Preparation of acetate-grade dissolving pulp from eucalyptus by processes including alkaline pretreatment and combined post-treatments with xylanase and alkali

In this investigation, alkaline pretreatment before kraft pulping and combined post-treatments with xylanase and alkali after bleaching were applied to obtain an acetate-grade dissolving pulp. Bleaching sequences using oxygen or hydrogen peroxide were also studied. The brightness, α-cellulose content, and degree of polymerization (DP) of the bleached pulps from different bleaching sequences were evaluated. Alkaline pretreatment resulted in a higher α-cellulose content in the pulp. When a D1ED2P bleaching sequence was applied, the pulp obtained had an ISO brightness of 87.5%, a DP of 1050, and an α-cellulose content of 92.7%. The requirements for an acetate-grade dissolving pulp can then be met when followed by combined post-treatments with xylanase and alkali under the optimal conditions of 120 IU•g–1 xylanase dosage and 4% sodium hydroxide concentration.