Adsorption-based atmospheric water harvesting powered by solar energy: Comprehensive review on desiccant materials and systems

Atmospheric water harvesting has been inexorably proliferated as a potential source of freshwater, notably for remote areas that lack access to water and electricity. This technology could be significantly operated with renewable energy sources. The current study comprehensively reviews the state-of-the-art atmospheric water harvesters and their desiccant materials. Firstly, a detailed survey on desiccant materials, silica gel, Metal-organic frameworks (MOFs), hydrogels, zeolite, hygroscopic salts and composite desiccant materials is illustrated. The review particularly focuses on the materials adsorption capability, kinetics, proper matching with climate conditions. Moreover, the most suitable adsorbents are thoroughly surveyed for a wide range of climate conditions, especially for water scarcity regions (i.e., arid zones) that are characterized by low relative pressures. Moreover, various designs of solar-powered atmospheric water harvesters are comparatively summarized, including fixed and portable installations. It can be concluded that MOF-801, MOF-808, MOF-841, HKUST-1, and CPO-27(Ni) have a superior potential for water harvesting in arid areas. Additionally, MIL-101(Cr) has superior water uptake and kinetic at high relative pressure (i.e., humid areas), and it is irrelevant for water harvesting at dry zones. It is found that the cost of the collected water from atmospheric water harvesting technology is about 0.062–0.86 $/kg of adsorbent. This work provides beneficial perspectives for selecting the most relevant desiccant materials beside the appropriate solar system for water harvesting applications.