Polyester-polyamide interpenetrating network-structured nanofiltration membranes for efficient natural surface water purification

Conventional polyamide nanofiltration (NF) membranes face limitations in water treatment due to perm-selectivity trade-offs and chlorine sensitivity. This study introduced a phloroglucinol (PG) post-treatment strategy to construct polyester-polyamide interpenetrating network (IPN) NF membranes capable of overcoming these limitations. The IPN membranes featured a unique Turing surface morphology and a compact crosslinked network, which increased the effective filtration area while forming a thinner yet denser selective layer. This structural design enhanced hydrophilicity and negative surface charge, resulting in improved water permeance (24.5 L·m −2 ·h −1 ·bar −1 ) and a high organic matter rejection of 90.7 %. Notably, the modified membranes demonstrated remarkable chlorine stability, maintaining over 93 % of their initial rejection efficiency even after extreme chlorine exposure (20,000 ppm·h). This advancement addresses the rapid degradation of traditional polyamide membranes in chlorinated environments. Such extraordinary stability arises not only to from the inherent chlorine resistance of the polyester network but also from the multi-layered protective architecture enabled by the unique IPN configuration. The proposed IPN strategy provides an effective pathway for developing next-generation potable water treatment membranes.