DIFFUSION OF ETHANOL-LIQUID CO2 IN SILICA AEROGEL

A crucial stage in silica aerogel production in which extraction with liquid (or supercritical) carbon dioxide is used is alcohol diffusion through alcogel to CO2. The quality of samples produced ranged from perfect monoliths (long diffusion times) to completely damaged specimens (the shortest diffusion times). In intermediate conditions, a non-transparent damaged zone was observed inside samples. On the basis of the dependence of damage size on diffusion time, the values of the diffusion coefficient of ethanol in the liquid CO2 inside the silica gel were identified for two temperatures.