Bio-inspired stearic acid functionalized polylactic acid nanofibers with nanodome architecture for enhanced oil–water separation

Growing environmental risks from oil spills and pressing demand for sustainable oil–water separation solutions underscore an urgent need for eco-friendly, efficient, and cost-effective sorbent materials. In this study, we developed superhydrophobic nanofibers for rapid and efficient oil–water separation through surface modification with stearic acid. Polylactic acid (PLA) pellets were covalently grafted with stearic acid to introduce long-chain alkyl groups by Steglich-like esterification, followed by air-spray nebulization of the surface functionalized PLA to fabricate extremely light-weight nanofibrous sorbents with enhanced properties. Stearic acid modification significantly enhanced the hydrophobicity, surface roughness, and oleophilicity of the PLA nanofibers, resulting in superior oil sorption performance. Morphological and structural analyses (scanning electron microscopy, atomic force microscopy, and Brunauer–Emmett–Teller) confirmed the formation of nanodome-like structures on the surface of the nanofibers, that contributed to strong water repellency. The engineered nanofibers exhibited remarkable oil adsorption performance across various petroleum products and edible oil, including both heavy and light oils. Diesel uptake capacity reached 65 g g⁻¹, far surpassing that of unmodified PLA nanofibers (14.3 g g⁻¹). Wettability studies revealed a clear transition from hydrophobic (130° ± 2°) to superhydrophobic (151° ± 2°) phase upon surface modification. The PLA-SA–grafted nanofibers maintained robust oil sorption performance across a broad pH range (3–11), demonstrating excellent stability under varying environmental conditions. This surface modification strategy presents a promising approach for developing biodegradable, high-performance nanofibrous sorbents with strong potential for practical oil–water separation applications.