Ion Exchange Applications Research Articles

New Resins for Ion Exchange Applications and a Process for Their Sustainable Regeneration

The report is concerned with the design and synthesis of a mixed bead resin for high salt level desalination. The resin allows for the simultaneous exchange of both anions and cations, within the same polymer. This improves the efficiency of desalination at seawater levels. A novel process for sustainable and low energy desalination for brackish water has already been achieved via ion exchange resins as explained below. The advance in resin technology improves a novel membrane process with closed–cycle regeneration of the resin. It is a superior alternative to reverse osmosis.

Application of Ion Exchange and Adsorption Techniques for Separation of Whey Proteins from Bovine Milk

Background:The world production of whey was estimated to be more than 200 million tons per year. Although whey is an important source of proteins with high nutritional value and biotechnological importance, it is still considered as a by-product of the dairy industry with low economic value due to low industrial exploitation. There are several challenges in the separation of whey proteins: low concentration, the complexity of the material and similar properties (pI, molecular mass) of some proteins.Methods:A narrative review of all the relevant papers on the present methodologies based on ion-exchange and adsorption principles for isolation of whey proteins, known to the authors, was conducted.Results:Traditional ion-exchange techniques are widely used for the separation and purification of the bovine whey proteins. These methodologies, based on the anion or cation chromatographic procedures, as well as combination of aforementioned techniques are still preferential methods for the isolation of the whey proteins on the laboratory scale. However, more recent research on ion exchange membranes for this purpose has been introduced, with promising potential to be applied on the pilot industrial scale. Newly developed methodologies based either on the ion-exchange separation (for example: simulated moving bed chromatography, expanded bed adsorption, magnetic ion exchangers, etc.) or adsorption (for example: adsorption on hydroxyapatite or activated carbon, or molecular imprinting) are promising approaches for scaling up of the whey proteins’ purification processes.Conclusion:Many procedures based on ion exchange are successfully implemented for separation and purification of whey proteins, providing protein preparations of moderate-to-high yield and satisfactory purity. However, the authors anticipate further development of adsorption-based methodologies for separation of whey proteins by targeting the differences in proteins’ structures rather than targeting the differences in molecular masses and pI. The complex composite multilayered matrices, including also inorganic components, are promising materials for simultaneous exploiting of the differences in the masses, pI and structures of whey proteins for the separation.

Ion exchange and vacuum UV: A combined approach for removing organic matter and microcystins from natural waters

UV based advanced oxidation exhibits promising potential for the degradation of cyanobacterial toxins from natural waters. However, degradation is hindered by the presence of natural organic matter (NOM), which absorbs both 185 nm and 254 nm photons and scavenges hydroxyl radical (•OH), affecting mechanisms of UV/vacuum UV (VUV) degradation and requiring higher fluences (exposure times) to achieve microcystin reduction. In addition to obstructing UV/VUV degradation, NOM is associated with the formation of harmful disinfection by-products (DBPs) with drinking and recycled waters. Hence, technologies that are capable of removing NOM are desirable. In this study, we investigated the synergistic application of ion exchange (IX) resins and VUV for the removal of NOM and Microcystin-LR (MCLR) from natural waters. A pre-treatment with 1 mL/L dosage of IX resins removed >80% of the dissolved organic carbon (DOC) and UV254 absorbing compounds. This increased the MCLR degradation rates (up to three folds) in the tested surface waters. A progressive analysis on the degradation products indicated subsequent degradation of the toxic ADDA moiety of MCLR confirmed by the formation of compounds with a specific mass to charge ratio (m/z) of 835.5 855.3 and 791.4. More importantly, pre-treatment with IX resulted in reducing VUV’s electrical energy per order (EEO) by up to four folds and the overall chlorine demand by eight folds for surface waters. Hence, the results of this study indicate that a combined IX-VUV will be highly effective at reducing microcystins in impacted natural waters.

Jonska izmjena natrijuma sa hlorovodoničnom kiselinom na zeolitu ZSM-5

ZSM-5 zeolites are highly silicate materials that have significant application in catalytic processes in petrochemistry, especially due to their high selectivity. Most reactions in the petrochemical industry are acid-catalyzed. The acidic properties of zeolite depend on the number of acid centers, i.e. the presence of hydrogen ions, and therefore, in this paper the possibility of reducing the sodium content in the pores of high silicate zeolite ZSM-5 with the modulus (SiO2 / Al2O3 = 1000) will be investigated, by applying ion exchange with hydrochloric acid. Chemical analysis of samples before and after ion exchange, and application of instrumental methods of X-Ray diffraction, FT-IR spectroscopy, and SEM analysis monitored the influence of the quantity of hydrogen ions on the chemical composition and the structure of ZSM-5 zeolite at different acid concentrations and at different exchange times. It has been shown that the application of ion exchange with hydrochloric acid can reduce the sodium content in zeolite. Even with the application of 5% HCl for 6 hours, the content of sodium in the zeolite is reduced by over 98%. A similar effect is achieved by applying more concentrated hydrochloric acid solutions for a shorter ion exchange time. By prolonging the ion exchange time, there are no significant changes in terms of the final ion exchange. On the other hand, the application of HCl solutions of higher concentrations leads to a slight decrease in the aluminum content in the zeolite, which may partially affect the structural stability of the zeolite. The results obtained by FT-IR and SEM analysis and X-Ray diffraction confirm the possibility of ion exchange with hydrochloric acid, without significant changes in the crystal structure of the zeolite.

Groundwater quality and geochemical signatures in the northeastern Haryana, India

This investigation aims to monitor the sub-surface water quality in Yamunanagar and Ambala districts in northeastern Haryana for domestic and irrigation purposes and to possibly assess the causes leading to the impendence of prime constituents in sub-surface water. For the combined observation of two seasons each of the years 2017 and 2018, the local variation of total hardness, total alkalinity, total dissolved solids, and pH indicated that 93.33%, 91.67%, 90%, and 100% of samples, respectively, were within the permissible ranges of sub-surface water quality. Similarly, 98.33% of samples for anions, 96.11% for cations, and 93.33% for iron were appraised to be within the “permissible” band. Hydro-geochemistry indicated dominant mixed Ca2+–Mg2+–HCO3−, Na+–Cl−, Ca2+–Na+–HCO3−–, and Ca2+–Mg2+–Cl− sub-surface water. Metallic composition appraisal by the Stiff plot indicated the dominance of Ca2+–HCO3−, and Na+–K+–Cl− in ratio during the pre-and post-monsoon seasons, respectively. According to the Schoeller’s diagram, the relative abundance of metals in mg/l showed Na+ + K+ > Ca2+ > Mg2+ and HCO3− + CO32− > Cl− > SO42−. The sub-surface water has high salinity, Na+ hazards, and presence of chloride, fluoride, calcium, sulfate, and iron. Hydro-geochemical reactions manifested through Durov diagram showed anthropogenic sources as the possible reasons besides applications of fertilizers, salinization, ion-exchange, carbonate dissolution, and weathering. A benchmarking of laboratory outcomes with the geographic information system maps is in good agreement. Subject to consumption based on cations, anions, and a suite of metal ions, the sub-surface water has been found to be not risking residents’ well-being, crops, and industries.

Removal of Arsenic, Chromium and Uranium from Water Sources by Novel Nanostructured Materials Including Graphene-Based Modified Adsorbents: A Mini Review of Recent Developments

Groundwater is commonly used as a drinking water resource all over the world. Therefore, groundwater contamination by toxic metals is an important issue of utmost concern for public health, and several technologies are applied for their effective removal, such as coagulation, ion exchange, adsorption, and membrane applications like reverse osmosis. Adsorption is acknowledged as a simple, effective and economic technology, which has received increased interest recently, despite certain limitations regarding operational applications. The respective scientific efforts have been specifically focused on the development and implementation of novel nano-structured adsorbent materials, which may offer extensive specific surface areas, much higher than the conventional adsorbents, and hence, are expected to present higher removal efficiencies of pollutants. In this paper, the recent developments of nanomaterial applications for arsenic, chromium and uranium removal from groundwaters are critically reviewed. Particularly, the use of novel composite materials, based mainly on hybrid metallic oxide nanoparticles and on composites based on graphene oxide (GO) (i.e., graphene-based hybrids), showed promising evidences to achieve efficient removal of toxic metals from water sources, even in full scale applications.

Synthesis, Characterisation and Application of New Low-Cost Composite Ion Exchangers

Synthesis, Characterisation and Application of New Low-Cost Composite Ion Exchangers

Tổng hợp zeolite NaA/NaX từ tro trấu không nung bằng phương pháp thủy nhiệt

The development of technology and science as well as the growth of population cause the seriously polluted environment, especially the pollution of heavy metals. Synthesis of zeolites and their applications in adsorption, solid catalysts and ion exchange have been concerned. In this study, zeolite was synthesized from the precursor of sodium silicate originated from rice husk ash (RHA) without calcination by using hydrothermal method. The percentage of silica recovery from RHA without calcination was reached at about 90% when the optimal reaction conditions were at the ratio of RHA to NaOH = 1:10 (g/mL), the concentration of NaOH of 5 M, the reaction time of 3 h, the stirring speed of 300 rpm and the reaction temperature of 90oC. The parameters affected zeolite NaA/NaX synthesis such as ratio of SiO2 to Al2O3, the reaction temperature T1 (oC), reaction time t1 (h) and aging time t2 (h) were investigated. The results showed that crystal percentage of zeolite NaA/NaX was obtained at 52,7% during 4 h, 100oC, aging time of 12 h, ratio of Al2O3 to SiO2 of 2,5 and the ratio of Al:NaOH = 1:2 Although the crystal percentage of zeolite NaA/NaX in this study was not as high as that of other published researches, the in-situ synthesis used RHA without calcination and recovery of silica during the synthesis of zeolite NaA/NaX. Therefore, the synthesized process is environmental friendly as well as time and energy savings.

Potential dependent ionic sieving through functionalized laminar MoS2 membranes

Laminar MoS2 membranes show outstanding potential for practical applications in energy conversion/storage, sensing, and as nanofluidic devices. The re-stacking of exfoliated MoS2 creates nanocapillaries between the layers of MoS2 nanosheets. These MoS2 membranes have been shown to possess a unique combination of ionic rejection properties, high water permeation rates, and long-term solvent stability, with no significant swelling when exposed to aqueous or organic solvents. Chemical modification of MoS2 membranes has been shown to improve their ionic rejection properties, however the mechanism behind this improvement is not well understood. In this work, we elucidate the ion-sieving mechanism by the study of potential-dependent ion transport through functionalized MoS2 membranes. The ionic permeability of the MoS2 membrane is transformed by chemical functionalization with a simple naphthalene sulfonate dye (sunset yellow) and with a resultant attenuation of permeability by at least an order of magnitude, compared to the pristine MoS2 membranes and permeability reported for graphene oxide and Ti3C2Tx (MXene) membranes. The effects of pH, solute concentration, and ionic size/charge on the ionic selectivity of the functionalized MoS2 membranes are also reported. Understanding the mechanism of ionic sieving within functionalized MoS2 membranes will enable future applications in electro-dialysis and ion exchange for water treatment technologies.

Understanding the sorption behaviour of Pu/U on zirconium phosphosilicate prepared by gelation route

Abstract Zirconium phosphosilicate (ZPS) has been prepared by gelation route for its ion exchange applications. ZPS was characterised by X-ray diffraction technique (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), Fourier transformed Infrared Spectrometry (FTIR) and surface area analysis. K+ ion exchange behaviour was studied by pH titration. The material was found to extract Pu selectively over U from different mineral acids. Pu sorption behaviour on ZPS packed column was also been carried out. The pore volume was evaluated as 0.1336 mL g−1. The FTIR revealed the presence of –OH and PO4 3− groups on the surface of the material, while the SEM image indicates the irregular morphology and size of the sorbent. Different isotherm model: Langmuir, Freundlich, Dubinin–Rodushkevich and Temkin were used to understand the nature of sorption, while Lagergren 1st order, Intraparticle diffusion and pseudo 2nd order kinetics were used for modelling sorption kinetics. Suitable elution method was used for quantitative stripping of plutonium from sorbent. The radiolytic stability of the sorbent was evaluated upto 1500 kGy. A comparative evaluation of the sorption process has also been carried out with that reported in literature.

Application of Ion Exchange, Solvent Extraction, and Ion-Imprinted Methods for Separation of 203Pb

Lead-203 was produced by proton bombardment of natural thallium target. For producing 203Pb, natTl was electroplated on copper backing as target and was bombarded by energetic proton beam. After bombardment, the target was dissolved in 1 M HNO3. Ion exchange, solvent extraction, and nanomagnetic ion-imprinted polymer methods were used for separating 203Pb from thallium. The separation efficiency of these methods was studied. γ-Ray spectroscopy was applied for evaluating 203Pb and others radionuclides. The separation efficiency was determined from the γ-ray spectra. The separation efficiency of the methods using ion exchange, solvent extraction, and nanomagnetic ion-imprinted adsorbent was 98, 99.3, and 96.4%, respectively.

Structural Diversity of Bipyridinium-Based Uranyl Coordination Polymers: Synthesis, Characterization, and Ion-Exchange Application.

As well-known functional groups with excellent electro/photochromic and ion-exchange properties, bipyridinium motifs have been used in functionalized metal-organic coordination polymers, but they are still rarely applied to construct actinide coordination polymers. In this work, we utilized a bipyridinium-based carboxylic acid, 1,1'-bis(4-carboxyphenyl)-4,4'-bipyridinium bis(chloride) ([H2bcbp]Cl2), as the organic ligand to assemble with uranyl cations. By the introduction of different kinds of auxiliary ligands and adjustment of the pH, five novel uranyl coordination compounds, 1-5, have been synthesized through hydrothermal reactions. Starting from uranyl ions and terephthalic acid (H2TP) and H2bcbp ligands, [(UO2)2(bcbp)(TP)2]·3H2O (1) has a wave-shaped two-dimensional (2D) structure consisting of dinuclear units connected by terephthalate linkers and further supported by the longer H2bcbp ligands. [(UO2)2(bcbp)(PA)2]·4H2O (2) has a zigzag chain of dimeric uranium units, and [(UO2)2(bcbp)(bpdc)2]·5H2O (3) forms a one-dimensional ribbonlike structure. The 2D structures of [(UO2)(bcbp)(OH)(H2O)]·Cl (4) and [(UO2)(bcbp)Cl]·Cl (5) are similar, both of which are constructed from dinuclear uranyl units and bcbp2- ligands. Furthermore, the performance for perrhenate removal of compound 4 with a cationic framework is assessed, and we found that compound 4 can efficiently remove ReO4- from an aqueous solution in a wide range of pH values. This work extends the library of viologen derivative-based uranyl coordination polymers, provides to some extent broader insights into actinide coordination chemistry of functionalized ligands, and may facilitate the ion-exchange applications of related coordination polymers.

PolyHIPEs for Water Treatment

PolyHIPEs (polymers synthesized within high internal phase emulsions) are porous materials with high specific surface area which suggests their use in ion exchange applications. We have successfully synthesized and functionalized such materials to make then hydrophilic by mixing an oil phase and an aqueous phase containing deionized water and sulphuric acid. The PolyHIPE samples were also subjected to a further microwave-assisted post-sulphonation process to increase hydrophilicity and water uptake. Post sulphonation results in a higher concentration of benzenesulphonic acid groups which are necessary for ion exchange. PolyHIPE beads processed in this manner were able to remove low concentrations (∼20mg/l) of nickel and copper ions from solution with high removal efficiency (80-95%) depending on the initial pH of the water. However, recovery of the metal through regeneration at different pH levels was less successful.

Synthesis and sorption properties of porous resorcinol–formaldehyde resins prepared by polymerization of the emulsion dispersion phase

Resorcinol–formaldehyde resins for the removal of Cs from liquid media have been synthesized by polymerization of the emulsion dispersion phase. Chemical stability and kinetic parameters of the ion-exchange process in the porous ion exchangers have been estimated using the diffusion coefficient and the exchange half-time. The results of Cs (Cs-133 и Cs-137) removal under static and dynamic conditions are provided. The efficiency of Cs removal from the simulated solution of the evaporator concentrate (EC) containing Cu2+, Co2+, Cr3+, and Ni2+ cations has been estimated. Good prospects of application of porous ion exchangers in the function of materials for Cs removal from highly mineralized alkali media have been demonstrated.

Fast preparation of Ce3+-activated scandate for high-color- rendering warm white-light illumination by cation exchange

High-color-rendering illumination is an important application direction in the development of white-light-emitting diodes (WLEDs). In this work, the Ce3+-activated Sr3Sc4O9-CaSc2O4 phosphors are successfully obtained by cation exchange from Sr3Sc4O9:Ce3+. Due to the high reaction activity and reaction rate in CaCl2 melt, the exchange process can be realized under much lower temperature than that of traditional high-temperature sintering, even near the melting point of CaCl2 (1058 K). The color tunability of as-prepared phosphors from orange to green is also easily tailored by adjusting the content of CaCl2. What is more, combining the exchanged phosphor and a blue LED, a high-color-rendering warm WLED is also demonstrated (CCT = 3555 K, Ra = 88, R9 = 94), which is comparable to most of commercial WLEDs. The obtained results not only manifest the potential application of ion exchange in preparing luminescent materials and adjusting corresponding spectral properties, but also provide a promising platform in developing the high-color-rendering warm white-light illumination.

Development of Pilot Scale System for Production of Nylon-6 Fibers Grafted with Polydimethylaminoethylmathacrylate (PDMAEMA) for the Application as Ion Exchange

In this work an affective and simple technology for pilot scale production of grafted Nylon-6 fibers with Polydimethylaminoethylmathacrylate (PDMAEMA) for ion exchange application is suggested. This technology consists of the creation of antimicrobial substance (AS) in Nylon-6 fibers followed by grafting with dimethylaminoethylmathacrylate (DMAEMA) using Cu2+-K2S2O8 redox system. Factors affecting the yield of grafted PDMAEMA were investigated and the optimal conditions for grafting process were evaluated. The availability of modified Nylon-6 fibers grafted with PDMAEMA as polymer sorbent for removal of cations as Cu+2, Pb+2 and anions Cr2O7-2, SO4-2 was investigated. The influence of various adsorption parameters on the degree of extraction (R %) and adsorption capacity (SC mg/g) was calculated.

Application of Ion Exchange for Preparation of Selected Metal Perrhenates—Precursors for Superalloy Production

Methods for the preparation of selected metal perrhenates and their mixtures are presented in this paper. These materials are suitable for reduction, and therefore for production of alloy powders containing rhenium and other superalloy components, i.e., Cr, Ni and Co. Prepared compounds may be also used as substrates for electrowinning of binary and ternary rhenium alloys. All developed methods are based on an ion exchange technique. This technique allows management of waste solutions, limitation of valuable metals losses, and, importantly, production of high-purity components.

How Intercalated Sodium, Copper, and Iron Cations Influence the Structural Arrangement of Zirconium Sulfophenylphosphonate Layers? Theoretical and Experimental Points of View

A structural arrangement of sodium, copper, and iron cations intercalated in zirconium 4-sulfophenylphosphonate (ZrSPhP), as a potential material for ion-exchange applications, was suggested by mol...

Self-Assembly of a Midblock-Sulfonated Pentablock Copolymer in Mixed Organic Solvents: A Combined SAXS and SANS Analysis.

Ionic, and specifically sulfonated, block copolymers are continually gaining interest in the soft materials community due to their unique suitability in various ion-exchange applications such as fuel cells, organic photovoltaics, and desalination membranes. One unresolved challenge inherent to these materials is solvent templating, that is, the translation of self-assembled solution structures into nonequilibrium solid film morphologies. Recently, the use of mixed polar/nonpolar organic solvents has been examined in an effort to elucidate and control the solution self-assembly of sulfonated block copolymers. The current study sheds new light on micellar assemblies (i.e., those with the sulfonated blocks comprising the micellar core) of a midblock-sulfonated pentablock copolymer in polar/nonpolar solvent mixturesby combining small-angle X-ray and small-angle neutron scattering. Our scattering data reveal that micelle size depends strongly on overall solvent composition: micelle cores and coronae grow as the fractionof nonpolar solvent is increased. Universal model fits further indicate that an unexpectedly high fraction of the micelle cores is occupied by polar solvent (60-80 vol %) and that partitioning of the polar solvent into micelle cores becomes more pronounced as its overall quantity decreases. This solvent presence in the micelle cores explains the simultaneous core/corona growth, which is otherwise counterintuitive. Our findings provide a potential pathway for the formation of solvent-templated films with more interconnected morphologies due to the greatly solvated micellar cores in solution, thereby enhancing themolecular, ion, and electron-transport propertiesof the resultant films.

Minimalistic Synthesis of α-Zirconium Diammonium Phosphate and Zirconia for Applications in Ion Exchange and Catalysis

α-Zirconium diammonium phosphate (α-Zr(NH4PO4)2·H2O) and ZrO2 find useful applications as ion-exchangers and catalysts. The current syntheses of these compounds are usually via solution-precipitation methods that require solvents and excess of reagents. An essentially solvent-free approach with only the water of crystallization for homogenization has now been developed, by which α-zirconium diammonium phosphate and ZrO2 can be synthesized with minimalistic ratios of reactants. α-Zr(NH4PO4)2·H2O was directly accessible in a single step, in contrast to the currently used two-step solution processes. Highly crystalline α-Zr(NH4PO4)2·H2O was obtained from a reaction composition of ZrOCl2·8H2O:4(NH4)2HPO4:0.05NaF after heating at 120 °C for 1 day. α-Zr(NH4PO4)2·H2O showed excellent sorption for Pb2+ and Cu2+ with removal efficiencies ≥99% and high distribution coefficients of 106–107. Similarly, by this minimalistic approach, different modifications of ZrO2 were obtained depending on the base and temperature. Monoclinic ZrO2 formed at 160 °C from stoichiometric mixtures of ZrOCl2·8H2O and ammonium carbonate or with 1.5 times excess urea. Tetragonal ZrO2 was obtained with a stoichiometric amount of NaOH. The monoclinic ZrO2 showed higher activity than the tetragonal form in the Meerwein–Ponndorf–Verley reduction of furfural to furfuryl alcohol.