Rigid amine-incorporated silica aerogel for highly efficient CO2 capture and heavy metal removal

Abstract

Although aminated silica aerogels have already been identified as potential materials for adsorption, separation, and thermal insulation applications, their extensive use is limited by their natural brittleness and costly production. In this study, aminated silica aerogel monoliths were synthesized via a facile route utilizing 3-aminopropyl triethoxysilane (APTES) acting as both an amination precursor and a self-catalyst as well as tetraethyl orthosilicate (TEOS). The fabricated TA-NH2-x (i.e., using an APTES/TEOS molar ratio of x) adsorbents had high CO2 selectivity, efficient heavy metal removal capability, and good mechanical strength. Remarkably, the TA-NH2-2.5 aerogel exhibited a high CO2 capture capacity (3.10 mmol/g) and CO2/N2 selectivity (951) under typical flue gas conditions. Moreover, it showed efficient removal of hazardous heavy metal ions such as Pb2+, Hg2+, Ni2+, and Cu2+, as well as excellent mechanical strength (13.96 MPa) and thermal conductivity (29.1 mW/mK). These results suggest that synthesizing aminated aerogel monoliths via self-catalyzed polycondensation using APTES is an efficient strategy for developing rigid multifunctional adsorbents for CO2 capture and heavy metal removal.