Magnetite in water remediation: advances in synthesis methods, catalytic applications, and contaminant adsorption

Magnetite (Fe 3 O 4 ) has emerged as a highly relevant nanomaterial in environmental remediation owing to its inverse spinel structure, magnetic recoverability, and redox activity. This review provides a critical overview of magnetite nanoparticle synthesis routes, including conventional chemical, green, electrochemical, and hybrid approaches, and examines how synthesis conditions influence phase composition, particle size, surface functionality, and practical applicability. Adsorption and catalytic mechanisms in advanced oxidation processes (Fenton, photo-Fenton, and electro-Fenton) are discussed together with the role of structured composite platforms in improving dispersion, interfacial reactivity, stability, and recovery. Particular attention is given to the relationships among synthesis route, interfacial design, treatment performance, regeneration, and sustainability constraints. Current limitations include agglomeration, reproducibility issues in green synthesis, incomplete regeneration data, and the scarcity of pilot-scale and life-cycle-based evaluations. Emerging research opportunities include in situ functionalization during synthesis, hybrid strategies for morphology control, magnetite-based electrocatalytic platforms, and validation under real wastewater conditions. Overall, this review highlights magnetite's potential as a versatile platform for water treatment while clarifying the material-design and sustainability challenges that must be addressed for practical implementation.