Liquid Membranes, Supported and Emulsion

Abstract

Liquid membranes (LMs) constitute an emerging technique that can be used as an alternative for separation processes, mainly due to their high efficiency, and as such are being looked into for industrial applications. This article provides information on two types of LMs, supported liquid membrane (SLM) and emulsion liquid membrane (ELM), presenting the principles, methods of preparation, transport mechanisms, stability, and applications of a number of separation processes. SLMs use porous supports impregnated with a solvent. Solute molecules dissolve into the membrane at the feed/membrane interface, and the dissolved species diffuse through the membrane and desorb at the receiving phase. Numerous processes based on SLMs have been proposed as effective methods for the separation of different chemical species, such as organic compounds, metal ions, gas mixtures, or pharmaceutical compounds. Nevertheless, the application of SLMs on a large scale is still limited due to inadequate membrane stability. Much effort has been put into to improve SLM stability, and one possible alternative is to substitute organic solvents in the membrane by room temperature organic liquids (ILs), which possess unique properties that are interesting in the context of LMs. Thus, supported ionic liquid membranes (SILMs) receive special attention in this article. ELMs are prepared by the intensive mixing of two nonmiscible phases (e.g., water droplets in an oil phase) and the addition of some strong surfactant. Some recent advances in this field are presented.

Ecotoxicity assessment of dicationic versus monocationic ionic liquids as a more environmentally friendly alternative

“…In this way, it is possible to control several physical properties, such as hydrophobicity, viscosity, density, solubility and their biodegradability and toxicological behaviour (Ventura et al, 2012). Because of these properties, monocationic ILs can be used in a wide variety of applications in different inter-disciplinary research areas, such as in the field of chemical engineering, organic synthesis, separation process, material science, catalysis, biocatalysis, green chemistry, sensoristics, medicine, electrochemistry, electronic devices (Galinski et al, 2006;Hough et al, 2007;Kogelnig et al, 2010;Kore et al, 2013;Wasserscheid and Welton, 2008) and supported liquid membranes (Víllora, 2013).…”