Functionalized ultrafiltration membrane with complementary adsorption and self-cleaning performances by blending-to-entrapping modification

Abstract

Combining membrane ultrafiltration with adsorption and advanced oxidation processes is considered to be an efficient strategy to improve removal capacity, alleviate membrane fouling and extend membrane lifespan for the treatment of wastewater with complex organic pollutants. The removal efficiency of small-molecule pollutants is closely related to the amount of adsorption sites, which is limited with the loading level of adsorbents. Herein, we proposed a blending-to-entrapping two-step method to load spherical resorcinol-formaldehyde (RF) resins, a metal-free photocatalyst with phenolic hydroxyl groups on surface, utmost possibly in the polyethersulfone (PES) membrane for removing small-molecule cationic pollutants from aqueous solution in an ultrafiltration process. By entrapping adequate RF resin microspheres in the finger-like pores of a PES ultrafiltration (UF) membrane blended with the RF resin microspheres, the obtained membrane possessed ultrafiltration and adsorption simultaneously based on pore size exclusion effect and electrostatic attraction, respectively. Owning to the photocatalytic in situ H₂O₂ production ability of RF resins, the membrane also showed good reusability through a visible-light-induced self-cleaning process based on Fenton reaction. This work provides a feasible strategy to construct renewable adsorptive composite UF membranes for complex wastewater treatment.