Abstract:

 Fe2O3-SiO2 aerogels have been prepared from tetraethoxysilane (TEOS) and ferric nitrate by sol-gel process and supercritical drying technique, and the structure of the aerogel samples has been characterized. The final aerogels which consist of colloidal particles with diameters of about 8 nm were found to be monolithic non-crystalline solid materials with low density and high porosity. The effect of forming conditions of Fe2O3-SiO2 alcogels was also studied, showing that the presence of ferric nitrate aqueous solution in the co-culture medium is essential for efficient preparation and the highest effective concentration of feric nitrate solution is 0. 3500 mol•L-1 over pH range 0 ～ 3 in the sol-gel process. Results were compared with those obtained in measuring single SiO2 aerogels, the strength and the specific surface area of the resultant aerogel samples can be improved apparently by the addition of Fe3+ to the precursor solution in sol-gel process, and the density, specific surface area of the resultant aerogel samples can be controlled by adjusting the concentration, pH value of ferric nitrate aqueous solution. The specific surface area of the aerogel sample can achieve as high as 625. 4 m2• g-1 when the concentration of ferric nitrate aqueous solution is 0.1736 mol•.L -1 at pH=2. 

Key words: Aerogel, Fe2O3-SiO2, Preparation, Supercritical drying, Sol-gel process