N-(3-Aminopropyl)-imidazole modified polyamide reverse osmosis membrane for improved permeability and selectivity

Reverse osmosis (RO) membrane technology is applied widely on the water desalinization for relieving the challenge of freshwater scarcity. Polyamide (PA) membranes with superior water flux and rejection in the RO process are currently in high demand. In this study, a novel reactive additive N-(3-Aminopropyl)-imidazole (N-IM) was utilized to optimize the interfacial polymerization (IP) process and enhance PA-RO membrane performance. N-IM made the nascent film more porous and created an RO membrane with a thicker PA separation layer. The modified membrane exhibited a more hydrophilic surface, ascribing to more carboxylic acid groups. This membrane exhibited an improved water flux, increasing from 59.67 L/(m 2 ∙h) of original membrane to 82.76 L/(m 2 ∙h) of the modified membrane with the addition of 0.5 % w/v N-IM concentration, which was attributed to the enhanced hydrophilicity and increased water trapping capacity provided by the imidazole ring in N-IM. Additionally, the NaCl rejection increased from 98.75 % to 98.97 %, which can be attributed to the thicker separation layer and more carboxylic acid groups. In addition, the membrane showed excellent stability of performance and good pH stability. The study presents a novel approach to producing RO membranes with exceptional performance.