Abstract
Presented herein is the integral valorization of residual biomass to film composites by their fractionation into building blocks in a multicomponent cascade isolation approach. First, pine cones were subjected to alkaline pretreatment, followed by soda pulping. Two different hemicellulose/lignin-based fractions were recovered from the extractives of these treatments, with a yield of 19%. Then, chloride- and peroxide-based bleaching methods were proposed to treat the soda-pulped samples, obtaining two cellulose-rich fractions with different chemical compositions and recovery yields (32% and 44%, respectively). From these cellulose fractions, two types of nanocelluloses with different lignin contents were obtained: cellulose nanofibrils (CNF), with a lignin content of 1%, and lignocellulose nanofibrils (LCNF), with a lignin content of 16%. The LCNF displayed lower crystallinity and viscosity but greater diameter and thermal stability than the CNF. The reinforcing capability of different amounts of both nanocelluloses on the first hemicellulose/lignin-based fraction (PCA-L) to form films was evaluated. The thermomechanical, barrier, antioxidant, moisture sorption, and mechanical properties were assessed and compared. In general, the LCNF films showed less moisture sorption and better thermomechanical and antioxidant properties than the CNF films. These results reveal LCNF to be a promising reinforcing agent for designing all-lignocellulose-based composite films to be used in food packaging applications.
Highlights
A biorefinery is an array of processes where lignocellulosic biomass may be fractionated and converted into high-valueadded products.[1−8] In Europe, the forest is the most abundant biomass feedstock, with approximately 182 million hectares of forest,[9] which generate a turnover of more than 486 billion euros
The lignocellulose nanofibrils (LCNF) films showed less moisture sorption and better thermomechanical and antioxidant properties than the cellulose nanofibrils (CNF) films. These results reveal LCNF to be a promising reinforcing agent for designing all-lignocellulose-based composite films to be used in food packaging applications
Despite retaining the same amounts of hemicelluloses during the pretreatment and soda pulping, the peak at 1720 cm−1 related to the C O vibrations in carboxylic acids and acetyl and methyl ester groups associated with the lateral branches of the hemicelluloses[4] and/ or related to the lignin−carbohydrate complex bonds of hemicelluloses[52] disappeared in the PCAA-S spectra. These results suggested that soda pulping debranched the hemicelluloses, probably via alkaline hydrolysis,[53] unlike pretreatment
Summary
A biorefinery is an array of processes where lignocellulosic biomass may be fractionated and converted into high-valueadded products.[1−8] In Europe, the forest is the most abundant biomass feedstock, with approximately 182 million hectares of forest,[9] which generate a turnover of more than 486 billion euros. Alkali pretreatment was performed as reported previously elsewhere with two objectives to open up the cell wall structures to enhance the isolation of the cellulosic fibers in the following chemical steps and to recover the extracted amorphous cell wall components from the liquid fraction (hemicelluloses and lignin) generated during this pretreatment.[4,32] First, 100 g of PC was added to 1 L of 1.5 M NaOH in an autoclave inside a glycol bath at 110 °C for 1 h. The samples were dried at 105 °C overnight and weighed again The difference between these two weights divided by the dry weight of the material was defined as the moisture uptake.[34]. Approximately 3 mg of each film was placed in a DSC crucible and heated from 30 to 350 °C at 5 °C/min under an oxygen atmosphere (250 mL/min)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
