Improving the humidity control performance of MIL-100(Fe) with lithium chloride and ethyl cellulose

Abstract

The metal-organic framework MIL-100(Fe) is a novel humidity-regulating material, but it has poor water vapour desorption performance. To address this issue, MIL-100(Fe) was modified using 20% lithium chloride (LiCl), forming stable coordination bonds through ion-dipole interactions. These bonds attract water molecules, enhancing the adsorption capacity and improving the structural stability of the material. After modification, its moisture capacity was increased by 2.42 times, and the desorption amount was increased by 7.22 times, with an overall improvement in moisture adsorption–desorption equilibrium. However, the use of inorganic salts presents a leakage problem in high-humidity environments. To counter this, a 3% ethyl cellulose (EC) coating was applied to the modified MIL-100(Fe). Through surface interactions, this modification improved the material's adsorption performance in non-polar environments, preventing deliquescence in long-term high-humidity conditions. The hydrophobic angle of the modified composite material reached 93°, making the surface hydrophobic. The moisture capacity of the composite material was 1.83 times that of the pure MOF, and the desorption amount was increased by 5.2 times, significantly enhancing the material's environmental humidity regulation performance. Additionally, the material demonstrated good reusability, extending its lifespan, making it suitable for use as an intelligent humidity control material in construction.