Reducing the Amount of Catalyst in TEMPO-Oxidized Cellulose Nanofibers: Effect on Properties and Cost.

Albert Serra,Helena Oliver-Ortega,Pere Mutjé,Marc Delgado-Aguilar,Israel González,Quim Tarrès

doi:10.3390/polym9110557

Abstract

Cellulose nanofibers (CNF) are interesting biopolymers that find numerous applications in different scientific and technological fields. However, manufacturing costs are still one of the main drawbacks for the industrial production of highly fibrillated, transparent CNF suspensions. In the present study, cellulose nanofibers were produced from bleached eucalyptus pulp via TEMPO-mediated oxidation with varying amounts of NaClO and passed through a high-pressure homogenizer. The CNFs were chemically and physically characterized; cellulose nanopapers were also produced to study tensile properties. Production costs were also calculated. Results indicated that CNF properties are strongly dependent on the carboxyl content. Manufacturing costs showed that chemicals, in particular TEMPO catalyst, represent a large part of the final cost of CNFs. In order to solve this problem, a set of samples were prepared where the amount of TEMPO was gradually reduced. Characterization of samples prepared in this way showed that not only were the costs reduced, but also that the final properties of the CNFs were not significantly affected when the amount of TEMPO was reduced to half.

Highlights

The interest in cellulose nanofibers (CNFs) for scientific and technological applications has grown progressively during the last few years
The fact that cellulose can be obtained from a variety of sustainable raw materials and the possibility of performing chemical modification on fibers, make it possible to modify the properties of CNF depending on the requirements and applications
The first attempts to produce CNF came from experiments where wood cellulose fiber suspensions were forced to pass through high pressure homogenizers

Summary

Introduction

The interest in cellulose nanofibers (CNFs) for scientific and technological applications has grown progressively during the last few years. Properties such as biodegradability, low density, good tensile strength and rigidity, biocompatibility and high availability make CNFs a target for researchers seeking versatile, novel biomaterials. In order to effectively obtain nano-sized cellulose fibers it became necessary to pass the fibrous suspensions through the homogenizer many times, which resulted in large amounts of energy being applied. This heavily elevates production costs, making cellulose nanofibers impractical to be manufactured on an industrial scale [14]. Clogging of the equipment was identified as a major problem when producing cellulose

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