Water Harvesting from Air Using Nano-composites

Recently, the World Economic Forum has addressed the water rarity as the greatest global risk in the near future. Among water sources distributed across the earth, only ca. 1.2% of all fresh waters (2.5%) is surface waters which 3% of its amount is present in the atmosphere. So, it seems to be necessary to investigate the novel strategies for supplying fresh water from atmosphere. In this way, appropriate adsorbents with good structural quality such as high surface area, porous framework, and high water uptake performance play incredible role [1]. Amongst various adsorbents, zeolites are well-known solids with intrinsic hydrophilic feature depended on their Si to Al ratios [2]. The aim of this study is to investigate the adsorption ability of FAU zeolite framework for water vapor adsorption from air. At First, the composite of commercial granular FAU zeolite with CaCl2.4H2O was provided by an impregnation method. ICP elemental analysis was carried out to measure Ca2+ content in the pores of the zeolite; it was calculated 0.873 ppm. In addition, zeolite 13X powder was synthesized hydrothermally and its physicochemical properties were determined using different techniques such as FT-IR, XRD and SEM. The calcium-exchange process was also fulfilled for the sample the same as before. Fig.1 shows the FT-IR spectra of both commercial and synthetic zeolites. To assess the water harvesting tests from air, an adsorption set-up including a sorbent reactor, humidity analyzer and a wet air cylinder has been designed. According to the high water sorption capacity of the composite, it could be a promising idea to gain fresh water from air even at low relative humidity using the proposed adsorbent