Spinel ferrite nanoparticles in environmental remediation: Adsorption, catalysis, and sustainability perspectives

Spinel ferrite nanoparticles (MFe 2 O 4 , M = Co, Ni, Zn, Cu, Mg) are emerging as versatile materials for environmental remediation because they combine surface reactivity with magnetic separation. This review critically evaluates the efficiency of MFe 2 O 4 catalyst(s) for treatment diverse pollutants, including heavy metals, organic dyes, pharmaceuticals, radionuclides, gaseous contaminants, and inactive microorganisms. Particular attention is given to how cation distribution, particle size, and synthesis route control surface hydroxyl density, point of zero charge, and magnetization, and how these properties govern adsorption, photo-catalysis, Fenton-like reactions, and magnetic recovery. Reported studies demonstrate strong pollutant removal efficiencies, yet most remain confined to idealized laboratory conditions, limited regeneration cycles, and short-term testing. Functionalization and hybrid systems improve selectivity and catalytic activity, but often increase synthesis cost and complexity. Despite promising results, challenges remain in scaling synthesis while preserving performance, verifying durability in real effluents, and integrating ferrites into continuous treatment systems. Life cycle considerations, including long-term transformation, toxicity, and environmental fate, are rarely addressed but essential for responsible application. By separating demonstrated capabilities from unresolved gaps, this review identifies where MFe 2 O 4 can realistically contribute to remediation technologies and outlines priorities for advancing their sustainable deployment. • Spinel ferrite nanoparticles combine surface reactivity with magnetic separation for recyclable remediation systems. • Structure-property relationships are evaluated across composition, particle size, and synthesis routes. • Reported adsorption and catalytic performances depend strongly on test conditions, limiting direct comparison. • Quantitative benchmarking exposes trade-offs between removal efficiency, kinetics, and reusability. • Sustainability and life-cycle considerations determine the feasibility of real-world deployment.