SYNTHESIS OF COBALT OXIDE NANOPARTICLES FOR CATALYTIC OXIDATION OF ORGANIC POLLUTANTS

Abstract

In this study, Co3O4 nanoparticles were synthesized in two different solvents, one with ethanol (CoEt) and another was double-distilled water (CoDd) by precipitation-calcination method. The characterization of the prepared samples were done using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Brauner-Emmet-Teller (BET), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) techniques. Diffraction peaks of cobalt oxalate dihydrate confirmed the synthesis of the almost pure phase of CoC2O4.2H2O. XRD diffraction peaks of the obtained product after calcination confirms the formation of pure Co3O4, no other characteristic peak was obtained. TGA of CoEt and CoDd was done and phase transformation occurs at 310 ℃ and 292 ℃. However, the samples were calcined at 500 ℃ to increase crystallinity. BETshows different values of surface area for CoEt and CoDd. The surface area of CoEt was 22 m2/g and for CoDd was 15 m2/g. Therefore, CoEt was more porous as compared to CoDd. FTIR showed two sharp absorption peaks at 563 cm-1and 652 cm-1confirms the synthesis of Co3O4. Absorption peaks for CoDd observed at 540 cm-1and 563cm-1with slight shift. FESEM was used to determine the morphology of prepared samples. Images revealed that prepared samples were in nano range and in rod-like shapes. DLS analysis of the solution of Co3O4 in ethanol gives an idea about the hydrodynamic diameter of particles which was 3.96 nm for CoEt with a polydispersity index (PDI) of 0.406 while the hydrodynamic diameter of particles of CoDd was 4.131 nm with PDI of 0.413. Furthermore, we studied the effect of time on the degradation of organic compounds such as ofloxacin and pyridine with the use of Co3O4 nanorods complemented by H2O2 in a catalytic peroxidation process