Salt confined in MIL-101(Cr) - tailoring the composite sorbents for efficient atmospheric water harvesting

ChemSusChem. 2023 Jun 5:e202300520. doi: 10.1002/cssc.202300520. Online ahead of print.ABSTRACTThe adsorption method for atmospheric water harvesting (AWH) is considered as a promising heat driven technology for potable water supply in arid regions. This research is focused on the novel composite sorbents based on hygroscopic salts loaded in the pores of MIL-101(Cr) developed for AWH. The composites based on LiCl, LiBr, CaCl2, and Ca(NO3)2 were synthesised and comprehensively studied by SEM, XRD, N2 adsorption, and TG methods. We evidence that the CaCl2/MIL-101(Cr) composite demonstrates a high net water uptake of 0.52-0.59 g_(H2O)/g_(composite) per cycle under conditions of Saudi Arabia and the Sahara Desert as the reference regions with extra-dry climate. It is shown that water adsorption on the composite cannot be presented as a combination of the adsorption on the components, thus indicating on a synergistic effect. A detailed characterization of water coordination, mobility and hydrogen bonding within the confined CaCl2 hydrates and salt solution with solid state 2H NMR has been performed. It is established that pores confinement promotes a prolonged transition to a dynamically melted state of the hydrated salt and a notable decrease of the melting temperature, which facilitates the molecular transport of water and causes the alteration of sorption properties of CaCl2 inside MIL-101 pores.PMID:37272258 | DOI:10.1002/cssc.202300520
Source: ChemSusChem - Category: Chemistry Authors: Source Type: research