Effect of the chemical and structural characteristics of pulps of Eucalyptus and Pinus on the deconstruction of the cell wall during the production of cellulose nanofibrils

Impact of the Enzyme Charge on the Production and Morphological Features of Cellulose Nanofibrils

“…Table 1 shows the percentage distribution of the solid residue and the fraction of solubilized carbohydrates from the eucalyptus pulp after the enzymatic pretreatments. As expected, the enzyme complex solubilized part of the hemicelluloses and cellulose of the raw material, whose initial chemical composition was: 77.7 ± 0.5% of cellulose, 21.1 ± 0.5% of hemicellulose and, <1% of lignin, which coincided with what was reported by other authors for this type of pulp [15,23,30]. The first enzymatic treatment (P E ), which was identical for the 5 CNFs, solubilized a lower amount of cellulose and xylan than the pulps with double enzymatic treatment, hence the carbohydrate yield in the solid fraction was higher.…”

“…Pulp was rehydrated, filtered, and pelleted according to ISO 5263. The chemical characterization of cellulosic fibers was performed through acid hydrolysis based on the method described by Mendonça et al [25] and Andrade et al [23].…”

“…On the one hand, Andrade et al [23] determined that, for CNFs produced from the same raw material and with the same enzymatic-mechanical treatment, the aspect ratio was 330. On the other hand, in their study, Albornoz-Palma et al [22] produced CNFs with an aspect ratio of 303, from the same raw material and mechanical treatment, but with a different type and charge of enzyme.…”

“…The DP of cellulose decreases between 72 and 81% for the CNFs produced, with DP values between 278 and 447, which coincides with those reported by various authors who produced CNFs with similar enzymatic and mechanical pretreatments. For example, in their study, Albornoz-Palma et al [22] used cellulase enzymes (1.2 wt%) to produce CNFs with a degree of polymerization of 228; Tarres et al [14] used endoglucanase enzyme (0.032%) to produce CNFs with a DP of 309, and Andrade et al [23] used the same raw material and enzyme cocktail, with a charge of 0.1% of the enzyme in two treatments (0.05% each) producing CNFs with a DP of 303, causing a decrease of 75% with respect to the initial raw material. Additionally, Qing et al [1] used a different mechanical treatment (SuperMassCollider-Microfluidization 15 passes at 1500 bar) and produced CNFs with a DP of 280 when dosing 3 FPU of enzyme/g fiber.…”

“…The effect of cellulase enzymes on the degree of the polymerization of cellulose and the mechanical fibrillation process is widely reported [1,12,[20][21][22][23]. However, the available information does not allow specific relationships to be established between the enzymaticmechanical treatment applied, the degree of polymerization, and the characteristics of the CNFs.…”