Biomass derived self-regenerative multifunctional superhydrophobic film for oil-water remediation and drag-reduction...

Wheat (Triticum aestivum) is vital for global food security, providing a basic nutritional source for billions. The wheat straw (WS), a byproduct, is barely valorized and often discarded or burned, causing environmental and health hazards. This study repurposes underutilized WS to develop an economical, non-fluorinated bulk superhydrophobic film using a spray-casting approach. WS fibers were initially cleaned, dried, and ball-milled into particles (WSP). One portion of WSP was directly incorporated into the spray casting process, while the other was converted into nano SiO₂ particles (SP), which is used for imparting nanoscale roughness essential for superhydrophobicity. The optimized composite film from both particles (WSP and SP) exhibited excellent superhydrophobicity (>150°), ultra-low water adhesion (∼10 μN), and sustainability features such as self-healing and self-regenerative capabilities under extreme working conditions. Additionally, these films demonstrated superior underwater superhydrophobicity, achieved 90 % drag-reduction, and had excellent selective oil absorption capability. Altogether make them a promising solution for autonomous oil recovery systems in marine environments while saving energy due to anti-drag characteristics. These fluorine-free, flexible films upcycle the on-farm wheat straw waste into a high-value multifunctional films, offering farmers a sustainable outlet for their residue and a new source of rural income.