High-Lignin-Containing Cellulose Nanofibrils from Date Palm Waste Produced by Hydrothermal Treatment in the Presence of Maleic Acid

Lignin-containing cellulose nanofibrils (LCNFs) haveattractedgreat attention because the presence of lignin brought additionalmerits to cellulose nanofibrils including hydrophobicity, ultraviolet(UV)-shielding capacity, and reduced water sensitivity. In the presentwork, LCNFs with lignin content up to 21 wt % were prepared with ahigh yield exceeding 70 wt %, from neat date palm waste, by a hydrothermaltreatment (HTT) at 120-150 degrees C in the presence of 20-30wt % maleic acid, followed by high-pressure homogenization. The chemicalcomposition, degree of polymerization, morphology, and colloidal andrheological properties of the LCNFs were investigated to understandhow the HTT in the presence of MA affected the properties of the resultingLCNFs. Nanopapers prepared from the LCNF suspensions exhibited mechanicalproperties lower than those from lignin-free CNF-based nanopapers,yet with decreased hydrophilicity. A mechanism explaining how theHTT in the presence of MA facilitated the disintegration of the biomassinto nanoscale material was proposed. Overall, the present work demonstrateda feasible and scalable approach for the sustainable production ofLCNF suspensions from neat agricultural residues, with a high yieldand a high lignin content, without any need to perform a preliminarypartial delignification.