The use of enzymatic pre-treatment to facilitate and reduce the energy consumption of unbleached cellulose micro/nanofibrils production from Eucalyptus spp. and Pinus spp. kraft pulps

Cellulose micro/nanofibrils have gained prominence due to their structure, which is composed of crystalline and amorphous regions, and varying extraction approaches can generate different micro/nanofibrils morphology and structure. This work aimed to evaluate the application of endoglucanase enzyme in different types of unbleached cellulosic pulps as a pre-treatment to reduce energy consumption in mechanical fibrillation. Chemical, morphological and mechanical properties of fibers and micro/nanofibrils pre-treated with and without enzyme were evaluated. Kraft pulps from Eucalyptus spp. and Pinus spp. were dispersed in water (3% w/w) and pre-treated with enzyme A, enzyme B, and without enzyme, as a control. The pulps were rinsed, resuspended (2% w/w,) and submitted to mechanical extraction by 5 cycles through a grinder, recording the energy consumption. Results indicated that the chemical and compositional characteristics of all pulps have not been affected by the enzymatic pre-treatment. There was an increase in water stability and a decrease in the mean diameter of the micro/nanofibrils. The tensile strength of the films also increased with increasing grinding cycles. All kraft pulps pre-treated with enzymes A and B showed a decrease in energy consumption, with up to 44% of energy savings in Eucalyptus spp. kraft pulp while 67% for Pinus spp. Thus, the enzymatic pre-treatment proved to be a sustainable alternative for cellulose nanofibril extraction, generating well-fibrillated micro/nanofibrils at low energy consumption.