Influence of different activation strategies on the activity and stability of MIL-53(Fe) as a dark-Fenton heterogeneous catalyst

Abstract

MIL-53(Fe) was synthesized using solvothermal method without HF. Three different activation methodologies were applied in order to remove N,N-dimethylformamide (DMF) from the inner pores of the material. The incidence of these treatments in the activity and stability as heterogeneous catalyst in a dark-Fenton reaction was evaluated for Rhodamine 6G (Rh6G) degradation. Important improvements in the catalytic performance of MIL-53(Fe) were obtained after activation. Operational variables such as pH, reaction temperature, [H2O2]/[Fe3+] molar ratio, and initial Rh6G concentration were evaluated. Likewise, catalyst reusability assays were also performed. The obtained results indicate that a partial removal of DMF affects not only the stability but also the catalytic activity of MIL-53(Fe) in the Fenton reaction. Different solid state characterization techniques, including PXRD, SEM, FTIR, elemental analysis, XPS, and Mössbauer spectroscopy, were applied to the as-synthesized and activated materials as well as post-reaction catalysts in order to understand the catalytic behavior.