Effect of Xylanase-Assisted Treatment of Oxygen-Delignified Eucalypt Kraft Pulp on ECF Bleaching

The effects of treating industrial (laboratory-unwashed) oxygen-delignified eucalypt kraft pulp with a commercial endo-xylanase (X) on ECF bleaching performance were evaluated. Changes in fibre morphology, bleachability and quality, effluent parameters assessed. Although no significant morphological changes observed, fibres showed some external fibrillation. X stage reduced both the amount integrity xylans remaining fibres, causing their redistribution inside cell wall. In bleaching, treatment allowed reduction ClO2 NaOH loads by 20 10%, respectively. Furthermore, brightness stability enzyme-treated bleached pulps was improved, which assigned to decrease content hexenuronic acid residues. did not affect cellulosic counterpart cause impact papermaking properties, even when xylan degradation somewhat excessive. enzymatic caused increase chemical oxygen demand (COD) respective effluent. realistic conditions used provide better insight into overall this technology at mill.