Guanidinium-based loose nanofiltration membranes for dye purification and chlorine resistance

Loose nanofiltration membranes with high water permeance are desirable for the separation of dyes and salts; however, most membranes tend to be unstable when in contact with sodium hypochlorite solution, which has a significant influence on their properties. In this study, an innovative polymer membrane was fabricated on porous polyacrylonitrile substrates via interfacial polymerization, and a novel hydroxyl-containing guanidinium monomer (SaTGCl) were employed as an aqueous monomer. The fabricated polyester (PE) membranes exhibited high water permeance (97.2 L m(-2) h(-1) bar(-1)), high dye retention (99.4 %), and low salt retention (< 15.8 %). Furthermore, the PE membranes exhibited exceptional molecular sieving for dye/salts or dye/dye mixtures. The SaTGCl-based PE membranes displayed prominent chlorine resistance when soaked in aqueous NaClO. The PE membranes also exhibited distinct antifouling properties. Hence, the newly developed guanidinium-based PE membranes have enormous application prospects in dye purification. This work lays the foundation for the use of hydroxyl monomers in constructing thin-film composite membranes for various separations.

Automated summary

In this study, a novel polymer membrane was fabricated via interfacial polymerization on porous polyacrylonitrile substrates. The membrane showed high water permeance, high dye retention, low salt retention, exceptional molecular sieving, chlorine resistance, and antifouling properties, making it a promising candidate for dye purification and other separation processes.