De Novo Ion-Exchange Membranes Based on Nanofibers

Abstract

The unique functions of nanofibers (NFs) are based on their nanoscale cross-section, high specific surface area, and high molecular orientation, and/or their confined polymer chains inside the fibers. The introduction of ion-exchange (IEX) groups on the surface and/or inside the NFs provides de novo ion-exchangers. In particular, the combination of large surface areas and ionizable groups in the IEX-NFs improves their performance through indices such as extremely rapid ion-exchange kinetics and high ion-exchange capacities. In reality, the membranes based on ion-exchange NFs exhibit superior properties such as high catalytic efficiency, high ion-exchange and adsorption capacities, and high ionic conductivities. The present review highlights the fundamental aspects of IEX-NFs (i.e., their unique size-dependent properties), scalable production methods, and the recent advancements in their applications in catalysis, separation/adsorption processes, and fuel cells, as well as the future perspectives and endeavors of NF-based IEMs.

All-Perfluorosulfonated-Ionomer Composite Membranes Containing Blow-Spun Fibers: Effect of a Thin Fiber Framework on Proton Conductivity and Mechanical Properties

“…The amount of fixed charge groups ( N x ) in the samples is equal to the titer of KOH. The ion-exchange capacity (IEC) was determined using the equation I E C = N x w d r y where w dry is the weight of the sample in the dry state. The samples were vacuum-dried at 25 °C for 20 h, and the dry weight was determined.…”

“…Conventional PEMs that are used in commercial PEFCs are the PFSA ionomer membranes reinforced with porous expanded PTFE (such as Gore-Select and Nafion XL). ,, Recently, highly porous electrospun poly­(vinylidene fluoride) (PVDF) nanofibers were used as the reinforcement to improve the dimensional stability of PFSA ionomer membranes. , In addition, ion-conductive nanofibers can increase ionic transport pathways in a polymer matrix compared with ion-insulating nanofibers such as PVDF nanofibers . In line with this scenario, there are many reports on preparation of composite PEMs containing ion-conductive nanofibers for the electrochemical devices including fuel cells. − The ion-conductive three-dimensional (3D) nanofiber framework can improve the electrochemical properties of the composites and mechanically reinforce the polymer matrix. − …”

Recent update on electrospinning and electrospun nanofibers: current trends and their applications

“…With the help of IEX-NFS there is easy recycling or recovery of heavy or expensive metals, catalysts, and enzymes. 113 3.2.5 Energy storage. Electrospinning is extensively used in energy storage devices with great interest and have various applications including various type of batteries such as lithiumion batteries, redox ow batteries, metal-air batteries, and supercapacitors.…”

“…With the help of IEX-NFS there is easy recycling or recovery of heavy or expensive metals, catalysts, and enzymes. 113 …”

Biomimetic Core–Shell-Structured Nanofiber Membranes for Rapid and Portable Water Purification

“…Membrane technologies, such as ceramic membranes, microfiltration membranes, nanofiltration membranes, and reverse osmosis membranes, have been extensively studied for convenient water purification. ,− Among them, electrospinning nanofiber membranes (ENMs) are characterized by a large specific surface area, high porosity, high permeability, and excellent rejection of various ingredients. − Therefore, ENMs could be potentially used for fast water purification. However, they are partially restricted by the limited absorption capacity for metal ions and organic molecules.…”