Amino-modified zirconia aerogels for the efficient filtration of NO2: effects of water on the removal mechanisms

An amino-modified zirconia aerogel (AMZA) was prepared using a facile post-synthesis grafting strategy by introducing 3-aminopropyltriethoxysilane (APTES) into the zirconia sol-gel process and ambient pressure drying (APD). The AMZA shows a three-dimensional mesoporous network assembled by numerous sheet-like aggregates with polymolecular polysiloxane layers covering the surface. The AMZA has a density comparable to that of ASZM-TEDA impregnated activated carbon, which is approximately 65% less than that of porous zirconium hydroxide. NO2 breakthrough tests show that the AMZA has excellent NO2 filtration ability at different relative humidity (RH) levels, with a breakthrough time as long as 362 min and limited NO by-product evolution (