Evaluating different types of microporous materials for energy-saving atmospheric water harvest

Water extraction from air is a promising strategy for alleviating the current water crisis since it provides inexhaustible water resources to the places where surface and groundwater are scarce. This study systematically assesses 12 selected microporous materials out of zeolites, aluminophosphate zeotypes (AlPOs), and metalorganic frameworks (MOFs), the most promising adsorbents to meet the stringy criteria for economic water harvesting. Through a comparative study of water adsorption isotherms, desorption enthalpies, regeneration temperatures, water capacity, and kinetics at the same condition, the zeotype aluminophosphate with AEI framework topology (AlPO-18) stands out. Using AlPO-18, 0.29 g/g water uptake is achieved in a narrow relative humidity range before 13%. The adsorbent regeneration is almost completed below 70 C. Moreover, AlPO-18 is non-toxic and the synthesis is low-cost. Therefore, AlPO-18 is a good candidate for adsorbent in developing energy -saving atmospheric water harvest (AWH) technology to extract water from "dry" air.