Experimental determination of the diffusion of monovalent cation into wood:Effects of micro-cracks,wood structure,impregnation time and temperature on local concentration profiles

A thorough understanding of the key phenomena that take place during the chemical transport of reactants into a wood matrix is critical forthe success of today’s chemical pulp mills as well as future biorefinery operations. In the present article, our previous experimental methodologyhas been further developed to minimize the effect of micro-cracks present in wood pieces. The effects of wood structure (sapwoodand heartwood), impregnation time, and temperature on local concentration profiles in Norway spruce wood were investigated using LiCl asa tracer substance. For experimental conditions of neutral/low pH, Li+ ion concentrations in the eluate of slices taken from the outer surfacelayers of an impregnated wood piece were found to be higher than the native anionic group content (i.e., the cationic exchange capacity)of the wood piece. The method gave reasonable results, but defects in the wood piece (micro-cracks) still existed and were detectable