Carbon-13 NMR chemical-shift imaging study of dewatering of green sapwood by cycling carbon dioxide between the supercritical fluid and gas phases

Abstract

Carbon-13 chemical-shift imaging (CSI) was used to study the distribution of CO2 in green pine sapwood that was partially dewatered by a process in which CO2 was cycled between the supercritical fluid and gas phases. Proton magnetic resonance imaging (MRI) was used to characterise the corresponding distribution of water. The CSI experiment showed strongest signals from cells with weakest proton MRI signals. This was consistent with a mechanism in which latewood bands provide pathways for supercritical CO2 to penetrate into the interior of a specimen. Supercritical CO2 also penetrated earlywood exposed on surfaces of the specimen.