Effect of Enzymatic Treatment on Solubility of Cellulose in 7.6%NaOH-Water and Ionic Liquid

Abstract

The effect of enzymatic pretreatment on the properties of cellulose dissolved in aqueous 7.6%NaOH and in an ionic liquid (IL) was investigated and compared with viscose prepared from the same raw material and dissolved in 7.6%NaOH. The enzymatic pretreatment decreased by twice the DP of cellulose as compared with the initial one. This facilitated cellulose dissolution in NaOH. The flow of enzyme-treated pulp dissolved in 7.6%NaOH-water and in IL was studied and compared with cellulose xanthate dissolved in aqueous 4.5%NaOH-water. The solutions of enzyme-treated cellulose in NaOH-water gelled with heating in the same way as non-treated cellulose solutions. The dependence of the intrinsic viscosity as a function of temperature of the enzyme-treated cellulose dissolved in 7.6%NaOH showed the same trend and similar values as for microcrystalline cellulose dissolved in this solvent. The assumed presence of insoluble material in cellulose-NaOH solution was proved by flow cytometry, which indicated an average particle diameter of the insoluble or swollen entities being around 600 nm. Cellulose beads were prepared from NaOH-water solutions of enzyme-treated pulp and of viscose. SEM images showed that their surface topography was dependent on cellulose treatment. It was shown that the enzyme-treated pulp-NaOH-water system could be used for bead manufacturing.