Experimental investigation on water vapor adsorption performance of solvent-free synthesized MIL-100(Fe) and its composite adsorbent.

With high hydrothermal stability and hydrophilicity, MIL-100(Fe) has potential applications in sorption-based atmospheric water harvesting (SAWH). This paper reports the water vapor adsorption properties of MIL-100(Fe) prepared by solvent and solvent-free methods. Performance tests show that the MIL-100(Fe) prepared by solvent-free method has more advantages. To further improve the performance of the adsorbent, the composite adsorbent MgCl 2 @MIL-100(Fe) was obtained by impregnating MIL-100(Fe) with MgCl 2 solution. The results showed that the composite adsorbent had good adsorption performance, desorption properties, and fast adsorption rate. The equilibrium adsorption capacities of the composite adsorbent with 35% salt content were 0.533 g/g and 1.062 g/g at 25 °C with the relative humidity (RH) of 35% and 80%, respectively, which were 1.51 times and 1.74 times of the adsorption capacity of MIL-100(Fe) under the same working conditions. This showed that the solvent-free synthesized MIL-100(Fe) and its composite adsorbent have the potential for application in SAWH. This paper compares the solvent-free synthesis of MIL-100(Fe) with the hydrothermal synthesis of MIL-100(Fe) with solvent. Then, by evaluating the various properties (characterizations, adsorption performance, cycle stability, preparation cost, etc.) of materials prepared by two different methods, it is determined whether the MIL-100(Fe) prepared by the solvent-free synthesis method is more suitable for water vapor adsorption. Eventually, to further improve the adsorption performance of this material, MIL-100(Fe) was impregnated in MgCl 2 solution to develop a new composite adsorbent MgCl 2 @MIL-100(Fe) for further study. [Display omitted] • The solvent-free synthesized MIL-100(Fe) has excellent adsorption performance and cycle stability. • The composite adsorbent MgCl 2 @MIL-100(Fe) has rapid adsorption kinetics. • The adsorption capacity of the composite adsorbent with an MgCl 2 mass fraction of 35% can reach 1.062 g/g. • The composite adsorbent has good water absorption at low relative humidity, which can reach 0.533 g/g. [ABSTRACT FROM AUTHOR]