Constructing a monolithic amino-functionalized poly(ether sulfone) loose nanofiltration membrane for efficient dye/salt fractionation

• Published in: Separation and purification technology Vol. 354; p. 129504
• Main Authors: Xie, Lihua, Zhang, Ziyang, Li, Jingye, Zhang, Bowu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: Amination; Dye/salt separation; Immersion phase inversion; Loose nanofiltration membrane; Poly(ether sulfone); Immersion phase inversion; Loose nanofiltration membrane; Dye/salt separation; Amination; Poly(ether sulfone)
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129504

Loose nanofiltration (LNF) is a promising new technique for dye/salt separation, but LNF membranes still suffer from low permeance and inadequate selectivity. In this study, novel monolithic amino-functionalized poly(ether sulfone) (PES) LNF membranes were developed in three steps, PES powder-grafted with polyacrylonitrile (PAN) under gamma-ray irradiation and membrane preparation via non-solvent-induced phase separation, followed by an amination process. The resultant aminated PES LNF membrane with tetraethylenepentamine (APES-TP) had a thinner skin layer and unusual irregular vesicle-like pore structure in its sublayer compared with the original PES substrate. The amination process increased the hydrophilicity of the APES-TP membranes and partially neutralized the surface zeta-potential. The permeation test confirmed that the APES-TP membrane exhibited 100 % NaCl permeation together with high levels of pure water permeance (77.9 L m–2h−1 bar−1) and dye rejection (98.5 % for Congo red, 97.1 % for Nair blue, and 97.6 % for methyl blue). Even when paired with simulated industrial wastewater containing multiple direct dyes and inorganic salts (1 g L–1 dye and 5 g L–1 salts), the APES-TP membrane still rejected 99.4 % of the mixed dyes, proving its practical applicability to treating industrial dye wastewater. Furthermore, the APES-TP membrane exhibited excellent endurance to harsh conditions (such as acidic, alkaline, and oxidative) and exceptional recyclability (97.9 % permeance recovery rate). This study bridges the gap between conventional nonsolvent phase inversion and the emerging LNF membrane fabrication technology, allowing the LNF technique to be used to fractionate organic matters with salts in batch mode.