MIL-160(Al) MOF’s potential in adsorptive water harvesting

The water crisis is one of the main global risks based on its societal impact, particularly the access to safe drinking water in regions with a dry (arid) or mainly dry (semi-arid) climate. Several techniques are being developed, namely the use of regenerative desiccant (e.g., MOFs) to water capture through adsorption processes. MIL-160(Al) belongs to the fumarate-based MOFs family, and it is one of the most promising MOFs for water harvesting and heat transformation applications. In this study, the potential of MIL-160(Al) as an adsorbent for water sorption based applications was evaluated. For this purpose, adsorption equilibrium isotherms, dynamic adsorption experiments, and MIL-160(Al) granules characterization were performed. H2O vapor adsorption equilibrium isotherm was studied at 303, 323, and 343 K presenting a type V shape and was fitted using the Cooperative Multimolecular Sorption model and Polanyi’s theory model. Additionally, CO2, N2, and O2 adsorption equilibrium isotherms were also measured but at 283, 303, and 323 K, presenting the following order of adsorption affinity: CO2 > O2 > N2. Water vapor adsorption breakthrough experiments corroborate the shape of the water adsorption equilibrium isotherms on MIL-160(Al). Water co-adsorption history proved that the presence of the other air components (CO2, O2, and N2) does not affect water adsorption behavior on MIL-160(Al). DRIFTS measurements proved the MIL-160(Al) structure remains stable during the water vapor exposure. The optimization of the TSA process allowed us to achieve maximum H2O productivity of 305 L·day−1·ton−1 for a regeneration temperature of 353 K and flow rate equal to 0.50 m3·s−1.