Influence of Alkali Charge on Hexenuronic Acid Formation and Pulping Efficiency for Lo-Solids ～R Cooking of Eucalyptus

摘要

The goal of this work was to study the influence of the alkali charge on the hexenuronic acid content and pulping efficiency for the Lo-Solids ～R cooking process. Woods from 2 hybrids of 7-year-old Eucalyptus grandis x Eucalyptus urophylla (basic density of 0.499 and 0.559g/cm~3) were evaluated and the pulping process was conducted by applying active alkali charges (as Na_2O) of 13%, 15%, 17%, 19%, 21%, 23%, 24%, 25%, 27% and sulfidity of 30%. The results showed that in varying the alkali charge, it is possible to obtain unbleached pulp with different yields, carbohydrate composition, hexenuronic acid content from 10 to 65μmol/g and kappa numbers from 8 to 30. Although the hybrids studied presented different basic wood density, the pulping results obtained were not different, showing that both raw materials could be used for pulp production with Lo-Solids ～R pulping process, as it seems not to be significantly affected by basic wood density.