Recent advances in chitosan-based mixed matrix membranes for efficient wastewater treatment

Chitosan-based membranes are considered promising materials for wastewater treatment owing to their biodegradability, functional groups, and film-forming properties. However, pristine chitosan membranes often lack sufficient mechanical strength, chemical stability, and selectivity for practical applications. This review summarizes recent progress in the design and functional modification of chitosan-based mixed matrix membranes (MMMs) through the incorporation of metal oxides, carbon nanomaterials, metal-organic frameworks (MOFs), and synthetic polymers. Emphasis is placed on correlating material structure with pollutant removal performance, focusing on mechanisms such as electrostatic interaction, coordination complexation, and π-π interactions across various contaminants (heavy metals, dyes, pesticides, and antibiotics). Representative examples demonstrate outstanding performance, such as Ag@TiO₂-chitosan membranes achieving over 95% dye removal and 99% antibacterial efficiency, GO-chitosan hybrids removing 96.7% of Zn²⁺ within 38 min, and MOF-chitosan membranes eliminating more than 95% of Cu²⁺, Pb²⁺, and Cd²⁺ ions. By systematically correlating hybridization strategies with multi-contaminant removal pathways, this review uniquely integrates recent advances across different hybrid systems (particularly MOFs, carbon nanomaterials, and metal oxides) into a unified structure-performance framework. This material-centric perspective provides guidance for the rational design of multifunctional chitosan-based membranes aimed at efficient and sustainable multi-contaminant wastewater treatment.