Dissolving pulp from bamboo-willow

The production of dissolving pulp from bamboo-willow (Salix salicaceae or Zhuliu in Chinese) was investigated. It is one of the new fast-growing tree species with strong cold resistance and can grow well in arid areas. Bamboo-willow chips were prehydrolyzed with phosphoric acid and subsequently pulped via the Kraft process. Phosphoric acid was used to dissolve hemicelluloses from bamboo-willow. The resulting brown stock was bleached using oxygen delignification (O), sodium hypochlorite (H), Peroxide (P) and acid (A). Kraft cooking and O–H–P bleaching effectively removed lignin from prehydrolyzed bamboo-willow. The acid post-treatment decreased the ash and ferric ion content in bamboo-willow dissolving pulp. The obtained bamboo-willow dissolving pulp contained low pentosan and high α-cellulose content, and the pulp had high reactivity. The final ash contents, ferric ion, pentosan and α-cellulose content as well as the degree of polymerization and brightness were 0.0950%, 14.7 mg/kg, 2.86%, 95.1%, 547, and 87.2% ISO, respectively. Reactivity is the most significant quality parameter of dissolving pulp and has a large effect on the xanthation reaction during viscose preparation. The reactivity of the obtained bamboo-willow dissolving pulp reached 5.90 s, which implies that the produced dissolving pulp can be used in rayon production.