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1.
The sorption of Ba2+ ion on natural kaolinite and chlorite-illite clays was investigated at different initial concentrations and temperatures using the radiotracer method. The sorption data were well described by Freundlich and Dubinin-Radushkevich isotherms. Ba2+ sorption on both clays showed an exothermic behavior with ΔH° (kJ/mol) values being -7 and -5 for sorption on kaolinite and chlorite illite mixed clay, respectively. The ΔG° values indicate that the sorption was spontaneous with sorption energies corresponding to ion-exchange type sorption. X-ray diffraction studies showed that no significant change in the matrix of the clays occurred upon Ba2+ sorption. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

2.
Sorption-analytic studies of ion exchange equilibria combined with direct calorimetric measurements of the heats of ion exchange sorption of the Ca2+, Sr2+, and Ba2+ cations were performed over the whole range of solid phase fillings with sorbed cations on the Na forms of two mordenites prepared from natural specimens rich in Na+ and Ca2+ cations. Ion exchange constants were determined and the Gibbs energies and entropies of ion exchange were calculated. The thermodynamic characteristics obtained were analyzed taking into account the preferable localization of alkaline-earth metal ions on certain exchange centers in the structure of mordenite. The presence of natural mordenite memory effects with respect to extra-framework Ca2+ cations in the presence of which these zeolites were crystallized in nature was established.  相似文献   

3.
The spectroscopic properties of metal-ion complexes of several imidazopyrazinone derivatives with Li+, Mg2+, Ca2+, Ba2+, Sc3+, and La3+ ions were studied. The spectral characteristics and the formation constants of the complexes changed continuously depending on the Lewis acidity of the metal ion, suggesting that the imidazopyrazinones can find application as indicators of Lewis acidity. In the case of bis-imidazopyrazinone derivatives, the complexation abilities were enhanced by chelate effects.  相似文献   

4.
The complex formation of 2,5-bis[4-(1,7,10,13-tetraoxa-4-azacyclopentadec-4-yl)benzylidene]cyclopentanone and several model compounds, prospective metal-sensitive fluorescent probes, with Mg2+, Ca2+, and Ba2+ ions in acetonitrile was studied. The azacrown derivatives of dibenzylidenecyclopentanone have two complex formation centers, azacrown cycle and carbonyl group. The sequence of binding to these sites is different for different ions. The efficient ejection of the Ca2+ and Ba2+ ions from their complexes with azacoronands was observed in the excited state, whereas in the case of the Mg2+ ion, this process occurred only partially.  相似文献   

5.
A method was developed for the preparation of N-2-sulfoethylchitosan (SECH) via synthesis in a gel with the use of the reaction of chitosan and sodium 2-bromoethanesulfonate. This method makes it possible to conduct a polymer-like transformation without any acid or base. The structures of the obtained polymers were confirmed via IR and 1H NMR spectroscopy. The study of the sorption of Ag+, Cu2+, Zn2+, Ni2+, Co2+, Cd2+, Pb2+, Mn2+, Mg2+, Ca2+, Sr2+, and Ba2+ ions that were crosslinked by SECH during their joint presence in an ammonia-acetate buffer solution showed high values of selectivity in relation to those of silver(I) and copper(II). The selectivity of the sorption of silver(I) ions with respect to copper(II) ions increased with an increase in the degree of substitution of SECH.  相似文献   

6.
The gas-phase chemistry of anionic [M + Cat2+ – 3H]? complexes between Ca2+-specific peptides and the alkaline earth metal ions Mg2+, Ca2+ and Ba2+ is reported. The metal ion complexes were studied using fast atom bombardment, collision-induced decomposition (CID) and molecular mechanical calculations. The CID reactions and molecular mechanical calculations revealed that the Ca2+–peptide complexes are bound differently to the Mg2+– and Ba2+–peptide complexes and that the intrinsic (gas-phase) chemistry is reflected by known aqueousphase chemistry.  相似文献   

7.
The binding of ions Li+, Na+, K+, (group I), Mg2+, Al3+, Ga3+ (group II), Ca2+, Pb2+ (group III) ions, Ba2+ and paraquat by heterocyclophanes containing biindolizine and quinoxaline fragments connected by 3,6,9-trioxaundecane and 5,8,11,14,17-pentaoxageneicosane spacers, and also their acyclic analogues, in the acetonitrile-0.1 M Bu4NBF4 is studied by cyclic voltammetry. A conclusion is drawn that the ions of the group I are not bound by these compounds; the paraquat is not bound by heterocyclophane with the 5,8,11,14,17-pentaoxageneicosan spacers. For ions of the group II, reversible redox-switchable binding by the macrocycles with the 3,6,9-trioxaundecane and 5,8,11,14,17-pentaoxageneicosan spacers is observed: the initial compounds show the binding; their radical cations and dications do not. The binding of the ions of the group III and Ba2+ is determined by the macrocycles’ size. In particular, these ions are bound not only by the heterocyclophane with 3,6,9-trioxaundecane spacers but also by its radical cation or dication. The binding results in the corresponding dication stabilization. The heterocyclophane with the 5,8,11,14,17-pentaoxageneicosan spacers demonstrates the redox-switchable binding of Ca2+ and Pb2+ ions; no effect of Ba2+ ions on the cyclic voltammograms of this heterocyclophane was observed. In the ternary system “heterocyclophane with 3,6,9-trioxaundecane spacers + ions of the group II (Al3+, Ga3+) + ions of the group III (Ca2+, Pb2+)” either primary binding of the group III ion Pb2+ or concurrent binding of the ions of the group II and the group III, with the system’s reversible redox-switching from one metal complex to another, was observed.  相似文献   

8.
An ion exchanger on the basis of cellulose containing 1,2-dihydroxybenzene-3,5-disulphonic acid (Tiron) as a functional group was synthesized applying the principle of the reactive dye stuffs “Remazol” (TM of Hoechst AG). The capacity was 0.2 mmol/g, the exchange equilibrium with Fe3+-ions was reached within 3 min. The distribution coefficients K d for Cu2+, Hg2+, Fe3+ and the alcaline earth ions were determined for the region pH 0–3. Tiron contains two kinds of functional groups, phenolic groups in orthoposition and sulphonic acid groups in meta-position. Fe3+ ions are bound relatively strongly by chelate formation, whereas alkaline earth ions are bound only by the sulphonic acid groups, in the sequence Ba2+ > Ca2+ > Sr2+ > Mg2+.  相似文献   

9.
Investigation of the complexing of Na+, K+, Ca2+ and Ba2+ with some uncharged ligands by 13C-chemical shift and spin-lattice relaxation time measurements The influence of Na+, K+, Ca2+ and Ba2+ ions on 13C chemical shifts and on spin-lattice relaxation times of some electrically neutral ion carriers was investigated. In the solvents CD3CN and CD3OD and in presence of an excess of metal ions ligand 4 (see the Scheme) forms complexes of 1:1 stoichiometry. All four oxygen atoms of the ligand as well as solvent molecules take part in the coordination. In CDCl3 as solvent, for all ions investigated except sodium, only 1:2 complexes (metal/ligand) were observed with 4 . Sodium ions form both 1:1 and 1:2 complexes in this solvent. In the 1:2 complexes of the investigated monovalent ions only one, in those of the divalent ions both amide carbonyl groups of ligand 4 take part in the coordination.  相似文献   

10.
Silica-titania gels containing 25, 50 and 75 mol% TiO2 were prepared and the sorption of alkali and alkaline earth metal ions by these materials has been studied. Distribution coefficient values for Cs+ and Sr2+ ions were found to pass through broad maxima as a function of TiO2 content except in the case of Sr under alkaline conditions where there was a continuous increase. Capacity values also increased with TiO2 content and samples containing 50% (for K+ and Cs+), 75% (for Li+ and Na+) and 25%/50% (for Ca2+, Sr2+ and Ba2+) TiO2 exhibited maximum capacities. However, unlike with alkali metals, capacities of a given sorbent for the three alkaline earth ions were almost the same. Large capacities obtained for the latter ions seem to indicate a mineral-forming reaction with 25% and 50% materials. On the other hand, the 25% TiO2 gel seems to sorb Sr at trace level by an ion exchange mechanism. Coupled with its Cs sorption capability, this material may find potential use in large scale decontamination of low level waste solutions.  相似文献   

11.
The transport of metal ions (Ca2+, Sr2+, Ba2+, Na+, K+, Cs+) through hollow fiber supported dichlorobenzene liquid membrane has been studied. The transport of cations using 8-crown-6 ether as a carrier and picrate as co-counter ion as well as a pertraction device and capillary isotachophoresis (ITP) measurement of the cation concentration is described.  相似文献   

12.
The ruthenium unit was introduced into the redox-active molecular polygon to assembly new Ru-Fc metallocycles (Compound 1), in which the redox active (ferrocene) and fluoresecent (ruthenium) signaling subunits are directly attached by the putative cation-binding sites. The compound 1 displayed high selectivity for Ca^2 by electrochemical tests. The measurements of the fluorescence spectra on titration of 1 with Ca^2 , Li^ , Na^ , K^ , Mg^2 or Ba^2 ion indicate the unique ability of 1 to detect Ca^2 ions selectively.  相似文献   

13.
The standard real and chemical thermodynamic characteristics of resolvation for magnesium ions in the water-ethanol mixtures of different composition were determined by their Volta potential differences at 298.15 K. Based on our analysis of these characteristics, the regularities and peculiarities of solvation of investigated ions in the mixed solvent were established. It was shown that the energies of ion resolvation in dependence on their crystallographic radii correspond to the series Ba2+< Ca2+ < Cd2+ < Cu2+ < Mg2+ < Al3+.  相似文献   

14.
Abstract Structures and complex-formation energies, calculated with DFT (B3LYP/LANL2DZp) for the cryptands [2.2.phen] and [2.phen.phen] with endohedrally complexed alkali and alkaline earth metal ions, were utilized to predict their ion selectivity. Both cryptands [2.2.phen] and [2.phen.phen] have a cavity size smaller than [2.2.2], [phen.phen.phen] and [bpy.bpy.bpy], and prefer to bind K+ and Sr2+, whereas [2.2.phen] that is larger than [2.phen.phen], has a preference for Ba2+, and [2.phen.phen] favours Na+ and Ca2+. The cryptand flexibility is mainly attributed to the presence of CH2–NSP3···NSP3–CH2 groups. Graphical abstract Host–Guest Complexes of mixed Glycol-Phenanthroline Cryptands—Prediction of Ion Selectivity by Quantum Chemical Calculations III Ralph Puchta* and Rudi van Eldik Keywords Cation selectivity Host–guest DFT DFT-studies allow a sensitive analysis of selectivity and cage size. Calculations predict a favourable binding of K+, Sr2+ and Ba2+ by [2.2.phen], and binding of K+, Na+, Ca2+ and Sr2+ by [2.phen.phen]. The cryptands fold around the ions by twisting their torsion angles in order to reach the best coordination mode for each cation. For “Prediction of ion selectivity by quantum chemical calculations III” see, R. Puchta, R. van Eldik. Aust. J. Chem. 60, 889–897 (2007).  相似文献   

15.
Intensity-modulated photocurrent (photoadmittance) and electrochemical impedance of anodicoxidized iron electrode in neutral nitrate solutions and in the presence of Ba2+, Ca2+, Cl?, and C6H5COO? (benzoate) are studied. It is shown that the ion adsorption at passive iron affects but slightly the system’s impedance; by contrast, it affects the photocurrent value significantly: when adsorbing, the anions increase the photoeffect, while the cations decrease it. These effects are associated with the potential drop redistribution in the Helmholtz layer and the film. The dissimilar changes of the generation current in the presence of similarly charged ions at their equal concentration evidence their different adsorption activity. The correlation between the generation current and surface-active ion concentration in solution is found. The photoelectrochemical spectroscopy allows evaluating qualitatively the surface-active ion adsorption at the passive iron and judging on the ion adsorption by the dependence of the generation current on the ion concentration.  相似文献   

16.
The thermodynamic measurements was carried out to study the selectivity of cation exchange resin Amberlite IR-120 in protonated form with respect to Mg2+, Ca2+, Sr2+ and Ba2+ ions in solution. The equilibrium constant K was calculated using the activity coefficients of ions in solution as well as in the resin. The K values calculated for the reacting systems increase with temperature that suggests the endothermic exchange reactions with estimated enthalpy values of 38.8, 20.6, 8.45, and 7.24 kJ mol−1, respectively. On the basis of calculated parameters, the selectivity of ion exchange resin with respect to various bivalent ions in the solution was predicted. The method used in our experimental work provides a basis for characterization of ion exchange resins, which can be promising materials for efficient separation of ions from industrial waste effluents.  相似文献   

17.
Abstract

The complex forming ability of ethylene diamine tetraacetic acid at various pH values and the ion exchange behavior of tin(IV) arsenosilicate and arsenophosphate cation exchangers have been combined in a chromatographic study of some metal ions. As a result some interesting observations have been made, which have led to certain analyti-cally difficult separations such as Ca2+?Sr2+ Ca2+?Ba2+ and Hg2+ from Cu2+, Ni2+, Zn2+, Co2+ and Mn2+.  相似文献   

18.
Summary Phenyl acetic acid has been found to be a selective reagent for the estimation of zirconium. The acid gives a white crystalline precipitate which is quantitative between pH values of 3.00 to 5.40. As the composition of the precipitate varies somewhat, direct weighing is not possible and the compound is ignited to the oxide. The ions Be2+, Ca2+, Sr2+, Zn2+, Hg2+, Pb2+, Mg2+, Ni2+, and Co2+ do not interfere, whereas the ions Fe3+, UO2 2+, Cr3+, Ba2+, Au+, Al3+, V2O4 2+, Ti4+, Sn2+, and Ba2+ cause interferences in the estimation.
Zusammenfassung Zur gravimetrischen Bestimmung von Zirkonium wird Phenylessigsäure empfohlen. Die weiße, kristalline Fällung ist im pH-Bereich 3,00–5,40 quantitativ. Infolge schwankender Zusammensetzung des Niederschlages ist eine direkte Wägung nicht möglich; er wird daher zum Oxid verglüht. Folgende Ionen stören nicht: Be2+, Ca2+, Sr2+, Zn2+, Hg2+, Pb2+, Mg2+, Ni2+ und Co2+; dagegen verursachen Fe3+, UO2 2+, Cr3+, Ba2+, Au+, Al3+, V2O4 2+, Ti4+, Sn2+ und Ba2+ Störungen bei der Bestim mung.


Part VI: See Z. analyt. Chem. 175, 29 (1960).  相似文献   

19.
The standard real and chemical thermodynamic characteristics of transfer of the K+, Ca2+, Cd2+, and Br? ions from water into water-acetone solvents of various compositions were analyzed to study the rules governing the solvation of these ions in mixed solvents and its special features. All calculations were performed within the framework of the vertical jet method at 298.15 K. The energy of resolvation as a function of ion charges and crystallographic radii was found to increase in the series K+ < Ca2+ < Cd2+ < Al3+  相似文献   

20.
Separation and determination of some common metal ions was achieved with methyl 3‐amino‐3‐(pyridin‐3‐yl)propanoate dihydrochloride (MAPP) as an ion‐pairing reagent and pyridine as a detectable counter‐ion for indirect UV detection at 254 nm. The effects of the complexing reagent and chromophore concentrations, applied voltage, and organic solvent content on the separation were investigated. The optimized separation was carried out in a running electrolyte containing 16 mM MAPP and 20 mM pyridine at pH 4.0 and was successfully applied to the qualitative and quantitative analysis of Li+, Na+, Mg2+, Ca2+, Ba2+, Ni2+, and Zn2+ in pharmaceutical vitamin preparations and various water samples.  相似文献   

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