Enhancing oil-water separation efficiency via scalable fabrication of wear-resistant and eco-friendly superhydrophobic surfaces

Scalable and energy-efficient separation of oil–water systems is crucial for wastewater treatment, oil-spill remediation, and industrial liquid management. In this work, fluorine-free, mechanically, and thermally robust superhydrophobic membranes are fabricated based on industrial carbon cloth coated with hexamethyldisiloxane (HMDSO) in a radio-frequency (RF) atmospheric-pressure plasma using a 3D-plotter system compatible with roll-to-roll processing. SEM reveals a hierarchical micro/nano-texture, and FTIR confirms a low-surface-energy organosiloxane network; the membranes exhibit water contact angles (WCA) up to ~170° and maintain superhydrophobicity (WCA > 150°) after annealing up to 500 °C, repeated bending, water-jet exposure, and contact with various solvents. Gravity-driven separation of a VM-6 oil/water mixture (1:1 v/v) in vertical and horizontal configurations, including three consecutive cycles, as well as tests with more viscous SAE 5W-30 oil, show that the membranes efficiently separate oil and water. UV–Vis–NIR spectroscopy and optical microscopy of the aqueous phase confirm low residual oil content and high transparency, highlighting the potential of this plasma-chemical modification of carbon cloth for scalable, fluorine-free membranes and filters for oil-contaminated wastewater treatment.