Quantitatively Unveiling the Structure-Activity Relationship of Polyamide Nanofiltration Membranes with Complex Structures

Nanofiltration polyamide (NF PA) membranes are widely used in seawater desalination and wastewater treatment due to their excellent permeability. The structure-activity relationship of PA membranes has attracted extensive attention in decades. In this work, NF PA membranes with planar structure, nodular structure, and peak-valley structure were constructed, and the pure water permeance was calculated by nonequilibrium molecular dynamics simulation to quantitatively investigate the structure-activity relationship between the microstructure and water permeance. Results showed that the peak-valley structure had the highest effective utilization rate of the membrane surface, which had the highest number of water molecules that passed through membranes per unit cross-sectional area (7.09). Furthermore, with the increase of the specific surface area ratio, the water permeance of the NF PA with peak-valley increased at a rate about 2.5 times than that of the planar NF PA. Therefore, some molecular scale insights were supplied about the structure-activity relationship of NF PA membranes, which is helpful for the fabrication of high-performance NF PA membranes.