Understanding the influence of the ionic liquid composition and the surrounding phase nature on the stability of supported ionic liquid membranes

Abstract

in Wiley Online Library (wileyonlinelibrary.com).The industrial application of supported liquid membranes (SLMs) is still limited due to concerns about their stability. In a previous work, the selective separation of the substrates and products of a transesterification reaction was successfully carried out using Nylon membranes impregnated with ionic liquids (ILs). This article analyses the effect of both the IL composition and the nature of the surrounding phase on the stability of these SLMs to design highly stable supported ionic liquid systems. For this purpose, the stability of SLMs based on several ILs after immersion for a week in different feed/receiving phases was characterized using scanning electron microscopy combined with energy dispersive X-ray (SEM-EDX). The differential migration of the ILs observed from the membrane toward the surrounding phases was found to be correlated with the solubility of the ILs in the contacting phases. It was observed that SLM stability increased as the polarity of the solvent used as receiving phase decreased and as the hydrophilic character of the ILs used as liquid phase increased. Furthermore, the polymeric support was found to have a strongly stabilizing effect because losses of IL after immersion in a given surrounding phase were much lower than that derived from the solubility of the IL in this phase.

New application of supported ionic liquids membranes as proton exchange membranes in microbial fuel cell for waste water treatment

“…For instance, they show high ion conductivity [14] and wide electrochemical windows. Furthermore, they have near-zero vapor pressure and their good chemical and thermal stabilities, high viscosity and tunable solubility which allow obtaining highly stable supported ionic liquid membranes [15]. Due to these unique properties, supported ionic liquid membranes [16] have been applied for separating organic compounds [17,18], mixed gases [19,20] and metal ions [21].…”

Influence of ionic liquid composition on the stability of polyvinyl chloride‐based ionic liquid inclusion membranes in aqueous solution

“…Scanning electron microscopy (SEM) combined with energy dispersive x‐ray (EDX) analysis has been used to assess the operational stability of SILMs based on ionic liquids as well as to study the influence of the immobilization method and the nature of the surrounding phase on the performance of the membranes. The hydrophilicity of the ionic liquid used and the polarity of the surrounding phase are two key factors when it comes to designing highly stable supported ionic liquid membranes.…”

“…It has been demonstrated that the stability of SILMs decreases as the polarity of the receiving phase increases. Despite the good results reported in the literature in terms of stability for several hydrophilic ionic liquid immobilized in SILMs in contact with nonpolar organic solvents (n‐hexane, dimethyl sulfoxide, tert‐butyl methyl ether), ionic liquid losses of 100% were observed when water was the contact phase . In order to obtain stable membranes in water, the universal polar solvent, the casting method could be used to prepare PILIMs.…”

New application of polymer inclusion membrane based on ionic liquids as proton exchange membrane in microbial fuel cell

“…Among membranes based on ionic liquids supported liquid membranes (SILMs), porous supports whose pores are impregnated with a solvent, have been showing tremendous potential in different applications such as separation of organic compounds [37] and metal ions [24]. The use of ILs as liquids phase instead organic solvents in SLM resulted in the stabilization of the liquid membrane [38][39][40][41].…”

“…However instable supported ionic liquid membranes were found when polar solvent like water were used as contacting phases [41]. In order to obtain membranes stable in a universal and polar solvent, as water, and thereby extend the industrial applications to processes that mainly occurs in aqueous media, casting methods could be used to prepare polymeric inclusion membranes based on ionic liquids (PILIMs).…”