Mixed Matrix Membranes for Nanofiltration Application

Nanofiltration (NF) membranes with properties in between those of ultrafiltration (UF) and reverse osmosis (RO) have come a long way since they was first introduced in the late 80s. Existing NF membranes, typically polymeric in nature, are still restricted by several challenges, including the trade-off relationship between permeability and selectivity and high fouling tendency. Mixed matrix membranes, a new class of membranes fabricated by combining polymeric materials with inorganic materials, are emerging as a promising solution to these challenges. The advanced mixed matrix nanofiltration membranes could be designed to meet specific structural and physicochemical properties (e.g., hydrophilicity, porosity, charge density, and thermal and mechanical stability) and for introducing unique functionalities (e.g., antibacterial, photocatalytic or adsorptive capabilities). This chapter summarizes the recent scientific and technological advances in the development of mixed matrix nanofiltration membranes. They are classified according to their preparation method into: (1) asymmetric mixed matrix nanofiltration membranes prepared by phase inversion, (2) thin film nanocomposite (TFN) nanofiltration membranes prepared by interfacial polymerization, and (3) surface coating containing inorganic materials. Applications of mixed matrix nanofiltration membranes are also briefly discussed.