A comprehensive review on anti-fouling nanocomposite membranes for pressure driven membrane separation processes

The advantages of membrane technology over conventional separation methods are high removal capacity, flexibility of operation and cost effectiveness. However, the main limitation to the greater use of membrane technology is membrane fouling. Fouling is the phenomena of deposition or adsorption of colloids, particles, biomolecules and macromolecules (e.g. proteins, polysaccharides), salts, etc. on the membrane surface and/or inside pores and pore walls during filtration. This leads to a decline in permeation flux, change in selectivity and separability during filtration operation, and reduces membrane life. Various studies have concluded that intrinsic hydrophobicity of membrane materials is one of the main reasons for fouling. To overcome this drawback, various nanocomposite membranes are being tailored to impart certain properties such as hydrophilicity, anti-fouling, self-cleaning, photocatalytic, and photodegradation. This review is focused on the nanocomposite membranes that are made by incorporating nanoparticles (NPs) into polymeric membrane matrix by different methods like coating, blending, and deposition. Some of the nanocomposite membranes reported include metal-based NPs viz. TiO2, SiO2, Al2O3, Si, Ag, ZnO, ZrO2, Mg(OH)2, CaCO3, and TiSiO4; carbon-based NPs viz. graphene oxide (GO) and carbon nanotubes (CNTs); and NP composites viz. GO–SiO2, GO–TiO2, SiO2–TiO2, and Ag–SiO2.