Graphene oxide membranes using MOF@Chitosan core-shell nanoparticles as dual modulators for dye separation

GO membranes hold significant promise for the purification of water. However, GO membranes also face the problem of structural swelling, which limits their use in water treatment applications. In this work, a novel dual-modulated core-shell MOF@Chitosan (MOF@CS) was successfully synthesized and used as an intercalation crosslinker to optimize the interlayer spacing and stability of GO membranes. Molecular dynamics simulation confirms that MOF@CS, acting as an intercalator, accelerates the water diffusion rate within the channels of the GO layer compared to pure GO layer. At the same time, FTIR analysis reveals that MOF@CS serves as a crosslinker for covalently cross-linking the GO layer. The nanofiltration performance and stability of the improved MOF@CS-GO composite membranes were significantly enhanced. Compared to the pure GO membranes, the MOF@CS-GO composite membranes exhibited enhanced Congo red rejection rates (from 76.5% to 95.6%), while maintaining a high pure water flux (34.5 L m^-2·h^-1·bar^-1) and good structural stability (stable dye removal performance over 120 h). This dual regulation strategy is expected to effectively solve the swelling problem of GO membranes in aqueous media and open up avenues for advancing the performance of GO membranes.