Determination of the diffusion of monovalent cations into wood under isothermal conditions based on LiCl impregnation of Norway spruce

The impregnation of wood pieces in the course of pulping can be divided into primary (advective masstransport) and secondary (diffusive mass transport) penetration.Little is known about the latter partly because of the difficulties in the determination of the relevant diffusivities for this system. In the present article, a precise experimental methodology has been developed to measure the concentration profiles of cations as a function of wood piece dimensions, impregnation time, temperature,and wood structure. The cation concentration can be measured at any position in the impregnated wood piece.The impregnation of Norway spruce wood samples with LiCl was investigated. The impregnated wood pieces were cut mechanically into cubes, which were cut in slices by means of a microtome, and the eluate of the 0.4-mm-thick slices in HNO 3 was analyzed by flame atomic emission spectroscopy. The method gave reasonable results, and defects in the wood piece (microcracks) were detectable. The preliminary results presented here have to be verified with more replicates due to the heterogeneity of wood