Optimized synthesis and adsorption efficiency of magnetic spinel CuFe₂O₄ for dye removal from aqueous solutions

Magnetic nanoadsorbents with a spinel structure are highly effective for removing dye pollutants from aqueous environments due to their unique properties such as easy recoverability, chemical stability, and high surface area. In this study, a magnetic CuFe₂O₄ spinel nanoadsorbent was employed for the removal of methylene blue from aqueous solution. Magnetic CuFe₂O₄ spinel nanoparticles were synthesized via solution combustion method using glycine and sorbitol as dual fuels. By tuning the sorbitol-to-glycine ratio from 0 to 0.6, a highly porous spinel framework with a dominant surface particle size of 10–15 nm was achieved. Higher sorbitol content promoted greater gas evolution during combustion, enlarging pore diameters and enhancing the material’s textural properties. Using the optimized CuFe₂O₄ (G1/S0.4) formulation, zeta-potential measurements showed maximal dye-binding affinity at a sorbitol/glycine ratio of 0.4. Response surface methodology further pinpointed ideal adsorption conditions—pH 10.6, 1.18 g.L⁻¹ adsorbent dose, and 350 rpm stirring—under which 98 % of methylene blue was removed in 6 h. Equilibrium data fitted the Langmuir model, revealing monolayer adsorption with a maximum capacity of 19.4 mg.g⁻¹, while kinetics followed a pseudo-second-order mechanism. Thermodynamic analysis confirmed the process is spontaneous and exothermic. These results position CuFe₂O₄ (G1/S0.4) as a potent adsorbent for efficient dye removal in wastewater treatment.