Freshwater production from air dehumidification using novel SiO2-based supported material and solar energy: Colombia case study

Water is a vital liquid for developing biological, industrial, and social processes. However, by 2020, the availability of drinking water decreased by 20% worldwide, leaving more than 2 billion people without access to high-quality water. Thus, this work was based on freshwater production from air dehumidification using silica-based supported materials in two climate zones in Colombia to deal with this lack of water. The results showed that the material synthesized based on a hygroscopic CaCl2 salt supported on silica (SHS) has a high sorption capacity and efficiency even after ten sorption/desorption cycles. The obtained water isotherms had the same tendency for 20, 30, 40, and 60 degrees C, showing type II behavior based on the International Union of Pure and Applied Chemistry (IUPAC) classifications from 2015. A sorption capacity of 0.85 g.g(-1) for a relative humidity of 84% was obtained. Based on the thermodynamic properties of sorption, the process is defined as spontaneous and exothermic. For the field tests, simple equipment was designed for water sorption/capture during the night, while the desorption/condensation process occurs during the day. The exclusive use of solar energy generated productivity above 0.6 g.g(-1) in the environmental conditions of Santa Fe-Antioquia and the Tatacoa desert in Colombia. The relative humidity was less than 80% during the entire test. The desorption temperature was lower than 40 degrees C, which shows the high capacity of the SHS to produce water in semi-desert conditions at low temperatures. Thus, this SHS can produce water in challenging environments, generating a positive social impact by providing fresh water to those communities that need it most. (C) 2022 The Author(s). Published by Elsevier Ltd.