Comparative Study on Soda Ash-Anthraquinone Pulping of Wheat Straw, 1996 Pulping Conference Proceedings
Bangj Cao
University of Minnesota
Wheat straw pulps were made by soda ash-AQ (AP-AQ) and soda ash-AQ-H2 O2 (PAP-AQ) processes. Their strength and bleachability were compared with that of soda-AQ pulp. Alkali lignins separated and purified from spent liquors were subsequently studied. It was shown that while the tensile strength of AP-AQ pulp was improved by as much as 12% over soda-AQ pulp, its brightness and bleachability suffered. Causes for the color of the pulp are discussed in terms of the lignin reactions during pulping. The average molecular weight of AP-AQ lignin was found to be about 7851 compared with 5613 for soda-AQ lignin, which suggested that the degradation of lignin during AP-AQ pulping was milder than that during soda-AQ pulping. The syringyl and p-hydroxy phenylpropane lignin units showed different reactivities in pulping liquors. AnaIyses of carboxyl and total hydroxyl functions are also covered in this study.
Comparative Study on Soda Ash-Anthraquinone Pulping of Wheat Straw, 1996 Pulping Conference Proceedi