Potential of Engineered Electrospun Nanofiber Membranes for Nanofiltration Applications

In the area of filtration and separation processes, many variants of fibrous media have been used to improve the quality of water. Among woven and nonwoven filters, nonwoven filters are more commonly used in filtration technology, such as in water treatment, medical filtration processes, and pharmaceutical processes due to their high filtration performance. Nanofibers are the next generation of nonwoven filter media, which offer unique properties, such as a high specific surface areato-volume ratio, good interconnectivity of pores, and potential to incorporate active chemistry or functionality on a nanoscale. However, the use of nanofibers in water filtration is still at its infancy. Various parameters such as the nature of the polymeric materials, surface architecture, and pore size of the nanofibers influence its separation performance. Currently, as-spun electrospun nanofibrous membranes (ENMs) are applied as microfiltration (MF) membranes. Recently, replacement of the ultrafiltration (UF) middle layer in conventional thin-film composite (TFC) membranes (in three-tier arrangements) by ENMs was used to form thin-film nanocomposite (TFNC) membranes, which provide an improved flux over TFC membranes. Optimization of various parameters such as spinning conditions, TFNC membrane processing, and their influence on the removal of divalent and monovalent ions studied in nanofiltration (NF) applications are concisely reviewed.