Super/subcritical fluid extractions for preparation of the crystalline titania |
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Authors: | L. Matějová ,T. Cajthaml,Z. Matěj,P. Klusoň |
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Affiliation: | a Institute of Chemical Process Fundamentals of the Academy of Sciences of the Czech Republic, v. v. i., Rozvojová 135, 165 02 Prague 6, Czech Republic b Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Vídeňská 1083, 142 20 Prague 4, Czech Republic c Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic d Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2, Czech Republic |
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Abstract: | Various extraction techniques which use fluids in super/subcritical state (CO2, H2O, CH3OH) were used for the preparation of crystalline TiO2 from surfactant-mediated titania organogels (the amorphous reaction intermediate products of surfactant-mediated sol-gel synthesis). Crystallinity, purity and texture of TiO2 powders (titania aerogels) were studied in detail for different treatment modes of titania organogels. Suitable combinations of extraction solvents and extraction temperature and pressure were considered for synthesis of TiO2 powder crystalline phase (anatase) with high specific surface area and purity (carbon content < 0.1 wt.%). Optimum results were achieved by combined extraction procedures—subcritical water extraction and supercritical fluid extraction or pressurised liquid extraction. Moreover, the possible tuning of the TiO2 powder pore-size distribution by regulation of temperature at constant pressure for the combined subcritical water extraction and pressurised liquid extraction was found. |
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Keywords: | Supercritical fluid extraction Pressurised liquid extraction Subcritical water extraction Titania Nanostructure Crystalline |
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