Mesoporous Silica-Hydroxyapatite Inorganic Nanocomposites for CO2 Capture: Effect of Amine Grafting Route

The development of porous materials for CO₂ capture is a promising strategy to mitigate greenhouse gas emissions. In this work, hydroxyapatite (HAP) and mesoporous silica nanoparticles (MSN) were combined to obtain MSN-HAP nanocomposites exhibiting high surface area, mesoporosity, and basic inorganic sites. The silica-based surface was further modified with amine groups using two grafting routes: after template removal, yielding MSN-HAP-NH₂(A), and before template removal, yielding MSN-HAP-NH₂(B). The materials were characterized by FTIR spectroscopy, X-ray diffraction, and N₂ adsorption/desorption measurements to evaluate their structural and textural properties. CO₂ adsorption isotherms at 50 °C showed that MSN-HAP-NH₂(A) present the highest adsorption capacity, followed by MSN-HAP and MSN-HAP-NH₂(B). These results indicate that CO₂ capture depends on pore accessibility and mesoporosity preservation, which are influenced by the functionalization routes. Therefore, MSN-HAP nanocomposites are promising materials for CO₂ capture and highlight the importance of surface modification strategies in optimizing adsorption performance.