Preparation, Characterisations and Photocatalytic Studies of Nano Cobalt (II) Ferrite and Zirconia (ZrO2) Doped Nanoparticles for Aqueous Dye Degradations

K. Nivethitha Lakshmi, J. Santhana Lakshmi
Department of Physical chemistry, University of Madras, Guindy campus, Chennai-600025, India

A B S T R A C T
Transition metal ferrites (MFe₂O₄) are magnetic materials with inverse spinel structure and possess potential technological applications such as inductor core, transformer circuits, magnetic sensors, recording equipment, telecommunications, magnetic fluids, microwave absorbers and other high frequency appliances. Cobalt ferrite is one of the important ferrites because it has various properties like semi conducting, magnetic and electrical properties etc. It is used extensively in colour imaging, gas sensing, catalytic applications, ferrofluids and Photocatalysis. In the present work using wet chemical method involving poly N-vinyl pyrrolidone (PVP) as the stabilising agent, nano Cobalt ferrite and Zirconia doped Cobalt ferrite particles are prepared. The samples are ultra-centrifuged, washed and dried to fine powder and are subjected to size characterisations using PXRD and FESEM.  The most widely used dyes such as crystal violet (CV) and methylene blue (MB) are chosen for the oxidative degradation assisted by photo irradiation and catalysed by nano Cobalt Ferrite and Zirconia doped Cobalt ferrite. Adopting one pot batch type reactor assembly into which 1mg/20 ml of catalyst loading for 1 mM aqueous dye solution under irradiations are maintained. Pseudo first order kinetic conditions are maintained. The overall pseudo first order rate coefficient values are determined for the two dye degradations using nano Cobalt ferrite and ZrO₂ doped Cobalt ferrite catalyst for three different irradiations (UVA, Solar, IR). For complete degradation of dyes, H₂O₂ addition was tried and similar measurements are made in presence of H₂O₂ separately. In presence of H₂O₂ both catalysts produced higher yields of degradations. The trend observed for dye degradation is CV>MB. The salient results are discussed.
Keywords: Cobalt ferrite nanoparticles, Zirconia doped nanoparticles, Photo catalysis dye degradation.