Synthesis and adsorption performances of MIL-100(Fe) composites for air water intake

In this paper, the metal-organic framework material MIL-100(Fe) was synthesized by hydrothermal method, and then combined with LiCl, CaCl2, and MgCl2 by the impregnation method, and the resulting composite materials were named M/LiCl, M/CaCl2, and M/MgCl2. MIL-100(Fe) and its composites were characterized by SEM, BET, XRD, and TGA, and the open adsorption properties at different temperatures and RH were explored, and the desorption properties and cycle stability of the materials were explored. Experiments show that the equilibrium adsorption capacity of MIL-100(Fe) is greatly enhanced by the combination with hygroscopic salt, and the equilibrium adsorption capacity of M/LiCl, M/CaCl2, and M/MgCl2 is 1.77, 1.03 and 0.58 g/g, respectively, which is 4.4, 2.6 and 1.5 times that of MIL-100(Fe) under the condition of 25 °C and 65% RH. When the ambient RH increases from 35% to 65% at 25 °C, the equilibrium adsorption capacity of MIL-100(Fe) increases from 0.35 g/g to 0.40 g/g, and the equilibrium adsorption capacity of M/LiCl increases from 0.97 g/g to 1.77 g/g. The influence of temperature on the equilibrium adsorption capacity of the adsorbent is negligible, but the increase in temperature will greatly increase the initial adsorption rate of the adsorbent. When RH is 50%, the equilibrium adsorption capacity of M/MgCl2 at 15–35 °C is 0.51∼0.54 g/g, and the maximum adsorption rate is 2.52∼5.18 g/(g·100 min). MIL-100(Fe) and its composites can be completely desorbed after desorption at 130 °C for 70 min, the desorption rate is ≥98%, and the water vapor residue is ≤0.02 g/g. M/CaCl2 showed good cycling stability, and the adsorption capacity after 11 cycles was 94% of the first.