Dip-coated TiO2-SSM with polarity-regulated underliquid superlyophobicity for high-flux separation of immiscible liquids

Efficient separation of immiscible organic liquids and oil/water mixtures remains a critical bottleneck in industrial wastewater management due to their similar polarities and surface energies. A TiO 2 -functionalised stainless steel mesh (TiO 2 -SSM) was fabricated through a scalable sol−gel dip-coating route, with TiO 2 (8.0)-SSM (8.0 vol% TBOT) as the optimal architecture. Pre-wetting with a high-polarity liquid generates a stable liquid-infused interface that can be tuned on demand, endowing the membrane with exceptional underliquid superlyophobicity toward low-polarity liquids. The membrane separates at least 23 different liquid mixture pairs, with efficiencies exceeding 99% for 20 of these pairs and a excellent flux of 34,200 L·m −2 ·h −1 for formamide/n-hexane. The membrane exhibits exceptional durability, with <2% efficiency decline after 50 cycles, intact performance after 30 abrasion tests, and robust resistance to acid, alkali, and saline environments. Notably, TiO 2 (8.0)-SSM combines robust mechanical/chemical stability with remarkable photocatalytic activity, achieving >98.3% degradation of MB solution under simulated solar irradiation. This polarity-switchable TiO 2 (8.0)-SSM enables simultaneous separation and degradation of complex wastewater containing both immiscible liquids and soluble pollutants, offering a cost-effective solution for industrial wastewater treatment and resource recovery.