Properties of cellulose micro/nanofibers obtained from eucalyptus pulp fiber treated with anaerobic digestate and high shear mixing

High production costs remain the single greatest factor limiting wider use of cellulose micro/nanofibers by industry. The objective of the present study was to investigate the potential of using a low-cost bacteria-rich digestate (liquid anaerobic digestate-AD-supernatant) on milled eucalyptus fiber followed by high-shear mixing to obtain cellulose micro/nanofibers. The morphology, crystallinity, and thermal stability of micro/nanofibers obtained by this process were studied. The bacteria population in the AD-supernatant was comprised mostly of Bacteroides graminisolvens and Parabacteroides chartae. The digestate treatment partially removed amorphous components of the pulp fiber thereby decreasing micro/nanofiber diameters and enhancing the crystalline content. The treatment also increased the size of the crystalline cellulose. The morphology and crystallinity results demonstrate the effectiveness of digestate treatments coupled with high-shear mixing as a procedure for the production of micro/nanofibers.