A heterostructured PPy/ZnO layer assembled on a PAN nanofibrous membrane with robust visible-light-induced self-cleaning properties for highly efficient water purification with fast separation flux

Abstract

Developing superhydrophilic/underwater superoleophobic surfaces to restrict oil pollution during oil/water separation processes has been an effective approach. However, the inevitable adsorption and aggregation of organic contaminants onto the membrane surface from complex oily sewage usually causes an irreversible decrease in flux, damages the anti-oil-fouling properties and shortens the lifespan of the separation membrane. Thus, neoteric antifouling and renewable membranes are highly desired. Herein, based on stabilized PAN nanofibers and following the assembly of a heterostructured PPy/ZnO layer with hierarchical structure onto the nanofiber surfaces, we report a robust visible-light-induced self-repairable oil/water separation membrane. The SPAN–PPy/ZnO membrane displays superhydrophilicity (≈0°) and underwater superoleophobicity (>150°) toward different oils, with robust mechanical strength (Young's modulus ≈ 408 MPa) and a high underwater oil intrusion pressure (>120 kPa). Importantly, the as-prepared membrane not only exhibits ultrafast permeation flux and high separation efficiency for oil/dye/water emulsions, but it also displays robust recovery abilities (96%) from organic pollutants after 20 min of light irradiation. We anticipate that this composite membrane with outstanding separation capabilities and robust flux recovery capabilities can provide a novel method for the treatment and purification of large volumes of wastewater.