Production of Cellulose Nanofibers from Olive Tree Harvest—A Residue with Wide Applications

Abstract

With the aim of identifying new sources to produce cellulose nanofibers, olive tree pruning biomass (OTPB) was proposed for valorization as a sustainable source of cellulose. OTPB was subjected to a soda pulping process for cellulose purification and to facilitate the delamination of the fiber in the nanofibrillation process. Unbleached and bleached pulp were used to study the effect of lignin in the production of cellulose nanofibers through different pretreatments (mechanical and TEMPO-mediated oxidation). High-pressure homogenization was used as the nanofibrillation treatment. It was observed that for mechanical pretreatment, the presence of lignin in the fiber produces a greater fibrillation, resulting in a smaller width than that achieved with bleached fiber. In the case of TEMPO-mediated oxidation, the cellulose nanofiber characteristics show that the presence of lignin has an adverse effect on fiber oxidation, resulting in lower nanofibrillation. It was observed that the crystallinity of the nanofibers is lower than that of the original fiber, especially for unbleached nanofibers. The residual lignin content resulted in a greater thermal stability of the cellulose nanofibers, especially for those obtained by TEMPO-mediated oxidation. The characteristics of the cellulose nanofibers obtained in this work identify a gateway to many possibilities for reinforcement agents in paper suspension and polymeric matrices.

Stiffening Potential of Lignocellulosic Fibers in Fully Biobased Composites: The Case of Abaca Strands, Spruce TMP Fibers, Recycled Fibers from ONP, and Barley TMP Fibers

“…Natural fibers for use in plastic-based composites can be obtained from different lignocellulosic resources, being (i) annual plants [ 6 , 7 , 8 , 9 , 10 ], (ii) wood [ 11 , 12 , 13 , 14 , 15 ], (iii) recycled products [ 16 , 17 , 18 , 19 , 20 ], and (iv) agroforestry waste [ 21 , 22 , 23 , 24 ]. The extraction of these natural fibers from the raw biomass may be achieved by different procedures, which mainly involve mechanical, semi-chemical, and chemical procedures [ 25 , 26 , 27 ]. Hence, depending on the raw lignocellulosic source and the fiber extraction method, the chemical and morphological composition of the fiber will vary accordingly, also affecting the final properties of the composite material.…”

Valorisation of Olea europaea L. Olive Leaves through the Evaluation of Their Extracts: Antioxidant and Antimicrobial Activity

“…In Andalusia, 416,000 t of olive leaves were collected in the last season, being primarily destined to animal feed despite their bitter taste, which, in general, limits their use [ 3 ]. Due to the large amount of leaf waste generated in the production of olive oil, a system embracing a recycling approach is proposed, based on a circular bioeconomy model, in which the return of waste and by-products into the production cycle reduces the generation of residues [ 4 ]. Under this system, the management and recovery of this waste is carried out with the aim of both producing new materials and recovering active substances.…”

Cellulose Nanofibers from Olive Tree Pruning as Food Packaging Additive of a Biodegradable Film

“…Traditionally, this waste has no industrial applications and is usually burned or used as soil fertilizer. A better utilization of these products can be made, adding value, and reintroducing them into the economic cycle [ 23 , 24 ].…”