Rapid decolorization of dyes in heterogeneous Fenton-like oxidation catalyzed by Fe-incorporated Ti-HMS molecular sieves

Abstract

Fe-incorporated Ti-HMS molecular sieves were used as the new bimetallic catalysts for decolorization of methyl orange and methylene blue in heterogeneous Fenton-like oxidation. For comparison, Fe2+/HMS, Fe3+/HMS, Fe2+/Ti-HMS and Fe3+/Ti-HMS were synthesized via a room temperature crystallization method and characterized by a series of techniques including XRD, UV–vis spectroscopy, FT-IR, TEM and N2 physical sorption. UV–vis result confirmed that Fe species and framework Ti were successfully grafted in HMS. FT-IR result showed that the synergy effect of framework Ti on Fe species in Fenton-like catalysis possibly originated from the interaction between FeOSi and TiOSi bonds. N2 sorption showed that all the samples possessed the pores and surface properties of classic HMS, which provided sufficient space for adsorption and reaction. Fe2+/Ti-HMS with the mole ratio of Si:Fe at 50:1 obtained the highest decolorization of dyes of the four samples, which was attributed to the valence change of Fe2+ and the promotion of hydroxyl radicals by framework Ti. This Fenton-like reaction should be performed at pH 3. Reaction temperature showed exactly the opposite effect on decolorization of methyl orange and methylene blue. Rapid decolorization for the two dyes solution with a concentration of 10−4M was able to be achieved over Fe2+/Ti-HMS using a low concentration of H2O2 as oxidant.