Valorization of Invasive <i>Typha australis</i> : Synthesis and Analysis of Lignin-Containing Cellulose Nanofibers via Combined Pretreatments

This study presents a sustainable approach for producing lignin-containing cellulose nanofibers (LCNFs) from the invasive aquatic plant Typha australis. Sequential microwave-assisted liquid hot water (LHW) and alkaline pretreatments, followed by mechanical fibrillation, allowed efficient disruption of the lignocellulosic matrix while retaining residual lignin. Comprehensive characterization using Fourier transform infrared spectroscopy, X-ray diffraction, scanning/transmission electron microscopy, thermogravimetric analysis, and MorFi analysis confirmed enhanced crystallinity, improved thermal stability, and a nanoscale fibrillar network with moderate hydrophobicity. Films produced with the resulting LCNFs exhibited tensile strengths of ∼73 MPa, Young’s modulus of ∼7.4 GPa, and excellent oxygen barrier properties [oxygen transmission rate ≈0.058 cm3/(m2·day·bar)], positioning them as promising candidates for biocomposites, packaging, coatings, and biomedical scaffolds. Life cycle assessment revealed lower water use and acidification impacts compared to those of cotton-derived nanocellulose, although energy demand and carbon emissions remain higher, highlighting optimization needs. This work demonstrates the dual benefit of valorizing an invasive species while advancing renewable nanomaterials for sustainable applications.