Industrial oily wastewater discharge and oil spills pose significant environmental and economic challenges. Effective technologies for managing these pollutants are crucial. Membrane filtration offers a promising approach due to its convenience, low cost, and environmental friendliness. However, current membranes often suffer from poor oil-water separation efficiency, insufficient bactericidal properties, and low durability in harsh real-world conditions. Oily wastewater contains diverse components, including various oils, lubricants, metal residues, and pathogens. Existing membranes often lack the robustness to withstand damage from solid particles and prolonged exposure to harsh conditions. While superhydrophobic/superoleophobic coatings have shown promise, their long-term durability and antimicrobial properties remain inadequate. Electrospinning, a versatile technique for creating nanofibrous membranes, has been explored; however, the resulting membranes frequently lack sufficient mechanical strength and durability. Antimicrobial materials are often employed, but concerns exist regarding side effects like super-bacteria formation. This study aims to develop a highly durable and sustainable porous fiber for efficient oil-water separation and bacteria penetration blocking by utilizing an in-and-out fluorinated polyurethane (F-PU) coating on activated carbon fabric (ACF). The F-PU coating is designed to enhance hydrophobicity, impart scratch resistance, and provide effective bacterial blocking.

Numerous studies have explored membrane filtration for oil-water separation, often focusing on modifying membrane surface wettability using superhydrophobic/superoleophobic coatings to enhance separation performance. However, these membranes often lack sufficient durability and antimicrobial properties for real-world applications. Electrospun nanofibrous membranes, while offering high porosity and surface area, suffer from poor mechanical strength and long-term durability. The incorporation of antimicrobial agents into membranes has been investigated, but concerns regarding side effects and the development of resistant bacteria persist. The challenge lies in creating a membrane that effectively separates oil and water, resists damage, and inhibits bacterial growth, all while maintaining long-term functionality.

The researchers synthesized fluorinated polyurethane (F-PU) coating materials using perfluoroalkyl alcohol (1H,1H,2H,2H-Tridecafluoro-1-n-octanol, TDFO), ethylene glycol (EG), and isophorone diisocyanate (IPDI) via a two-step urethane reaction. The reaction involved first creating an IPDI-EG-IPDI prepolymer, followed by reaction with TDFO. The successful synthesis was confirmed using Fourier transform-infrared (FT-IR) spectroscopy. Activated carbon fabric (ACF) was pre-treated to enhance reactivity by reducing ketone groups to hydroxyl groups using sodium borohydride. The treated ACF was then immersed in the F-PU solution, and the in-and-out coating was achieved through urethane reactions between the ACF's hydroxyl groups and the F-PU's isocyanate groups at 80°C for 72 hours. The resulting fabric was characterized using various techniques: X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FE-SEM/EDS) to analyze surface morphology and elemental composition; Brunauer-Emmett-Teller (BET) analysis for nitrogen adsorption; contact angle goniometry to assess wettability; and universal testing machine (UTM) measurements to determine tensile strength. Oil-water separation performance was evaluated using a customized system, measuring separation efficiency and flux for various oil-water mixtures. The durability of the coating was assessed using a scratch test, and the bacterial penetration blocking ability was evaluated using a transwell system with *Staphylococcus aureus* and *Escherichia coli*. Cell viability tests were also performed to confirm the biocompatibility of the coating.

The in-and-out F-PU coated ACF exhibited a water contact angle of 133.3 ± 2.7°, indicating highly hydrophobic properties. FE-SEM/EDS and XPS analysis confirmed the presence of fluorine and nitrogen elements from the F-PU coating both inside and outside the ACF fibers. The oil-water separation efficiency for various oil-water mixtures was consistently above 95%, with a high flux rate exceeding 2 × 10⁴ L m⁻² h⁻¹. The fabric showed remarkable reusability, maintaining separation efficiency above 95% after 20 consecutive cycles. The scratch test demonstrated the high durability of the coating, with only a slight change in water contact angle even after 50 cycles. The tensile strength of the coated ACF (575.2 MPa) was significantly higher than that of the bare ACF (322.41 MPa), indicating improved mechanical properties. The F-PU coated ACF effectively blocked bacterial penetration by ≥99% for both *S. aureus* and *E. coli*, and this bacterial blocking performance persisted even after the scratch tests. The C2C12 cell viability test confirmed no significant toxicity from the coating materials.

The results demonstrate the successful fabrication of a highly durable and sustainable oil-water separation membrane with excellent antibacterial properties. The in-and-out F-PU coating strategy effectively modifies the ACF's surface wettability, providing both hydrophobicity and oleophilicity, leading to efficient oil-water separation. The high durability of the coating, as shown by the scratch test, addresses a major limitation of existing membranes. The effective bacterial penetration blocking, even after substantial wear, suggests a potential solution for preventing bacterial contamination in oily wastewater treatment. The superior mechanical strength of the coated ACF compared to the bare ACF further underscores its suitability for practical applications. The findings contribute significantly to the development of advanced membrane filtration technologies for efficient and sustainable oily wastewater treatment.

This study successfully demonstrates a novel strategy for creating a highly durable and sustainable heterogeneous fabric for oil-water separation and bacterial elimination. The in-and-out fluorinated polyurethane coating imparts superior hydrophobicity, mechanical strength, and antibacterial properties while maintaining high separation efficiency and reusability. Future research could explore different fluorinated polymers or explore variations in the coating process to further enhance performance or expand the range of applicable oils and oily wastewater types. Investigating the long-term stability and fouling resistance under various operational conditions in real-world scenarios would also be valuable.

The current study focused on specific types of oils and bacteria. Further investigation is needed to assess the performance of the developed fabric with a wider range of oils and microorganisms found in industrial wastewater. Long-term stability testing under continuous operation and various environmental conditions is also required to fully evaluate the practical applicability of the developed material. Scaling up the fabrication process for large-scale production needs to be addressed.