Investigation of volatile organic compounds adsorption capacities and regeneration properties of silica aerogel particles

Abstract

This study investigates the volatile organic compound adsorption and thermal regeneration properties of four different silica aerogels which were synthesized via supercritical carbon dioxide drying and spray drying using methyl ethyl ketone as a model indoor air pollutant. The goal was to assess the impact of structural properties (surface area, pore size, drying technique) and magnesium doping on both initial adsorption capacity and long-term reusability over 15 adsorption/desorption cycles. The silica aerogel dried with supercritical carbon dioxide, characterized by high BET surface area (976.7 ± 0.4 m²/g) and average pore size (11.7 ± 0.1 nm), exhibited the superior initial methyl ethyl ketone adsorption capacity compared to the spray-dried aerogels and commercial activated carbon. While magnesium doping did not significantly improve the initial uptake, it was associated with a more stable desorption performance. Regeneration temperature was found to be the dominant factor for performance retention. Increasing the regeneration temperature from 55°C to 130°C significantly mitigated capacity decline by enhancing methyl ethyl ketone desorption efficiency. Kinetic analysis revealed that methyl ethyl ketone adsorption on both the silica aerogel dried with supercritical carbon dioxide and commercial activated carbon was best described by the Pseudo-Second-Order model, suggesting a primary rate-limiting step involving surface adsorption. Overall, the silica aerogel dried with supercritical carbon dioxide sample demonstrated an initial adsorption capacity approximately 1.5 times higher than commercial activated carbon, proving that supercritically dried silica aerogels are highly promising, durable, and regenerable adsorbents for effective indoor volatile organic compound removal.