Kinetic and Equilibrium Study of the Adsorption of CO2 in Ultramicropores of Resorcinol-Formaldehyde Aerogels Obtained in Acidic and Basic Medium

In this work, aerogels were prepared using resorcinol-formaldehyde as a precursor in two synthetic routes, one basic and one acidic, to perform the adsorption of CO2 at 0 °C and atmospheric pressure. Aerogels were Characterization by N2 and CO2 Physisorption, Raman Spectroscopy, Scanning Electron Microscopy, and Infrared Spectroscopy. In general, was found that aerogels have a polymeric, disordered, three-dimensional structure and have a microporous surface. Langmuir, Freundlich, Sips and Toth equilibrium models present a good data fit of CO2 adsorption at relative pressure ranging between 1 × 10−4 and 3 × 10−2. The diffusion intra-particle kinetic model explains the setps of this process; the Elovich model also showed a good fit, therefore, there are an energetic heterogeneity of the CO2 superficial adsorption sites. The aerogel carbonized in basic medium at 1050 °C (ACB 1050) material was the best adsorbent of this pollutant, reaching an adsorption capacity of 6.43 mmol g−1.