Naringin-tailored highly chlorine resistant polyesteramide nanofiltration membrane for efficient antibiotic removal

Membranes with excellent chlorine resistance are required for stable operation and long service life. Traditional polyamide (PA) nanofiltration (NF) membranes typically suffer from inadequate chlorine resistance. To overcome this critical challenge and the long-standing problem of insufficient permeability, a novel polyesteramide (PEA) NF membrane was fabricated. Specifically, naringin (NG), a naturally occurring polyphenol rich in hydroxyl groups, was introduced as a co-monomer with piperazine (PIP) in the aqueous phase for interfacial polymerization with trimesoyl chloride (TMC) in the organic phase. The chlorine-susceptible amide groups were partially substituted by intrinsically chlorine-resistant ester groups in the fabricated PEA membrane. As a result, the chlorine resistance of the PEA membrane was greatly enhanced, with Na 2 SO 4 rejection remaining above 93 % after exposure to 20,000 ppm h of free chlorine. The resulting PEA membrane exhibited reduced surface roughness and selective-layer thickness, coupled with a slight increase in pore size and free volume fraction, which was attributed to intermolecular interactions between NG and PIP in the aqueous phase. Consequently, the PEA membrane demonstrated a water flux approximately twice that of the PA membrane, while maintaining a high Na 2 SO 4 rejection rate of 99 % and rejecting more than 98 % of various antibiotics (e.g., cephalosporins and tetracyclines). Furthermore, the PEA membrane exhibited favorable antifouling performance, satisfactory anti-swelling property, and filtration stability under various conditions.