Effect of Pulp Concentration during Cellulase Pretreatment on Microfibrillated Cellulose and Its Film Properties

Abstract

Pulp concentration was increased, during preparation of microfibrillated cellulose (MFC), in an effort to improve the efficiency of cellulase pretreatment. It was hypothesized that increased pulp concentration could possibly increase the interactions between cellulase and cellulose, therefore improving the cellulase pretreatment efficiency and benefiting MFC and its film properties. Results showed that higher pulp concentration enhanced the cellulase adsorption ratio from 70% to 90% for pulp concentrations of 2% and 10%, during the pretreatment process. While pulp concentration was changed from 2% to 10% during cellulase pretreatment, the specific area rose from 30.1 m 2 /g to 35.5 m 2 /g. Compared with the original eucalyptus pulp, the crystallinity degree of different pulp concentration was increased, presumably due to the enzymatic breakdown of amorphous cellulose. In addition, the aspect ratio of MFC rose from 19.1 to 35.5. Concurrently, MFC film properties showed better performance, as the elongation at break increased from 0.75% to 1.95%, tensile strength increased from 15.

Adsorption of Cellulases on BHKP Fibers during Pretreatment for MFC Film Preparation

“…Then the pulp was subjected to PFI (vertical) refining to 80 SR° before homogenization for MFC preparation (Z. J. Zhang et al 2016).…”

“…Then, the reactants were filtered through a pinhole filter (0.45 micron organic oil filter membrane) (Qin et al 2021) and the protein content at different temperatures and contact times of filtrate was measured using Bradford method (Khoshnevisan et al, 2011) to obtain the cellulase adsorption ratio by equation 2 (Z. J. Zhang et al 2016). Each test was carried out under the same filtering conditions.…”

“…The crystallinity index (CrI) was calculated according to Turley method (equation 8). The microstructure of MFC was analyzed by the scanning electron microscopy (SEM; JEOL IT300LV, Japan) with an accelerating voltage of 10 kV (Z. J Zhang et al 2016;Z. J. Zhang et al 2018)…”