Wood cellulose nanofibrils prepared by TEMPO electro-mediated oxidation

Abstract

A softwood bleached kraft pulp (SBKP) was subjected to electro-mediated oxidation in water with TEMPO or 4-acetamido-TEMPO without any chlorine-containing oxidant. Solid recovery ratios of water-insoluble fractions of the oxidized SBKPs were more than 80%, and C6-carboxylate contents increased up to approximately 1 mmol g -1 after oxidation for 48 h. Significant amounts of C6-aldehyde groups (0.17-0.38 mmol g -1 ) were also formed in the oxidized SBKPs. The degree of polymerization decreased from 2,200 to 520 and 1,400 by the oxidation for 48 h with TEMPO at pH 10 and 4-acetamido-TEMPO at pH 6.8, respectively. The original cellulose I crystal structure and crystallinity of SBKP were maintained after the oxidation, indicating that all C6-oxidized groups were selectively formed on crystalline cellulose microfibril surfaces. The oxidized SBKPs with carboxylate contents of more than 0.9 mmol g -1 were convertible to individual cellulose nanofibrils in yields of more than 80% by disintegration in water.

Electrochemical Alcohol Oxidation Mediated by TEMPO-like Nitroxyl Radicals

“…Similar results were extended shortly afterwards to wood cellulose, affording excellent cellulose nanofibrils . Remarkably, in the case of wood cellulose, along with 1 mmol g −1 C6‐carboxylate groups, significant amounts of C6‐aldehyde groups (0.17–0.38 mmol g −1 ) are also formed after oxidation for 48 h with TEMPO at pH 10 and with 4‐acetamido‐TEMPO at pH 6.8.…”

“… Cellulose TEM images of oxidized and then water‐dispersed cellulose fibrils electrochemically oxidized with 4‐acetamido‐TEMPO at pH 6.8 for 6, 12, 24 and 48 h. Reproduced with permission from Ref. . Copyright (2011) Springer.…”

Effect of Pulp Concentration during Cellulase Pretreatment on Microfibrillated Cellulose and Its Film Properties

“…PFI grinding refined the pulp to a beating degree of approximately 85 °SR. Eventually, pulp with a concentration of 1 wt% was diluted by distilled water and then passed 10 times through a homogenization machine (Shanghai Light Industrial Equipment Co., Ltd, Model GJJ, China) (Isogai et al 2011;Liu et al 2014).…”

Chemical Modification of Cellulose Isolated from Underutilized Hibiscus sabdariffa via Surface Grafting: A Potential Bio-based Resource for Industrial Application

“…A cellulose-based product or feedstock can serve as a green resource with numerous benefits. The performance of cellulose may be improved by simple chemical modification, although different modification has been reported in the past; [8][9][10] but there is the need for a cheap, green, and simple process of modification using underutilized plants as sources of cellulose.…”