Cellulosic materials as biopolymers and supercritical CO2 as a green process: chemistry and applications

In this review, we describe the use of supercritical CO2 (scCO(2)) in several cellulose applications. The focus is on different technologies that either exist or are expected to emerge in the near future. The applications are wide from the extraction of hazardous wastes to the cleaning and reuse of paper or production of glucose. To put this topic in context, cellulose chemistry and its interactions with scCO(2) are described. The aim of this study was to discuss the new emerging technologies and trends concerning cellulosic materials processed in scCO(2) such as cellulose drying to obtain aerogels, foams and other microporous materials, impregnation of cellulose, extraction of highly valuable compounds from plants and metallic residues from treated wood. Especially, in the bio-fuel production field, we address the pre-treatment of cellulose in scCO(2) to improve fermentation to ethanol by cellulase enzymes. Other reactions of cellulosic materials such as organic inorganic composites fabrication and de-polymerisation have been considered. Cellulose treatment by scCO(2) has been discussed as well. Finally, other applications like deacidification of paper and cellulosic membranes fabrication in scCO(2) have been reviewed. Examples of the discussed technologies are included as well.