Skinned carbonaceous composite membrane with pore channels bearing an anchored surfactant layer for nanofiltration

This study finds that a layer of a specific surfactant pair appended to the nanopores in a skinned carbonaceous composite membrane (CnCM) could impact the nanofiltration (NF) capability of the membrane. A CnCM is derived from a methacrylate copolymer coating that composites with a low dose of polymer microspheres. The microspheres have the core-shell structure with polyfurfurylalcohol core and a thin polydopamine shell (PDA@PFA). The polymer coating on a porous stainless-steel substrate is converted to the skinned CnCM through a controlled pyrolysis treatment in a reducing atmosphere. The interface between the microspheres and the carbonaceous matrix prevails the permeation. The functionalities present on the microspheres after pyrolysis thus equip pores with polar group sites, which facilitate growth of a stable binary surfactant layer (CTAC, cationic and Triton-X, nonionic) through adsorption upon the infiltration. An aqueous methylene blue (MB) solution (50 mg/L) was used to assess the membrane for NF. Retention above 98% with an average permeance of 3.5 L/m2⋅h bar could be sustained over 30 h owing to the surfactant layer comprising of cationic and non-ionic types. Softening the internal pore surface of CnCM by the adsorption of a surfactant layer offers a tactic for utilizing porous carbon medium different from the traditional CMS membrane to conduct nanofiltration of liquid solutions.