Electrostatically Tuned Graphene Oxide–Covalent Organic Framework Membranes for High-Flux Rejection of Low Molecular Weight Organic Compounds

) and exceptional rejection (>99%) of methylene blue (MB), a small cationic dye often used as a model LMWOC. Beyond performance metrics, this study provides a comprehensive analysis of the separation mechanism. A synergistic interplay of Donnan exclusion, size sieving, and transient interlayer restructuring was observed. Electrostatic repulsion governs the partial rejection of methyl orange (MO), while MB triggers charge compensation and interlayer compaction upon accumulation, narrowing the channels and reinforcing steric exclusion. This adaptive structural behavior accounts for the flux-rejection dynamics and antifouling resistance of the membrane under various filtration conditions. Our findings establish a mechanistic framework for understanding dye transport in 2D membranes and demonstrate a scalable, charge-guided strategy for designing high-performance membranes. This work bridges material design and transport physics, offering insights applicable to emerging separation technologies targeting persistent organic micropollutants.