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Research Project: Technologies for Improving Industrial Biorefineries that Produce Marketable Biobased Products

Location: Bioproducts Research

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

Author
item Tonoli, Gustavo - Universidade Federal De Lavras
item Holtman, Kevin
item Glenn, Gregory - Greg
item Fonseca, Alessandra - Universidade Federal De Lavras
item Wood, Delilah - De
item Williams, Tina
item Sa, Vania - Universidade Federal De Lavras
item Torres, Lennard - Universidade Federal De Lavras
item Klamczynski, Artur
item Orts, William - Bill

Submitted to: Cellulose
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2016
Publication Date: 2/20/2016
Citation: Tonoli, G., Holtman, K.M., Glenn, G.M., Fonseca, A., Wood, D.F., Williams, T.G., Sa, V., Torres, L., Klamczynski, A., Orts, W.J. 2016. Properties of cellulose micro/nanofibers obtained from eucalyptus pulp fiber treated with anaerobic digestate and high shear mixing. Cellulose. 23(2):1239-1256. doi: 10.1007/s10570-016-0890-5.

Interpretive Summary: Cellulose nanofibers are the primary structural building blocks of trees and agricultural residues such as grasses and straws that provide an abundant and renewable source of reinforcement to building materials and plastic. When isolated as discrete nanoparticles, these tiny particles are “stronger that steel” and can be used in small quantities to enhance the properties of a range of manufactured goods that can displace. The current technique for isolating cellulose nanofibers requires highly concentrated sulfuric acid which is environmentally unsuitable and costly. Enzymatic routes are also possible but require the use again of expensive chemicals (cellulases). The cost of isolation, has been addressed here by replacing high-cost enzymes with low-cost bacteria-rich digestate (liquid anaerobic digestate – AD supernatant). It would be desirable to obtain a low cost source for cellulolytic enzymes. Anaerobic digestion is utilized throughout the world for the treatment of municipal wastewaters and other industrial applications. Those waste streams, with their abundant cellulose content, are also rich in extracellular enzymes that break down cellulose. This digestate, the enzyme-rich solution derived from wastewater treatment facility was used here to break-down the complex carbohydrate cell wall structure inherent in eucalyptus into simple cellulose nanofibers. Results on eucalyptus pulp show that digestate is very effective in isolating nanofibers with industrially useful lengths and diameters. Isolated nanofibers had increased crystalline content and crystal size. Results demonstrated that digestate treatments of cellulose-rich pulps, coupled with high-shear mixing, is a low cost procedure for the production of micro/nanofibers for the plastics industry.

Technical Abstract: High production costs remain the single greatest factor limiting wider use of cellulose micro/nanofibers in the 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 results demonstrate the effectiveness of digestate treatments, coupled with high-shear mixing, as a low cost procedure for the production of micro/nanofibers.