Carbon Dioxide as a Sustainable Industrial Solvent to Replace Organic Solvents

Abstract

The discussion about global warming and climate change has led to an increasing demand for reduced emission of the greenhouse gas carbon dioxide. An intelligent industrial use of CO2 in chemistry or process technology could also help to save the environment by replacing other ecologically harmful substances. One of the possible applications for CO2 is its use as a solvent. Although the dissolving power of gaseous CO2 is low to non-existent, it improves significantly in the liquid and supercritical states. For extraction applications, the use of CO2 as a solvent is already very well developed. Especially in the food sector it is utilised for the mild extraction of residue-free oils, aromas, flavours and essences. In other branches, the solvent CO2 is not as widespread, although, there are some interesting examples in technical cleaning, purification, impregnation, dyeing, reaction techniques and atomisation that are described in this chapter. These examples show that CO2 has the potential to become a benign ‘green’ solvent in many more applications.