High performance polyamine-based acid-resistant nanofiltration membranes catalyzed with 1,4-benzenecarboxylic acid in interfacial cross-linking polymerization process

Acid-resistant nanofiltration (NF) membranes with both improved permeability and acid stability are in desperate demand for acidic wastewater treatment. Herein, we report a novel polyamine-based nanofiltration membrane with improved flux and excellent acid stability prepared via interfacial cross-linking polymerization reaction of branched polyethyleneimine (BPEI) and 1,4-benzenecarboxylic acid (TPA) with cyanuric chloride (CC) on porous polysulfone support. Evaluated using various characterization techniques, the optimized NF membrane achieved at 1.0% (w/v) BPEI, 0.10% (w/v) CC and 0.15 g/L TPA at 90 degrees C for 10 min exhibited high rejection of different model salt solutions in the order MgCl2 > Na2SO4 > NaCl, with excellent permeation flux up to 12.8 LMHbar(-1). Furthermore, membrane exhibited good acid stability even at extreme conditions. After exposure to 25% (w/w) H2SO4 and 5% (w/w) HNO3 acid solutions at 25 degrees C, 55 degrees C and 80 degrees C for 720 h, 72 h and 24 h respectively, the fluxes increased with a slight decline in their rejection levels. Meanwhile, a long hour stability test slightly dropped the MgCl2 rejection level by similar to 10%. The dynamic CuSO4/H2SO4 mixed solution acid test of the membrane also revealed good permselectivity. This fabricated membrane thus provides a prospect of good application in acidic wastewater treatment and acid recovery process.

Automated summary

The novel acid-resistant nanofiltration membrane prepared in this study demonstrated improved flux and excellent acid stability, with high rejection of different model salt solutions, making it suitable for acidic wastewater treatment. Various acid stability tests showed that the membrane's flux increased slightly under extreme conditions, with a slight decline in rejection levels.