Photodegradation of Rhodamine B and Crystal Violet using Al-doped Co–Mn nanoferrites and dielectric study

Abstract

Precious water resources are under threat by pollution due to toxic organic dyes from industries. As a solution for water pollution, we have developed a multifunctional photocatalyst that will effectively degrade the toxic pollutants in the water bodies. We synthesized aluminium-doped Co–Mn ferrites as a photocatalyst via citrate-gel method and investigated the degradation of toxic pollutants of water such as Rhodamine B (RhB), Crystal violet (CV) under visible light for their potential application in wastewater treatment. One of the compositions of the catalyst Co_0.75Mn_0.25AlFeO₄ has shown effective photocatalytic performance in degrading RhB and CV with ^⋅OH radical and holes (h⁺) as active species responsible for degradation. The dielectric and impedance properties of Co–Mn nanoferrites and the influence of Al were also studied from room temperature (RT) to 350 °C. Dielectric studies revealed a normal dielectric behaviour of the samples with regard to frequency at various temperatures as evident by Koop’s theory and Maxwell–Wagner bilayer model. A decline in the dielectric parameters such as dielectric loss and dielectric constant was observed with an increase in Aluminium doping. Influence of frequency and temperature on dielectric parameters and impedance was studied. Area under the curve of Nyquist plots decreased with rise in temperature that represent the tendency of ferrite samples to show better conductivity. Observed low dielectric loss by Al doping in Co–Mn ferrites makes these materials appropriate for microwave devices at high frequency with low eddy current losses.