Influence of pretreatment conditions of Shirasu-based materials on their adsorption ability of carbon dioxide

This study investigates the influence of solution treatment of Shirasu-based materials on their adsorption ability of carbon dioxide. Various concentrations of calcined Shirasu-based materials were treated in aqueous ammonia solution, and the adsorption ability of the treated materials significantly increased with decreasing the concentration. The material with the highest adsorption ability (0.41 mmol-CO 2 g[Formula: see text]) shows comparable ability to conventional solid absorbent materials. From the result of DRIFT spectra of the samples after adsorption of carbon dioxide, it is suggested that carbon dioxide molecules are physically adsorbed on bridging protonic acid sites and single protonic site of the treated Shirasu-based materials, and the adsorption amount of carbon dioxide on both the sites increases with decreasing the concentration of the sample treated in aqueous ammonia solution. The amount of adsorbed water on Shirasu-based materials also influences the adsorption ability to carbon dioxide, and the ability tends to increase with decreasing the amount of adsorbed bulk-like water.