Nanofiltration in Desalination, Separation Mechanism, and Performance

Nanofiltration (NF) established solid ground in the past years in desalination applications owing to its unique performance (i.e., higher water flux and lower operating pressure). NF is a great contender for the high removal of divalent ions and neutral organics. However, for desalination applications, NF has low selectivity toward monovalent ions. Understanding the separation mechanisms aids in the design of NF membranes, hence achieving the improved performance. This chapter provides an overview of the salt rejection mechanisms of NF membranes against several parameters and their effect on the membrane performance. The structural and physiochemical properties of NF membranes play an important role in their performance. These properties can be manipulated through innovations in materials and fabrication techniques. This chapter sheds light on the main membrane fabrication methods focusing on interfacial polymerization (IP). The fabrication–structure–property–performance relationships of IP-based NF membranes are also discussed. Optimization of the IP reaction process and the incorporation of new materials/fillers are basically the two strategies toward tuned NF membranes.