Constructing antifouling membranes through tannic acid-Fe complexation enhanced surface segregation for oil/water separation

The antifouling property of membrane is important for wastewater treatment, and surface segregation, as a bioinspired in-situ membrane construction approach enabling simultaneous modification of external membrane and internal pore surfaces, has been increasingly applied to improve membrane antifouling ability. Herein, a complexation enhanced surface segregation method is proposed to construct antifouling membrane for oil/water separation, with tannic acid (TA) as the surface segregation agent in casting solution and Fe 3+ as the crosslinking agent in coagulation bath. During the phase inversion process, TA spontaneously segregates toward the membrane surface to form the hydrophilic crosslinked separation layer through the complexation with Fe 3+ . Accordingly, the membrane exhibits the water permeance of 251 L m − 2 h − 1 bar −1 with oil rejection of over 99.7%. Moreover, hydrophilic crosslinked separation layer endows the membrane with enhanced hydrophilicity, underwater superoleophobicity and low oil adhesion as well as outstanding antifouling performance with water recovery ratio (FRR) of 95.7% for surfactant-stabilized pump oil-in-water emulsion. Meanwhile, the membrane presents effective antifouling ability in pH range of 3–11 and after prolonged aqueous immersion. Furthermore, after five-cycle filtration experiment, the membrane still maintains FRR of 90.2%. Our study provides a simple approach to constructing antifouling membrane through integrating surface segregation with complexation of TA and Fe 3+ .