Improving Water Vapor Adsorption Capacity at Low Humidity on Activated Carbon by Introducing Active Functional Groups Through Ozone Activation

Abstract

Water vapor adsorption on activated carbon (AC) for dehumidification purposes has gained much attention due to the abundance of benefits provided by AC. The working region limited in high water vapor relative pressure (P/P0) makes this material suitable only for removing water vapor at a highly humid region. In this study, ozone oxidation was conducted to introduce more oxygen-based functional groups on AC to attract more water molecules. Based on surface characterization results, ozone oxidation increases oxygen functional groups such as carboxylic on AC but decreases their pores. The more AC exposed to ozone, the more different properties could be observed. The increment of functional groups enhances the water vapor adsorption uptake at P/P0 ≤ 0.6, shifting the water sorption into lower P/P0.