Self-cleaning nanofiber membranes for sustainable dual removal of oils and dyes from wastewater

Traditional oil/water emulsion separation membranes often fail to maintain long-term stability and regeneration due to inadequate fouling resistance and low self-cleaning efficiency in practical applications. This study developed a superhydrophilic nanofiber membrane with a micro/nanolayer architecture and piezoelectric photocatalytic properties by combining polyacrylonitrile (PAN), polyethyleneimine (PEI), and silver-modified barium titanate (Ag-DBT). This membrane can effectively separate oils and dyes from complex emulsions, demonstrating high water permeation flux of 2492 L·m −2 ·h −1 , along with exceptional oil separation efficiency (~99 %) and dye adsorption (~99 %). In addition, the PAN-PEI/Ag-DBT membrane demonstrated an ultra-high degradation efficiency of approximately 99 % for methyl blue (MB) within 90 min. Notably, owing to the piezoelectric photocatalytic properties of Ag-DBT, the PAN-PEI/Ag-DBT nanofiber membrane maintained exceptional self-cleaning performance even after high contamination. To assess the self-cleaning performance and cycling stability of the PAN-PEI/Ag-DBT membrane, we conducted cyclic recovery experiments across three conditions: oil-in-water emulsions, dye-water solutions, and oil-in-dye-water emulsions. In the first three self-cleaning cycles, the self-cleaning membrane demonstrated water flux recovery rates that exceeded 90 % and irreversible fouling rates that were below 10 %. This research provides new insights into the advancement of multifunctional self-cleaning membranes.