Membranes with negatively-charged nanochannels fabricated from aqueous sulfonated polysulfone nanoparticles for enhancing the rejection of divalent anions

• Published in: Journal of membrane science 2020-05, Vol.602, p.117692, Article 117692
• Main Authors: Sun, Chuang-Chao, Zhou, Ming-Yong, Yuan, Jia-Jia, Yan, Yan, Song, You-Zhi, Fang, Li-Feng, Zhu, Bao-Ku
• Format: Article
• Language: English
• Subjects: Aqueous nanoparticles; Nanochannels; Rejection of anions; Sulfonated polysulfone
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2019.117692

Nanofiltration membranes (NFMs) with negatively-charged nanochannels (NCNs) are of critical significance for enhancing the rejection of divalent anions. Herein, NFMs with NCNs are fabricated through a facile coating-heating route. Sulfonated polysulfone (SPSF) nanoparticles (13–40 nm) dispersed in aqueous phase are used to generate a dense layer on PES ultrafiltration (UF) membranes with different molecular weight cut-off (MWCO). It is found that the differences in the roughness of the substrates have significant contributions to the packing process of the SPSF nanoparticles, which indicate the smooth surface can be the better one. Scanning electron microscopy (SEM) images suggest the successful fabrication of the dense layer about 200 nm on different substrates. The resultant membranes feature selective layers with the nanochannels from 0.7 to 1.2 nm in average and zeta potential measurements indicate the nanochannel layers are negatively charged, causing the salts rejection in the following sequence: Na2SO4 > NaCl > MgSO4 > MgCl2. Furthermore, the constructed membranes exhibit an excellent separation performance with the water flux of 7.2 L m−2 h−1 bar−1 and the rejection rate for Na2SO4 of 94%, which demonstrates a novel economic and effective approach towards fabrication of nanofiltration membranes. [Display omitted] •Negatively-charged nanochannels were successfully fabricated from aqueous sulfonated polysulfone nanoparticles.•A smoother substrate is benefit to the coating of the SPSF nanoparticles for a better performance.•The prepared nanofiltration membranes exhibited enhanced rejection of divalent anions.