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Wood quality effect on kraft pulping performance

Danila Morais de Carvalho Marcelo Rodrigues da Silva Jorge Luiz Colodette About the authors

The aim of this study was to evaluate the wood quality in the kraft pulping performance under two different pulping conditions at two delignification degrees based on results for the yield, brightness, viscosity, and k/kappa corrected index. Eucalyptus wood (A, B, and C) was analyzed about their physicochemical properties (basic and apparent density, insoluble and soluble lignin content, extractive content, ash and insoluble ash in hydrochloric acid) and used for pulp production by modified kraft cooking, using two different pulping conditions: Condition I (PI) - 16.5% effective alkali, 30% sulfidity, and 155º of cooking temperature; and Condition II (PII) - 17.5% effective alkali, 32% sulfidity,and 147ºC cooking temperature. Both conditions were performed to kappa number 15.5 ± 0.5 and 18.0 ± 0.5. The following pulping parameters and pulp properties produced were evaluated: H factor, screened yield, viscosity, brightness, hexenuronic acid content, and the k/kappa corrected index. The A wood, which had lower extractives and lignin content in its constitution, as well as lower basic and apparent density when compared with B and C woods, showed good results for cooking parameters, especially the pulp produced at PII condition at kappa number 18.0 ± 0.5.Also, the A wood showed higher screened yield, brightness, and viscosity comparing to the other pulps produced. Those pulps produced with higher kappa number have lower k/kappa corrected index.

Ecalyptus; wood quality; delignification degree; kraft pulping conditions

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