New directions in nanofiltration applications — Are nanofibers the right materials as membranes in desalination?

Abstract

Various desalination technologies are emerging to tackle the increasing water demand globally. Among them, nanofiltration (NF) has recently received an increased attention in the literature to desalt low salt content water. The developments of new membrane materials and novel processes have shown that NF can be potentially applied in the desalination due to enhanced flux, lower operational pressure and energy savings. Nanotechnology based products such as nanoparticles and nanofibers have been introduced to enhance the properties and performance of the membranes derived from conventional polymeric membrane materials and conventional phase inversion processes. When mid-layer made up of electrospun nanofibrous membranes (ENMs) produced by electrospinning has been applied in the thin film composite (TFC) configuration in NF application; higher permeate fluxes than conventional membranes were achieved. This has been ascribed to the high porosity, low transmembrane pressure and interconnected pore structure of ENMs. The ENMs as such or after mixing with nanoparticles are also explored in the area of membrane distillation for seawater desalination. In this article, recent developments of ENMs as TFC membranes in NF application and as desalination membranes in the membrane distillation, geothermal water desalination, and capacitive deionization application are summarized here.