Combining fluorescence microscopy and microfluidic devices as an innovative in-situ characterization technique for thin-film (nano)composite membranes

Interfacially polymerized (IP) polyamide (PA) thin-film composite membranes (TFC) are dominant in desalination, wastewater treatment and other industrial separation processes thanks to their high water fluxes and unrivaled salt rejection. However, these membranes suffer a trade-off between permeance and selectivity. A promising strategy to overcome this trade-off is by incorporating fillers into the selective top-layer of TFC membranes to form socalled thin-film nanocomposite membranes (TFN). Although this results in increased membrane performance, there is a lack in fully understanding the exact functioning of these membranes. It is believed that the acid, generated during IP, provokes partial/full degradation of fillers with low acid stability, which affects membrane formation. Therefore, the synthesis and functioning of TFN membranes will be studied in-situ via fluorescence microscopy and microfluidic devices. A drawback of PA TFC membranes is their low chemical robustness against chlorine exposure. However, the recently proven epoxide chemistry shows to be an excellent platform for the development of novel membranes with high performance under these harsh conditions. It is hypothesized that the positively charged quaternary ammonium groups, incorporated into the poly (epoxy ether) network, may have an important role in regulating the salt rejection of epoxide-based membranes. Therefore, the characteristic distribution of these charges will be investigated in this project.