Performance of new and commercial xylanases for ECF and TCF bleaching of eucalyptus kraft pulp |
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| Authors: | Cristina Valls Óscar Gallardo Teresa Vidal F I Javier Pastor Pilar Díaz M Blanca Roncero |
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| Institution: | 1.Textile and Paper Engineering Department ETSEIAT,Universitat Politècnica de Catalunya,Terrassa,Spain;2.Department of Microbiology, Faculty of Biology,University of Barcelona,Barcelona,Spain |
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| Abstract: | Since xylanases can differ widely in their bleaching efficiency, the performance of one new and two commercial xylanases was
evaluated in an eucalyptus kraft pulp following XD (X: xylanase; D: chlorine dioxide) and XP (P: hydrogen peroxide) sequences.
The new xylanase did not show a significant bleach boosting effect but increased the hexenuronic acid (HexA) removal by 10%
after the D stage. The two commercial xylanases behaved in a different way, being one of them (XC) the most effective in increasing delignification (9%) and brightness (3%ISO). Its effectiveness was related to its greater
action on releasing the xylan polymer, thus producing also a strong decrease in the HexA contents during the enzymatic stage
(15%). All xylanases produced morphological changes in the fibre surfaces, but only with XC cracks and holes that improved the diffusion of reactives were observed. Finally, the best bleaching results were obtained
with the XD sequence and therefore, a complete bleaching sequence XDEopD1 (Eop: alkaline extraction with oxygen and peroxide) was carried out with the best enzyme. |
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