Organic solvent nanofiltration membranes with tunable selectivity using meta-aramid supports: Effects of PDMS coating, interfacial polymerization, and hybrid PDMS-interfacial polymerization process

Abstract

Organic solvent nanofiltration (OSN) membranes face significant challenges in maintaining chemical stability and separation performance, particularly in solvents with diverse polarities, viscosities, and molar volumes. To address these limitations, this study developed three types of OSN membranes using hydrophilic meta-aramid–based supports, renowned for their exceptional solvent resistance. Distinct fabrication methods, including dip-coating, interfacial polymerization (IP), and a hybrid approach combining both techniques, were employed to tailor membrane properties for diverse separation applications. The dip-coated membrane with polydimethylsiloxane (PDMS) exhibited high permeance in low-viscosity solvents, including hexane (36.2 Lm⁻²h⁻¹ bar⁻¹), ethyl acetate (30.3 Lm⁻²h⁻¹ bar⁻¹), acetone (21.6 Lm⁻²h⁻¹ bar⁻¹), and toluene (26.9 Lm⁻²h⁻¹ bar⁻¹), with an MWCO of 980 g mol⁻¹ in acetone, making it suitable for separating solutes in such systems. The IP-fabricated membrane, utilizing piperazine and trimesoyl chloride, demonstrated superior separation performance in high-polarity solvents, such as acetonitrile (2.2 Lm⁻²h⁻¹ bar⁻¹) and methanol (1.6 Lm⁻²h⁻¹ bar⁻¹), as well as in water (3.3 Lm⁻²h⁻¹ bar⁻¹), achieving an MWCO of 275 g mol⁻¹ in acetone. Lastly, the hybrid membrane, combining PDMS coating with interfacial polymerization (IP), offered tunable MWCOs ranging from 624 to 248 g mol⁻¹, while maintaining high permeance in solvents such as acetone (1.5 Lm⁻²h⁻¹ bar⁻¹), acetonitrile (0.8 Lm⁻²h⁻¹ bar⁻¹), and ethyl acetate (0.7 Lm⁻²h⁻¹ bar⁻¹), demonstrating its versatility for a wide range of separation applications. This study provides critical insights into the design and optimization of meta-aramid–based OSN membranes, highlighting their potential to enable precise and efficient separation in pharmaceutical, chemical, and industrial applications.