Nanofiltration for Decolorization: Membrane Fabrication, Applications and Challenges

Decolorization is important for wastewater treatment and product purification. Compared to an adsorption method using activated carbon and ion-exchange resin, nanofiltration (NF) is a sustainable technique for decolorization because it enables dyes/pigments recovery (rather than disposal as waste) via a simpler and greener approach. However, the large-scale application of NF for decolorization is limited by insufficient separation selectivity and operational stability of the commercially available NF membranes as well as incomplete NF-based decolorization processes. Many efforts, therefore, have been dedicated to developing high-performance NF membranes for decolorization and establishing an integrated process for increasing resource recovery efficiency. This review summarizes recent progress on NF membrane fabrication and applications in dye wastewater treatment and bioproduct manufacturing. Besides, the existing challenges and future research directions in NF for decolorization are pointed out. This review is expected to provide an overview and guidance on the development of eligible NF membranes and processes for decolorization to achieve cleaner production.