JP Journal of Solids and Structures
Volume 6, Issue 1, Pages 11 - 26
(March 2012)
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SILICA AEROGELS PREPARED WITH SUPERCRITICAL CARBON DIOXIDE
Natália Fernanda Nunes Pessanha and Gerson Luiz Vieira Coelho
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Abstract: This study involved the production of aerogels, a material that belongs to the class of micro-mesoporous solids. The production of the aerogel began with the sol-gel polymerization using a molar ratio TMOS:MeOH:H2O:NH4OH in 1:12:3.6:3.5x10-3. Supercritical carbon dioxide was the extraction method applied in this study. The use of supercritical fluid allows the methanol to be removed in a less abrupt manner in the wet gel. The samples were analyzed with nitrogen adsorption and infrared spectroscopy. The extraction efficiency of the supercritical carbon dioxide was compared with the extraction at ambient pressure at 150°C. Based on data from the literature, the BET surface area produced by Rapid Supercritical Extraction method was smaller when compared with the surface area in the aerogel produced with supercritical CO2. In addition, a 5% increase in the BET surface area was observed due to the use of methanol in the unit. |
Keywords and phrases: shrinkage, cracking, extraction. |
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