Abstract
This paper presents the water sorption properties of a new selective water sorbent based on expanded vermiculite as a host matrix and calcium chloride as a hygroscopic salt. Sorption isobars, isosters and isotherms at T = 30–150°C and vapor partial pressure 8.2–42.0 mbar clearly show that at low water contents crystalline hydrates with 0.33, 1 and 2 molecules of water per 1 molecule of CaCl2 are formed in the pores. These hydrates are stable over a temperature change of 20–30°C and exhibit kinetically slow transformations. At higher water uptake, the vapor absorption leads to the formation of a CaCl2 aqueous solution inside the pores, which properties are close to those in the bulk. Isosteric sorption heat was found to depend on water sorption and change from 76.3 kJ/mol for solid hydrates to 39.1–46.6 kJ/mol.
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Aristov, Y., Restuccia, G., Tokarev, M. et al. Selective Water Sorbents for Multiple Applications. 11. CaCl2 Confined to Expanded Vermiculite. Reaction Kinetics and Catalysis Letters 71, 377–384 (2000). https://doi.org/10.1023/A:1010351815698
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DOI: https://doi.org/10.1023/A:1010351815698