Solutions Of Alkali Metal Salts Research Articles

Mechanism of forward current transport in modified-surface Au-CdTe photodiodes

Current-voltage characteristics of surface-barrier diodes based on n-CdTe substrates treated in aqueous solutions of alkali metal salts were studied. It was found that the forward current is controlled by recombination processes in the space-charge region and the above-barrier carrier transport.

Facile Conversion of the Surface Layers of Graphite to Capacitive Manganese Oxide Coatings

A simple method to convert graphite to manganese oxide coatings is presented in this paper. The as-grown coatings were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analyses, and thus verified to be largely amorphous manganese oxide. The coatings behave typically capacitive in various neutral aqueous solutions of alkali metal salts, e.g., 0.5 M LiCl, 0.5 M NaCl, and 0.5 M KCl. The capacitance per geometric electrode surface area from cyclic voltammetry in 0.5 M NaCl increased to when the conversion time was up to 120 min, obeying the logarithm law very well. In addition, the capacitance per mass of the coating of 362, 385, 380, and was achieved with the manganese coatings grown for 10, 30, 60, and 120 min, respectively. Electrochemical measurements demonstrated evident differences in capacitive behaviors of the coatings in the three above-mentioned electrolyte solutions. It was confirmed that this facile conversion of the surface layers of graphite offers a simple and efficient formation of thin-film supercapacitors promising for industrial applications.

Enthalpies of Dilution for myo-Inositol in Aqueous Alkali Metal Salt and Alkaline Earth Metal Salt Solutions

The enthalpies of dilution of myo-inositol in aqueous solutions of alkali metal salts and alkaline earth metal salts have been determined with flow-mix isothermal microcalorimetry at 298.15 K. The enthalpic interaction coefficients in the range of salt solutions have been calculated according to the McMillan−Mayer theory. The results show that enthalpic pairwise interaction coefficients h2 of myo-inositol are negative in aqueous alkali metal salt and alkaline earth metal salt solutions. The absolute value of h2 becomes small with an elongation of the radius of the alkali metal cation while it becomes large with an elongation of the radius of the alkaline earth metal cation. The results are discussed in terms of the different metallic ions, interactions of solute with solute and solute with solvent.

Studies in the Mineral and Salt-Catalyzed Formation of RNA Oligomers

Activated mononucleotides oligomerize in the presence of montmorillonite clay to form RNA oligomers. In the present study, effects of salts, temperature and pH on the clay-catalyzed synthesis of RNA oligomers were investigated. This reaction is favored by relatively high concentration of salts, such as 1 M NaCl. It was shown that the presence of divalent cations was not required for this reaction. High concentrations of NH4+ and HCO3- and 0.01 M HPO4(2-) inhibit the reaction. The yields of RNA oligomers decreased as the temperature was raised from 4 degrees C to 50 degrees C. A5' ppA was the major product at pH's below 6. The catalytic activity of a variety of minerals and three meteorites were investigated but none of them except galena catalyzed the oligomerization. ATP was generated from ADP but it was due to the presence of HEPES buffer and not due to the minerals. Meteorites catalyzed the hydrolysis of the pyrophosphate bonds of ATP. The results suggest that oligomers of RNA could have formed in pH 7-9 solutions of alkali metal salts in the presence of montmorillonite clay.

Dual-temperature reagent-less ion-exchange separations of alkali metal salts on zeolites

Ion exchange equilibria in the mixed K 2SO 4–Na 2SO 4 and CsCl–NaCl solutions with concentrations within the range of 2.2–2.9 equiv/l on the natural clinoptilolites have been studied. The equilibrium coefficients for the Na +–K + and Na +–Cs + exchanges on clinoptilolite decreased significantly with temperature when the equivalent fractions of K + and Cs + ions in the zeolite phase were very low. Accordingly, the differential enthalpy of ion exchange increased with a decrease of equivalent fractions of these ions in the zeolite phase. Dual-temperature ion-exchange separations and purifications of concentrated solutions of alkali metal salts on natural clinoptilolites and synthetic Y type zeolite without auxiliary reagents consumption were studied. Two types of dual-temperature techniques were used: the temperature-swing mode of separation and the parametric pumping.

Heats of Mixing of Mixed Solvent Solutions of Alkali Metal Salts of Substituted Benzenesulfonic Acids

The enthalpy change on mixing solutions of methyl-substituted benzenesulfonic acids and their salts, with salts having a common cation or anion, at constant ionic strength in mixtures of 1,4-dioxane with water, were measured at 25°C. The heat effects of mixing solutions having a common anion increase almost linearly with the reciprocal value of the dielectric constant of the solvent. The heat effects of mixing solutions having a common cation, which are all negative in water-rich solutions, become endothermic after a certain value of the dielectric constant is passed. The results are discussed in terms of the solute-solvent structural properties.

Heats of Mixing of Aqueous Solutions of Alkali Metal Salts of Substituted Benzenesulfonic Acids

The enthalpy change on mixing aqueous solutions of substituted benzene sulfonic acids and their salts, with salts having a common cation or anion, were measured at constant total ionic strength and at 25°C. The results are qualitatively interpreted in terms of solute–water structural properties and the ion size effect. The heat effects of mixing solutions having common anions obey the sign rule of Young and Smith. In anion–common cation mixings at concentration of 0.5 mol-kg−1 only exothermic heat effects were observed, whose magnitude increase with the increasing difference in size of the mixed anions. The magnitude of the mixing effect increased with the salt concentration in cation–common anion mixing processes, In anion–common cation mixings the enthalpy of mixing changes sign from negative to positive, indicating a predominantly endothermic effect as concentration increases.

95/03449 Conversion of carbon dissolved in iron powder into a mixture of hydrocarbons and acetone by heating with aqueous alkali metal salt solution

95/03449 Conversion of carbon dissolved in iron powder into a mixture of hydrocarbons and acetone by heating with aqueous alkali metal salt solution

Conversion of carbon dissolved in iron powder into a mixture of hydrocarbons and acetone by heating with aqueous alkali metal salt solution

Heating of iron powder containing carbon with aqueous alkali metal salt solution at 300°C gave a mixture of C 1C 6 hydrocarbons and acetone. Prolonged reaction of the iron powder with aqueous potassium carbonate solution gave larger amounts of hydrocarbons and acetone than the reaction with aqueous potassium hydroxide solution.

Conductometric Study of Ion Association between Tris(oxalato)chromate(III) and Alkali Metal Ions at Temperatures from 0 to 50 °C

Abstract Conductivities for aqueous solutions of alkali metal salts of tris(oxalato)chromate(III) ([Cr(ox)3]3−) were measured at various temperatures from 0 to 50 °C. Ion-association constants (KA) between the complex ion and alkali metal ions increased in the order Li+ << Na+ < K+ < Rb+ < Cs+ and had minimum values (KA(min)) at characteristic temperatures (tmin) in the observed temperature range except for the lithium ion. The appearance of minima of KA suggested the formation of contact ion pairs besides that of solvent-separated ones. The contact ion-pair formation was considered to be assisted by weak hydration of alkali metal ions and enhanced with decreasing their hydration strength. The lithium ion was presumed to form only solvent-separated ion pairs on the basis of extremely small ion-association constants. Temperature dependence of log KAfor each ion association could be represented by the equation: log KA = p(t − tmin)2 + log KA(min). A common relationship between p and tmin was found out for the ion-association systems of [Cr(ox)3]3−, [Co(NH3)6]3+, and [Co(en)3]3+ (en = ethylenediamine), and p was expressed by an empirical quadratic equation in tmin. The standard enthalpy changes of ion association (ΔHas°) at any temperature for these complex systems could be reproduced within ±0.2 kJ mol−1 by use of these equations with the experimental tmin. Hydration behavior of [Cr(ox)3]3− was also discussed based on limiting molar conductivities and their temperature dependence.

Dissociation Behavior of Surface-Grafted Poly(Acrylic Acid): Effects of Surface Density and Counterion Size

The effects of surface density and counterion size upon the dissociation behavior of poly(acrylic acid) grafted onto a polyethylene surface were investigated. The effect of counterion size was studied in aqueous alkali metal salt solutions (LiCl, NaCl, KCl, and CsCl) by potentiometric titration methods. To study the effect of surface density, we prepared a "poly(acrylic acid) gradient surface" where the density of poly(acrylic acid) changes gradually along the sample distance. The gradient surface was produced by the treatment of a polyethylene sheet using a corona with gradually increasing power, followed by graft polymerization in 10 wt% acrylic acid solution. The prepared gradient surface was characterized by Fourier transform infrared spectroscopy in the attenuated total reflectance mode. Potentiometric titration curves for the sections of the gradient surface were obtained in different salt solutions to measure the changes of electrostatic Gibbs free energy of the poly(acrylic acid) on the gradient surface. It was observed that the changes of electrostatic Gibbs free energy increase with the increasing density of the poly(acrylic acid) grafted onto the surface and the decreasing hydrated radius of the alkali metal ions in the solution. It was difficult to remove protons from the poly(acrylic acid) on the sections with high surface density and in the solutions containing alkali metal ions with small hydrated radii.

Flow configurations for interfacing automatic ion-exchange devices with sequential inductively coupled plasma atomic emission spectrometry: application to trace metal determination in pure alkali metal salts

An automatic ion-exchange (AIE) device was used to separate trace constituents from matrix elements in alkali metal salts. The preconcentrated trace elements were eluted and subsequently determined on-line by sequential inductively coupled plasma atomic emission spectrometry. Optimum flow rates for both instruments were achieved by inserting a T-junction between the outlet of the AIE device and the ICP nebulizer. The excess of eluent was trapped, mixed and subsequently nebulized to obtain steady-state analyte signals. Alternatively, the analyte was dispersed using efficient mixing coils. Elution kinetics and dispersion of trace metal ions were studied for standard and alkali metal salt solutions. These flow configurations facilitated on-line multi-element analyses of alkali metal salts.

Coordination in thionyl chloride solutions of alkali metal salts

The solution structure of alkali metal tetrachloroaluminates dissolved in thionyl chloride has been investigated using far infrared and Raman spectroscopy with measurements of depolarization ratios. The solvent is strongly coordinated to the alkali metal cation with a consequent shift of electron density away from the sulfur-chlorine bonds.

Calibration of ion spray mass spectra using cluster ions

AbstractMass calibration for ion spray mass spectrometry can be achieved by using cluster ions formed by flow injection of solutions of alkali metal salts in aqueous acetonitrile into the liquid flowing to the ion spray needle. Source contamination is thereby reduced to a minimum. For quadrupole mass analyzers, sodium iodide provides an ideal compromise between undesirable spectral complexity and spacings between calibrant mass peaks sufficiently close that interpolation errors are negligible. When much closer spacings are required, protonated water clusters provide an excellent calibration up to about m/z 1000. If higher mass ranges are required with a large number of calibrant peaks, a solution of mixed alkali metal iodides does provide the expected spectra but intensities are poor at higher m/z values. For liquid chromatography with on‐line mass spectrometry (LC/MS) the mass calibration may be checked without changing the mobile phase by post‐column flow injection of a cesium carbonate solution, since the carbonate anion is wholly displaced by the anion of the mobile phase acid modifier, resulting in no mixed clusters. The metal salt calibrants have the additional advantage of being useful over a wide range of tuning parameters in the atmospheric pressure ionization source, covering those appropriate to both relative molecular mass determinations of large proteins and to LC/MS of small analyte species.

Investigation of alkali metal-water interactions in acetonitrile

The exchange of acetonitrile into and out of the coordination sphere of alkali metal ions is fast on the NMR time scale and slow on the vibrational time scale. This results in separate infrared and Raman spectra for coordinated and non-coordinated solvents in solutions of alkali metal salts in acetonitrile. The 1H NMR spectra, on the other hand, are averages of coordinated and non-coordinated environoments. Addition of water to solutions of alkali metal salts in acetonitrile indicates that the cation is again preferentially solvated by water. The water completely replaces acetonitrile in the lithium coordination sphere until four waters have been added. Water also displaces the first acetonitrile from the coordination sphere of sodium and potassium ions. However, when additional water is added there is an equilibrium mixture of various species. Spectroscopic study of these solutions allows one to gain insights about the energetics and geometry of the cation. Experimental results from NMR, Raman and IR measurements along with extended Hückel molecular orbital calculations are used to discuss the alkali metal cation- water-acetonitrile system.

Sonoluminescence from alkali-metal salt solutions

Sonoluminescence spectra from alkali-metal salt solutions in water and in primary alcohols are characterized by unusually broad resonance line emission from excited-state alkali-metal atoms. The spectral width and positions of sonoluminescence from potassium in primary alcohols are independent of both solvent vapor pressure and inert gas (Ar/He) ratio. Since the intensity of cavitational heating is dependent on both of these parameters, alkali-metal sonoluminescence cannot be used to determine the local conditions created by acoustic cavitation, contrary to earlier reports. In contrast, the intensity of this sonoluminescence is highly dependent on these two factors. This apparent paradox is explained if the excited-state alkali-metal atoms are the result of secondary reactions of metal ions with high-energy radicals formed directly in the cavitation event. The large line width is caused by rapid collisional deactivation of the excited-state atoms.

THE EFFECT OF MONOVALENT CATIONS AND ANIONS ON THE RHEOLOGICAL PROPERTIES OF KAPPA‐CARRAGEENAN GELS1

ABSTRACTThe change in dynamic Young's modulus E' and in volume of 2% and 4% kappa‐carrageenan gels induced by immersion in alkali metal salt solutions was observed for various kinds of salts, LiCl, NaCl, KCl, CsCl, LiBr, NaBr, KBr, CsBr, Nal, KI, Csl, and for various salt concentrations. E' of the gels increased rapidly up to 1 h after immersion, and then it increased more gradually. However, E' decreased after a certain immersion time when the concentration of the salt exceeded a certain value which depended on the kind of the salt. The volume of the gel immersed in salt solutions for 24 h decreased with increasing concentration of the salt except in the case of Nal where the gel swelled remarkably.

The rheological study of the interaction between alkali metal ions and kappa-carrageenan gels

The rheological change in kappa-carrageenan and agarose gels immersed in alkali metal salt solution was studied by the measurement of longitudinal vibrations. The storage modulus of kappa-carrageenan gel increased remarkably by the immersion, while that of agarose gel did not change so much. The reason of this change in kappa-carrageenan was ascribed to the shielding effect of the electrostatic repulsion of sulfate groups by alkali metal ions. As a result of the shielding, the helical structure was thought to become the densely packed state. The difference of the action between the two groups (Li+, Na+) and (K+, Cs+) was discussed from the viewpoint that these ions are either structure makers or breakers for the structure of water.

The Interaction of a Neutral Polymer with Small Ions in Solution. II. The Binding of Alkali Metal Ions to Poly(oxyethylene) in Several Organic Solvents

Abstract The conductivities for several solutions of alkali metal salts, such as potassium thiocyanate, containing poly(oxyethylene) (POE) have been measured as functions of the POE concentration, Cp. A decrease in the conductivity with an increase in Cp has been observed, particularly in methanol, acetonitrile, propylene carbonate, and sulfolane. For these systems, the binding of the cation has been evaluated from the decrease in conductivity and analyzed by a method based on the one-dimensional lattice model. As well as the solvent effects, the effects of the salt concentration and the effect of the alteration of salt on the binding constant have been discussed.

Solvent extraction of alkali metal cations from aqueous solutions by highly lipophilic crown ether carboxylic acids

Competitive solvent extractions of alkali metal cations from water into chloroform by 2-(sym-dibenzo-16-crown-5-oxy)-butanoic acid (5), 2-(sym-dibenzo-16-crown-5-oxy)hexanoic acid (6), 2-sym-dibenzo-16-crown-5-oxy)octanoic acid (7), 2-(syn-dibenzo-16-crown-5-oxy)decanoic acid (8), and 5-(sym-dibenzo-16-crown-5-oxy)pentanoic acid (9) are reported. For 6, 7, and 8 the complexing agents are sufficiently lipophillic that they remain totally in the organic phase when chloroform solutions of the crown ether carboxylic acids are contacted with highly alkaline aqueous alkali metal salt solutions.