Phase Transitions in Ion Exchangers during the Sorption of Water
The sorption of water vapor by ion-exchange materials is studied using a model that incorporates the interplay between changes in the energy of dissociation of ion-exchange groups and the osmotic effect. It is shown that first-order phase transitions in which a thin film of a sorbed liquid transform...
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Veröffentlicht in: | Russian Journal of Physical Chemistry A 2021-12, Vol.95 (12), p.2478-2485 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The sorption of water vapor by ion-exchange materials is studied using a model that incorporates the interplay between changes in the energy of dissociation of ion-exchange groups and the osmotic effect. It is shown that first-order phase transitions in which a thin film of a sorbed liquid transforms into a thick film are possible at realistic values of system parameters and at both high and low values of relative air humidity. A criterion for a phase transition is established and the reasons for it are discussed. The phase transitions obtained in this work are observed experimentally as hysteresis in water vapor adsorption–desorption curves. At the same time, hysteresis observed in earlier studies at both high and low relative air humidities was explained by relying on different models developed separately for high and for low ranges of humidity. This work allows us to explain these critical phenomena using a single mathematical model. |
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ISSN: | 0036-0244 1531-863X |
DOI: | 10.1134/S0036024421120098 |