Transforming volcanic mud into mesoporous silica xerogel and its performance for efficient humidity adsorption

A high humidity level in the environment leads to the development of desiccants as hygroscopic material for adsorbing water vapor. Mesoporous silica xerogel, one of the solid adsorbents used for humidity adsorption, was synthesized from hazardous waste of volcanic mud via sol–gel methods by controlling the pH of the solution. The disordered amorphous silica was obtained, with the properties varied depending on the pH of the solution. Silica xerogel obtained at pH 8 exhibits the highest specific surface area of 576.527 m²g⁻¹ and mesoporous surface area of 527.842 m²g⁻¹. It also has the highest adsorption capacity of 18.90% g_w/g_ads determined from the conventional method and 22.14% g_w/g_ads from TG analysis. The performance for humidity adsorption exceeds the commercial silica with an efficiency of 0.9–7% g_w/g_ads. This result indicates that the potential SiO₂ extracted from volcanic mud can be commercialized as desiccants for humidity adsorption.