Low MWCO nanofiltration membranes prepared by stepwise depositing polyphenol and aminosilane coupling agent with the assistance of ethanol-regulated oxidation for antibiotic removal

Mussel-inspired catechol amine chemistry has emerged as a novel strategy to fabricate nanofiltration (NF) membranes. However, the preparation takes hours, and the molecular weight cut-off (MWCO) of the resulting membranes is usually not low enough to reject small molecules. This work described a new method to prepare dense NF membranes using tannic acid (TA) and aminosilane coupling agent (KH792 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane)) as materials, with the assistance of ethanol-regulated oxidation. The NF membranes were made by stepwise depositing oxidized-TA and KH792 on PSF substrates. The oxidation of TA was regulated by adjusting the solvent composition or the dosage of NaIO 4 . The effect of NaIO 4 on the chemistry of TA was explored by various characterizations. The selective layer of an NF membrane, with a flux of 26.7 L·m −2 ·h −1 ·bar −1 and a MWCO of 200 Da, formed only within 10 min. The membrane had high rejections of naproxen, bezafibrate, and ibuprofen (>90 %), and the rejection of NaCl was lower than 20 %, exhibiting a good selectivity for antibiotics toward monovalent ions. Compared with literature-reported mussel-inspired membranes, the proposed method resulted in a membrane with much higher permeance and a lower MWCO, indicating the improvement and advantages among the Mussel-inspired methods for the synthesis of NF membranes.