Mass transfer challenges in wood decomposition

“Cellulose is the most abundant biopolymer. It can be extracted from the primary cell wall of green plants. The primary resource for production of cellulose is wood, where it is attached to other biopolymers such as hemicelluloses and Lignin. A challenging step in material biorefinery is separation of Lignin from cellulose, in which mass transport and/or adsorption of lignin in the cell wall has been recognized as the rate determining step. However, due to very complex structure of wood matrix and various components of lignin, the relative importance of mass transport and adsorption has not been extensively studied. In order to obtain more comprehension on this matter, studies using model systems can be advantageous. In this study first lignin transport through cellulosic based model membrane will be studied. Lignin is a heterogeneous molecule with different molecular weights and functionalities, therefore, for a better understanding various fractions of lignin will be used. The mass transport of these lignin fractions through model cellulose membranes will be determined. Different membranes with various porosity and pore sizes made of cellulose or cellulose and hemicellulose will be used. Transport of lignin molecule through these membranes will be studied by using diffusion cells and labelling lignin molecules radioactively.The adsorption of lignin and enzymes to cellulosic materials will also be studied by using QCM-D, where cellulosic membranes will be casted and the different fractions of lignin rinsed over the QCM-D surface. The effect of different pre-selected enzymes on the molecular weight of lignin will be studied by rinsing the enzymes over a QCM-D surface covered with bound lignin molecules.”