Effect of alkalinity on the diffusion of solvent-fractionated lignin through cellulose membranes

Abstract Mass transport of liberated lignin fragments from pits and fiber walls into black liquor is considered a determining step in the delignification process. However, our current understanding diffusion through cellulose influential parameter on this process very limited. A comprehensive detailed study mass cellulosic materials is, therefore, great importance. In study, cell methodology implemented to systematically investigate fractionated kraft molecules model membranes. Pulping complex heterogenous material therefore perform more diffusion, we included an additional solvent fractionation step. One benefits method that setup can be adjusted various experimental conditions allowing chemical reactions occurring during pulping, which would affect transfer lignin, avoided. Here, effects alkalinity aqueous solution molecular weight their were investigated. Additionally, NMR spectroscopy, size exclusion chromatography, UV/Vis spectroscopy used characterize starting passed membrane. Lignin detected acceptor chamber cells had lower weights, indicating between donor chamber. showed higher concentrations ionized conjugated chamber, sign fractionation. This suggests small pores enhanced by decreasing average diffusing increasing alkalinity.