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 bamboowillow. 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 bamboowillow dissolving pulp. The obtained bamboo-willow dissolving pulp contained low pentosan and high acellulose content,and the pulp had high reactivity.The final ash contents, ferric ion, pentosan and a-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.

Phosphoric acid efficiently dissolved hemicelluloses from bamboo-willow. The prehydrolysis of bamboowillow chips, which included 1% phosphoric acid addition, can decrease the pentosan content from 27.6 to 13.2%. The decrease is accompanied by pentosan removal of 63.8%, and the a-cellulose retention of 94.2%.Acid insoluble lignin content of prehydrolyzed bamboo-willow was 21.3%. Kraft cooking and O–H–P bleaching could efficiently remove lignin from prehydrolyzed bamboo-willow. The kappa number decreased from 20.0 for cooked pulp to 0.670 for the peroxide bleached pulp. After pulp bleaching using an O–H–P sequence, the degree of polymerization (DP) of pulp decreased from 1.16 9 10 3 for the cooked pulp to 594 for the peroxide bleached pulp. The acid post-treatment could effectively decrease the ash and ferric ion contents of bamboo-willow dissolving pulp. The final bamboo-willow dissolving pulp contained low pentosan and high a-cellulose contents, and the pulp had high reactivity. Its ash, ferric ion, pentosan, and a-cellulose contents 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. In addition, the reactivity of the obtained bamboo-willow dissolving pulp reached 5.90 s.

https://doi.org/10.1007/s10570-017-1596-z