PROGRESS IN POST BLEACHING FOR HIGHEST BRIGHTNESS
The target of all bleaching processes is a higher brightness. The pulp bleaching history has a great influence on the performance of a final hydrogen peroxide bleaching stage as concerns bleachability and selectivity parameters and bleached pulp properties. A final peroxide stage completes bleaching and extracts all remaining potential chromophores. This stage needs temperature and alkalinity to be effective. The reaction with chromophores or precursors of chromophores is rather fast. Peracetic acid is a highly selective bleaching chemical by the use of which good strength properties of the pulp can be maintained. Xylanases are the most commonly used enzymes in pulp bleaching. Their application before or after oxygen delignification is an environmentally friendly alternative to chemical treatment improves bleaching process efficiency. The purpose of this work is an investigation into hydrogen peroxide, peracetic acid and xylanase treatment as a final stage in pulp bleaching. Experiments in this paper have been carried out with bleached hardwood industrial kraft pulp post-treated with hydrogen peroxide, peracetic acid - Kemirox WT17 and xylanase product Pulpzyme HC. The comparative post-bleaching is performed at optimal conditions, which are in conformity with the bleaching reagents charge. The results of the investigations show that peracetic acid bleaching lead to a higher final pulp brightness comparing to peroxide and xylanase treatment. The peroxide treatment leads to lowest Post color number, but the selectivity of the pulp bleaching with this reagent is lowest, too. It is observed insignificant change on the pulp strength properties after peroxide, peracetic acid and enzyme treatments. Paa bleaching stage gives more significant bleaching effect and cleaner fiber surface, which can be benefit for paper production.
post-bleaching hydrogen peroxide peracetic acid xylanase
Petya B. Tsekova Jordan A. Gaidarov Ivo V.Valchev Ventsislav N. Blyahovski
UCTM- Sofia, Dept. Pulp, Paper and Printing Arts, Kliment Ohridski 8, 1756 - Sofia, Bulgaria Svilocell EAD- Svishtov, Western Industrial Zone, 5253-Svishtov, Bulgaria
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
761-765
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）