Environmentally Friendly Multifunctional Superwettable Coatings with pH-responsiveness for High-efficiency and Controllable Separation of Multiphase Oil-water Mixtures and Organic Compounds

Advanced application of the superwettable surface with intelligent stimulus-responsive property invents a new way for designing controllable and effective oil-water separation material. Here, a smart superwettable fabric with tunable wettability has been fabricated via a low-cost and eco-friendly approach. With synergistic effect of the well-define micro/nano-hierarchical structure and pH-sensitive undecylenic acid, the as-prepared superwettable coating exhibits an excellent switchable surface wettability, which can reversibly transit between superhydrophobicity and superhydrophilicity in accordance with pH values of the contacting aqueous water. By virtue of the special wetting property, the obtained superwettable coating can be exploited to controllably and efficiently separate various oil-water mixtures, showing attractive separation efficiency (99 %) and favorable durability. Moreover, the complex oil/water/oil three-phase system also can be successfully separated with the superwettable coating as separation membrane, revealing an excellent in situ pH-responsiveness. Besides, it is worth noting that the superwettable coating is competent to selectively remove organic from oil, which has been seldom reported in previous works and providing a viable strategy for separating organic from oil. In light of the above advantages, it is believed that the functionalized smart coating with controllable tunable surface wettability will be a promising candidate for oily wastewater remediation under various harsh settings.