Bleach-boosting effect of crude xylanase from Bacillus stearothermophilus SDX on wheat straw pulp.

Pretreatment of wheat straw pulp using cellulase-free xylanase produced from Bacillus stearothermophilus SDX at 60°C for 120min resulted in 4.75% and 22.31% increase in brightness and whiteness, respectively. Enzyme dose of 10U/g of oven dried pulp at pH 9 decreased the kappa number and permanganate number by 7.14% and 5.31%, respectively. Further chlorine dioxide and alkaline bleaching sequences (CDED(1)D(2)) resulted in 1.76% and 3.63% increase in brightness and whiteness, respectively. Enzymatic prebleaching of pulp decreased 20% of chlorine consumption without any decrease in brightness. Improvement in various pulp properties like viscosity, burst factor, burstness, breaking length, double fold, gurley porosity, tear factor, and tearness were also observed after bleaching of xylanase treated wheat straw pulp.