The aim of this study was to evaluate the production potential of cellulose nanofibers from two different industrial bio-residues: wastes from the juice industry (carrot) and the beer brewing process (BSG). The mechanical separation of the cellulose nanofibers was by ultrafine grinding. X-ray diffraction (XRD) and Raman spectroscopy revealed that the materials were mechanically isolated without significantly affecting their crystallinity. The carrot residue was more easily bleached and consumed less energy during grinding, using only 0.9 kWh/kg compared to 21 kWh/kg for the BSG. The carrot residue also had a 10% higher yield than the BSG. Moreover, the dried nanofiber networks showed high mechanical properties, with an average modulus and strength of 12.9 GPa and 210 MPa, respectively, thus indicating a homogeneous nanosize distribution. The study showed that carrot residue has great potential for the industrial production of cellulose nanofibers due to its high quality, processing efficiency, and low raw material cost

Use of switchable ionic liquid (SIL) pulp offers an efficient and greener technology to produce nanofibers via ultrafine grinding. In this study, we demonstrate that SIL pulp opens up a mechanically efficient route to the nanofibrillation of wood pulp, thus providing both a low cost and chemically benign route to the production of cellulose nanofibers. The degree of fibrillation during the process was evaluated by viscosity and optical microscopy of SIL treated, bleached SIL treated and a reference pulp. Furthermore, films were prepared from the fibrillated material for characterization and tensile testing. It was observed that substantially improved mechanical properties were attained as a result of the grinding process, thus signifying nanofibrillation. Both SIL treated and bleached SIL treated pulps were fibrillated into nanofibers with fiber diameters below 15 nm thus forming networks of hydrophilic nature with an intact crystalline structure. Notably, it was found that the SIL pulp could be fibrillated more efficiently than traditional pulp since nanofibers could be produced with more than 30% less energy when compared to the reference pulp. Additionally, bleaching reduced the energy demand by further 16%. The study demonstrated that this switchable ionic liquid treatment has considerable potential in the commercial production of nanofibers due to the increased efficiency in fibrillation.

In this work, three-dimensional (3D) aerogels and hydrogels based on lignin-containing arabinoxylan (AX) and cellulose nanofibers (CNF) were prepared. The effects of the CNF and the crosslinking with citric acid (CA) of various contents (1, 3, 5 wt%) were evaluated. All the aerogels possessed highly porous (above 98%) and lightweight structures. The AX-CNF hydrogel with a CA content of 1 wt% revealed a favorable network structure with respect to the swelling ratio; nanofiber addition resulted in a five-fold increase in the degree of swelling (68 g of water per g). The compressive properties were improved when the higher CA content (5 wt%) was used; when combined with CNF, there was a seven-fold enhancement in the compressive strength. The AX-CNF hydrogels were prepared using a green and straightforward method that utilizes sustainable resources efficiently. Therefore, such natural hydrogels could find application potential, for example in the field of soft tissue engineering.