Separation Of Alkali Metal Ions Research Articles

(Invited) Atomistic Insights on Prussian Blue Analogues for Aqueous Electrochemical Separations

Prussian blue analogues (PBAs) containing metal centers bridged by cyanide ligands exhibit one of the simplest structures among metal organic frameworks, which lends them to facile and reversible insertion of monovalent cations. Such a property has motivated their use in aqueous electrochemical separations, including our most recent demonstration of brackish water desalination with only 25% more energy consumption than thermodynamic minimum.1 Despite their selectivity bias toward cations of small hydrated radius being known for 36 years,2 the microscopic mechanisms responsible for such bias that could be used to inform the rational design of future materials are not well understood.Accordingly, we report on our recent efforts3,4 to uncover the interactions between inserted cations, interstitial water, and PBA lattices that produce selectivity bias. To understand the interplay between structural distortion, bonding, and water uptake from contacting electrolyte we use a first-principles approach that combines machine learning with density functional theory and grand potential analysis to explore the potential energy landscapes of disordered arrangements of interstitial species in nickel hexacyanoferrate PBA. Here, a competition for dative bonds of acidic interstitial cations between basic oxygen in interstitial water and basic cyanide ligands is shown to result in complexation between cations and water that deviate fundamentally from bulk hydration in pure water, despite the common attribution of PBA selectivity to purely steric effects of cation hydration. Van der Waals interactions are further shown to enhance the formation of water clusters and extended hydrogen-bonded networks within the PBA host, depending on the bare ionic radius of inserted cations. Grand potential analysis is performed to ultimately produce previously observed selectivity bias (Cs+ > K+ > Na+) and to determine the equilibrium hydration degree of the PBA in both reduced and oxidized forms. This analysis shows that small (Na+) and moderately sized (K+) cations require two to four water molecules per formula unit in both reduced and oxidized forms of the PBA, while large cations (Cs+) exhibit much smaller hydration levels in oxidized form and exhibit no hydration in reduced form. References Reale, E. R., Regenwetter, L., Agrawal, A., Dardón, B., Dicola, N., Sanagala, S. & Smith, K. C. Low porosity, high areal-capacity Prussian blue analogue electrodes enhance salt removal and thermodynamic efficiency in symmetric Faradaic deionization with automated fluid control. Water Res. X 13, 100116 (2021).Ikeshoji, T. Separation of Alkali Metal Ions by Intercalation into a Prussian Blue Electrode. J. Electrochem. Soc. 133, 2108 (1986).Liu, S. & Smith, K. C. Linking the polyatomic structure of interstitial H2O and cations to bonding within Prussian blue analogues ab initio using gradient-boosted machine learning. Phys. Rev. Mater. 5, 035003 (2021).Liu, S. & Smith, K. C. Effects of interstitial water and alkali cations on the expansion, intercalation potential, and orbital coupling of nickel hexacyanoferrate from first principles. J. Appl. Phys. 131, 105101 (2022).

Membranes for separation of alkali/alkaline earth metal ions: A review

The alkali metal and alkaline-earth metal elements, located in the adjacent main-groups of the periodic table, always have similar electronic structures and chemical properties. Thus, they are usually coexisting in ores or water resources. The separation of alkali metal ions and alkaline-earth metal ions has significant application prospect in seawater desalination, resource recovery and energy storage, which are paramount for the sustainable development of the environment, resources and energy. Membrane technologies have been investigated extensively in this area and have attracted widespread attention because of their advantages of environmental friendly and energy efficient. Accordingly, this work reviews recent advances in various types of membranes focused on the separation of alkali and alkaline earth metal ions, including organic membranes, inorganic membranes and mixed matrix membranes. Moreover, this review provides insights into the design and fabrication of membranes, the separation mechanisms, and the advantages and current challenges of each membrane.

Effect of photoirradiation on chromatographic separation of alkali metal ions using crowned-spirobenzopyran-immobilized silica

We successfully developed a novel photocontrollable chromatographic system for separation of alkali metal ions. Based on the finding that the metal-ion complexation of spirobenzopyran derivatives bearing a crown ether moiety, which we call crowned spirobenzopyran, can be drastically changed by photoirradiation, crowned spirobenzopyrans were immobilized covalently onto silica gels for stationary phases of ion chromatography. Under dark or UV-light irradiation conditions, a marked separation between Li+ and K+ was attained by silica gels modified chemically with crowned spirobenzopyran bearing an 18-crown-6 ring. On the other hand, no significant separation between the two metal ions was found under visible-light irradiation conditions. This result originates from the fact that the K+-complexing ability of crowned-spirobenzopyran-immobilized silica is switched by photoisomerization of the spirobenzopyran moiety from its merocyanine form to spiropyran form. Furthermore, computer simulations of separation of alkali metal ions by crowned spirobenzopyrans in the silica phase were conducted using molecular dynamics calculations.

ChemInform Abstract: Synthetic Inorganic Ion-Exchange Materials. Part 60. Ion Exchange and Chromatographic Separation of Alkali Metal Ions on Cubic Ammonium Molybdate. A Novel Cation Exchanger.

ChemInform Abstract: Synthetic Inorganic Ion-Exchange Materials. Part 60. Ion Exchange and Chromatographic Separation of Alkali Metal Ions on Cubic Ammonium Molybdate. A Novel Cation Exchanger.

Ion exchange properties of monolithic and particle type iminodiacetic acid modified silica.

A 10 cm silica monolith has been modified with iminodiacetic acid (IDA) groups and characterised for its selectivity toward alkali, alkaline earth, and selected transition metal cations. Physical characterisation of the modified monolith found non-homogeneous modification along the length of the monolith, although sufficient capacity was achieved to facilitate significant retention of alkaline earth and transition/heavy metal ions over a range of eluent pH and ionic strength conditions. For alkaline earth and transition/heavy metal ions, selectivity of the 10 cm IDA monolith closely matched that seen with a 25 cm IDA modified silica gel particle packed column, although the separation of alkali metal ions was noticeably poorer on the monolithic column. Peak efficiencies for most metal ions were of a similar order for both column types, except for Zn(II), which showed significant peak broadening on the IDA monolithic column.

ChemInform Abstract: Extractive Separation of Alkali Metal Ions by Mono‐ and Bis‐o‐xylyl Crown Macrocyclic Compounds in an Aquatic Environment.

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Applications of capillary zone electrophoresis in clinical chemistry Determination of low-molecular-mass ions in body fluids

Investigations were carried out on parameters influencing separation selectivity in the capillary zone electrophoresis of inorganic cations. Copper sulphate can be recommended as a carrier electrolyte salt for the separation of alkali and alkaline earth metal ions. Its separation selectivity is different from that of the widely used aromatic amines and it is compatible with indirect UV detection at 214 nm. The addition of organic solvents to the electrolyte results in a general increase in the migration times of divalent cations relative to monovalent cations. Ion-pairing reagents such as sodium dodecyl sulphate were found to exhibit specific effects on some ions (especially strontium and barium), but are less useful owing to interferences with the separation of alkali metal ions by sodium introduced with the ion-pairing reagent. Applications to the determination of cations relevant in clinical chemistry are demonstrated for serum samples. Further, the determination of anions in serum was investigated using chromate as electrolyte. Generally, the advantage of capillary zone electrophoresis over ion chromatography can be seen in the fact that proteins need not be removed from the sample and do not interfere with the separation of low-molecular-mass ions.

Chromatographic selectivity for amino acid esters and alkali metal ions on a silica bonded calix[4]arene tetraester stationary phase

A silica bonded tetrameric calix[4]arene ester stationary phase has been used in the chromatographic separation of alkali metal ions and amino acid esters. Under reversed phase conditions, baseline resolution of a standard test mixture of benzamide, benzophenone and biphenyl was achieved using an MeOH—H2O mobile phase. In the chromatography of the amino acid ester hydrochlorides, retention appears to be related to the hydrophobicity of the esters studied, with tryptophan methyl ester being the longest retained.

Enhanced Chromatographic Selectivity for Na+Ions on a Calixarene-Bonded Silica Phase

Abstract Functional esters of calixarenes, which are phenolic metacyclophanes annulated by a single methylene bridge, are immobilised onto silica particles for use in the separation of alkali metal ions by high performance liquid chromatography with conductivity detection. The immobilisation of tetrameric and hexameric calixarene ethyl esters was carried out using the triethoxy silane derivatives of p-allylcalix[n]arene ethyl esters. At an injected concentration of 10−2M, optimum selectivity for Na ions was achieved using a mobile phase of 30% MeOH/H2O with the calix[4]arene ester stationary phase. A mixture of four alkali metal chlorides is shown on injection to give a clear separation of Na+ from the other unresolved ions, the retention order being Na+ » K+ > Cs+ > Li+ = to.

Synthetic Inorganic Ion-Exchange Materials LX. Ion Exchange and Chromatographic Separation of Alkali Metal Ions on Cubic Ammonium Molybdate–A Novel Cation Exchanger

Abstract The ion-exchange selectivity of H+-form of cubic ammonium molybdate (H-CAM) was studied for alkali metal ions in both HNO3 and NH4NO3 media. Ideal ion-exchange reaction was observed in both the media with high selectivity for Rb+ and Cs+. The selectivity sequence was found to be Li+<Na+<K+<Rb+<Cs+ in accordance with the Eisenman sequence-1 in both the media, with separation factors greater than the commercial polystyrene strong acid exchange resin. Efficient separation of alkali metal ions could be achieved on H-CAM column.

ChemInform Abstract: Separation of Alkali Metal Ions by Intercalation into a Prussian Blue Electrode.

ChemInform Abstract: Separation of Alkali Metal Ions by Intercalation into a Prussian Blue Electrode.

Separation of Alkali Metal Ions by Intercalation into a Prussian Blue Electrode

not Available.

Convenient, efficient crown ether-containing stationary phases for chromatographic separation of alkali metal ions: dynamic coating of highly lipophilic crown ethers on octadecylsilanized silica

Novel immobilization of highly lipophilic crown ether derivatives by coating the crown ethers onto insoluble supports through hydrophobic interactions provides stationary phases for efficient chromatographic separation of alkali metal ions.

Synthetic inorganic ion-exchange materials : XV. Chromatographic separation of alkali metalions using phosphoantimonic(V) acid as a cation exchanger

The use of phosphoantimonic(V) acid as a cation exchanger in the chromatographic separation of alkali metal ions has been investigated. The mutual separation of alkali metal ions (except the Li +-Na + pair) was achieved by using a relatively small column (6.0 × 0.8 cm I.D.) with ammonium nitrate solution as the eluent.

Separation of Alkali-Metal Ions from Each Other and from Other Metal Ions on Ion-Exchange Papers

Abstract Cation-exchange paper chromatography with mixed solvents provides for the mutual separation of the alkali-metal ions. Development with a complexing solution on anion-exchange paper provides for the separation of the alkali metals as a group from other monovalent and multivalent metal ions.

Separation of Alkali Metal Ions as Polyiodide Complexes by Thin Layer Chromatography.

Separation of Alkali Metal Ions as Polyiodide Complexes by Thin Layer Chromatography.

Ion exchange procedure : VII. Separation of alkali metal ions

Ion exchange procedure : VII. Separation of alkali metal ions

Chromatographic separation of alkali metal ions on paper impregnated with ammonium molybdophosphate

Strips of Whatman No. I filter paper, impregnated with 3.2 mg/cm/sup 2/ AMP, were used to determine the R/sub F/ values of alkali metal ions. The chromatograms were developed by the ascending method for 2 to 3 hr. With a suitable developing solvent, clear separation of any two ions is possible. The difficulty in obtaining a separation of the 5 alkali metals on the same strip at the same time with a single eluant is due to the considerable difference in the affinity of the AMP for the elements in question. A procedure for obtaining complete separation is given. (P.C.H.)