Phoenix dactylifera lignocellulosic biomass as precursor for nanostructure fabrication using integrated process.

Agricultural residue is an inevitable byproduct of agricultural activities. Valorization of agricultural residue is necessary to avoid wastage. In this study, we developed an integrated process for fabricating various nanostructures using Phoenix dactylifera (PD) lignocellulosic biomass as a sustainable bioprecursor. The PD biomass was treated using a hydrothermal method at 180 °C to derive the liquid fraction containing carbon nanodots (CDs). After pretreatment, the biomass was treated with an alkali solution to disassociate the lignin and cellulose. The extracted lignin was dissolved in tetrahydrofuran and subjected to a dialysis process. During the dialysis process, the lignin transformed into lignin nanoparticles (LNPs). The cellulose-containing fraction was transformed into cellulose nanostructures (CNs) via a sequential process (bleaching and acid hydrolysis). The structural properties, morphological features, crystallinity, and thermal stability of the fabricated CDs, LNPs, and CNs were analyzed. The synthesized CDs and LNPs had a spherical shape with different sizes: 2-10 nm (CDs) and 100-900 nm (LNPs). The CNs exhibited a fibrillated architecture and were 5-10 nm wide and 400-700 nm long. A biocompatibility analysis indicated that the synthesized nanostructures are nontoxic to human mesenchymal stem cells at concentrations of up to 200 μg/mL. This process is suitable for synthesizing nanostructures using different types of plant lignocellulosic biomass.