Theoretical and Experimental Investigation of the Mechanisms of Superhydrophobic Surface Functionality in Electrospun Polymer Nanofibre Membranes for Oil-Water Separation in Niger Delta Remediation

Oil-water separation in Niger Delta remediation contexts demands materials with extreme water repellence and selective oil absorption capability, achievable through superhydrophobic nanofibre membrane architectures. This research investigates both theoretically and experimentally the mechanisms of superhydrophobic surface functionality in electrospun polymer nanofibre membranes, establishing structure-property relationships for optimised oil-water separation performance in South South Nigerian remediation applications. The theoretical framework applies Cassie-Baxter and Wenzel wetting state models to explain contact angle behaviour as a function of nanofibre diameter distribution, surface roughness at multiple length scales, and hydrophobic coating chemistry. Polyvinylidene fluoride and polystyrene nanofibre membranes were produced by electrospinning at systematically varied processing conditions to generate a library of nanofibre morphologies. Surface hydrophobisation was achieved by deposited fluorosilane and stearic acid coatings. Comprehensive characterisation included contact angle goniometry, scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Oil-water separation efficiency using crude oil from a Niger Delta field and diesel was assessed at oil phase fractions of 10, 30, and 50 percent. Anti-fouling performance was characterised through cyclic separation tests. Results demonstrate that Cassie-Baxter wetting state with contact angles above 155 degrees was achieved for nanofibre mats with mean diameter below 300 nm and fluorosilane surface treatment. Separation efficiency exceeded 99.2 percent for all oil/water ratios tested under gravity-driven conditions. Flux through the membrane reached 4800 L/m2/h, substantially higher than microporous membrane alternatives. Anti-fouling stability through 30 separation cycles showed only 8 percent flux decline, confirming robust separation performance. The research provides a mechanistically grounded design methodology for superhydrophobic nanofibre membranes for scalable oil-water separation technologies in Niger Delta remediation programmes. Keywords: superhydrophobic, electrospun nanofibre, oil-water separation, Niger Delta, Cassie-Baxter model