Contribution of nano-network structure and charge manipulation of 2D laminar membrane to selectivity and fouling control in wastewater treatment

The assembly of two-dimensional (2D) nanomaterials into laminar membranes with sub-nanometer interlayer spacing provides a platform for fouling control in wastewater treatment with membrane technology. However, the strong stacking of nanomaterials limits membrane applications, and although studies have been conducted to modulate the interlayer structure, the enlarged interlayer channels weaken salt ions rejection and foulants removal. Therefore, this study proposed strategies for designing steric network nanostructures and altering the electrical properties at the sub-nanometer scale to improve the interlayer channels of MXene nanosheets and enhance membrane application properties. The functionalized composite membranes exhibit excellent stability due to hydrogen and covalent bonding effects that enhance the binding energy between the nanomaterials. The formation of three-dimensional (3D) nano-interwoven structures significantly enhanced the rejection of salt ions, and the optimized M/PC membrane retained 79.9% of CaCl 2 compared to only 5.3% of the pristine membrane, and without attenuating the water flux due to the deposition of nanomaterials. The improvement of the positive electrical characteristics, competitive adsorption and polar force-driven enabled the effective separation of organic matter and salt ions in the leachate and synthetic solution, the selectivity value of HA/NaCl reached to 40.6. Theoretical calculations showed that polar acid-base ( ΔG AB ) dominated the resistance of membrane fouling and that M/PC membrane significantly repel foulants. This work highlights the importance of MXene sub-nanofluidic channels improvement and interfacial charge modulation for permeability, selectivity and elucidates the mechanisms of fouling control using functionalized membranes.