Tannin-inspired robust fabrication of superwettability membranes for highly efficient separation of oil-in-water emulsions and immiscible oil/water mixtures

In this work, a simple and facile approach was developed to modify hydrophobic polyvinylidene fluoride (PVDF) microfiltration membrane with superhydrophilicity and excellent underwater anti-oil adhesion properties. The approach involves a rapid deposition of tannic acid (TA) on the membrane surface followed by its oxidation by sodium periodate (NaIO₄). The modified membrane not only showed a promising oil/water separation (greater than 98%) with an average water flux ranging from 38 ± 13 to 401 ± 97 L/m²-h for different kinds of surfactant-stabilized oil-in-water emulsions driven by vacuum pressure but also exhibited excellent recyclability and chemical stability. The modification method is versatile, can be applied on different types of substrate materials, such as non-woven textile and mesh, and thus has a great potential to fabricate materials at large-scale for industrial oily wastewater treatment.