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Compressed fluid technologies
in the EU 7FWP

There are a number of calls which involve green fluid technologies ...

Cellulosic aerogels


Aerogels, materials with extreme porosity and very low bulk density, can be made using the so called 'Critical Point Drying'- technique.

In a recent study aerogels were prepared from cellulose, xylan, lignin, their mixtures and from spruce wood. The procedure was:

- dissolution of the lignocellulose material in an ionic liquid
- creating a hydrogel by precipitating the dissolved polymeric material
with aqueous ethanol
- exchanging the aqueous precipitant to pure ethanol
- exchanging ethanol to liquid carbon dioxide
- increasing the temperature to above the Tc of carbon dioxide and
- releasing the pressure slowly to obtaing the aerogel material

aerogel preparationAerogel properties

The aerogels made from pure cellulose, cellulose-lignin or -xylane mixtures or from spruce wood had open pore structures and were brittle. The aerogels had bulk densities as low as 25 g / litre and BET areas up to 500 m2/ g



Aaltonen, O., Jauhiainen O., The preparation of Lignocellulosic Aerogels from Ionic Liquid Solutions, Carbohydrate Polymers 75 (2009) 125-129.