A Review on Ionic Liquid Gas Separation Membranes

Abstract

Ionic liquids have attracted the attention of the industry and research community as versatile solvents with unique properties, such as ionic conductivity, low volatility, high solubility of gases and vapors, thermal stability, and the possibility to combine anions and cations to yield an almost endless list of different structures. These features open perspectives for numerous applications, such as the reaction medium for chemical synthesis, electrolytes for batteries, solvent for gas sorption processes, and also membranes for gas separation. In the search for better-performing membrane materials and membranes for gas and vapor separation, ionic liquids have been investigated extensively in the last decade and a half. This review gives a complete overview of the main developments in the field of ionic liquid membranes since their first introduction. It covers all different materials, membrane types, their preparation, pure and mixed gas transport properties, and examples of potential gas separation applications. Special systems will also be discussed, including facilitated transport membranes and mixed matrix membranes. The main strengths and weaknesses of the different membrane types will be discussed, subdividing them into supported ionic liquid membranes (SILMs), poly(ionic liquids) or polymerized ionic liquids (PILs), polymer/ionic liquid blends (physically or chemically cross-linked ‘ion-gels’), and PIL/IL blends. Since membrane processes are advancing as an energy-efficient alternative to traditional separation processes, having shown promising results for complex new separation challenges like carbon capture as well, they may be the key to developing a more sustainable future society. In this light, this review presents the state-of-the-art of ionic liquid membranes, to analyze their potential in the gas separation processes of the future.

A Review on Ionic Liquids-Based Membranes for Middle and High Temperature Polymer Electrolyte Membrane Fuel Cells (PEM FCs)

“…Over the last decade, ILs have attracted great attention from scientists and organizations which is sensible by increasing the number of published papers and books [ 73 , 74 , 75 ]. ILs are organic salts which are made-up by ions (organic cation and inorganic/organic anions) and they are usually liquid at temperature lower than 100 °C [ 76 , 77 , 78 , 79 ].…”

Pressure-Dependent Clustering in Ionic-Liquid-Poly (Vinylidene Fluoride) Mixtures: An Infrared Spectroscopic Study

“…As a semi-crystalline polymer, polyvinylidene fluoride (PVdF) consists of five main phase structures, namely α, β, γ, δ, and ε phases [ 1 , 2 , 3 , 4 , 5 , 6 ]. Owing to the specific conformation of the carbon chain backbone, considerable attention has been paid to the β structure of PVdF, which is known to have piezo-, pyro-, and ferroelectric applications [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ].…”

“…As a semi-crystalline polymer, polyvinylidene fluoride (PVdF) consists of five main phase structures, namely α, β, γ, δ, and ε phases [ 1 , 2 , 3 , 4 , 5 , 6 ]. Owing to the specific conformation of the carbon chain backbone, considerable attention has been paid to the β structure of PVdF, which is known to have piezo-, pyro-, and ferroelectric applications [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Unlike piezoelectric ceramics, piezoelectric polymers such as PVdF are flexible, which may be crucial in the development of wearable electronic mobile devices in the future [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

“…Owing to the specific conformation of the carbon chain backbone, considerable attention has been paid to the β structure of PVdF, which is known to have piezo-, pyro-, and ferroelectric applications [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Unlike piezoelectric ceramics, piezoelectric polymers such as PVdF are flexible, which may be crucial in the development of wearable electronic mobile devices in the future [ 1 , 2 , 3 , 4 , 5 , 6 ]. PVdF and its derivative copolymer (as well as piezoelectric ceramic–PVdF composites) may be promising candidates for tactile sensors, pressure sensors, shock sensors, and thermal measurement devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”

“…Unlike piezoelectric ceramics, piezoelectric polymers such as PVdF are flexible, which may be crucial in the development of wearable electronic mobile devices in the future [ 1 , 2 , 3 , 4 , 5 , 6 ]. PVdF and its derivative copolymer (as well as piezoelectric ceramic–PVdF composites) may be promising candidates for tactile sensors, pressure sensors, shock sensors, and thermal measurement devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Following polymerization from 1,1-difluoroethylene (CH 2 =CF 2 ), PVdF with a >CF 2 moiety may interact with cations of ionic liquids (ILs) [ 10 , 11 , 12 ].…”