Alkali Resistance of Thin-Film Composite Membranes with Different Nonwoven Fabric Supports: Experimental Evaluation and Numerical Simulation

Polyethylene terephthalate (PET) nonwoven fabric (NWF) is widely used as a support for thin-film composite (TFC) membranes. However, its ester bonds are susceptible to hydrolytic degradation under alkaline conditions, compromising the membrane stability during chemical cleaning. In this work, TFC membranes were fabricated on polypropylene (PP) and PET substrates with systematic characterization via experiments and simulations. After immersion in 20 wt % NaOH at 80 °C for 25 min, the PP TFC membrane exhibited a Na2SO4 rejection of 96.75%, whereas that of the PET TFC membrane decreased to 86.12%. Moreover, the tensile strength of the former was nearly three times that of the latter. Simulations further indicated that PP substrates exhibited higher OH– resistance, thereby mitigating the polyamide (PA) layer backside degradation. These findings underscore the critical role of NWF support in enhancing the chemical stability of TFC membranes, offering practical guidance for improving membrane performance and service life in alkaline environments.