The Optimum of Preparation and Characterization of Aerogels like Hydrophobic Titania by Ambient Pressure Drying

Abstract

The influence of different factors in the alcogel preparation process and ambient pressure drying process on packing density of hydrophobic TiO2 aerogel synthesized by ambient pressure drying (APD) and the optimum preparation conditions were investigated by the orthogonal test with four-factor and three-level L9(34), respectively. The morphology and structural properties of hydrophobic TiO2 aerogels with different density were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetry (TG), N2 adsorption-desorption measurement and Scanning Electron Microscope (SEM). The results showed that the most important factors in the preparation process for TiO2 aerogels with low-density under ambient pressure are aging time, the volume ratio of C2H5OH to TBT, ethanol immersion time and hydrophobic modification time. The optimized preparation conditions are that aging time is 24 h, the volume ratio of C2H5OH to TBT is (7+7) : 5, the volume ratio of H2O to TBT is 1.7 : 5, the volume ratio of HAc to TBT is 1.7 : 5, ethanol immersion time is 24 h, hydrophobic modification time is 48 h, hexane solvent replacement time is 24 h and the drying temperature is 393 K. TiO2 aerogels with density of 460 kg/m3 was obtained at the optimized conditions. TiO2 aerogel with lower density displays higher specific surface area, porosity and pore volume as well as the larger pore size.