Supercritical fluid extraction (SFE) as an effective tool in reducing auto-oxidation of dried pine sawdust for power generation

Abstract

Supercritical carbon dioxide was an ideal solvent for the extraction of fatty and resin acids from pine sawdust. This green extraction process significantly reduces the potential for uncontrolled auto-oxidation within this valuable fuel, thereby removing the risk of combustion during storage and processing. Experimental design was utilised to maximize the yield of the extractives. Within the experimental conditions investigated (74–250 bar and 40–60 °C), higher pressures and lower temperatures gave preferentially high extraction yields, with 97% of the fatty and resin acids in 2 h at 250 bar, 40 °C, 40 g min⁻¹ and with 10% ethanol co-solvent. The calorific value of the pelletized sawdust was not significantly affected by the extraction process and the resulting extracts have demonstrated a significant potential for conversion to a biodiesel liquid fuel or higher value chemicals.