Superparamagnetic Fe₃O₄/ZnO/ZnFe₂O₄ nanocomposites for efficient photocatalytic degradation of methylene blue from water under UV light.

SA A new series of porous, superparamagnetic nanocomposites was developed by combining Fe₃O₄ and ZnO, as well as ZnFe₂O₄, using a protic poly (ionic liquid) (PIL) as a template. These materials were synthesized at low temperatures, eliminating the need for high-temperature calcination, and were evaluated as photocatalysts for degrading methylene blue (MB), a cationic dye pollutant in water (30 ppm concentration). A linear PIL (LPIL) served as a capping agent to produce well-dispersed ZnO nanoparticles. This ZnO.LPIL was then dispersed during the crosslinking of protic ionic liquid monomer to form a crosslinked PIL (CPIL) nanocomposite matrix. Both the LPIL and CPIL were synthesized via the radical polymerization of triethanolammonium-2-acrylamidomethylpropane sulfonate and triethanolammonium acrylate monomers, with N, N’-methylenebisacrylamide added as a crosslinker for the CPIL. Using an in-situ technique, three types of magnetic nanocomposites (MNCs) were prepared within this matrix: magnetite (Fe₃O₄), zinc ferrite (ZnFe₂O₄), and a core-shell Fe₃O₄@ZnO structure. The chemical composition, crystal structure, and surface morphology of these MNCs were thoroughly characterized. Their thermal, optical, surface, and magnetic properties confirmed their superparamagnetic behavior, porosity, and thermal stability. The photocatalytic performance of these catalysts was assessed for the degradation of MB at pH 12 using a low catalyst dose of 20 mg under light/UV irradiation. The MNCs demonstrated exceptional efficiency and reusability, successfully degrading over 99.4% of the MB dye within 30 min and maintaining this high performance for more than 10 consecutive cycles.