Synergistic screening of intralayer pores and interlayer channels: Two-dimensional porous mica membrane for efficient dye/salt separation

The efficient separation of dyes and salts from textile wastewater is crucial for water resource recovery, yet remains challenging for membranes to achieve both high permeability and selectivity. This study proposes an “intralayer pore + interlayer channel” collaborative screening strategy. A two-dimensional porous mica/polyethyleneimine (PMica/PEI) composite membrane was fabricated via controlled acid etching and interlayer assembly. The acid etching selectively dissolved metal cations within the mica nanosheets, creating abundant in-plane nanopores that provide vertical mass transfer shortcuts. Simultaneously, positively charged PEI co-assembled with the negatively charged porous mica nanosheets via electrostatic interaction, which not only stabilized the lamellar structure but also optimized the chemical microenvironment of the interlayer channels. This unique dual-channel architecture significantly reduced water transport resistance. The optimized PMica/PEI membrane exhibited exceptional water permeability (230.68 L·m −2 ·h −1 ·bar −1 ) and high rejection rates for large-molecular-weight dyes (Brilliant Blue 99.72%, Congo Red 97.81%), while maintaining low salt rejection (NaCl 6.42%, MgCl 2 8.44%), thereby achieving efficient dye/salt separation. Furthermore, the membrane demonstrated excellent antifouling performance and long-term stability. Compared to commonly used synthetic two-dimensional material membranes, our approach based on natural mica offers distinct advantages of low cost, simple operation, and environmental friendliness, providing a promising technological pathway for treating high-salinity textile wastewater.