Speaker
Description
Variations in relative humidity (RH) can drive phase transitions of salts: crystallization upon water evaporation, and deliquescence (spontaneous crystal dissolution) upon RH increase. In porous materials, these phenomena play a central role in various applications, e.g., in heritage preservation, civil engineering, energy conversion/storage, or water management. While bulk deliquescence and crystallization are well understood in bulk situations, understanding the impact of confinement on these transitions remains challenging, especially in nanoscale pores.
Here, we systematically investigate how sodium chloride (NaCl) solutions confined in synthetic mesoporous materials (3 to 20 nm in diameter) respond to controlled RH cycles, as a function of pore size and salt concentration. Using these model materials, we observe large, well-defined and reproducible shifts of the deliquescence and crystallization points relative to the bulk, which are more pronounced as the pore size is reduced. We rationalize our observations using a theoretical model coupling nanoscale capillary effects (Kelvin equation) with osmotic contributions and classical nucleation theory. Our results, while fundamental, also suggest design rules for composite materials with controllable water content as a function of RH, or tunable crystallization and dissolution conditions for the salt.
| References | Bellezza, H., Poizat, M. & Vincent, O. Salt crystallization and deliquescence triggered by humidity cycles in nanopores. Preprint at https://doi.org/10.48550/arXiv.2510.27309 (2025). |
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| Country | France |
| Green Housing & Porous Media Focused Abstracts | This abstract is related to Green Housing |
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