Abstract:
Enzymatic bleach boosting and fiber properties modification
are among the few strategies developed to influence the efforts for conserving energy and: safeguarding the environment. This aspect was studied with reference to Bagasse and Eucalyptus pulps.
A 0.05% xylanase pretreatment for 60 minute was given to
bagasse and eucalyptus pulps, cooked. by modified techniques, this resulted in an increase of 2.7 and 2.8 points in brightness for bagasse and eucalyptus pulps. respectively. This amounts to-a saving of about 50% of chlorine dioxide consumption to achieve the same level of brightness.. Thus, it was possible to obtain an ISO brightness Of about 90 + with only 1.45% and 2.4% of total C102 application on bagasse andeucalyptus pulps respectively following XDED bleaching sequence. The bonding ability of pulps is only slightly affected due to the hydrolysis of xylan. The results obtained suggest that this technology is also pertinent for 'the pulps cooked by modified techniques. -
The experiments were also carried out to assess the use of xylanase for the modification of fiber properties. When fully bleached bagasse and eucalyptus pulps were -,treated with 0.1% of enzyme solution.for 180 minutes,,a 5 point and 7 point rise in
•SR were obtained with minor loss in the yield.. The xylanase
seems to-give some., external as;-well as internal fibrillation by hydrolysing-native xyian. Thus, as a result of some internal modification in the fiber skeleton., the beatability of pulps as well as is strength properties were improved even after xylan hydrolysis. This may be due to the fact, that such internal modification occurring in the fiber wall more thar compensates. the effect of the removal of xylans.
In order to make these processes more of ective and economical, it is recommended to develop better strains which produce lower molecular size enzyme. A study-to investigate the possibility of reutilisation-of enzymes is also-
recommended.
