Advancements on Fe3O4-based nanocomposite adsorbents for the removal of contaminants of emerging concern from water: a review on mechanism, regeneration, and fate.

The rise of contaminants of emerging concern (CECs) in freshwater ecosystems, driven by industrial growth, rapid urbanization, and the widespread use of pharmaceuticals and agrochemicals, has become a major challenge to global water quality and public health. Conventional treatment technologies exhibit poor removal efficiencies for these persistent, bioactive, and trace-level pollutants in water, necessitating the development of advanced, selective, sustainable, and cost-effective removal strategies. Magnetic separation offers a transformative route towards highly selective, energy-efficient water remediation. Among available materials, Fe3O4-based nanocomposites have emerged as leading materials due to their superparamagnetic properties, high surface area, versatile surface chemistry, and rapid recovery under low-intensity magnetic fields. Integrating Fe3O4 nanoparticles with carbonaceous materials, biopolymers, metal-organic frameworks, and clay minerals yields nanocomposites with substantial adsorption capacity and efficiency, tunable porosity, enhanced selectivity, and facile magnetic separability, consistently surpassing conventional adsorbents across multiple metrics. This review comprehensively examines recent advances in Fe3O4-based nanocomposite synthesis, evaluates the adsorption performance of these nanocomposites across a broad spectrum of CECs, elucidates the key removal mechanisms, and discusses the environmental fate and repurposing potential of spent nanocomposites. Despite current challenges related to large-scale synthesis, long-term stability, regeneration efficiency, validation in complex real-world matrices, and potential nanoparticle toxicity, Fe3O4-based nanocomposites are promising as sustainable, next-generation adsorbents for advanced wastewater remediation.