Reconstructing polyamide with nucleophilic catalyst for enhancing reverse osmosis membrane performance

Abstract

In this work, the permselectivity of PA RO membrane was significantly improved by treating the PA layer with 4-dimethylaminopyridine (DMAP) aqueous solution. With the assistance of DMAP, more residues in PA layer released during water soaking, unblocking the water channel in the PA layer. DMAP could also catalyze the reaction between the low activity amino groups and acyl chloride groups in PA, thereby reconstructing the resultant PA layer of RO membranes, generating a highly hydrophilic and negatively charged neonatal PA layer in-situ, and enhancing PA main part crosslinking. These factors were beneficial to membrane permselectivity. Consequently, the selectivity of the DMAP modified membrane could be increased by 62% at most (21594) with a 90% increase in permeance (3.37 L·m⁻²·h⁻¹·bar⁻¹) compared with those of the virgin membrane (13,294, 1.78 L·m⁻²·h⁻¹·bar⁻¹). This work provides a facile and low-cost strategy for preparing advanced RO membrane with outstanding permselectivity, exhibiting the potential for industrial application.