Laboratory of Renewable Resources Engineering and Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN, United States.
School of Materials Engineering, Purdue University, West Lafayette, IN, United States.
Carbohydr Polym. 2017 Oct 15;174:120-127. doi: 10.1016/j.carbpol.2017.06.058. Epub 2017 Jun 16.
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.
在这项研究中，我们证明了木质素单体作为制浆或木质纤维素生物质生物加工的副产物，是一种有效的增强剂，可以用臭氧氧化纤维素表面，从而生产出纤维素纳米纤维（CNF）。从未干燥的、最小程度丝光化的软木浆进行酶处理，得到了具有更高反应性的均匀纸浆浆料。在室温下和 pH 值为 11 的条件下，以丁香酸（木质素降解模型化合物）作为氧化增强剂，通过臭氧气体对浆料进行氧化。透射电子显微镜（TEM）观察表明，在水中对氧化产物进行超声处理后，得到了具有 3-10nm 宽度和 >100nm 长度的稳定 CNF 束。对新型 CNF 薄膜的广泛表征表明，纳米纤维的羧酸盐含量与通过 TEMPO 介导氧化制备的传统羧化纤维素相似。基于 NMR 谱，提出了在氧化过程中丁香酸的化学转化。
