Modeling insights into the role of support layer in the enhanced separation performance and stability of nanofiltration membrane

A fundamental understanding of the correlation between membrane support characteristics and nanofiltration (NF) membrane performance is of great significance for further development of membranes for water treatment. This work investigated the effect of the support layer on the separation performance and stability of NF membrane and elucidated the mechanism by the Donnan-Steric Pore Model with dielectric exclusion (DSPM-DE) model. The properties of the support were regulated using nanomaterials, and the NF membrane prepared by interfacial polymerization on it was called the SM-C-NF membrane. The rejection ratios of the SM-C-NF membrane for artificial seawater and four dyes improved by 0.3%–20.7% compared with the pristine membrane (SM-0-NF). DSPM-DE modeling results demonstrated that the difference in the support layer varied the membrane parameters of the NF membrane, which were quantitatively related to the separation performance of the NF membrane. The changes in NF membrane parameters were attributed to the morphology and physicochemical properties of the support affecting the formation of the polyamide separating layer. Surprisingly, the variation of electrical parameters of the NF membrane induced by the support was the key factor for the membrane separation performance. The enhanced chemical and structural stability of the SM-C-NF membrane were ascribed to the robust polyamide layer formed by the support with large pore size and hydrophilic and rough surfaces. Taken together, our findings underscore the importance and great potential of the support layer in regulating the performance of NF membrane, which is conducive to broadening the perspective on the design of high-performance membranes.