Electrodeposition-Based Janus Membrane for Unidirectional Transportation and Oil–Water Separation

The increasing prevalence of oily wastewater from industrial processes and recurring oil spill incidents poses severe environmental and ecological challenges. Traditional oil-water separation methods often involve complex, multistep fabrication processes, resulting in scalability, cost, and environmental sustainability limitations along with decrease in the separation performance during the repeated and continuous filtration cycles. This study introduces a Janus membrane with opposite wettability characteristics on its two faces fabricated through a dual-step process combining selective electrodeposition and chemical vapor deposition (CVD). The hydrophilic, underwater superoleophobic face is created via electrodeposition and selectively applied to a conductive porous nickel foam while masking the opposite side. Subsequently, the masked face undergoes CVD to achieve hydrophobicity. This innovative fabrication approach provides precise control over surface properties without requiring extensive post-processing or hazardous chemicals. The Janus membrane demonstrates efficient directional liquid transport, with the hydrophilic face enabling high water flux and the hydrophobic face preventing fouling and selectively transporting oil. The membrane achieves a separation efficiency of 99.4% and a flux of 29,832 L m^-2 h^-1, maintaining durability and performance even under harsh conditions. Furthermore, the membrane exhibits superior long-term performance with a minimal decline in separation efficiency over repeated cycles and demonstrates excellent chemical stability, making it suitable for use in challenging environments. This scalable and eco-friendly method offers a transformative solution to pressing environmental challenges, including oily wastewater treatment and oil spill remediation, advancing the field of oil-water separation.