Ultrathin Polyamide Nanofiltration Membrane Fabricated on Brush-Painted Single-Walled Carbon Nanotube Network Support for Ion Sieving

Recently, ultrathin polyamide nanofiltration membranes fabricated on nanomaterial-based supports have overcome the limitations of conventional supports and show greatly improved separation performance. However, the feasibility of the nanomaterial-based supports for large-scale fabrication of the ultrathin polyamide membrane is still unclear. Herein, we report a controllable and saleable fabrication technique for a single-walled carbon nanotube (SWCNT) network support via brush painting. The mechanical and chemical stability of the SWCNT network support were carefully examined, and an ultrathin polyamide membrane with thickness of ∼15 nm was successfully fabricated based on such a support. The obtained thin-film composite (TFC) polyamide nanofiltration membranes exhibited extremely high water permeability of ∼40 L m^–2 h ^–1 bar^–1, a high Na₂SO ₄ rejection of 96.5%, and high monovalent/divalent ion permeation selectivity and maintained highly efficient ion sieving throughout 48 h of testing. This work demonstrates a practical route toward the controllable large-scale fabrication of the TFC membrane with an SWCNT network support for ion and molecule sieving. This work is also expected to boost the mass production and practical applications of state-of-the-art membranes composed of one-dimensional and two-dimensional nanomaterials as well as the nanomaterial-supported TFC membranes.