Synthesis of spinel ferrites and application in the photodegradation of Rhodamine in water via pH control assistance

Abstract

Nanostructured powders of cobalt ferrite with stoichiometry CoxFe3-xO4, where 0.4 ≤ x ≤ 1.2, were synthesized by the wet chemical route from the Co-precipitation method. Single-phase and crystalline nanopowders of spinel type structure with cubic symmetry and space group Fd3‾m were characterized by X-ray diffraction. The structural refinement was carried out by the Rietveld Method showing a transition of normal spinel to an inverse spinel, as a function of Co2+concentration. Both spectra, Infrared Spectroscopy and Diffuse reflectance spectroscopy were used to characterize chemical bonds Co2+ in tetrahedral coordination, for higher cobalt concentration, and band gap analysis, respectively. The photoactivity of powders was evaluated from the photodegradation of the Rhodamine 6G dye under UV light. CoFe2O4 nanoparticles showed the best photocatalytic degradation with 90.9% in an alkaline medium, which obeys a pseudo-first order kinetic reaction, being the maximum apparent rate constant equal to 10.23 × 10−3. Effects of the occupation of tetrahedral and octahedral sites in the spinel structure in the photoactivity parameter are discussed.