Organic solvent nanofiltration (OSN) membrane with polyamantadinamide active layer for reducing separation performance inconformity

Abstract

Organic solvent nanofiltration (OSN) membranes suffer from separation performance inconformity (SPI) after the OSN application process in industry. In this work, a membrane and an indicator are proposed to solve this problem. Briefly, an adamantane (AD) structure is introduced into the active layer via 3-amino-1-adamantanol (AAMO) interfacial polymerization with acyl chloride to build a semi adamantane-amide active layer (SAAAL) on the aramid substrate. The substrate is also enhanced by the introduction of a certain amount of AAMO. The TFC membrane with SAAAL exhibits an “onion ring” surface morphology, lowered water contact angle, increased surface energy (γS) and acceptable OSN performance, in which the pure methanol (MeOH) permeance reaches 29.5 L·m−2·h−1·bar−1 and the removal ability toward fast green FCF (FCF) approaches 84.4%. In addition, a novel concept named the SPI index is proposed here to estimate the level of the SPI phenomena. According to the evaluation results based on five dyes in three solvents, the as-developed SAAAL-covered membranes show lower SPI indices compared to conventional aromatic polyamide layer (APAL)-covered membranes in the nanofiltration (NF) range. Long-term stability operation results also identify the potential of the AD structure in fabricated membranes showing both excellent OSN performance and mitigation of SPI phenomena.