Browsing by Author "Kiselev, A. V."

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Effect of silica surface dehydroxylation on adsorption of aromatic hydrocarbons from solution in n-alkanes
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (5), 1972) Eltekov, Yu. A.; Khopina, V. V.; Kiselev, A. V.
The adsorption of a series of aromatic hydrocarbons from solution in saturated hydrocarbons on hydroxylated and dehydroxylated silica surface has been investigated. Dehydroxylation of silica surface sharply diminishes the adsorption of aromatic hydrocarbons. Since the molecules of aromatic hydrocarbons on the hydroxylated silica are oriented parallel to the surface, the influence on adsorption of the size of molecules at the same orientation was investigated and distribution functions for several systems were determined. The equilibrium constants and the activity coefficients of surface benzene + n-hexane phases on hydroxylated and dehydroxylated silica and on graphitized carbon black surfaces have been calculated.
Heat Capacity of the H2O/KNaX Zeolite Adsorption System
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (3), 1973) Berezin, G. I.; Kiselev, A. V.; Sinitsyn, V. A.
The heat capacity of the H2O/KNaX zeolite system has been measured at 34°C for various amounts of adsorption. The dependence of measured heat capacity of this system and calculated average molar heat capacity of adsorbate on the amount of adsorption passes through two distinct maxima. These maxima correspond to previously obtained waves in the plot of the heat of adsorption of water against the amount of adsorption for the same H2O/KNaX zeolite system. The maxima are due mainly to the contribution to the heat capacity of the heat of transfer of a part of the water molecules from the adsorption sites with higher heat of adsorption to those with lower heat of adsorption. The thermal stability of different water associates in zeolite pores has been investigated. The differential heat capacities of adsorbed water were calculated and the changes in the heat of adsorption of water when the temperature of the system was increased were determined. The results show that with increasing temperature there is a smoothing out of the waves produced in the plot of the differential heat of adsorption as the function of the amount of water adsorbed.
Spectral and Energetic Aspects of Water Adsorption by Li-, Na-, K- and Cs-X Zeolites
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Kiselev, A. V.; Lygin, V. I.; Starodubceva, R. V.
The infra-red spectra of water adsorbed by X-typc zeolites containing different alkali-metal cations have been studied. With small amounts of adsorption in LiNaX, NaX and KNaX zeolites water molecules interact mainly with the zeolite cations. The spectra show that one hydroxyl group of an adsorbed water molecule is bound to the oxygen of the zeolite skeleton and the other is “ free ”. In the case of CsX zeolite, where adsorption is weaker, both hydroxyl groups of the adsorbed water molecules interact, presumably, with the oxygen atoms of the zeolite. The relative amounts of water molecules interacting with the exchange cations, zeolite oxygen atoms and water molecules forming mutual hydrogen bonds depend on the cation and the number of water molecules in the zeolite cages. As these arc filled there is a change in the energy of hydrogen bond formation between water molecules and the zeolite oxygen skeleton and between one another. This change becomes particularly apparent in the case of KX zeolite and is in accordance with the wave-like change of the differential heat of water adsorbtion by KX zeolite and with the maxima and minima of the heat capacity of adsorbed water.