Study on the thin film composite poly(piperazine-amide) nanofiltration membrane: Impacts of physicochemical properties of substrate on interfacial polymerization formation

This work contributes to a better understanding of the correlation between the substrate membrane and the formation of poly(piperazine-amide). Factors affecting the properties of the poly(piperazine-amide) layer of the thin film composite (TFC) nanofiltration membrane were analyzed by studying the variation in the physicochemical properties of the substrates made of three different polymer materials, i.e. polysulfone (PSf), polyethersulfone (PES) and polyetherimide (PEI). The resulting substrates and TFC membranes were characterized by FESEM, AFM, ATR-IR, XPS and contact angle goniometer. Results revealed that the physicochemical properties of the resulting TFC membranes as well as their separation performances were altered with the use of substrate of different properties. The flux of membrane decreased in the order of PEI-based TFC > PES-based TFC > PES-based TFC, which coincide with the characteristics of each polyamide layer formed over the three different substrates. Compared to PES-based TFC and PEI-based TFC membranes, it is found that the polyamide layer of PSf-based TFC was more compact and more likely cross-linked which as a result led to lower water flux and higher salt rejection as observed in filtration experiments.