Novel production of lignocellulosic nanofibrils with diverse physical and chemical characteristics from wheat straw

Abstract

As the demand for sustainable materials grows, lignocellulosic nanofibrils (LCNFs) have gained attention for their abundance, renewability, and promising properties. However, widespread commercialization remains limited by unsustainable production methods, high costs, and the narrow functionality of currently available nanocellulose, which often lacks tunable properties. Existing LCNF production techniques frequently rely on expensive feedstocks, hazardous chemicals, or lack clarity on how process modifications affect material properties, making it difficult to tailor products for specific applications. This research addresses these challenges by developing process conditions to produce LCNFs with diverse physical and chemical properties from wheat straw. Seven fractionation treatments were conducted, varying sodium hydroxide (7.5–15%), hydrogen peroxide (0–7.5%), and temperature (50–95 °C), followed by chemical composition analysis. Two treatments were oxidized with 7.5% peracetic acid, while three others were oxidized at both 7.5% and 30%. Resulting samples were cast into films and thoroughly characterized using FTIR, conductometric titrations, SEM, XRD, UV–vis spectroscopy, TGA, contact angle measurements, and tensile testing. Lowering fractionation parameters (temperature and chemical charge) increased hemicellulose and lignin retention, enhancing yields and producing LCNFs with smaller diameters, semi-crystalline structure, low UV transmittance, moderate thermal and mechanical properties, and low wettability. Residual lignin content correlated with several properties: higher lignin led to less uniform fibrils, reduced optical transparency, increased UV absorption and haze, and lower thermal mass loss. Mechanical strength and elastic modulus declined with lignin content, except in samples treated with 30% PAA. Lignin also decreased surface hydrophilicity. Additionally, charge demand and mechanical performance were dictated not only on lignin content but also on whether lignin was primarily removed during fractionation or oxidation. This work contributes to sustainable material development by offering an adaptable platform for producing LCNFs with tunable properties suitable for a wide range of end-use applications.