The biological bleaching of kenaf caustic soda pulp

Scientists from the Department of Forest Resources Science at Shizuoka University of Agriculture in Japan used white rot fungi to test the biological bleaching of kenaf bast-caustic-AQ pulp. Two kinds of raw materials for the test were used: (1) Kenaf bast fiber after water soaking in China, and (2) Kenaf bast fiber without water soaking in Japan. The caustic soda-AQ cooking process conditions and results are as follows: the two raw materials sodium hydroxide dosages are 13% and 16% respectively, the AQ dosage is 0.2%, the liquid ratio is 1:5, the maximum cooking temperature is 170°C, the holding time is 2h, the pulp The yields were 63% and 48%, respectively, and the Kappa values ​​were 6.3 and 21, respectively. Pulp bleaching was performed using a three-stage FEP bleaching procedure. The pulp was treated with P.Cbrysosporium for 6 days, followed by alkali treatment. The slurry was concentrated at 10%, the sodium hydroxide was used at 1.5%, and the temperature was kept at 50°C for 1 hour. The hydrogen peroxide was bleached. The amount of hydrogen peroxide used was 2% and 4.5% respectively, the amount of sodium hydroxide was 1.0%, the temperature was 70°C, and the temperature was kept for 1 h. After two days of pulp treatment with white rot fungi, the Kappa number of the pulp decreased from 6.3 to 4.2 and from 21 to 7, respectively, and the whiteness increased from 45% to 64% and from 22% to 41%, respectively. CEH three-stage bleached pulp was used as a reference for comparison. Biobleaching of both pulps was superior to conventional CEH.
The three-stage bleaching and bleaching yields were 59% and 51% (made in China), 41% and 39% (made in Japan), and the opacity was slightly higher.