Chitosan-based nanocomposite membranes for dye removal via membrane filtration: A review

This review examines the recent progresses in chitosan-based nanocomposite polymeric membranes for efficient dye removal from wastewaters via membrane filtration. Chitosan, a biodegradable and biocompatible biopolymer, exhibits inherent antimicrobial and adsorption properties, making it an attractive membrane matrix. However, its limitations in mechanical strength, porosity, and stability necessitate enhancement through incorporation of various nanofillers. We discuss the integration of diverse nanomaterials-including metallic nanoparticles (Ag), metal oxides (Fe₃O₄, TiO₂, SiO₂), clay minerals (montmorillonite), MOFs (metal-organic frameworks), layered double hydroxides (e.g., MgAl LDH), carbon-based nanostructures (carbon nanotubes, graphene oxide, graphitic carbon nitride), and biopolymer-based nanoparticles (chitosan nanoparticles, cellulose nanocrystals)-to fabricate multifunctional membranes with tailored porosity, hydrophilicity, and antifouling characteristics. These nanocomposites exhibit superior water permeability, high dye rejection efficiencies (often >95%), augmented mechanical and thermal stability, as well as self-cleaning and antimicrobial activities, addressing key operational challenges such as membrane fouling and durability. The review highlights fabrication techniques, performance metrics, and mechanistic insights into dye removal via adsorption, size exclusion, and photocatalytic degradation pathways. Furthermore, the integration of AI (artificial intelligence) and ML (machine learning) approaches offers opportunities to predict fouling behavior, optimize nanofiller combinations, and accelerate scalable membrane design. Moreover, recent developments in hybrid and stimuli-responsive membranes, and prospects for sustainable large-scale applications, are emphasized. Finally, challenges related to long-term stability, nanofiller leaching, and economic feasibility are addressed, providing a roadmap for future research aimed at developing robust and eco-friendly membrane technologies for global wastewater treatment needs.