Formation of low-molecular-mass compounds during the oxygen delignification of pine kraft pulp

The formation of low-molecular-mass degradation products was studied by gas-liquid chromatographic analyses during the oxygen delignification of pine kraft pulp. Depending on the alkali charge and bleaching time the total amount of carbohydrate-derived aliphatic acids and monomeric lignin degradation products varied between 0.1—1.7% and 0.2—0.5% of pulp, respectively. Formic, glycolic, acetic, 3-deoxypentonic, and deoxytetronic acid were the most abundant aliphatic acids, while acetovanillone, 5-formylvanillin, 5-carboxyvanillin, and vanillic acid predominated (70—90% of the aromatics detected) among the monomeric lignin-derived degradation products