Use of Aliphatic Polymeric Polyvinyl Amine as an Aqueous Phase Reactant During Interfacial Polymerization for Fabricating Efficient Organic Solvent Nanofiltration Membrane for Molecular Sieving

The potential of polymeric amines in fabricating organic solvent nanofiltration (OSN) membranes has largely been unexplored. In this study, we employed polyvinyl amine (PVAm) as an aqueous monomer, cross-linked with trimesoyl chloride (TMC) as an organic phase monomer, to fabricate a polyamide (PA) active layer on polyacrylonitrile (PAN) support. A set of nine membranes was prepared for optimizing the membrane structure by varying the PVAm concentration and duration of IP. It was found that increasing the PVAm concentration or IP duration resulted in increasing the rejection and lowering the permeance of the membranes. This was due to decreasing molecular weight cutoffs (MWCOs) of the membranes. Among different membranes, M2a was found to be best optimized with an MWCO of around 350 Da and demonstrated superior rejection capabilities, exceeding 99% for congo red (CR) and eriochrome black T (EBT), while 93% and 90% for methyl orange (MO) and methylene blue (MB), respectively. Among the polar solvents, methanol achieved the highest permeance of 3.8 L m⁻² h⁻¹ bar⁻¹, while n-hexane, a nonpolar solvent, showed a permeance of 4.2 L m⁻² h⁻¹ bar⁻¹. This study highlights the potential of polymeric amines, varying their concentrations and duration of IP in developing efficient OSN membranes.