Effects of enzymatic pretreatment on micro/nano cellulose production

Industrial applications of microfibrillated (MFC) and nanofibrillated cellulose (NFC) have been in use for some time; however, there is a need to improve the production steps and at the same time to obtain better quality products. The aim of this study was to improve the production efficiency and quality of MFC and NFC by examining the enzymes (Pulpzyme HC 2500 and Celluclast 1.5 L) employed in pretreatment sequences. NFC and MFC were generated kraft pulp, produced from red gum tree plant (Eucalyptus camaldulensis). Enzymatic hydrolysis was combined with mechanical shearing and high-pressure homogenization. The generated NFC and MFC were characterized by HPLC, FTIR, TGA and 13C-NMR. Morphological and viscoelastic properties were investigated with SEM and Rheometer, respectively. Results indicated that using Celluclast 1.5 L caused selective hydrolysis in amorphous cellulose and produced high aspect ratio nanoscale cellulose elements. A fairly homogeneous NFC with a width of 35 ± 12 nm was produced in this study. Employed treatments to produce MFC and NFC decreased the cellulose crystallinity of bleached kraft pulp and lower total crystalline index (TCI) and lateral order index (LOI) values were observed for MFC and NFC in FTIR examinations. Lower crystallinities were also defined by 13C-NMR (46.2 ppm), which was substantiated with C6 peaks in the amorphous domain. Obtained MFC and NFC revealed shorter fiber dimensions with less ordered cellulose structure causing lower thermal degradation. Consequently, the methods examined in this study produced MFC and NFC with improved physicochemical and structural properties.