'Single lay out' and 'mixed lay out' enzymatic processes for bio-bleaching of kraft pulp

Xylanase alone as 'single lay out' (strategy I) and in combination with pectinase as 'mixed lay out' (strategy II) was used to investigate their bio-bleaching potentials. Strategy I was carried at 70 degrees C using 5 U/g of xylanase at pH 9.5 and 12.5 whereas strategy II was carried out at 70 degrees C using 5 U/g of each of the enzyme, respectively at pH 9.5. Bio-bleaching caused 15% and 20% less Cl-2 consumption though strategy I and II, respectively over chemical bleaching. Strategy II was proved to be 35.71% more efficient in ClO2 saving than conventional method. Significant improvement in various pulp properties viz. tensile strength 25.70%, breaking length 21.80%, burst factor 20.00%, burstness 13.86%, tear factor 6.61% and tearness 18.88%, was also observed through 'mixed lay out' strategy. (C) 2009 Elsevier Ltd. All rights reserved.