TCF bleaching of wheat straw organocell pulp

Laboratory prepared Organocell straw pulp was bleached using O-L-P, O-X-P, O-P, as well as Eop-X-P, Eop-L-P, and Eop-P bleaching sequences. Ligninase prebleaching was more effective than xylanase prebleaching. Maximum brightness (72.9 % ISO) was obtained with an O-L-P bleaching sequence. Poor performance of the peroxide stage was observed. The peroxide stage performance can be improved by using chelation pretreatment. Slightly lower brightness was obtained with chelation but without an acid wash. The effect of increasing xylanase charge in the X-Q-P bleach sequence was tested. Maximum improvement of brightness (82.4% ISO) with chelation and 0.5% NaHSO 5 in the S-Q-P sequence was reached at a xylanase dose of 3 U/g o.d. pulp, while the brightness of Q-P belached pulp was 79.9% ISO.