Influence on brightness in the paper pulp bleaching

A 2.0-g sample of homemade pulp was accurately weighed, and 100 mL of water was added and blended with it. The pulp was then treated with 2% hydrogen peroxide and 1% NaOH and was also bleached with the crude xylanase solution (0.4, 0.6, 0.8, 1.0 and 1.2 mL, respectively). The brightness of the pulp was measured for comparison with the values recorded for the pulp treated with the enzyme solution without rare earth ions. The brightness of the pulp was measured using a WSB-1 whiteness meter (Simulation D65 lighting) according to the Chinese National Standard GB/T 7933-87.