Unlocking the magnetic potential of Fe₂O₃ nanoparticles by single-step synthesis of cobalt-infused nanomaterials for chromium removal

The study optimized the chromium removal capacity of Fe₂O₃ nanoparticles through the infusion of cobalt using a single-step synthesis method. This approach not only enhanced their magnetic properties but also employs less-chemical synthesis techniques, ultimately yielding highly magnetic CoFe₂O₄ nanoparticles and less impurities. The prepared materials underwent comprehensive testing, encompassing examinations of their optical properties, structure, chemical composition, and surface characteristics using various analyticals methods. In a span of 90 min under visible light exposure, CoFe₂O₄ nanoparticles exhibit the ability to remove more that 90% of chromium. This was corroborated through analysis using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Moreover, the study illustrates that increased temperatures amplify the endothermic process of chromium adsorption. Positive ΔH°, negative ΔS°, and heightened Cr(IV) adsorption are linked to the temperature effects on solubility, mobility, and dissolved oxygen. Both Langmuir (R² = 0.95, R_L = 0.055) and Freundlich models (R² = 0.98, n = 0.69) suggest favorable adsorption. The efficient Cr(IV) adsorption by CoFe₂O₄ nanocomposite is attributed to a rapid reaction rate and substantial capacity, following pseudo-second order kinetics (rate constant 0.01 g mg⁻¹ min⁻¹, R² = 0.99).