An investigation of the performance of catalytic aerogel filters

Gas permeable, photoactive and crack-free titania-silica aerogels of high titanium content (i.e., up to Ti/Si = 1) were prepared by two-steps acid-base catalyzed method involving an acid-catalyzed prehydrolysis of silicon alkoxide followed by a base-catalyzed hydrolysis/condensation reactions with a chelated titania precursor. The prepared titania-silica aerogels displayed good mechanical strength (>30 kN m(-2)), large surface area (>550 m(2)/g), mesoporous structure (8-11 nm) and good gas permeation. The porous aerogels trap and filter airborne particulates and the titania-silica aerogel have a fair performance for aerosol (65%) and bioaerosol (94%) filtrations. The photoactive anatase nano-TiO2 crystallized within the aerogel displays an order of magnitude higher reaction rate for UVA photooxidation of trichloroethylene compared to commercial Degussa P25 TiO2. The bactericidal activity of the titania-silica aerogel for Bacillus subtilis cells under UVA was also six orders of magnitude better. (C) 2008 Elsevier B.V. All rights reserved.