Sorption Properties of Calcium Nitrate Dispersed in Silica Gel: The Effect of Pore Size Full article
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Russian Journal of Physical Chemistry A
ISSN: 0036-0244 , E-ISSN: 1531-863X |
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Output data | Year: 2005, Volume: 79, Number: 8, Pages: 1307-1311 Pages count : 5 | ||||
Tags | Crystalline materials; Differential scanning calorimetry; Hysteresis; Nanostructured materials; Pore size; Silica gel; Sorption; Synthesis (chemical); Vapor pressure; X ray diffraction analysis | ||||
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Abstract:
New composite Ca(NO3)2-in-silica gel mesopore sorbents of water were synthesized and analyzed. Sorption isobars at a water vapor pressure of 17 mbar and various sizes of silica gel pores (6, 10, 12, and 15 nm) were measured over a temperature range of 30 to 160 °C. It was demonstrated that the composite sorbs water by three mechanisms: (a) heterogeneous adsorption on silica gel, (b) the formation of salt dihydrate, and (c) formation of salt aqueous solution in silica gel pores. The modification of silica gel with the salt increased significantly its sorption capacity for water (from 0.04-0.06 to 0.2-0.3 g/g). The sorption properties of the composite were found to deviate from those predicted by a linear combination of the properties of silica gel and bulk calcium nitrate. The temperature of conversion of the water-free salt into its crystalline dihydrate shifts increases with decreasing size of the pores in the host matrix. Near this transition, a sorption hysteresis was observed, which narrowed with increasing dispersity of Ca(NO3)2. The properties of a solution in the pores were found to be identical to those of the corresponding bulk solution, with no hysteresis observed. Measurements with the use of differential solvation, X-ray diffraction, and differential scanning calorimetry demonstrated that the properties of the salt change due to its being dispersed into nanosized grains rather than due to its interaction with the matrix.
Cite:
Simonova I.A.
, Aristov Y.I.
Sorption Properties of Calcium Nitrate Dispersed in Silica Gel: The Effect of Pore Size
Russian Journal of Physical Chemistry A. 2005. V.79. N8. P.1307-1311. WOS Scopus РИНЦ
Sorption Properties of Calcium Nitrate Dispersed in Silica Gel: The Effect of Pore Size
Russian Journal of Physical Chemistry A. 2005. V.79. N8. P.1307-1311. WOS Scopus РИНЦ
Original:
Симонова И.А.
, Аристов Ю.И.
Сорбционные свойства нитрата кальция, диспергированного в силикагеле: влияние размера пор
Журнал физической химии. 2005. Т.79. №8. С.1477-1481. RSCI РИНЦ
Сорбционные свойства нитрата кальция, диспергированного в силикагеле: влияние размера пор
Журнал физической химии. 2005. Т.79. №8. С.1477-1481. RSCI РИНЦ
Dates:
Submitted: | Aug 30, 2004 |
Published print: | Aug 1, 2005 |
Identifiers:
Web of science | WOS:000230855900023 |
Scopus | 2-s2.0-24644435401 |
Elibrary | 13484631 |
Chemical Abstracts | 2005:702389 |
Chemical Abstracts (print) | 143:236011 |