Interfacial transport: A versatile and facile preparation method for thin-film supported liquid membranes

Abstract

Supported liquid membranes (SLMs) show promising selectivity and permeability for CO₂/N₂ separations. However, the CO₂ permeance they can achieve is limited as they are mostly prepared by saturating an entire porous support with a liquid. This work establishes interfacial transport (IT) as an easy and versatile tool for the preparation of thin-film SLMs. IT relies on the preferred transport of a dissolved compound from an organic phase, across the interface into an aqueous phase, for which the compound has a higher affinity. By saturating the support pores with the aqueous solution, a thin film of the selective compound can be formed. A proof of concept for IT is delivered by using poly(ethylene glycol dimethyl ether) (PEGDME) as the selective compound to make gas selective SLMs. Several parameters are optimized, including contact time, PEGDME concentration, and solvent choice. The optimal membrane, synthesized in only 1 min, exhibits a CO₂/N₂ separation factor of 28 and a CO₂ permeance of 61 GPU. Notably, IT is compatible with green solvents like anisole and diethyl carbonate. Additionally, PEGDME-based IT membranes exhibited stable performance for 96 h under mixed gas conditions and could withstand N₂ pressures up to 10 bar when using a sealing layer. This work establishes IT as a new, facile, and fast synthesis method to obtain thin-film SLMs.