A robust multilayer membrane with chitosan-encapsulated ZIF-8 for high-efficiency removal of dyes and oils from wastewater

The treatment of complex wastewater containing dyes and oils remains a significant challenge due to the limitations of conventional methods, including high cost and secondary pollution. In this study, a multifunctional composite membrane with a hierarchical protective structure was developed for efficient and simultaneous removal of dyes and oils. The membrane was constructed by sequentially depositing carboxylated carbon nanotubes (CNTs-COOH), polydopamine-coated ZIF-8 (PDA@ZIF-8), and carboxymethyl chitosan (CS) onto a PVDF substrate. The resulting membrane exhibited exceptional structural stability, superhydrophilicity, and underwater oleophobicity. The synergistic effects of the multilayer architecture which including electrostatic adsorption, high-surface-area adsorption, and dynamic hydration layer formation, enabled high rejection rates for dyes and oils and excellent flux recovery over multiple filtration cycles. The membrane also demonstrated outstanding mechanical and chemical stability under harsh conditions. This work provides a robust and scalable strategy for designing advanced separation membranes with enhanced antifouling performance and long-term operational stability.