Preparation of highly permeable nanofiltration membranes with interfacially polymerized biomonomers

To enable the wide application of nanofiltration (NF) membranes to increase the fresh water supply, the development of new membrane materials and preparation techniques are still highly desired. In this work, thin-film composite (TFC) NF membranes were fabricated via interfacial polymerization (IP) using three different kinds of biomonomers with trimesoyl chloride (TMC) on a polysulfone (PSf) substrate. Biomonomers such as dopamine hydrochloride (PDA), norepinephrine (PNE), and tannic acid (TA) are highly hydrophilic and environmentally friendly. Moreover, these materials can not only strongly adhere to substrates but can also form chemically stable cross-linked networks. The influence of these monomers on the formation of the selective layer was systematically investigated. Furthermore, a series of characterization techniques, including attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential measurement, molecular weight cutoff (MWCO), X-ray photoelectron spectroscopy (XPS) and separation performance experiments, were used to study the properties of the TFC NF membranes. Biomonomer-based TFC NF membrane exhibited a higher water permeability of 8.14 L/m2 h bar with a high rejection for divalent ions (Na2SO4) of 93% compared to TFC NF membranes.