Mayer-bar continuous fabrication of covalent organic framework nanosheet tuned graphene oxide membranes for high-salinity dyeing wastewater recycling

The treatment and reuse of high-salinity dyeing wastewater remains a critical challenge in the cotton textile industry, where lamellar graphene oxide (GO) membranes show significant potentials but are limited by permselectivity and stability of their channels. Herein, the porous covalent organic framework nanosheets (CONs) incorporated GO (GO/CON) membranes with engineered separation nanochannels were fabricated by a continuous rod-coating strategy using Mayer bars. Specifically, the incorporation of porous TpPa-SO₃H nanosheets into GO membranes enhanced membrane permeability and dye/salt selectivity, attributed to the introduction of additional porous channels and the strengthened electrostatic properties from CONs. This GO/CON membrane exhibits exceptional durability during continuous cross-flow operations exceeding 300 h in high-salinity dyeing wastewater. Furthermore, the high-salinity permeate was successfully reused for dyeing cotton fabrics, producing textiles with minimal color differences, thereby demonstrating both environmental sustainability and economic viability for practical industrial applications.