Solvent-free green preparation of reinforced FEP/SiO2-SSM composite membrane for high temperature waste oil treatment

Traditional separation membrane preparation techniques require the use of a large amount of organic solvents, which can easily lead to secondary pollution. Moreover, most separation membrane materials have limited research in the field of high-temperature waste oil treatment. Stainless steel mesh (SSM) is favored for its high-temperature resistance and physical and chemical stability, while polyperfluoroethylene propylene (FEP) is chosen for its low surface energy and corrosion resistance. This study presents the development of a hydrophobic composite membrane that combines rigidity and flexibility based on a coating-sintering method. The membrane is composed of FEP as the membrane-forming polymer, polyvinyl alcohol (PVA) as the pore-forming agent, and SSM serving as the matrix reinforcement. Additionally, silicon dioxide (SiO₂) particles, known for their high-temperature resistance and minimal shrinkage, are incorporated to create a micro-nanostructured surface, enhancing the membrane's ability to efficiently permeate oil. The results showed that the composite membrane exhibited a uniform membrane pore structure and good high-temperature oil permeation flux when the addition of SiO₂ was 2 wt%, and the separation efficiencies of silicone oil suspension and kerosene-in-water emulsion could reach up to 99.76 % and 98.6 % respectively, which demonstrated excellent retention performance. After five cycles of experiments, the recovery efficiency of kerosene flux and high-temperature lubricating oil flux stabilized at over 84.1 % and 83.75 % respectively. Therefore, the composite membrane shows promise for advancement in the recovery of high-temperature oils and in the separation of emulsions.