SUPERCRITICAL CARBON DIOXIDE EXTRACTION OF SOUTHERN PINE AND PONDEROSA PINE

Abstract

Pine wood and bark were extracted with supercritical (SC) carbon dioxide under various experimental conditions. The extractive yields ranged from 20-60% relative to the total diethyl ether extractive content. The yields were dependent on temperature, pressure, particle size, and fluid to wood ratio. The addition of ethanol to bark particles prior to SC CO, extraction produced higher yields of extracts relative to extractions without the addition of ethanol. Gas chromatographic (GC) analysis of selected SC carbon dioxide extracts revealed that the concentration of resin acids, as well as the yield of pure abietic acid, increased with temperature at constant pressure. Fatty acids were more soluble in SC carbon dioxide relative to diethyl ether. The concentration of fatty acids in SC carbon dioxide extracts did not appear to follow definite trends. In addition, observation of the wood particles with scanning electron microscope (SEM) revealed that the supercritical extraction process did not appear to sig-nificantly alter the wood surface structure.