Material characteristics and selection criteria for adsorption-based atmospheric water harvesting: An overview Ibrahim I. El-Sharkawy a,b,* , Mohamed G. Gado c , Hamzeh Sabouni a , Mahmoud M. Abd-Elhady d , Ali Radwan a,b , Ahmed G. Abo-Khalil a , Belal Dawoud e a Sustainable and Renewable Energy Engineering Department, College of Engineering, University of Sharjah, Sharjah, P.O. Box 27272, United Arab Emirates b Mechanical Power Engineering Department, Faculty of Engineering, Mansoura University, El-Mansoura 35516, Egypt c Mechanical Power Engineering Department, Faculty of Engineering - Mataria, Helwan University, P.O. 11718, Cairo, Egypt d Department of Mechanical Engineering, Faculty of Engineering, Damietta University, New Damietta, Damietta, Egypt e Faculty of Mechanical Engineering, East Bavarian Technical University of Applied Sciences (OTH-Regensburg), Regensburg, Germany ARTICLE INFO Keywords: Adsorption Atmospheric water harvesting (AWH) Fresh water Selection criteria Solar energy ABSTRACT Nowadays, atmospheric water harvesting (AWH) attracts great attention due to its potential to address water scarcity, especially in arid regions. A key component of adsorption-based atmospheric water harvesting is the adsorbent materials, which are porous materials characterized by high surface area and the ability to adsorb water vapor from the atmospheric air effectively. In this review article, a comprehensive overview of several adsorbent materials has been conducted, highlighting their inherent characteristics. Mainly, conventional ad- sorbents (silica gel and zeolite), hygroscopic salts, metal–organic frameworks, hydrogels, and composite ad- sorbents have been thoroughly discussed, along with their potential applications. Several AWH systems have also been presented. The review showed that the utilization of zeolite 13X under lower humidity levels is profoundly better; however, the vapor release entails elevated regeneration temperature. Moreover, MOF-801-P and MOF- 841 showed appreciable performance based on material adsorption, recyclability, and water stability. Also, MCM-41 and Basolite A300 exhibited superior volumetric uptakes, notably at higher relative humidity (RH). MIL-101(Cr) has a remarkable adsorption uptake at high relative humidity. However, it is reported that MIL-101 (Cr) could be used for low RH by shifting its step uptake using an internal cooling component. The review also indicated the main guidelines for selecting ideal adsorbents, highlighting the impacts of adsorption capacities, kinetics, regeneration, and climatic conditions on the proper selection of adsorbents for efficient AWH applications. 1. Introduction Given the severe impacts of worldwide water scarcity, the life of millions of people around the world is on edge [1]. Over 4 billion people worldwide have monthly experiencing critical water supplies [2]. Increasing the demand for freshwater, coupled with declining resources, has led to severe water shortages in many regions. Climate change, population growth, and inefficient water use are just a few of the factors that contribute to water scarcity [3]. In Fig. 1, a map of global water scarcity is presented based on the Falkenmark indicator, which is a tool used to assess water scarcity levels in different regions of the world [4]. It calculates the number of available water resources per capita and determines if the region is facing water scarcity, water stress, or water surplus [3]. The consequences of the water scarcity crisis are far- reaching and can include economic hardship, health problems, and environmental degradation. It is essential to take immediate action to address this issue through sustainable water management practices and innovative freshwater production solutions. Atmospheric water har- vesting (AWH) is a prosperous technology for delivering water supplies in arid and semi-arid regions [5]. Generally, AWH techniques can be classified into three basic cate- gories for AWH: direct harvesting, vapor concentration, and integration systems [6]. The direct harvesting type, for instance, fog and dewing techniques, where they mainly rely on condensation to leverage water * Corresponding author at: Sustainable and Renewable Energy Engineering Department, College of Engineering, University of Sharjah, Sharjah, P.O. Box 27272, United Arab Emirates. E-mail address: ielsharkawy@sharjah.ac.ae (I.I. El-Sharkawy). Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener https://doi.org/10.1016/j.solener.2024.112996 Received 15 February 2024; Received in revised form 23 September 2024; Accepted 6 October 2024 Solar Energy 283 (2024) 112996 Available online 23 October 2024 0038-092X/© 2024 International Solar Energy Society. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.