Correlations between the chemical nature of Fe-containing phases in P-Fe/C nanocomposites and photocatalytic activity under solar irradiation

MATOS, J.; MONTAÑA, R., GONCALVES, G.; SCHETTINO, M.; PAAASMANI, E.; FREITAS, J.:
Livro de Atas de XXVI Congresso Ibero-americano de Catálise (CICAT-2018), Setembro 2018, pp 462-467.

Abstract

Correlations between the photocatalytic activity and the chemical constitution of the P-Fe-containing phases present in P-Fe-based nanocomposites supported on activated carbon were found. Activated carbon was prepared by chemical activation with H3PO4 of the endocarp of babassu coconut. The synthesis of the nanocomposites was conducted by aqueous impregnation of the activated carbon with Fe(NO3)3-9H2O and NH4OH, followed by heat treatments under N2 flow at temperatures from 700 to 1000 °C. The adsorption capacity of the composites to remove methylene blue by adsorption and the photodegradation under solar irradiation were studied. Results were compared against a commercial activated carbon. The formation of iron phosphates and phosphides phases enhanced the adsorption capacities of the nanocomposites. The formation of iron phosphates (FePO4) was the driven-force for the enhancement in the methylene blue degradation, with a remarkable increase in the photocatalytic activity up to 10 times higher than the commercial activated carbon. The increase of the temperature up to 900°C led to a reduction of iron (III) to iron (II) phosphates, with a concomitant decrease in the photoactivity. The formation of iron phosphides at 1000°C was detrimental to the photocatalytic activity. It can be concluded that the formation of new Fe- containing phases is due to the chemical reactions involving the iron oxide nanoparticles dispersed in the phosphorus-containing carbon support. The P-Fe-based nanocomposites exhibited an important photocatalytic activity for the methylene blue degradation under solar irradiation, pointing to a promising application of these materials.

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