CeO2-Fe2O3 mixed oxides: Synthesis, characterization and evaluation in the photocatalytic degradation of nitroaromatic compounds from wastewater of the explosives industry

Abstract

Cerium-iron mixed oxides were synthesized by the polymeric precursor method with three Fe/(Fe + Ce) ratios (0.1, 0.2 and 0.3). The incorporation of iron caused significant changes in the properties of CeO2 such as decrease in the crystallite size and lattice parameter, formation of oxygen vacancies, redshift of the absorption edge and reduction of the band gap energy. The photocatalytic performance of the mixed oxides using ultraviolet and visible radiation was evaluated in the degradation of nitroaromatic compounds present in the effluent known as red water (RW), typical of the explosives industry. The reaction performed with the catalyst with the lowest iron content (7.5 g L-1) under ultraviolet radiation at pH 3.0 resulted, after 360 min, in 96% of degradation of nitroaromatic compounds and 90% of reduction in toxicity of the effluent. Such performance characterizes the potentiality of cerium-iron mixed oxides as alternative materials for the photocatalytic treatment of recalcitrant chemical species.