Iron oxide dispersed over activated carbon: support influence on the oxidation of the model molecule methylene blue

Abstract

In this work materials based on iron oxide dispersed over activated carbon were prepared and tested in the H2O2 decomposition and removal of the methylene blue (MB) model from aqueous solution. Two different supports were evaluated: a commercial activated carbon (CAC) and an activated carbon produced by coffee used grounds (ACK). These materials, after iron impregnation (CAC/Fe and ACK/Fe), were characterized using XRD, SEM, N2-sorption, XPS and Mössbauer spectroscopy. The main results suggest the formation of composites with high surface area and iron dispersion containing Fe3+ on the surface of both catalysts. Catalytic tests revealed high capacity for H2O2 decomposition by both composites with more activity for ACK/Fe. MB removal experiments showed intense removal of the model through combined adsorption and oxidation processes. The detection of known MB oxidation intermediates observed by ESI-MS studies confirmed the occurrence of MB oxidation processes and also showed more activity for ACK/Fe.