Characterization of Lignins from Organosolv Pulping According to the Organocell Process, Part 2. Residual Lignins

Abstract

Residual lignins were isolated from cooking residues obtained from 20 1 batch cookings of spruce chips by either ball-milling or enzymatic treatment. The lignins were characterized in terms of yield, elemental composition, polysaccharide moieties and functional groups and compared with the corresponding dissolved lignins. The residual lignins generally proved to be less changed than the dissolved lignins. They show considerable adherence to cellulose and xylose portions. Aliphatic OH groups were found to decrease remarkably towards the end of the cook, which was explained by the formation of new lignin-lignin and lignin-polysaccharide bonds as well as by side chain degradation. Lignin methylation by methanolic liquor was almost negligible.