RESUMO Neste trabalho, ferrita de cobalto (CoFe2O4) foi sintetizada sobre aluminato de magnésio (MgAl2O4) e zeólita ZSM-5 e a atividade catalítica desses materiais na reação foto-Fenton visando a decomposição de um poluente orgânico em solução aquosa foi avaliada. Ferrita de cobalto foi sintetizada sobre os suportes pela rota solvotérmica. Os materiais magnéticos foram caracterizados por difração de raios-X, isotermas de adsorção/dessorção de nitrogênio, microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raios-X. Os catalisadores foram avaliados na degradação de corante amaranto sob irradiações visível artificial e solar. Os sistemas produzidos CoFe2O4/MgAl2O4 e CoFe2O4/ZSM-5 apresentaram satisfatórias atividades catalíticas, sendo superior comparado a ferrita de cobalto pura. As atividades catalíticas para ambos os sistemas foram superiores quando do uso de irradiação solar, atingindo 95 % de descoloração e 80 % de mineralização em 30 e 240 min de reação, respectivamente. Portanto, MgAl2O4 e ZSM-5 como suportes para a ferrita de cobalto apresentam-se como materiais promissores para a degradação de poluentes orgânicos em soluções aquosas através da reação foto-Fenton heterogênea.

ABSTRACT In this work, cobalt ferrite (CoFe2O4) was synthesized on magnesium aluminate (MgAl2O4) and ZSM-5 zeolite and the catalytic activity of these materials in the photo-Fenton reaction for the decomposition of an organic pollutant in aqueous solution was evaluated. Cobalt ferrite was synthesized on the supports by the solvothermal route. The magnetic materials were characterized by X-ray diffraction, adsorption/desorption isotherms of nitrogen, scanning electron microscopy and X-ray dispersive energy spectroscopy. The catalysts were evaluated for the degradation of amaranth dye under artificial visible and solar irradiations. The produced materials CoFe2O4/MgAl2O4 and CoFe2O4/ZSM-5 presented satisfactory catalytic activities, being superior compared to pure cobalt ferrite. Both the systems showed higher catalytic activity when solar irradiation was used, reaching 95% of decoloration and 80% of mineralization at 30 and 240 min of reaction, respectively. Therefore, MgAl2O4 and ZSM-5 as supports for the cobalt ferrite are promising materials aiming the degradation of organic pollutants in aqueous solutions through the heterogeneous photo-Fenton reaction.

In this work, cobalt ferrite (CoFe2O4) was synthesized by solvothermal route for application as a catalyst in the ozonation reaction for the decolorization and mineralization of melanoidin from aqueous solution. The structural properties of CoFe2O4 sample were investigated by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, Fourier-transform infrared spectroscopy (FTIR), particle-size distribution, scanning electron microscopy (SEM) and X-ray dispersive energy spectroscopy (EDS). Single-phase CoFe2O4 particles with a predominantly mesoporous structure containing a high specific surface area were obtained. Results showed that the CoFe2O4-catalyzed ozonation reaction has higher activity for the decolorization and mineralization of melanoidin when compared with the ozonation reaction without the presence of catalyst. Therefore, this material can be very promising for the application in catalytic ozonation systems for the melanoidin removal from liquid effluents.

Mesoporous Fe2O3-supported ZSM-5 zeolites were prepared by carbon-templating and subsequently evaluated as photo-Fenton catalysts to degrade a dye used as a model heavy organic pollutant. The synthesis procedure of the mesoporous ZSM-5 zeolites was performed employing a nucleating gel and carbon particles as mesopores template. Thereafter, the precursor salt of the iron oxide (Fe2O3) was impregnated and then calcined to obtain the final catalyst. For comparison purposes, a conventional Fe2O3-supported ZSM-5 zeolite was also prepared. The results showed that the amount of intracrystalline mesopores formed in the ZSM-5 crystals was influenced by the amount of carbon added into the synthesis mixture. In comparison to the conventional prepared catalyst, the mesoporous Fe2O3/ZSM-5 ones showed an improved performance in the degradation of the target organic pollutant by the photo-Fenton reaction, which was attributed to the improvement of their textural properties as consequence of the mesopores generation.