Improvements in ECF bleaching: Use of activated oxygen species and xylanase

Softwood and hardwood kraft pulps were pretreated with xylanase followed by treatment with hydrogen peroxide, dimethyidioxirane (DMD), or hydrogen peroxide reinforced with nitralamine (Pnt). The resulting pulps were then further bleached with a DEDED sequence. Bleaching studies demonstrated that activated peroxide in the form of DMD or Pnt was an effective method of reducing the total applied charge of chlorine dioxide while still achieving 90+ ISO brightness values. Application: This paper gives preliminary results on studies of enzymes and peroxide agents as alternative ECF bleaching protocols to further reduce AOX.