Aquaporin-inspired thin–film composite nanofiltration ceramic hollow fiber with the modification of arginine

The interfacial polymerization (IP) process has been widely applied for nanofiltration membranes and thin film composite (TFC) membranes due to its high selectivity and flexibility. The performance of polyamide (PA) TFC membranes can be affected by many factors, including the selection of monomers, additives, and substrates. Arginine (Arg) is an amino acid used as the building block of aquaporin in the human cell. It acts as a potential additive for the IP process because arginine is widely known for its high hydrophilicity and zwitterionic amphiphiles in the water transport of aquaporin. Compared to flat sheet membranes, alumina hollow fibers have the advantages of organic solvent resistance, high-temperature resistance, high packing density, prominent hydrophilicity and a narrow pore size distribution. In this study, a PA TFC membrane was fabricated on an alumina hollow fiber substrate by the polyamide IP process with the addition of Arg. The Arg addition led to higher stability for the IP process of PA membranes. When 0.15 wt% Arg was added, the maximal recorded permeate flux was 22.09 ± 0.41 LMH/bar with outstanding retention of commercial dyes, including methylene blue (98.23 ± 0.41%), methyl orange (99.96 ± 0.03%), Victoria Blue B (99.72 ± 0.25%) and Evans blue (99.65 ± 0.49%). Hence, the as-prepared membrane demonstrates potential industrial application to reject positively and negatively charged dyes with smaller molecular weights.