Production of cellulose nanofibers using phenolic enhanced surface oxidation

• Published in: Carbohydrate polymers 2017-10, Vol.174, p.120-127
• Main Authors: Beheshti Tabar, Iman, Zhang, Ximing, Youngblood, Jeffrey P., Mosier, Nathan S.
• Format: Article
• Language: English
• Subjects: Carboxyl groups; Cellulose nanofibers; Phenolics; Surface oxidation
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.06.058

•Use of a wood by-product with ozone offers a novel pathway to cellulose nanofibers.•Syringic acid as lignin model compound enhanced ozone cellulose surface oxidation.•Syringic acid, a byproduct of wood pulping, is a biorenewable oxidation enhancer.•Enzyme treatment increased cellulose surface reactivity toward oxidation.•New cellulose nanofiber pathway could have significant process advantages. In this study we demonstrate that lignin monomers formed as byproducts of pulping or bioprocessing of lignocellulosic biomass is an effective enhancer to oxidize cellulose surfaces with ozone for the production of cellulose nanofibers (CNF). Never dried softwood pulp with minimum mercerization was enzymatically treated leading to a homogeneous pulp slurry with a higher reactivity. The slurry was oxidized by ozone gas in the presence of syringic acid, a lignin degradation model compound, as an oxidation enhancer at room temperature and pH 11. Transmission electron microscopy (TEM) observations showed that stable CNF bundles with 3–10nm widths and lengths >100nm were obtained after ultrasonication of the oxidized product in water. Extensive characterization of the new CNF films revealed the nanofibers had carboxylate content similar to conventional carboxylated cellulose prepared by TEMPO-mediated oxidation. Based on NMR spectra, chemical conversion of the syringic acid during oxidation is proposed.