Electrostatic interaction enhanced surface segregation towards heterogeneous antifouling membrane for oil/water separation

Abstract

The surface segregation method, as an in-situ surface modification method, has been increasingly used to construct heterogeneous membrane surfaces with hydrophilic microdomains and low surface energy microdomains. Herein, we constructed a heterogeneous antifouling membrane surface using electrostatic interaction enhanced surface segregation method with negatively charged perfluorosulfonic acid (PSFA) as surface segregation agents in casting solution and positively charged polyethyleneimine (PEI) as crosslinker in coagulation bath. The electrostatic interaction between PSFA and PEI enhanced the driving force of surface segregation, intensifying surface segregation of PSFA and residence stability of PSFA and PEI to construct low surface energy microdomains and hydrophilic microdomains, respectively. The resulting membrane exhibited super-oleophobicity and super-low oil adhesion underwater. Meanwhile, the addition of PSFA facilitated the phase inversion to enhance membrane permeability. Accordingly, our membrane exhibited water permeation flux of 367 L m⁻²h⁻¹ with a water flux recovery ratio of more than 95 % when separating various surfactant-stabilized oil-in-water emulsions. Moreover, after three-cycle filtration experiment, the water flux recovery ratio maintained above 90 %. Our study may provide a facile method to construct heterogeneous antifouling membrane through controlling surface segregation process using commercially available chemicals