APTES-Based Silica Nanoparticles as a Potential Modifier for the Selective Sequestration of CO2 Gas Molecules

Abstract

In this work, we have described the characterization of hybrid silica nanoparticles of 50 nm size, showing outstanding size homogeneity, a large surface area, and remarkable CO₂ sorption/desorption capabilities. A wide battery of techniques was conducted ranging from spectroscopies such as: UV-Vis and IR, to microscopies (SEM, AFM) and CO₂ sorption/desorption isotherms, thus with the purpose of the full characterization of the material. The bare SiO₂ (50 nm) nanoparticles modified with 3-aminopropyl (triethoxysilane), APTES@SiO₂ (50 nm), show a remarkable CO₂ sequestration enhancement compared to the pristine material (0.57 vs. 0.80 mmol/g respectively at 50 °C). Furthermore, when comparing them to their 200 nm size counterparts (SiO₂ (200 nm) and APTES@SiO₂ (200 nm)), there is a marked CO₂ capture increment as a consequence of their significantly larger micropore volume (0.25 cm³/g). Additionally, ideal absorbed solution theory (IAST) was conducted to determine the CO₂/N₂ selectivity at 25 and 50 °C of the four materials of study, which turned out to be >70, being in the range of performance of the most efficient microporous materials reported to date, even surpassing those based on silica.