High‐Permeance Nanofiltration Membranes via Dimethylsilicone Oil‐Modulated Interfacial Polymerization

ABSTRACT Nanofiltration membranes are increasingly applied in the treatment of high‐salinity wastewater, drinking water purification, and seawater desalination, offering effective removal of divalent ions and organic contaminants. The preparation of high‐flux and selective nanofiltration membranes remains a challenge. In this study, the addition of dimethylsilicone oil (DSO) to the organic phase solution in interfacial polymerization (IP) was used to adjust the monomer diffusion process, successfully preparing TFC&DSO nanofiltration membranes. The DSO slowed down the IP process and optimized the membrane formation, resulting in a decrease in the thickness of the selective polyamide layer as the DSO concentration increased. Under the optimized conditions of 50% DSO, 0.20 wt% piperazine, 0.25 wt% trimesoyl chloride, and a reaction time of 60 s, the TFC&DSO‐50 membrane exhibited a thickness of approximately 80 nm, an average roughness of 13.5 nm, and a water contact angle of 38.8°. The as‐prepared membrane demonstrated high water permeability (13.6 L·m −2 ·h −1 ·bar −1 ) and excellent selectivity (21.4) over sulfate ions and chloride ions. Its superior ion separation performance, long‐term operational stability, and scalability suggest significant potential for application in various water treatment.