Enhancing chlorine resistance in polyamide membranes with surface & structure modification strategies

Abstract

Higher efficient reverse osmosis (RO) membrane development is a significant issue due to the payoff among salt rejection and water flux and permissive chlorine attacking and fouling potential. Weak chlorine resistance is a distinctive challenge for composite polyamide thin-film reverse osmosis membranes. A commercial aromatic membrane was modified by grafting nitrogen-doped graphene oxide quantum dots (N-GOQDs) to enhance chlorine resistance, embedding two-dimensional MXene Ti3C2Tx, introducing synthetically reductive thioether units and oxidized graphitic carbon nitride (OGCN). In this work, salt rejection, chlorine resistance, and water flux increased compared to the pristine membrane. Comprehensive arrangement of desalination performance and chlorine resistance was achieved by varying time and concentrations of prepared chemicals. For instance, improved chlorine resistance, after 12 hours of grafting time by N-GOQDs doped membrane, was 32.8%, after 6 hours of exposure time by MXene Ti3C2Tx membrane was 27.4%, after 1 hour of exposure time by thioether membrane was 28.1% and after 40 hours of doping time by OGCN membrane was 31.3%. N-GOQDs doped membrane showed a good chlorine resistant property, but on the other hand, thioether nano units showed other properties more effectively, including water flux, salt rejection, and less reaction time. HIGHLIGHTS Chlorine degradation techniques.; Preparation and grafting of nitrogen-doped graphene oxide quantum dots (NGOQDs), MXenes Ti3C2Tx, thioether units, and oxidized graphitic carbon nitride by ontology doping method.; Economical analysis of grafted membranes.; Enhancing salt rejection and water flux.;

Keywords

• chemical grafting
• chlorine resistance
• interfacial polymerization
• polyamide membranes
• reverse osmosis