with using open-source radioactive isotopes can present significant difficulties, the use of hot cells and escalated costs in radioanalytical laboratory research. A solution to this is the use of low-hazard alternatives that mimic the migration and dispersion characteristics of notable fission products (in this case 137Cs). The use of NaI(Tl) as a detection medium for naturally-abundant levels of 40K in a range of media is widespread, but the use of 40K as a radioactive tracer has not been reported. The use of such low-activity sources is often complicated by the ability to detect them efficiently. In this paper a scintillator detector designed to detect the naturally-abundant 40K present in potassium chloride in tracer applications is described. Examples of the use of potassium chloride as a tracer are given in the context of ion exchange and electrochemical migration studies, and comparisons in performance are drawn from literature with hyper pure germanium semiconductor detectors, which are more commonly utilised detectors in high-resolution counting applications.

Impact of urbanization in groundwater of south Chennai City, Tamil Nadu, India

Chennai is one of the four major metropolitan cities in India, and is located in the southeastern part of the country. The average rate of population growth of the city is 25 % per decade and this is recurrently reducing the green-covered area in the city. Exceptionally, during the post-economic liberalization period (i.e., between the years 1997 and 2007), the city lost up to 99 % of its green-covered areas at some parts. Subsequently, the Chennai City started to experience wide range of environmental issues, including groundwater pollution and the effects of groundwater depletion. As a consequence of these factors, a study was undertaken to determine the impact of urbanization on the groundwater quality. In the present study, groundwater samples were collected from 54 stations from the study area during the premonsoon and postmonsoon seasons for the year 2011–2012 and were analyzed for physico-chemical parameters and trace elements. The type of water that predominated in the study area was assessed based on hydrochemical facies. The study of the hydrochemical characteristics of the major ions in these waters shows that in premonsoon, the alkalis and the alkaline earth metals are found to be balanced by chlorides and bicarbonates and sulphates, respectively. Reverse ion exchange study illustrates that Ca, Mg and Na concentrations are interrelated through reverse ion exchange. Box and whisker plots illustrate the seasonal effect on the chemical parameters of the groundwater. Gibbs’ diagram reveals that the chemical composition of the groundwater in the study area is predominated by rock–water interaction. Besides, suitability of groundwater for irrigation was evaluated based on sodium adsorption ratio, Kelley’s ratio, magnesium ratio, Wilcox and USSL diagrams.

A novel approach to the industrial preparation of mesostructured silica: Use of ion exchange resin and study of the effect of composition variables

Structured mesoporous silica was successfully synthesized using ion exchange resin as proton source to avoid the use of HCl during the synthesis and preventing the ions being freed in the media. The material was obtained from sodium silicate solution, which acts as a silica source and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EO19PO39EO19 denoted as P84) was used as structure-directing agent. The influence of two composition variables was studied: the ratio of silica used and the ratio of surfactant. The obtained materials were characterized through, SEM, TEM, SAXS and nitrogen adsorption–desorption isotherms. The use of sodium silicate solution as silica source instead of TEOS or TMOS and the possibility to obtain a material through an ion exchange resin is important from an application point of view due to relative cheap raw materials and equipments. The process using the ion exchange resins has around 65% of efficiency respect to Si source, which is an important data not reported in other papers, and it must be considered when planning an industrial approach to obtain these structured materials.

Effect of novel antibacterial gallium-carboxymethyl cellulose on Pseudomonas aeruginosa

Gallium has emerged as a new therapeutic agent due partly to the scarcity in development of new antibiotics. In this study, a novel antibacterial gallium exchanged carboxymethyl cellulose (Ga-CMC) has been developed and tested for the susceptibility on a common bacteria, Pseudomonas aeruginosa. The results show that an increase in average molecular weight (MW) from 90 k, 250 k to 700 k of Ga-CMC caused a decrease in antimicrobial activity against planktonic P. aeruginosa. Gallium loading of the Ga-CMC (250 k) samples was altered by varying the amount of functionality (0.7, 0.9 and 1.2 acid groups per mole of carbohydrate) which affected also its antimicrobial activity against planktonic P. aeruginosa. Further, the ability to prevent the growth of biofilms of P. aeruginosa was tested on MW = 250 k samples with 0.9 acid groups per mole of carbohydrate as this sample showed the most promising activity against planktonic P. aeruginosa. Gallium was found to reduce biofilm growth of P. aeruginosa with a maximum effect (0.85 log(10) CFU reduction compared to sodium-carboxymethyl cellulose, Na-CMC) after 24 h. Results of the solubility and ion exchange studies show that this compound is suitable for the controlled release of Ga(3+) upon their breakdown in the presence of bacteria. SEM EDX analysis confirmed that Ga(3+) ions are evenly exchanged on the cellulose surface and systematic controls were carried out to ensure that antibacterial activity is solely due to the presence of gallium as samples intrinsic acidity or nature of counterion did not affect the activity. The results presented here highlight that Ga-CMC may be useful in controlled drug delivery applications, to deliver gallium ions in order to prevent infections due to P. aeruginosa biofilms.