An Oleogel‐Based Slippery Membrane via Green Solvent‐Free Strategy for Paraffin Oil/Water Separation

ABSTRACT Membranes with slippery liquid‐infused porous surfaces (SLIPS) have emerged as highly promising candidates for oil/water separation owing to high separation efficiency and anti‐fouling properties. However, the fabrication of SLIPS is complex and often involves organic solvents, posing environmental and cost concerns. This study developed an oleogel‐based slippery membrane via a green solvent‐free method. A beeswax/paraffin oil oleogel was hot‐pressed onto the surface of polypropylene (PP) membrane. The obtained PP‐OleG membrane exhibited self‐lubricating property, enabling water droplets to slide on the surface. Further infusion of paraffin oil yielded a PP‐OleG‐oil membrane with enhanced slippery property and anti‐protein adhesion. The oleogel and oil layers on the membrane surface demonstrated good stability. Both PP‐OleG and PP‐OleG‐oil membranes outperformed unmodified PP in water‐in‐oil emulsion separation. Notably, the PP‐OleG‐oil membrane protected by oleogel and oil layers prevented direct contact between contaminants and the membrane substrate, resulting in excellent anti‐fouling performance. After six cycles of filtration, the flux recovery rate reached 86%, and the separation efficiency remained above 98.5%. This oleogel‐based membrane offers a feasible approach to enhancing anti‐fouling performance in oil/water separation and also provides insights for wastewater treatment through green strategies.