Oxidative treatments for cellulose nanofibers production: a comparative study between TEMPO-mediated and ammonium persulfate oxidation

In the recent years, several methods for producing cellulose nanofibers (CNF) have appeared. Depending on the type of treatment and its conditions, the source of cellulose and the fibrillation method, different properties and characteristics can be obtained. TEMPO-mediated oxidation has been extensively used for CNF production and it is considered as one of the most suitable treatments to obtain high-performance CNF with superior properties and reduced size. However, the recovery of the catalyst and its cost is still a challenge. In the recent years, the oxidation by means of ammonium persulfate (APS) has appeared as a potential alternative, although it is commonly used for cellulose nanocrystals production. The present work aims at comparing the properties of CNF obtained by means of TEMPO-mediated oxidation (TOCNF) and ammonium persulfate oxidation (APSCNF). For this, a similar oxidation degree was selected, adjusting the treatment conditions of both oxidative methods. The obtained results exhibited that similar properties can be obtained with different production costs associated. In addition, the APSCNF exhibited a significantly lower degree of polymerization and slightly higher transmittance, indicating the presence of higher crystalline regions. Finally, both types of CNF were tested over a recycled paper substrate, revealing that both APSCNF and TOCNF significantly increased the mechanical properties of paper with low effect on pulp drainability, representing a great advantage for the paper industry.