Copper-doped akaganeite: application in catalytic cupro-fenton reactions for oxidation of methylene blue

Abstract

In this work an iron oxide – akaganeite – was obtained and used as a Fenton catalyst for the oxidation of methylene blue. The ability of dye oxidation was evaluated after incorporating copper into the structure of akaganeite to improve the catalytic properties of the material. EDS spectroscopy shows the presence of copper in iron oxide whereas XRD, XANES and EXAFS reveal that copper is indeed incorporated into akaganeite’s structure. Color removal of methylene blue (MB) was monitored by UV–vis Spectroscopy. The results obtained by this technique showed that akaganeite doped with a higher percentage of copper presented better MB removal capacity, reaching 65.7% at 180 min. The study by ESI–MS showed the formation of the intermediates during the degradation of this dye. Moreover, this material presented a significant mineralization of MB with removal of 45.5% of the organic carbon. The synergistic effect between iron and copper ions into the akaganeite structure favored formation of hydroxyl radicals, promoting the oxidation of the methylene blue dye.