Date of Award
Bachelor of Science
Pulp and Paper Technology
During cold soda pulping, sodium hydroxide reacts with the lignin-carbohydrate complex to form soluble sodium lignate, and the carbohydrates are made soluble by hydrolysis (17). This lignin reaction, however, occurs only after a major portion of the caustic soda has been consumed in neutralizing the readily available acetyl and methoxyl groups and in hemicellulose dissolution. After the pulping process, the high-yield cold soda hardwood pulps exhibit a brown discoloration. A microscopic examination of the woods from which these pulps were produced (21) revealed that the brown discoloration was due to materials located in the cells of the wood. In addition it was observed that in the heartwood these substances are darker and more abundant than in the sapwood. Chemically these incrustations are not identical with lignin, but they probably develop from the same precursors.
Pratley, Harry, "Brightness Improvement During Cold Soda Pulping" (1965). Paper Engineering Senior Theses. 422.