Spectral-luminescent properties of water-alcohol solutions of coumarin derivatives with additions of lithium chloride

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 6, pp. 965–969, June, 1991.     

Transport of glycine in systems with cation-exchange membranes in hydrochloric acid solutions: Effect of a heterogeneous protonation reaction

The electrical mass transfer of cations in electromembrane systems (EMS) with an MK-40 cation-exchange membrane and glycine in aqueous solutions of hydrochloric acid is studied using the method of a rotating membrane disk. Limiting current densities and limiting steps of the transport of cations in such systems are determined. Shown is the possibility of an increase in the electrical mass transfer of glycine as a consequence of the occurrence of a heterogeneous reaction of protonation of its zwitterions. The effect of the membrane surface state on the kinetic regularities of transport of cations in EMS with glycine in solutions of hydrochloric acid is exposed.     

Electron spin echo as a tool for investigation of surface structure of finely dispersed fractal solids

The ESE method was successfully used for investigating the texture of the adsorbents and catalysts. Equations were obtained for the kinetics of ESE signal decay due to dipole-dipole interaction between motionless paramagnetic centers distributed uniformly on the fractal surface of solid.

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Sorption of carbon dioxide by the composite sorbent “potassium carbonate in porous matrix”

Sorption of CO₂ in the presence of water vapor by the K₂CO₃—-Al₂O₃ composite sorbent was studied by IR spectroscopy in situ, X-ray diffraction analysis, and the differentiating dissolution method and reasons for a decrease in its dynamic capacity are given. The samples containing K₂CO₃·1.5H₂O in pores are characterized by the maximal dynamic capacity. A mechanism for CO₂ sorption was proposed, which qualitatively explains the obtained dependence of the capacity on the water content in the composite sorbent. A high dynamic capacity can be maintained by regeneration of the sorbents by water vapor at 170 °N. The capacity of the sorbents decreases during the first 10 sorption—regeneration cycles due to the formation of an inactive phase of potassium aluminum carbonate.     

Abnormally high fractal dimension of silica surfaces measured by adsorption of aliphatic alcohols

Factors leading to abnormally high fractal dimension D of silica surfaces measured by adsorption of aliphatic alcohols have been analyzed. , D .     

Determination of the activation energy of tuneling recombination for radiation-induced defects in CaO

Tunneling recombination between surface Fs_s ⁺- and bulk V^–-centers has been studied by ESR technique over the temperature range of 77–240 K. The activation energy has been measured.

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F_s ⁺- V^–- 77–240 .

     

Glycine and L-Lysine Ionization in a Mixed Aqueous Solution

In mixed aqueous solution of glycine and L-lysine the ionization of both amino acids increases due to the proton transfer from glycine zwitterion to lysine zwitterion. This is manifested by a considerable nonlinear (pairwise interaction of amino acids) increase in the mixed solution electroconductivity at high amino acid concentrations. The solution pH varies negligibly, as the amino acids in aqueous solutions demonstrate buffering. The refraction coefficient additively depends on glycine and L-lysine concentrations.     

Sorption equilibrium of methanol on new composite sorbents “CaCl<Subscript>2</Subscript>/silica gel”

This paper presents experimental data on methanol sorption on new composite sorbents which consist of mesoporous silica gels and calcium chloride confined to their pores. Sorption isobars and XRD analysis showed the formation of a solid crystalline solvate CaCl₂⋅2MeOH at low methanol uptake, while at higher uptake the formation of the CaCl₂–methanol solution occurred. The solution confined to the silica pores showed the sorption properties similar to those of the CaCl₂–methanol bulk solution. Calorimetric and isosteric analyses showed that the heat of methanol sorption depends on the methanol uptake, ranging from 38±2 kJ/mol for the solution to 81±4 kJ/mol for the solid crystalline phase CaCl₂⋅2MeOH. The above mentioned characterizations allowed the evaluation of the methanol sorption and the energy storage capacities, clearly showing that the optimal applications of these new composite sorbents are the methanol removal from gaseous mixtures, heat storage and sorption cooling driven by low temperature heat.