The Separation Power of Highly Porous 3D Nanofiber Sponges

Sponges formed by the self-assembly of nanofiber building blocks are versatile materials used in various fields such as filtration, thermal insulation, scaffolding or sound absorption. Their potential seems to be constantly expanding given the variety of possible fiber materials, from bio-based to fossil polymers to inorganic nanofibers. In general, nanofiber sponges - also called nanofiber aerogels - are flexible, have low density, and a large specific surface area thanks to their tunable open-porous nanofiber based architecture. The latter property makes nanofiber sponges an interesting material for separation problems, as recently demonstrated for a variety of mixtures such as aerosols, emulsions, dispersions, solutions or two-phase systems. Due to their highly porous structure, they generally exhibit high filtration efficiency, flow rate and capacity. This article reviews the state of the art in the application of 3D nanofiber sponges for the different classes of mixtures. We will discuss on a mechanistic basis why nanofiber sponges are particularly well suited for separation applications. Finally, their performance in terms of efficiency, flow rate, capacity and regeneration will be compared to other fiber-based filter media.