Prospects of practical application of hybrid membranes

Abstract

Membrane technologies using novel types of ion-exchange membranes comprising nanoparticles of inorganic substances-hybrid materials-have been vigorously developed in recent years. This modification leads to significant changes in the system of pores and channels and in the transport properties of the membranes. Owing to the changes, these materials exhibit considerable advantages over conventional membranes. This brief review analyzes the prospects for the use of hybrid ion-exchange membranes in water treatment systems, electrolysis cells, electrochemical current-generation devices, and sensors and in catalysis and gas separation processes.

Selectivity of Transport Processes in Ion-Exchange Membranes: Relationship with the Structure and Methods for Its Improvement

“…It is generally accepted that the composition of this electrically neutral solution is close to that of the solution contacting with the membrane. When membranes are used in electrodialysis or reverse electrodialysis, the concentration of contacting solution can be rather high [ 16 , 31 , 66 ]. Moreover, in the central part of the pore, there are a lot of cations and anions which can contribute significantly to the conductivity.…”

“…Some authors also note an improvement in their mechanical properties [ 177 , 207 , 208 ]. Although it is not always achieved, the mechanical properties of hybrid membranes are usually sufficient for their practical use [ 16 , 209 ].…”

“…A noteworthy advantage of hybrid membranes is often their reduced permeability of methanol and other fuel gases [ 202 , 210 , 211 , 212 ]. This determines, in particular, the widespread use of hybrid membranes in direct methanol fuel cells (DMFCs) [ 16 , 213 , 214 ]. A comparison of proton conductivity and methanol permeability for a number of hybrid membranes is given in Table 1 .…”

“…Ion exchange membranes (IEMs) are actively used in modern technologies, including water purification, concentration, electrochemical synthesis, and sensors [ 1 , 2 , 3 , 4 , 5 ]. Their use in fuel cells [ 6 , 7 , 8 , 9 ], in energy storage and conversion systems, e.g., metal-ion batteries [ 10 , 11 , 12 ], reverse electrodialysis [ 13 , 14 , 15 ], and redox batteries [ 16 , 17 , 18 , 19 ] has received the most attention in recent years. There are a number of other technologies in which ion-exchange membranes can also be used.…”

“…At the same time, the ion separation by membranes never occurs with 100% selectivity and is usually accompanied by an undesired transfer of molecules or opposite charged ions. Despite the fact that these processes proceed to a much less extent, they usually determine the decrease in the efficiency of electrodialysis, fuel cells and other devices based on ion-exchange membranes [ 16 , 28 , 29 , 30 ]. That is why their understanding is so important for numerous membrane technologies.…”