Performance and characterization of in-situ cross-linking preparation of anti-fouling and temperature-resistant polyamide nanofiltration membranes

Thermal stability of membranes has become an emerging pivotal feature in treating hot process water at its original temperature through membrane filtration. Inspired by the highly thermal stability of cross-linked polymers, amide group was designed to enhance the chemical interaction between selective layer and support layer which was constructed by diethylenetriamine (DETA) modified intra-cross-linked colloidal PAN particles to reinforce the thermal stability of selective layer. The T_g of polyamide (PA) selective layers was elevated from 50.09 °C to 105.06 °C by the chemical interaction. Accordingly, the thermally stable PAN-DETA-C nanofiltration (NF) membrane exhibited stable permeance of 9.6 L m⁻² h⁻¹ꞏbar⁻¹ and rejection to Na₂SO₄ of 96.5 % at 90 °C for 32 h. The thermal stability mainly stemmed from the robust cross-linked chains, which was not only intra-cross-linked but also was chemically anchored on support layer, in selective layer. Moreover, PAN-DETA-C exhibited excellent anti-fouling performance at 90 °C, where the FRR of 0.97–0.99 against HA, BSA, and SA was obtained. This study developed a strategy for constructing thermally stable NF membrane with commercial materials through the same manufacture process as commercial NF membrane dose.