Cathodic-Dehalogenation-Polymerized Membranes for Efficient Oil–Water Separation

Low-cost and efficient oil–water separation of oily and emulsion wastewater from households and industries is very challenging but highly desirable. Among various methods for treating oil–water mixtures, membranes with specialized characteristics and high chemical stability have emerged as one of the most efficient and cost-effective approaches. In this research, we report a robust “bottom-up” fabrication of ultrathin, carbon-rich active films via cathodic-dehalogenation polymerization. Utilizing electrons as a “green catalyst”, the carbon–carbon coupling can be achieved under mild conditions, circumventing the metallic contamination inherent in traditional electrochemical polymerization. Two uniform and continuous films (denoted CityU-70, CityU-71) with a thickness of ca . 50 nm were constructed from 1,3,5-tris(4-bromophenyl)benzene (TBPB) and fluorinated analog, 1,3,5-trifluoro-2,4,6-tris(4-iodophenyl)benzene (TFTIPB), respectively. Structure characterization via X-ray photoelectron spectroscopy, Raman, and FTIR confirmed the formation of highly cross-linked conjugated carbonaceous networks. Both membranes exhibit >97% separation efficiencies in the separation trials for surfactant-stabilized toluene and chloroform emulsion. Remarkably, the fluorinated membrane showed a nearly 2-fold increase in permeation flux compared to its nonfluorinated counterpart. These cathodic dehalogenation membranes offer a promising approach for energy-efficient treatment of specialized industrial oily wastewater.