Activation of nanoparticles of nickel ferrite by divalent metal ions co-doping for the methyl orange dye’s photocatalytic degradation: a kinetic and adsorption isotherm study

Divalent metal ions co-doped nickel ferrites, M_x^MʹyNi_1−x−y Fe₂ O₄ (x = 0.00, 0.03, and 0.05; y = 0.00, 0.03, and 0.05; M = Ca, Zn, and Mʹ = Mg, Mn), synthesis was proceeded through co-precipitation method. The characterization of prepared samples was conducted through XRD (particle size—6.16 to 20.5 nm), VSM (magnetic properties), FTIR (functional groups), FESEM–EDX (surface morphology–elemental composition), UV–visible (band gap energy), and XPS (binding energy) techniques. The synthesized samples were assessed by methyl orange (MO) dye’s degradation under sunlight in batch mode. Dye removal percentage varies directly with photocatalyst dosage as well as contact time and inversely with dye’s initial concentration at neutral pH. The co-doped nickel ferrite possesses higher dye removal percentage (81.65%) than pure nickel ferrite nanoparticles (70%). The photocatalyst degradation of dye is confirmed with liquid chromatography–mass spectrometry study through various intermediate products. The MO dye’s degradation over prepared nanoparticles followed nonlinear pseudo-second-order with R² = 0.97267 and the Freundlich model with R² = 0.99744 and has q_max of 22.24 mg g⁻¹ at ambient temperature. After use, the collection of prepared samples was done using an external magnetic field and their reusability makes them a potential material for environmental remediation.