Drying - generic application

There are several methods developed for removing the solvent from the gel under supercritical conditions. The first one is the one suggested in the pioneering work by Kistler, in which the solvent is brought to supercritical conditions in an autoclave and evacuated under these conditions. In order to pressurize the autoclave to a pressure above the critical value for the alcohol, more alcohol is added to the autoclave. Supercritical conditions of the solvent are reached by supplying heat to the autoclave. After the pressure 

In another method, developed by Jacobucci and co-workers, alcohol is removed by supercritical CO2 extraction in a semi-continuous system. 

Solvent exchange is another method utilized to dry alcogels. The liquid in the pores (excess water of the hydrolysis) of the wet-gel is first displaced by alcohol and then alcohol is displaced by liquid CO2 at about 16-20 C and 100 bar. After solvent exchange, the temperature of the system is increased to 40 C and supercritical carbon dioxide is vented out of the system.  

Schneider, in Supercritical Fluids, Fundamentals for Application, E. Kiran, and J.M.H. Levent Sengers, Eds., Kluver Academic Publishers, Dordrecht, 1994, pp. 91-115. 

Schneider, in Water-A Comprehensive Treatise, vol. 2, F. Frank Ed., Plenum Press, New York, 1973, Chp. 6. 

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The main future. effort in this standard development will be to develop the specific appendixes containing detailed checklists applicable to design standards for an AFR, a dry storage facility, and other fuel cycle components. With these appendixes, the standard will become a very valuable complement to the more generic standards pertaining to nuclear criticality control It will provide a much needed information base to support design efforts and fuel handling procedure development in the nuclear fuel cycle. 

When the Europeans first explored Central and South America, they found that the natives coagulated the exudation (latex) of certain trees to make balls which bounced. Also, the latex was spread on fabric and allowed to dry to give a product from which waterproof shoes and flexible bottles were made. In 1770, Priestley named the solid material rubber after finding it could be used to rub out pencil marks the name has remained although this application is a very minor one. It may be noted that the term rubber is now commonly used also as a generic name for any material with rubber-like properties to avoid confusion the latter materials may be called elastomers . 

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