Development of a biomimetic polyvinylidene fluoride membrane with a lotus leaf-inspired structure for enhanced oil-water separation

Abstract

Efficient oil-water separation is crucial for environmental protection and industrial wastewater management; however, existing separation membranes often lack durability and suffer efficiency loss over multiple cycles. This study introduces a bio-inspired polyvinylidene fluoride (PVDF) membrane with a hierarchical lotus leaf-like surface, designed to overcome these limitations by enhancing separation efficiency, operational stability, and reusability. A polyvinylidene fluoride/polyvinylpyrrolidone (PVDF/PVP) composite membrane was fabricated as a support, onto which PVDF/silicon dioxide (SiO₂) micro-nanoparticles were electrostatically sprayed to create a micro-nano papillae structure. This was followed by in-situ polymerization of dopamine (DA), forming a polydopamine (PDA) coating that enhances hydrophilicity and underwater oleophobicity. Optimization experiments identified a 20-minute spraying duration as ideal, achieving uniform micro-nanoparticle distribution and maximizing water permeability, with a pure water flux of 14,321 L·m⁻²·h⁻¹. The PDA/M-P/S-20 membrane demonstrated over 99.9 % separation efficiency for various oil-water mixtures and maintained stable performance across 15 cycles with only a 2.1 % flux loss, a significant improvement over conventional membranes, which often experience rapid fouling and efficiency decline. Additionally, the membrane exhibited underwater oil contact angles above 140°, confirming its excellent underwater oleophobicity and self-cleaning capabilities. This research highlights the critical role of biomimetic design and precise structural control in addressing the durability and reusability limitations of existing separation technologies, offering a scalable, sustainable solution for industrial applications in petrochemical processing and wastewater treatment.