In situ synthesis of Fe3O4 nanocatalyst in chitosan-agarose hydrogel membranes for the sustainable and efficient degradation of organic compounds
Ángel Viteri, Júlia Laugé, Lucas Lutz, Maria‐Pau Ginebra, José García‐Torres
Abstract
The efficient degradation of organic pollutants is critical for environmental sustainability, driving the search for eco-friendly catalytic materials. Biopolymer-based magnetic hydrogels are promising candidates, though current systems often face challenges such as poor mechanical stability, uneven nanocatalyst distribution, and complex synthesis. Here, we present a green, simple, and scalable method for fabricating chitosan-agarose dual-network hydrogels incorporating Fe₃O₄ nanoparticles (NPs) synthesized in situ from two iron salts. This strategy ensures uniform NPs dispersion within a mechanically robust and biocompatible matrix, enabling multifunctional hydrogels that combine catalytic efficiency, magnetic responsiveness, and reusability. The Fe₃O₄ content was systematically varied to tune the hydrogel's physicochemical, mechanical, and magnetic properties. Structural characterization by X-ray diffraction and transmission electron microscopy confirmed successful in situ Fe₃O₄ NPs formation, with differences in size and morphology depending on the iron precursor. Rheological analysis showed increased stiffness with higher Fe₃O₄ content, while swelling tests revealed reduced water uptake due to pore filling. Catalytic performance was evaluated using model pollutants achieving up to 94 % degradation within 90 min under mild conditions. These nanocomposite hydrogels offer a sustainable, magnetically recoverable, and reusable platform for efficient pollutant removal, highlighting the synergistic advantages of dual-biopolymer matrices and in situ nanocatalyst formation for water remediation.