Photocatalytic degradation of Congo red dye with cobalt-doped manganese aluminium ferrite nanoparticles

Abstract Water pollution caused by the discharge of dyes is a serious environmental problem worldwide.Cobalt-doped manganese aluminium ferrite CoXMn1-XAl0.2Fe1.8O4 (X=0,0.2) nanoparticles synthesized via the sol-gel combustion technique exhibited excellent photocatalytic activity for Congo Red dye degradation under visible light irradiation. Comprehensive materials characterization revealed their structural, optical, morphological, and electronic properties. XRD reveals a cubic spinal ferrite structure, FTIR shows cobalt incorporation, SEM shows nanoparticle morphology, EDX confirms stoichiometric composition, and BET analysis reveals a high surface area. Cobalt incorporation tunes the optical bandgap from 2.8 to 2.5 eV, enabling visible light absorption (UV-DRS). Dielectric and conductivity measurements confirm semiconductor behaviour and indicate cobalt doping introduces additional charge carriers. Cobalt-doped manganese aluminium ferrite exhibited excellent Congo Red dye photodegradation efficiency of 99.9% under normal conditions of pH 7, catalyst dose of 100 mg/L, and dye concentration of 10 ppm following first-order kinetics. Scavenger test observed Hydroxyl and superoxide radicals degrade dyes. Cobalt doping facilitates charge dynamics, narrowing the bandgap and enhancing interfacial charge transfer, leading to superior photocatalytic performance. Cobalt-doped ferrite nanoparticles are reusable. Cobalt-doped manganese aluminium ferrite is an efficient and stable photocatalyst for wastewater treatment.