Energy Efficient Process for Preparing Nanocellulose Fibers

摘要

A scalable, energy efficient process for preparing cellulose nanofibers is disclosed. The process employs a depolymerizing treatment with one or both of: (a) a relatively high charge of ozone under conditions that promote the formation of free radicals to chemically depolymerize the cellulose fiber cell wall and interfiber bonds; or (b) a cellulase enzyme. Depolymerization may be estimated by pulp viscosity changes. The depolymerizing treatment is followed by or concurrent with mechanical comminution of the treated fibers, the comminution being done in any of several mechanical comminuting devices, the amount of energy savings varying depending on the type of comminuting system and the treatment conditions. Comminution may be carried out to any of several endpoint measures such as fiber length, % fines or slurry viscosity.

主权项

1. A process for forming cellulose nanofibers from a cellulosic material, comprising:
treating the cellulosic material with an aqueous slurry containing a depolymerizing agent selected from (a) ozone at a charge level of at least about 0.1 wt/wt %, based on the dry weight of the cellulosic material for generating free radicals in the slurry; (b) a cellulase enzyme at a concentration from about 0.1 to about 10 lbs/ton based on the dry weight of the cellulosic material; or (c) a combination of both (a) and (b), under conditions sufficient to cause partial depolymerization of the cellulosic material; and concurrently or subsequently comminuting the cellulosic material to liberate cellulose nanofibers; wherein the overall process achieves an energy efficiency (as defined herein) of at least about 2%.