Metal-organic frameworks with high working capacities and cyclic hydrothermal stabilities for fresh water production

In this work, we evaluated the working capacities of eight hydrothermally stable metal-organic frameworks (MOFs) for water adsorption under typical humidity conditions in three representative dry regions. Remarkably, three MIL-100(M) materials (M = Cr, Al, and Fe) and MIL-101(Cr) exhibited very high working capacities for medium and high humidity conditions due to their large surface areas. All of the MOFs consisting of only M-III sites (MIL-101(Cr), MIL-100(Cr), and MIL-100(Al)) showed good cyclic water adsorption/desorption performances and good hydrothermal stabilities. Due to the presence of Fe-II sites formed during activation at 250 degrees C, MIL-100(Fe) showed a considerable decrease in its water adsorption isotherm during the 2nd cycle although almost unchanged water uptakes were observed in the following cycles. When MIL-100(Fe) was activated at 150 degrees C (MIL-100(Fe)_150) to prevent formation of Fen sites, the sample showed good cyclic adsorption/desorption performance and good hydrothermal stability. Considering the high working capacities, cyclic adsorption/desorption behaviors, and good hydrothermal stabilities, MIL-101(Cr), MIL-100(Cr), MIL-100(AI) and MIL-100(Fe)_150 are promising adsorbents for producing drinking water in dry regions with medium or high humidity conditions during the night. (C) 2015 Elsevier B.V. All rights reserved.