PENETRATION OF SODIUM-SULFITE INTO BLACK SPRUCE AND ASPEN WOOD CHIPS

Scanning electron microscopy (SEM) and energy dispersive Xray analysis (EDXA) combined with stepwise microtoming were used to measure sodium sulphite concentration simultaneously in three directions within an impregnated wood chip under simulated chemimechanical pulping (CMP) conditions. This approach is move appropriate for studying penetration and diffusion of chemicals into wood than traditional analysis based on electrical conductivities and can be used on samples of various dimensions. The analysis revealed that after 15 minutes sodium sulphite had not completely impregnated the centre of the wood chips. This was more evident in black spruce than in aspen. Concentration measurements confirmed that sodium sulphite diffusion at a pH of 10.4 was faster into aspen than into black spruce chips under comparable conditions.