Residual Lignin in Uneleached Kraft Pulp. Part I.: -Allkalli-Extraction of Residual Lignin from Unbleached Kraft Pulp Solution-

Unbleached kraft pulp containing 4.7% Klason lignin has been found to dissolve completely in several nonaqueous cellulose solvents. Extraction of the residual lignin in the unbleached kraft pulp from these solutions was attempted using several kinds of solvents for kraft lignin and hemicellulcoes. When the solvents for only kraft lignin were used, a small amount of the residual lignin (<7% of the original residual lignin) was extracted. On the other hand, 24% sodium hydroxide solution extracted approximately one-half of the residual lignin together with polysaccharides. These results indicate that the residual lignin has sane chemical linkages with sane polysaccharides.