Electrospun membrane fabrication from waste PET plastic bottles and hydrophilic spray coating modification for efficient oil/water separation

Long-term discharge of industrial oily wastewater and frequent oil spills create an urgent demand for high-performance oil-water separation membranes. Conventional membranes are limited by high cost, poor stability, and a trade-off between separation efficiency and recyclability. Meanwhile, massive waste PET plastics trigger severe environmental pollution and resource loss. Herein, waste PET bottles are recycled to fabricate porous electrospun nanofiber substrates, followed by spray-coating nano-silica/epoxy hydrophilic composite layers to obtain superhydrophilic/underwater superoleophobic PET-SE membranes. Combined FTIR, XPS, SEM and EDS characterizations verify successful epoxy grafting and uniform SiO₂ immobilization, with abundant hydrophilic amino, amide and siloxane groups enriched on fiber surfaces. Mechanical tests show the tensile stress rises from 0.78 MPa to 2.3 MPa after modification. The optimized PET-SE3 achieves an ultrahigh water flux of 12756.91 L·m⁻²·h⁻¹ . Its separation efficiency exceeds 98% for six types of immiscible oil-water mixtures, and oil rejection surpasses 90% for corresponding oil-in-water emulsions. After 30 separation cycles, oil rejection remains above 98%, and the membrane exhibits excellent chemical and structural stability. This work realizes resource recovery of waste PET. The PET-SE membrane integrates superior separation performance, robust reusability and scalable eco-friendly preparation, presenting a promising candidate for practical oily wastewater treatment.