Title
Development of combined organosolv–TEMPO oxidation treatment for obtaining cellulose nanofibres
Authors
PABLO LIGERO, ALBERTO DE VEGA and XOAN GARCÍA

Received December 27, 2022
Published Volume 57 Issue 1-2 January-February
Keywords organosolv fractionation, performic acid delignification, alkaline TEMPO-oxidation and nanofibers of cellulose

Abstract
The aim of this work was to study and optimize the production of nano-size cellulose fibrils (NFC) by combined performic acid treatment, totally chlorine-free (TCF) bleaching and TEMPO-oxidation prior to mechanical treatment. For this purpose, a face-centered design was developed in order to optimize the independent variables governing performic treatment. Under the optimal conditions, a kappa index of 13 was achieved, which decreased to 2.2 after bleaching treatment. These low-lignin pulps were TEMPO-oxidized under different oxidizing conditions, while monitoring cellulose yield, carboxylic acid content and the degree of polymerization. The optimized conditions produced oxidized pulp with 1.4 mmol COOH/g dried nanofibre. Finally, this oxidized cellulose was subjected to high-pressure mechanical processing in order to obtain cellulose nanofibres. From the results, it can be concluded that neither the number of homogenizer passes nor the pressure affected to diameter of fibrils.