Target kappa number for AS/AQ pulping of wheat straw

Jing Liu*, Katsuya Nagata

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Alkaline sulfite/anthraquinone (AS/AQ) pulping of wheat straw under different conditions was conducted in this study. A transition point of kappa number at approximately 6.5 was observed based on all experimental results. This transition point can be regarded as the phase transfer point in AS/AQ pulping from bulk to residual delignification. Effective delignification without great lost of pulp yield can be achieved before kappa number was below this transition point during AS/AQ pulping of wheat straw. It is found that the ratio of cooking liquid to solid should not be lower than 6, if good mass transfer of chemicals and lignin dissolving is needed. As the ratio of Na2SO 3 to NaOH dosage ranged from 0.4 to 2.4, low proportion of Na 2SO3 allows effective delignification while no serious degradation of carbohydrate. Moreover, similar to kraft pulping, addition of AQ in the range of 0.05% to 0.25% is useful to remove lignin and protect the carbohydrate during AS/AQ pulping. Finally, although the transition point of kappa number may be changed while different raw material used for same pulping process or different pulping process for same raw materials, it is of interest and important for mill practice.

Original languageEnglish
Title of host publicationAdvanced Materials Research
Number of pages6
Publication statusPublished - 2011
Event2011 International Conference on Chemical Engineering and Advanced Materials, CEAM 2011 - Changsha
Duration: 2011 May 282011 May 30

Publication series

NameAdvanced Materials Research
ISSN (Print)10226680


Other2011 International Conference on Chemical Engineering and Advanced Materials, CEAM 2011


  • Alkaline sulfite/anthraquinone (AS/AQ)
  • Pulp yield
  • Target kappa number
  • Transition point
  • Wheat straw

ASJC Scopus subject areas

  • Engineering(all)


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