Freshwater production from air dehumidification using novel SiO[formula omitted]-based supported material and solar energy: Colombia case study

Abstract

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 °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 °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.