Ion-promoting-penetration phenomenon in the polyethyleneimine/trimesic acid nanofiltration membrane

Abstract

The preparation methods of nanofiltration (NF) membranes are various. Designing composite layer structures can obtain NF membranes with special properties. In our work, the polyethyleneimine/trimesic acid NF membrane exhibited high permeability. Based on this, the NaCl solution caused the permeate flux improving (ion-promoting-penetration phenomenon), and the flux was responsive to the solution concentration within a certain range. The detailed analysis of cross-linked structure, membrane pores, and solutions were made. The ion-promoting-penetration effect level, the highest growth rate Rg, could achieve about 70% (from 40 to 68 L m−2 h−1). This feature was still significant in mixed salt solutions, which had the potential to be applied to deep water treatment. After long-term treatment with the NaCl solution, the PEI/TMA membrane still maintain the excellent desalination performance (rejection of MgCl2, >90%). The discussion of these contents was beneficial to deepen the understanding of the NF process.