THE EFFECT OF THERMOSTABLE AND ALKALINE TOLERANT XYLANASE PRETREATMENT ON THE BLEACHABILITY AND LIGNIN OF O2 DELIGNIFIED PULP
A pretreatment with high pure thermostable and alkaline tolerant xylanase (XTA) towards pulp before bleaching is more advantageous than that with common xylanases in the aspects of commercial bleaching technologies and economics. The selectivity and effect of the XTA pretreatment on D0E1D1D2 bleaching pulp properties were studied in detail by kappa number, viscosity, brightness, chemical and morphologic analysis of the pulps. The results show that XTA pretreatment of the pulps has high selectivity, without causing an obvious decrease in the pulp viscosity, the effective pretreatment conditions can be varied among pH 8.0~9.5 and 75 ~80 ℃ ℃, and the final brightness of the bleached pulps with the pretreatment by XTA was 1％ ISO higher than that of the unpretreated bleached pulps (89.2％ ISO brightness), but the viscosities during the pretreatment and bleaching were almost unchanged under the same conditions, and the ClO2 dosage in the D0 stage could be saved by about 30％ for achieving the same brightness (88.2％ ISO) of the unpretreated bleached pulp. The study also shows that the porosity increase of the fibers by the pretreatment is one of the main factors of improving bleachability although the decrease of hexenuronic acid, lignin and hemicelluloses contents in the fibers by the pretreatment may have influence on improving the bleaching properties. The lignin structure is not influenced by the pure XTA pretreatment.
xylanase ECF oxygen delignification bleachability
Wang Chu Zhai Huamin Zhang Lin
Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing,210037, China
国际会议
广州
英文
462-466
2010-11-08（万方平台首次上网日期，不代表论文的发表时间）