Micro- and Nanofibrillated Cellulose from Annual Plant-Sourced Fibers: Comparison between Enzymatic Hydrolysis and Mechanical Refining

Abstract

The current trends in micro-/nanofibers offer a new and unmissable chance for the recovery of cellulose from non-woody crops. This work assesses a technically feasible approach for the production of micro- and nanofibrillated cellulose (MNFC) from jute, sisal and hemp, involving refining and enzymatic hydrolysis as pretreatments. Regarding the latter, only slight enhancements of nanofibrillation, transparency and specific surface area were recorded when increasing the dose of endoglucanases from 80 to 240 mg/kg. This supports the idea that highly ordered cellulose structures near the fiber wall are resistant to hydrolysis and hinder the diffusion of glucanases. Mechanical MNFC displayed the highest aspect ratio, up to 228 for hemp. Increasing the number of homogenization cycles increased the apparent viscosity in most cases, up to 0.14 Pa·s at 100 s–1 (1 wt.% consistency). A shear-thinning behavior, more marked for MNFC from jute and sisal, was evidenced in all cases. We conclude that, since both the raw material and the pretreatment play a major role, the unique characteristics of non-woody MNFC, either mechanical or enzymatically pretreated (low dose), make it worth considering for large-scale processes.

Prediction of cellulose micro/nanofiber aspect ratio and yield of nanofibrillation using machine learning techniques

“…On the other hand, the viscosity of nanocolloids is known to increase with increasing particle size (Wang et al 2011). In any case, what we often observe when increasing nanofibrillation is that the consistency index and the flow behavior index do not follow the same trends (Aguado et al 2022), and thus the apparent viscosity itself is not as adequately correlated to the yield of nanofibrillation as the consistency index from the Ostwald-De Waele equation. Aspect ratio and yield share a common mechanical basis, as the progressive breakdown of a fiber into its constituting fibrils implies the generation of thinner particles.…”

Improving the Barrier Properties of Paper to Moisture, Air, and Grease with Nanocellulose-Based Coating Suspensions

“…The resulting CNFs had an average degree of polymerization of 197, a carboxylate content of 1526–1640 COO − /g, and a transmittance at 600 nm of 85%. Characterization methods are described elsewhere [ 19 , 20 ]. The CNF suspension was stored in plastic bottles and kept at 4 °C to prevent degradation.…”

Synergies between Fibrillated Nanocellulose and Hot-Pressing of Papers Obtained from High-Yield Pulp

“…In this aspect, the in situ production and application of NC is considered. From this point of view, NC produced from fibers containing lignin, called lignocellulosic micro/nanofibers [ 55 , 56 , 57 , 58 ], and from recycled fibers, is attracting more attention since paper improvements were observed in z-strength, tensile index, tear index, burst index, E-modulus, strain at break, tensile stiffness, and air resistance [ 59 , 60 ].…”