Synthesizing Fe_۳O_۴, Mn_۳O_۴ and Mn_۳O_۴/Fe_۳O_۴ nanocatalysts using the sol-gel method as new precursors for the degradation of phenol by catalytic ozonation

Ozone has received much attention in wastewater treatment as an impressive oxidation agent. In this work, three new metal complexes, [pyda.H][Fe(pydc)(pydc.H)].H۲O, (I); [pyda.H][Fe(pydc)۲].H۲O, (II); and [pyda.H۲]۵[Mn(pydc.H)۲].[pydc]۵.۸H۲O, (III), where [pyda.H]+ = ۲,۶ -diaminopyridinium and [pydc]۲- = ۲,۶ -pyridinedicarboxylate, have been synthesized by the ultrasonic-assisted synthesis method and then characterized by field emission scanning electron microscope (FE-SEM), Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TGA), and elemental analyses. According to the SEM image, the morphology of compound III was a nanorod. Compounds I, II, and III were then used as precursors for the preparation of Fe۳O۴, Mn۳O۴, and Mn۳O۴/Fe۳O۴ using the sol-gel and impregnation methods, respectively. Characterization of the synthesized nano-catalysts was carried out by FE-SEM, X-ray powder diffraction (XRD), and energy diffraction X-ray (EDX), the vibrating sample magnetometer (VSM) was replaced by magnetic studies. The VSM result showed that Fe۳O۴ and Mn۳O۴/Fe۳O۴ were superparamagnetic and ferromagnetic compounds, respectively. The Mn۳O۴, Mn۳O۴/Fe۳O۴, and Fe۳O۴ nanocatalysts were applied for the decomposition of phenol in an aqueous solution by catalytic ozonation. Phenol degradation efficiency was obtained as ۹۷.۲۶, ۹۷.۷۴, and ۸۸.۶۲ %, respectively.

Keywords:

Mn۳O۴/Fe۳O۴ nanocomposite , sol-gel method , Synthesis , catalytic ozonation , phenol degradation