THE EFFECT OF ACID PRETREATMENT AND PEROXIDE REINFORCEMENT IN ALKALINE EXTRACTION ON OPTICAL AND STRENGTH PROPERTIES OF EUCALPYTUS CAMALDULENSIS KRAFT PULP DURING DED BLEACHING SEQUENCE
SARA Kajforush, Hossein Resalati
Unbleached kraft pulp from Eucalyptus camaldulensis with an initial kappa number of about 31 and brightness of 13% was used to perform bleaching experiments. The results of the first part of this research (using D0ED1 bleaching sequence at different kappa factors of 0.2, 0.3, and 0.4 in D0 stage) showed that the final brightness, even at a kappa factor of 0.4, was relatively low (about 75%). Thus, the effects of acid pretreatment (A stage) and peroxide reinforcement in alkaline extraction (EP versus E stage) in D0ED1 bleaching sequence on optical and strength properties of paper were investigated in this study. By applying these treatments, especially peroxide reinforcement, final kappa number, yield, yellowness, opacity, and air resistance were reduced, while brightness and lightness were increased at similar or superior strength properties in comparison with the reference bleaching sequence.