Factors Affecting Bleachability of Eucalypt Pulp

Daniela Correia Martino, Jorge Luiz Colodette, Teresa Cristina Fonseca Silva, Dalton Longue Júnior, Dayana Mendes Louzada de Paula, Marco Antônio Bandeira Azevedo


Unbleached and oxygen-prebleached pulps were produced both in industrial and laboratory scale using Eucalyptus urograndis woods from two different sites (A and B) as a raw material. Quantitative chemical analysis of wood and pulp was performed, aiming to find a correlation with bleaching performance. Fiber dimensions measurements in wood were also performed. Carbohydrates and lignin composition in wood from A and B were found to be similar, while extractives in acetone presented variations of about 0.5% between wood from site A and B. Laboratory-made unbleached pulps from A and B had brightness varying 0.3% ISO, whereas pulps from industry presented variations over 4% ISO from each other. By virtue of its high unbleached pulp brightness, the industry-made sample A presented a higher bleachability than its sample B counterpart. The higher bleachability of the industry-made sample A was traced to its much higher content of hexenuronic acids (HexA), which was caused by differences in pulping conditions in mill sites A and B.


Eucalyptus; Bleachability; LoSolids® pulping, HexA

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