Reconstructing nanofiltration membrane structure and pore size for PA selective layer with different organic solvents based on dissipative particle dynamics

Organic solvents have important influences on the morphology and performance of nanofiltration (NF) membranes. However, it is still unclear how organic solvents affect the polyamide (PA) selective layer of NF membrane. In this work, dissipative particle dynamics (DPD) simulation is employed to reveal the four hierarchical structures (Surface Structure Layer, Smooth Structure Layer, Heterogeneous Layer, Homogeneous Layer) of PA selective layer due to organic solvent (Pentane-PEN, Hexane-HEX, Heptane-HEP and Octane-OCT) gradients. And the method of dot-field reconstruction is proposed to analyze the morphology and pore structure of Homogeneous Layer. Moreover, the separation performances of Homogeneous Layer formed in different solvents were evaluated. It is proposed how to choose a suitable solvent, indicating the theoretical feasibility of preparing large-flux and high-rejection NF membranes.