Comparative analysis of four metal-organic frameworks for adsorption desalination

Abstract

The adsorption desalination cycle is a promising technique to address water scarcity. However, its production rate is low due to the low capacity of adsorbent materials. In this study, four metal organic frameworks namely aluminum fumarate, MOF–801, MIL–100(Fe), and CAU–10 H are synthesized and characterized and are tested for an application in adsorption desalination. After synthesizing the adsorbents, powder x-ray diffraction patterns for the samples are obtained to ensure a successful synthesis. The samples then undergo thermogravimetric water adsorption measurements at three different temperatures of 30 °C, 50 °C, and 70 °C at varying evaporator pressures. The water adsorption isotherms are also correlated with the Sun-Chakraborty adsorption isotherm model. It is found that the maximum water uptakes of aluminum fumarate, MOF–801, MIL–100(Fe), and CAU–10 H are 0.47, 0.35, 0.72, and 0.31 kg of water/kg of adsorbent, respectively. The highest water uptake of MIL–100(Fe) is due to its largest BET surface area and pore volume of 1634 m2/g and 0.47 m3/g, respectively. Consequently, MIL–100(Fe) provides the highest specific daily water production for adsorption desalination. Adsorption desalination cycles using MIL–100(Fe) could produce 2.2 and 2.3 times the freshwater obtained employing silica gel and CAU–10 H, respectively, with a heat recovery loop between the evaporator and condenser sections.