New photocatalysts based on MIL-53 metal-organic frameworks for the decolorization of methylene blue dye

The photocatalytic decolorization of methylene blue dye in aqueous solution using a novel photocatalyst MIL-53(Fe) metal-organic frameworks was investigated under UV-vis light and visible light irradiation. The effect of electron acceptor H2O2, KBrO3 and (NH4)(2)S2O8 addition on the photocatalytic performance of MIL-53(Fe) was also evaluated. The results show that MIL-53(Fe) photocatalyst exhibited photocatalytic activity for MB decolorization both under UV-vis light and visible light irradiation, and the MB decolorization over MIL-53(Fe) photocatalyst followed the first-order kinetics. The addition of different electron acceptors all enhances the photocatalytic performance of MIL-53(Fe) photocatalyst, and the enhanced rate follows the order of H2O2 > (NH4)(2)S2O8 > KBrO3 under UV-vis light irradiation, while in the order of (NH4)(2)S2O8 > H2O2 > KBrO3 under visible light irradiation. Moreover. MIL-53(Fe) did not exhibit any obvious loss of the activity for MB decolorization during five repeated usages. The photocatalytic activities over MIL-53(M) (M = Al, Fe), the isostructure to MIL-53(Fe), indicate that the metal centers show nil effect on the photocatalytic activity of MIL-53(M) photocatalysts. (C) 2011 Elsevier B.V. All rights reserved.