Fabrication and modification of nanofiltration membranes by solution electrospinning technique: A review of influential factors and applications in water treatment

Nanofiltration (NF) is the most promising process for the efficient treatment of contaminated air and water environments due to its flexible processing and excellent separation efficiency. Electrospinning is a membrane fabrication and modification process that can generate electrospun nanofiber membranes (ENMs) with large specific surface area, selective wettability, and reasonable interconnected pore structure. The modification of ENMs with multifunctional nanomaterials has extended their applications to a wide range of separation processes, mainly water treatment. Due to their superior advantages, this review summarizes the recent advancements of the solution electrospinning-based NF membranes, preceded by a detailed discussion on its general concepts and influential processing factors, polymer solution properties, and electrospinning variables. Another appealing modification approach of ENMs is their post-treatment, which endows them with unique features to improve the filtration performance of NF membranes. Moreover, potential challenges in the large-scale production of ENMs for treating water via the NF process are represented. Overall, future electrospinning-based developments could focus on designing a well-controlled system to produce more durable ENMs and developing multifunctional composite ENMs for improved practical NF-based water treatment.