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Fundamental thermodynamic properties of sorbents for atmospheric water capture

Ulrich Legrand, Juan-Ricardo Castillo-Sánchez, Richard Boudreault, Jean-Luc Meunier, Pierre-Luc Girard Lauriault and Jason Robert Tavares

Article (2022)

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Abstract

The thermodynamic properties of various sorbents, namely carbon-based sorbents, silica gel and metal–organic frameworks (MOFs) were assessed and compared based on their adsorption isotherms at 25, 30 and 35 ◦C. The isotherms were measured in a custom-made and calibrated environmental chamber using a gravimetric method. Gibbs free energy demonstrated the spontaneity of the adsorption process and the hygroscopicity variation of the sorbents depending on their surface chemistry. The carbon-based sorbent, nanoporous sponges (NPS), and one of the MOFs, Cr-MIL-101, had lower sorbent-adsorbate interactions and thus had integral enthalpies converging rapidly to the heat of vaporization of pure water. As such, these samples would release less heat during an adsorption step with partial filling of the sorbent. Integral entropy showed that, for most of the environmental conditions, adsorbed water molecules had an entropy equivalent to pure water for most of the sorbent materials, except for silica gel, due to its higher energy sites and higher water-sorbent interactions. NPS and Cr-MIL-101 were shown to be entropically advantageous for the recovery/removal of water. Enthalpy and entropy can provide insight to select favorable conditions to perform adsorption–desorption cycles in a practical water capture system.

Uncontrolled Keywords

sorbents, water adsorption, Gibbs free energy, enthalpy of adsorption, entropy

Subjects: 1800 Chemical engineering > 1800 Chemical engineering
Department: Department of Chemical Engineering
Research Center: CRCT - Centre for Research in Computational Thermochemistry
CREPEC - Center for Applied Research on Polymers and Composites
Funders: Natural Sciences and Engineering Research Council of Canada (NSERC), Prima, Mitacs, Awn Nanotech Inc.
Grant number: CRDPJ 522391-17, R16-46-003, IT16469
PolyPublie URL: https://publications.polymtl.ca/50425/
Journal Title: Chemical Engineering Journal (vol. 431, no. part 2)
Publisher: Elsevier B.V.
DOI: 10.1016/j.cej.2021.134058
Official URL: https://doi.org/10.1016/j.cej.2021.134058
Date Deposited: 18 Apr 2023 14:58
Last Modified: 08 Apr 2024 03:13
Cite in APA 7: Legrand, U., Castillo-Sánchez, J.-R., Boudreault, R., Meunier, J.-L., Girard Lauriault, P.-L., & Tavares, J. R. (2022). Fundamental thermodynamic properties of sorbents for atmospheric water capture. Chemical Engineering Journal, 431(part 2), 134058 (8 pages). https://doi.org/10.1016/j.cej.2021.134058

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