Sol–gel synthesis of highly TiO2 aerogel photocatalyst via high temperature supercritical drying

Abstract

Nanocrystalline powders of TiO 2 xerogel and aerogel were prepared by using acidmodified sol-gel approach. For TiO 2 aerogel material (TA), the solvent was high temperature supercritically extracted at 300°C and 100 bars. However, the TiO 2 xerogel material (TX) was dried at 200°C and ambient pressure. The effects of the drying processes on the crystalline structure, phase transformation and grain growth were determined by Raman spectroscopy, SAED and Xray diffraction (XRD) analyses using Rietveld refinement method. The TiO 2 aerogel was composed of anatase crystalline structure. The TiO 2 xerogel material was composed of anatase, brookite and small amount of amorphous phase with anatase as dominant phase. The TX sample still contains a relatively high concentration of carbon than that of TA, indicating the amorphous character of TiO 2 xerogel. These materials were applied as catalyst for the degradation of indigo carmine in aqueous medium. Photo-degradation ability of TA and TX was compared to the TiO 2 commercial Degussa P25. The photo-catalytic results showed that the degradation efficiency was in the order TA > P25 > TX. The photo-degradation of indigo carmine followed pseudo first order reaction kinetics. Ó 2017 King Saud University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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