Silica gel-MIL 100(Fe) composite adsorbents for ultra-low heat-driven atmospheric water harvester

The present study focuses on the synthesis and characterization of new composites comprising of RD silica gel and metal-organic framework (MOF) MIL-100(Fe) to upgrade the performance of the adsorption-based atmospheric water harvesting system. The impact of adding MIL-100(Fe) on the porous properties, thermal conductivity, and water adsorption characteristics of the composites has been experimentally investigated. Furthermore, three performance indicators are introduced to investigate the performance of the system, including net adsorbate uptake (Δq) and the efficiency estimation using two different approaches. Results showed that the maximum increment in the thermal conductivity was found in the composite having the highest concentration of MIL 100(Fe) (69 wt%). Thermodynamic cycles were drawn to show the performance of the composites with heat source temperatures of 50 °C and 70 °C. A composite of 29 % RD silica gel, 69 % MIL 100(Fe), and 2 % PVP showed the highest value of Δq (213.8 % increment over parent RD silica gel). In contrast, the efficiency of the system was enhanced up to 187 % than that of the silica gel-based AWH system. •RD silica gel and MIL 100 (Fe) based consolidate composites were synthesized.•Water adsorption isotherm's shape was modified from type II to type V.•Thermal conductivity of the studied composites increased significantly.•Majority of the composites can utilize heat sources as low as 50 °C for their regeneration.