An Investigate on of the Possibility of .Xylanase Enzyme use for Prebleaching of Beech Kraft Pulp

The feasibility of using xylanase enzyme for prebleaching Beech kraft pulp, was investigated. A
commercial xylananse from Trichoderma viride was added to pulp at various doses of 25,50 and 100
IU/g pulp for different reaction times of 12,16 and 20 h. Then, the enzyme - treated pulp was bleached
in HEH sequences, namely, B1: hypochlorite 2% (1h) + extraction + hypochlorite 0.75% (lh), and B2:
hypochlorite 2% (2h) + extraction + hypochlorite 1.5%(2h). The results indicated that enzyme-treated
samples wich were bleached with B2 sequences, exhibited lower kappa number, higher brightness and
lower yellowness, as scompared to those bleached with B1 sequences. Regardless of bleaching
sequences, enzyme treatments using a Xylanase dose of 25 IU/g for 16h, showed the lowest kappa
number, the highest brightness and the lowest yellowness. Kappa number, brightness and yellowness
of control pulps (B1 and B2 sequences) were 11.2, 46.4 (lSO%), 34.3% and 8.9, 55.4(ISO%), and
29.7% respectively. Whereas, kappa number, brightness and yellowness of enzyme-treated samples
using 25 IU/g in 16h bleached with B1 sequences, were 10.21 , 27.4(ISO%) and 26.5% and those
bleached with B2 sequences, were 7.3 , 65.5(lSO%) and 22.3% respectively. The increase of enzyme
dose and reaction time decreased pulp yield. Enzyme-treated samples using a xylanase dose of 25 IU/g
in 16h, had a medium level of variation. Therefore , regardless of bleaching sequences, a xylanase dose
of 25 IU/g for 16h reaction time, could be suggested as optimal using condition of xylanase.