Supercritical extraction as an effective first-step in a maize stover biorefinery

Supercritical carbon dioxide (scCO sub(2)) has been investigated for the generation of valuable waxy compounds and as an added-value technology in a holistic maize stover biorefinery. ScCO sub(2) extraction and fractionation was carried out prior to hydrolysis and fermentation of maize stover. Fractionation of the crude extracts by scCO sub(2) resulted in wax extracts having different compositions and melting temperatures, enabling their utilisation in different applications. One such fraction demonstrated significant potential as a renewable defoaming agent in washing machine detergent formulations. Furthermore, scCO sub(2) extraction has been shown to have a positive effect on the downstream processing of the maize stover. Fermentation of the scCO sub(2) extracted maize stover hydrolysates exhibited a higher glucose consumption and greater potential growth for surfactant (in comparison with non-scCO sub(2) treated stover) and ethanol production (a 40% increase in overall ethanol production after scCO sub(2) pre-treatment). This work represents an important development in the extraction of high value components from low value wastes and demonstrates the benefits of using scCO sub(2) extraction as a first-step in biomass processing, including enhancing downstream processing of the biomass for the production of 2 super(nd) generation biofuels as part of an integrated holistic biorefinery.