Electrodeposition of Large-Scale and Uniform Hydrophilic and Oleophobic Surfaces on Cylindrical Nickel Foam for Oil–Water Separation

The development of metal-based membranes featuring hydrophilic and oleophobic properties is essential for industrial oil-water separation. Most industrial filters have a cylindrical shape to match other filter components. The modification of the cylindrical surface is much more difficult than the plane surface owing to the challenges of reaction and mass transfer on the tubular surface. To address this issue, we developed an electrochemical deposition method that enables the direct construction of a hydrophilic and underwater oleophobic coating on a cylindrical nickel foam substrate through precise mass transfer control. By optimizing the mass transfer dynamics and employing a stepwise deposition strategy, we achieved uniform functionalization on an industrial-scale cylindrical membrane with a length of 25 cm. The modified membrane exhibits an underwater-oil contact angle exceeding 140° coupled with excellent durability, chemical stability, and thermal resistance. Notably, it demonstrates high separation efficiency, reducing the oil content in water from 1500 to below 200 ppm. This work presents a scalable and reliable fabrication route for high-performance cylindrical oil-water separation membranes with significant industrial potential.