Cation exchange, interlayer spacing, and thermal analysis of Na/Ca-montmorillonite modified with alkaline and alkaline earth metal ions

Na-montmorillonites were exchanged with Li⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺, while Ca-montmorillonites were treated with alkaline and alkaline earth ions except for Ra²⁺ and Ca²⁺. Montmorillonites with interlayer cations Li⁺ or Na⁺ have remarkable swelling capacity and keep excellent stability. It is shown that metal ions represent different exchange ability as follows: Cs⁺?>?Rb⁺?>?K⁺?>?Na⁺?>?Li⁺ and Ba²⁺?>?Sr²⁺?>?Ca²⁺?>?Mg²⁺. The cation exchange capacity with single ion exchange capacity illustrates that Mg²⁺ and Ca²⁺ do not only take part in cation exchange but also produce physical adsorption on the montmorillonite. Although interlayer spacing d ₀₀₁ depends on both radius and hydration radius of interlayer cations, the latter one plays a decisive role in changing d ₀₀₁ value. Three stages of temperature intervals of dehydration are observed from the TG/DSC curves: the release of surface water adsorbed (36?C84?°C), the dehydration of interlayer water and the chemical-adsorption water (47?C189?°C) and dehydration of bound water of interlayer metal cation (108?C268?°C). Data show that the quantity and hydration energy of ions adsorbed on montmorillonite influence the water content in montmorillonite. Mg²⁺-modified Na-montmorillonite which absorbs the most quantity of ions with the highest hydration energy has the maximum water content up to 8.84%.     

Assessment of Bhatiari Lake water quality: Pollution indices,hydrochemical signatures and hydro-statistical analysis

This study aimed at evaluating the water quality of Bhatiari Lake (BL) for the first time based on water quality parameters, pollution indices, hydrochemical signatures and hydro-statistical analysis. Lake water samples were collected from the lake during April–May 2019 and wide ranges of parameters were considered for the investigation. Except for COD and Fe, all the parameters were within the permissible limit. COD crossed Bangladesh standards and testing institution (BSTI) and United States environmental protection agency (USEPA) standards. In contrast, Fe crossed World health organization (WHO), Bureau of Indian Standards (BIS) and USEPA standards. Hydrochemical analysis indicated the water as soft-fresh where near neutral low-metal was noticed from the Ficklin-Caboi diagram. Ca²⁺-Mg²⁺-HCO₃^- type water was confirmed from Piper and Chadha diagram, whereas Durov and Schoeller's diagram were indicated the influence of Mg²⁺-HCO₃^-. The trend of cations and anions were Ca²⁺> Mg²⁺> Na⁺>K⁺ and HCO₃^? > Cl^? > NO₃^? > SO₄^2? > PO₄^3? as stated by pie chart. Most precipitation dominant water was confirmed from the Gibbs diagram. Principal component analysis (PCA), Cluster analysis (CA) and Correlation matrix (CM) indicated the co-existence of geogenic and anthropogenic sources for pollution. Good water quality was observed via an integrated approach namely degree of contamination (C_d), Single-Factor Pollution Index (SPI), Comprehensive pollution index (CPI), Heavy metal evaluation index (HEI), Heavy metal pollution index (HPI), Nemerow's pollution index (NPI) and Ecological risk index (ERI). In addition, water quality index (WQI) remarked the water is excellent. Taken collectively, the present study indicates the BL water can be considered pollution-free.     

A new sulfonamide derivative as magnesium ion receptor: N-tosyl-2,6-diisopropyl-4-(2,3-dimethoxylbenzoylamide)aniline

N-Tosyl-2,6-diisopropyl-4-(2,3-dimethoxylbenzoylamide)aniline (1) has been synthesized and its metal ion (Na⁺, K⁺, Ca²⁺, Mg²⁺) coordinating properties investigated by FT-IR, ESI-MS, and ¹H NMR methods. Among the tested metal ions, the overall stability constant (log K) for Mg²⁺ (6.89) is the highest (Na⁺, 5.64; K⁺, 5.43; Ca²⁺, 5.51) in 10% water/THF at 25.0 ± 0.5 °C determined by UV-vis spectroscopy, indicating that 1 is a potent ionophore for Mg²⁺ ion.     

Determination of sodium,potassium, calcium and magnesium cations in biodiesel by ion chromatography

This work reports an ion chromatographic (IC) method for the quantitative determination of inorganic cations (Na⁺, K⁺, Mg²⁺ and Ca²⁺) in biodiesel samples that were synthesized from different vegetable oils and fat. The proposed method uses water extraction, heating and ultrasound. The limits of detection (LOD) for each ion, in milligrams of the analyte per kilogram of biodiesel (mg kg⁻¹), were respectively: 0.11 (Na⁺); 0.42 (K⁺); 0.23 (Ca²⁺); and 0.36 (Mg²⁺). The accuracy of the method was studied through recovery tests. For comparison, two samples were also analyzed using an Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) procedure. The paired Student t test and the Snedecor F test showed that both methods offer equivalent results in terms of accuracy and precision. The operational simplicity, accuracy and precision of the proposed method suggest that it can be a good alternative for the determination of inorganic cations in biodiesel samples.     

Selective Separation of Lithium,Magnesium and Calcium using 4-Phosphoryl Pyrazolones as pH-Regulated Receptors

Ensuring continuous and sustainable lithium supply requires the development of highly efficient separation processes such as LLE (liquid-liquid extraction) for both primary sources and certain waste streams. In this work, 4-phosphoryl pyrazolones are used in an efficient pH-controlled stepwise separation of Li⁺ from Ca²⁺, Mg²⁺, Na⁺ and K⁺. The factors affecting LLE process, such as the substitution pattern of the extractant, diluent/water distribution, co-ligand, pH, and speciation of the metal complexes involved, were systematically investigated. The maximum extraction efficiency of Li⁺ at pH 6.0 was 94 % when Mg²⁺ and Ca²⁺ were previously separated at pH<5.0, proving that the separation of these ions is possible by simply modulating the pH of the aqueous phase. Our study points a way to separation of lithium from acid brine or from spent lithium ion battery leaching solutions, which supports the future supply of lithium in a more environmentally friendly and sustainable manner.     

Metal Cation Transport Studies Comparing Dibenzo-18-crown-6 (DB18C6) with N,N,N′,N′-Tetrakis (n-propyl)-2,3- naphthalenedioxydiacetamide (NPr)

The previously synthesized3,6-dioxa-4,5-disubstitutedoctanedicarboxamides including NPr bind cationsin methanol in the order: Ca²⁺ > Sr²⁺ >Ba²⁺ > Mg²⁺ > Na⁺,K⁺. These compounds also extract Group II cations better thanGroup I cations from water to dichloromethane. In contrast, thesediacetamides were found by W. Simon et al., to sense Na⁺ >Ca²⁺ when they were incorporated into ion-selective electrodesusing a low dielectric constant solvent. It was of interest to determine theorder of Group I and Group II cation transport rates of these compoundsusing a three-phase system with a liquid organic phase of low dielectricconstant. We now report that NPr transports thiocyanates in such a systemusing dichloromethane in the order K⁺ (7.2) >Ca²⁺ (6.6) > Ba²⁺ (5.8) > Na⁺(1). The transport rate for KSCN with DB18C6 is 20.5 times faster than withNPr.     

金属组学在急性心肌梗死早期诊断的应用

为探讨急性心肌梗死(AMI)患者血清中K⁺、Na⁺、Ca²⁺、Fe²⁺、Mg²⁺含量变化，并研究其与心肌梗死患者之间的关系。选取2022年5月至2023年2月收治的AMI患者37例，同时选取健康体检者35例作为对照组。依据入院时或体检时收集的抽血样本进行临床生化分析，比较两组间血清K⁺、Na⁺、Ca²⁺、Fe²⁺、Mg²⁺含量，采用判别方程、主成分分析法(PCA),判断分析哪种金属离子对于心肌梗死的诊断价值大。结果表明，AMI患者的血清中Ca²⁺和Fe²⁺含量低于健康对照组，差异具有统计学意义。基于血钙、铁水平两组具有显著性差异，以它们为基础进行判别分析，获得判别函数式。将血清中K⁺、Na⁺、Ca²⁺、Fe²⁺、Mg²⁺     

Magnesium selective electrodes for blood serum studies and water hardness measurement

Magnesium selective ionophores are described which induce a rejection of Na⁺ and K⁺ in solvent polymeric membranes by factors of up to 6300 and 5000, respectively. Depending on the membrane composition, ion selective electrodes may be obtained with equal selectivity for Mg²⁺ and Ca²⁺ as well as sensors with a discrimination of Ca²⁺ by a factor up to 8. Sensors of the type described are candidates for water hardness determination as well as for an Mg²⁺ assay in blood by chemometric procedures.On leave from the Chemistry Department, University of Warsaw, ul. L. Pasteura 1, PL-02-093 Warsaw, PolandOn leave from the Shanghai University of Technology, 149 Yanchang Road, Shanghai, People's Republic of China     

Affinity capillary electrophoresis employed for determination of stability constants of antamanide complexes with univalent and divalent cations in methanol

Affinity capillary electrophoresis (ACE) and pressure‐assisted ACE were employed to study the noncovalent molecular interactions of antamanide (AA), cyclic decapeptide from the deadly poisonous fungus Amanita phalloides, with univalent (Li⁺, Na⁺, K⁺, and NH₄⁺) and divalent (Mg²⁺ and Ca²⁺) cations in methanol. The strength of these interactions was quantified by the apparent stability constants of the appropriate AA‐cation complexes. The stability constants were calculated using the nonlinear regression analysis of the dependence of the effective electrophoretic mobility of AA on the concentration of the above ions in the BGE (methanolic solution of 20 mM chloroacetic acid, 10 mM Tris, pH_MeOH 7.8, containing 0–50 mM concentrations of the above ions added in the form of chlorides). Prior to stability constant calculation, the AA effective mobilities measured at actual temperature inside the capillary and at variable ionic strength of the BGEs were corrected to the values corresponding to the reference temperature of 25°C and to the constant ionic strength of 10 mM. From the above ions, sodium cation interacted with AA moderately strong with the stability constant 362 ± 16 L/mol. K⁺, Mg²⁺, and Ca²⁺ cations formed with AA weak complexes with stability constants in the range 37–31 L/mol decreasing in the order K⁺ > Ca²⁺ > Mg²⁺. No interactions were observed between AA and small Li⁺ and large NH₄⁺ cations.     

A study of reconstituted anion channels using lipid bilayers

A chloride channel from impermeant sarcoplasmic reticulum (SR) was embedded in a planar lipid bilayer (BLM) and its electrical properties determined. Studies using ER-derived vesicles fused with BLMs have shown that they are permeable to Na⁺, K⁺, choline and Cl⁻ but less permeable to Ca²⁺ and Mg²⁺. Though highly permeable to K⁺, the liver ER membrane has been postulated to a lack of an efficient ion-conducting structure for K⁺ channel in the SR. The present study was undertaken with the aim to look at the anionic, Ca²⁺ and K⁺ permeability pathways present in the ER membrane. Our reconstituted system exhibits considerable anionic permeability following the sequence: SCN⁻>I⁻>Br⁻Cl⁻>gluconate. The findings suggest the chloride channels have low field-strength sites. It can be pharmacologically dissected to Zn²⁺-sensitive and DIDS-sensitive types. The gating of the channel is weakly voltage-dependent and at higher positive or negative voltages the channel prefers the low sub-conductance states.     

Chemical composition and crystal structure of β-alumina type R+-gallate (R+ = K+, NH+4)

The crystal structures of β-alumina type K⁺-gallate (K⁺-β-gallate), Mg²⁺-doped K⁺-β-gallate, and NH⁺₄-β-gallate were refined by the single crystal X-ray diffraction method. The positive charges of excess K⁺ ions in K⁺-β-gallate were compensated by O^2? ions in the mO site which coordinated with interstitial Ga³⁺ ions. The charge compensation mechanism mentioned above was changed by doping with Mg²⁺ ions. The excess charges in Mg²⁺-doped K⁺-β-gallate were compensated by the replacement of Mg²⁺ ions for Ga³⁺ ions at the middle of spinel block. No defects were found in NH⁺₄-β-gallate for the charge compensation, which was completely consistent with the result of thermal analysis that indicated a stoichiometric composition of NH⁺₄-β-gallate.     

Cyclic Octa- and Decapeptides as Ionophores for Magnesium

Cyclic octa- and decapeptides have been prepared, and their ion selectivity in solvent polymeric membranes was studied. Cyclo(-LPro-DLeu-)₅ behaves as an ionophore which selects Mg²⁺ over Ca²⁺ by a factor of 100. Cyclo(LPro-LLeu)₅ induces selectivity in membranes for Mg²⁺ over Li⁺, Na⁺ and K⁺ by a factor of 400, 200 and 10, respectively, while selectivity of Mg²⁺ over Ca²⁺ is poor. Some evidence is presented which indicates that certain ionophores exhibit high selectivity for monovalent magnesium complexes.     

Synthesis,Characterization, and Energetic Properties of Alkaline and Alkaline Earth Salts of 5,5′‐bistetrazole‐1,1′‐diolate

5,5′‐Bistetrazole‐1,1′‐diolate‐based energetic salts from alkaline (Li⁺, K⁺, and Na⁺) and alkaline earth metal salts (Mg²⁺, Ca²⁺, and Ba²⁺) were synthesized in a simple, straightforward manner and were characterized by IR and NMR spectroscopy, and elemental analysis. Single‐crystal X‐ray diffraction of 4 salts (Li⁺, Na⁺, K⁺, and Mg²⁺) is given. The X‐ray structures show that in the title compounds, the metal atoms are bonded to the nitrogen and oxygen in the bistetrazole ring to form the sandwich structure. In addition, thermal stabilities of all title compounds were determined with differential thermal analysis‐thermal gravity analysis. All these new materials exhibit excellent thermal stabilities, high density, and excellent insensitivity to impact (h ₅₀ > 60 cm). Especially, the potassium salt is of interest as potential “green heat‐resistance explosive” with high density and high thermal stability as well as low sensitivity.     

Capillary ion electrophoresis-capacitively coupled contactless conductivity detection of inorganic cations in human saliva on a polyvinyl alcohol-coated capillary

Capillary ion electrophoresis–capacitively coupled contactless conductivity detection (CIE-C4D) with a polyvinyl alcohol chemically coated capillary (PVA capillary) was used to analyze inorganic cations (Na⁺, K⁺, NH₄⁺, Mg²⁺, and Ca²⁺) commonly found in human saliva. The PVA capillary, which was made by our laboratory, minimized electro-osmotic flow in the wide pH range of the background electrolyte (BGE), and the PVA layer adsorbed to capillary wall did not affect the conductimetric background level. In this study, we determined an optimized BGE of 30 mM lactic acid/histidine plus 3 mM 18-crown-6 for the CIE-C4D system using the PVA capillary, which could simultaneously improve the separation of Mg²⁺ and Ca²⁺ from Na⁺ and that of K⁺ from NH₄⁺. This system obtained highly reproducible separation of cations in human saliva samples within 8 min at 20 kV without deprotonation. The quantifiability of cations in human saliva samples on the CIE-C4D system was demonstrated through identification by ion chromatography with satisfactory results.     

Chromium uptake from tricomponent solution in zeolite fixed bed

Removal of Cr³⁺,Ca²⁺,Mg²⁺ and K⁺ in equilibrium isotherms and in tricomponent solutions (Cr/Ca/K, Cr/Ca/Mg and Cr/Mg/K) were investigated in NaX and NaY packed beds at 30^∘C. The equilibrium selectivity was obtained as Cr⁺³ > Mg²⁺ > Ca²⁺≈K⁺ for zeolite NaY and Ca^{2 +}≫Cr^{3 +} > Mg^{2 +}≈K⁺ for zeolite NaX. The breakthrough curves showed sequential ion exchange where chromium ions are able to replace the competing cations. Some mass transfer parameters, such as length of unused bed and overall mass transfer coefficient, were investigated. Chromium retention was also investigated through a mass balance. Based on the breakthrough results, it was concluded that chromium-uptake mechanism was hardly influenced by the competition and interaction between the entering ions. NaY showed a higher affinity towards Cr³⁺ for both equilibrium and dynamic systems and its sites were more efficiently used in the ion exchange process. Chromium was less retained in NaX due to the high selectivity towards calcium ions.     

金属离子(Na~+、K~+、Ca~(2+)、Mg~(2+)、Zn~(2+))与鸟嘌呤异构体配合物的稳定性

在B3LYP/6-311++G**水平上用极化连续介质模型(PCM)系统研究了金属离子(M+/2+=Na+,K+,Ca2+,Mg2+,Zn2+)和十三种鸟嘌呤异构体形成的配合物GnxM+/2+(n为鸟嘌呤异构体的编号,x表示M+/2+与鸟嘌呤异构体的结合位点)在气(g)液(a)两相中的稳定性顺序.着重探讨了液相中配合物的稳定性差异,并且从溶质-溶剂效应、结合能、形变能及异构体的相对能量等几个方面分析了造成稳定顺序发生变化的原因.报道了溶液中这五种金属离子与鸟嘌呤异构体结合形成的六种基态配合物:aG1N2,N3Na+,aG1N2,N3K+,aG1O6,N7Ca2+,aG1N2,N3Mg2+(aG1O6,N7Mg2+),aG2N3,N9Zn2+.可以看出,除了在Zn2+配合物中鸟嘌呤异构体为G2外,构成其余四种金属离子配合物的鸟嘌呤异构体都是G1,但结合位点不同.同时对气相中各类配合物稳定性也进行了系统的排序,并报道了几种较稳定的配合物,如:gG3N1,O6K+,gG5N1,O6K+,gG3N1,O6Ca2+/Mg2+,gG4O6,N7Ca2+/Mg2+.     

Ion transport,ion extraction,and ion binding by synthetic cyclic octapeptide

Cyclic octapeptide, cyclo[Gly-L-Lys(Z)-Sar-L-Pro]₂, (CGLSP2) was synthesized as an ionophore model. Its ion-transport ability through a chloroform membrane was investigated in connection with ion extractability (K_ex) and conformational properties. CGLSP2 transported the picrate salts of Ba²⁺ and Ca²⁺ efficiently. The K_ex sequences were Ba²⁺>Ca²⁺Mg²⁺ and K⁺>Rb⁺>Na⁺, showing good agreement with the selectivity in ion transport. In addition, cation-binding properties of CGLSP2 to alkali and alkaline earth metal ion were investigated in acetonitrile by CD and NMR spectroscopy. Titration curves obtained from CD data revealed three kinds of CGLSP2/cation complexes. The values of 1:1 complex-formation constants (K₁) decreased in the order Ba²⁺>Ca²⁺>Mg²⁺>Li⁺Na⁺K⁺.¹H- and¹³C-NMR data showed that free CGLSP2 exists in at least five different conformational states in acetonitrile. After the addition of equimolar amounts of Ba(ClO₄)₂, these conformations converged into a single C₂-symmetric conformation with all-trans peptide bonds.     

Paper‐Based Electronic Tongue

We present a low cost paper‐based electronic tongue capable of discriminating forged water samples. System comprises of 4 paper‐based potentiometric sensors (sensitive to Cl^?, Na⁺/K⁺, Ca²⁺/Mg²⁺, ) and a traditional Ag/AgCl reference electrode. Different electrode materials and methods of insulation were tested with best results obtained for pencil graphite and lamination. The presented electronic tongue was able to distinguish tap and lake water from mineral water samples (PCA – Principal Component Analysis and KNN ? K‐nearest neighbour). In total 14 different water samples were used in this study. Sensors presented good signal repeatability, selectivity and reasonable sensitivity.     

Simultane Bestimmung freier Ca2+- und Mg2+-Konzentrationen durch Ionenaustausch

Zusammenfassung Die simultane Bestimmung freier Ca²⁺- und Mg²⁺-Konzentrationen in Anwesenheit relativ hoher Konzentrationen einwertiger Kationen mit einem erweiterten Ionenaustauschverfahren wird beschrieben. Die Auswertung der Meßergebnisse beruht auf der Theorie der Ionenaustauschgleichgewichte. Die relativen Fehler von [Ca²⁺] und [Mg²⁺] wurden auf der Basis ihrer Bestimmungsgleichungen für einen großen Konzentrationsbereich abgeschätzt. Bei Na⁺- bzw. K⁺-Konzentrationen zwischen 100 und 200 mmol/l lassen sich freie Ca²⁺- und Mg²⁺- Konzentrationen im Bereich von ca. 0,05–5 mmol/l mit einer relativen Standardabweichung zwischen 2 und 5% bestimmen.

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Simultaneous determination of free Ca²⁺ and Mg²⁺ concentrations by ion-exchange

Summary The simultaneous determination of free Ca²⁺ and Mg²⁺ concentrations in the presence of relatively high concentrations of monovalent cations by an improved ion-exchange method is described. The evaluation of the measured results is based upon the theory of ion-exchange equilibria. Relative errors of [Ca²⁺] and [Mg²⁺] were estimated for large ranges of cation concentrations using the error propagation law. In the presence of 100–200 mmol/l of Na⁺ and/or K⁺, [Ca²⁺] and [Mg²⁺] can be determined in the range of about 0.05–5 mmol/l with relative standard deviations from 2 to 5%.

Wir danken Frau Ingrid Schwabe für die ausgezeichnete technische Mitarbeit, sowie Herrn Dr. Oswald und Herrn Dr. Tietz für die Unterstützung bei elektrometrischen Messungen. Herrn Prof. Dr. H. Frunder danken wir für die Durchsicht des Manuskripts.     

Synthesis,crystal structures and competitive complexation property of a family of calix-crown hybrid molecules and their application in extraction of potassium from bittern

A family of calix-crown hybrid molecules containing calix[4]arene and crown-5/6, either at lower rim or at both upper and lower rims, have been synthesised, characterised and their competitive complexation property towards alkali and alkaline earth metal ions in aqueous media have been investigated. The competitive metal ion extraction study, carried out with equimolar mixture of Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺ and Sr²⁺ in aqueous media, revealed that the amount of K⁺ extracted is remarkably high compared to other metal ions. Complexation with K⁺ has been investigated by ¹H NMR, association constants and thermodynamic parameters have been determined by isothermal calorimetric study. The molecular structures of one of the receptors and two of the K⁺ complexes have been established by single crystal X-ray study. One of the receptors formed bimetallic complex and it exhibited interesting polymeric network structure with bridged picrate anion. These receptors have been applied for extraction of metal ions from bittern.