Transparent Superhydrophilic Coating with Robust and Persistent Anti-Oil-Fouling Properties for Efficient Long-Term Oil/Water Emulsion Separation

Abstract

Porous membranes with superhydrophilicity and underwater superoleophobicity have attracted considerable attention for efficient oil/water emulsion separation. However, such membranes fail to remediate severe oil contamination in long-term applications and exhibit a serious water flux decline. Herein, a universal combination strategy integrating the high coverage of a mussel-inspired sticky interlayer and a double rigid cellulose nanofiber-amorphous calcium carbonate (CNF-ACC) composite outer layer is proposed to prepare a superhydrophilic coating surface with superior anti-oil-fouling properties on diverse substrates. The introduction of the mussel-inspired interlayer not only provides a stable and complete coverage interface but also offers an anchor to fix the outstanding hydration of the outer CNF-ACC composite layer. The high-coverage and double rigid superior hydration CNF-ACC layer provides excellent anti-oil-fouling characteristics, irrespective of the type of oil, under various conditions, such as water-prewetted or oil-fouled environments. Owing to its superior anti-oil-fouling property, the coating-modified membrane shows efficient and long-term separation of diverse oil/water emulsions without significant flux decline and with a flux recovery ratio of nearly 100%. In addition, this coating exhibits antifogging and high transparency, which may show promising applications in diverse optical devices.