Enhanced CO2 geological sequestration using silica aerogel nanofluid: Experimental and molecular dynamics insights

CO2 geological storage holds great promise for mitigating anthropogenic CO2 emissions. Maximizing CO2 storage capacity necessitates enhancing CO2 solubility in brine and reducing CO2 mobility. Silica aerogel, with its adjustable properties and expansive surface area, emerges as a potential adsorbent for CO2 capture. This study investigates the application of silica aerogel nanofluid for CO2 geological sequestration. Through a combined approach of experimental investigations and molecular dynamics (MD) simulations, we demonstrate that the undissolved CO2 molecules can be adsorbed into the nanopores of the silica aerogel particles, thereby enhancing the solubility of CO2 in the aqueous phase. The presence of aerogel nanoparticles facilitates their adsorption at the CO2-brine interface, reducing interfacial tension. Experimental and MD simulation results confirm the foamforming and bubble-stabilizing capabilities of aerogel nanoparticles. We comprehensively examine the formation process and dynamics of foam within porous media, elucidating the interplay between CO2 foam and the porous matrix, which significantly influences foam stability and flow dynamics. The resistance exerted by aerogelstabilized foam redirects injected CO2 flow, mitigating preferential pathways. Notably, dynamic interactions between foam and CO2 flow manifest as wave-like changes in resistance. Visualizing and analyzing the blocking process underscore the instrumental role of foam in curbing CO2 mobility, enhancing sweep efficiency, and facilitating CO2 storage. In the presence of the aerogel nanofluid, injected CO2 molecules can permeate through the foam films and enter the bubble interiors, leading to foam volume enlargement. This study provides valuable insights into the underlying mechanisms driving improved CO2 sequestration using silica aerogel nanofluid, offering fresh perspectives on CO2 storage in geological formations.