Robust loose nanofiltration membrane with fast solute transfer for dye/salt separation

Abstract

In today's energy crisis and shortage of resources, resource recycling on the premise of saving energy is a crucial topic. Large volumes of wastewater containing dye/salt mixtures in the textile industry are generated. In the process of treating textile wastewater, a membrane with better solute transport properties can be used to selectively remove solutes at constant energy input to save energy. Moreover, due to the challenging environment of typical textile wastewater, the membrane also needs to have a certain robustness. In this study, β-cyclodextrin and mussel-inspired polydopamine were combined using host-guest chemistry and then cross-linked by glutaraldehyde to form a robust loose separation layer. The results show that the membranes obtained by this process have a dye rejection greater than 99% and a salt rejection of about 16%. With the high degree of crosslinking at the surface, the membrane was found to exhibit excellent robustness in corrosive media at different pH values. Due to the high degree of cross-linking of the surface, the modified membrane also has good anti-fouling and anti-bacterial properties. Filtration using different concentrations of dye/salt mixed solutions demonstrated the stability of the membrane for filtration in highly concentrated salt solutions. In addition, a long-term stability test proved that the membrane operates stably for more than 60 h, maintaining its selectivity. This membrane with excellent robustness can provide technical guidance and theoretical support for the large-scale application of loose nanofiltration membranes.