Abstract
Residual lignin from a series of softwood kraft pulps was isolated and structurally characterized by nuclear magnetic resonance. Results of these analyses showed that residual lignin structure differs depending upon the lignin content of the pulp and the pulping technology employed. The lower lignin content pulps had reduced contents of aliphatic hydroxyl groups and β-O-4 structures and higher contents of phenolic hydroxyl groups, carboxylic acid groups, and condensed structures compared to higher κ number pulps. Analysis of residual lignins isolated from conventional kraft pulps (CK) and extended modified kraft pulps (EK) indicated that the CK pulps had lower contents of β-O-4 structures and higher contents of condensed structures. These differences potentially explain the improved delignification selectivity of EK kraft pulping because residual lignin with a higher content of β-O-4 structures and a lower content of condensed structures would be more reactive under pulping conditions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.