Optimization of ultrathin polyamide nanofiltration membranes with sulfonated polyethersulfone interlayers for enhanced performance
Weijiao Jiang, Jin An, Feng Gao, Yiwen Hu, Xiuduo Song, Dandan Chen, Ruizhang Xu, Jian Kang, Ya Cao, Ming Xiang
Abstract
The “trade-off” effect of nanofiltration membranes may lead to problems of lower flux and higher energy cost, which limit their applications. In this work, an ultra-thin polyamide selective layer (34 nm in thickness, much lower than the conventional polyamide selective layer) was prepared by constructing a sulfonated polyethersulfone interlayer on the surface of polysulfone ultrafiltration membranes by liquid-phase deposition, taking advantage of the inhibitory effect of sulfonated polyethersulfone nanoparticles on the diffusion of piperazine. The prepared nanofiltration membrane exhibits a water flux per unit pressure of 33.2 L·m −2 ·h −1 ·bar −1 , which is more than 2.5 times higher than that of the nanofiltration membrane without the introduction of the interlayer (12.2 L·m −2 ·h −1 ·bar −1 ). Additionally, it has a high rejection of 98.8 % for Na 2 SO 4 , which surpasses the upper limit of the equilibrium of trade-off. The study also delves into the modulation mechanism of the interfacial polymerization process by the presence of a sulfonated polyethersulfone interlayer and explores the potential reasons for the water flux enhancement. This research will likely provide theoretical support and practical experience for further optimization of nanofiltration membrane performance.