Development of Volumetric Adsorption Isotherms for Volcanic Fly Ash from Egypt for Carbon Dioxide Capture Under Elevated Pressure and Temperature

One of the most promising methods for direct carbon dioxide (CO2) capture from the atmosphere is using material-based adsorption. Fly ash, a solid waste material, has been found to have good adsorption potential for CO2. Since different fly ashes have different properties, their CO2 adsorption behaviors differ; therefore, it is important to develop separate isotherms for each fly ash to quantify its CO2 adsorption capacity. This research investigates the adsorption capacity of an extremely abundant volcanic fly ash in Egypt that is currently being researched for use in CO2 capture applications in Egypt. Adsorption was measured using the volumetric adsorption principle. Four adsorption isotherms for the volcanic fly ash were developed at different temperatures, including 23, 40, 60, and 80 °C. The adsorption capacity was found to be impacted by the temperature of the experiment, the pressure of the CO2, and the interactions occurring between the CO2 and the fly ash. As the temperature increased, the adsorption capacity increased significantly. This was primarily due to the expansion of fly ash particles at elevated temperatures, which resulted in a higher contact surface area between the fly ash and the CO2. This created more adsorption sites for the CO2, therefore increasing the CO2 adsorption potential significantly. This research can help facilitate the use of volcanic fly ash for CO2 capture applications in Egypt in the near future, hence reducing the overall CO2 emissions to the atmosphere.