Comparative study of catalytic activity of different Fe-pillared bentonites in the presence of UV light and H2O2

To study the relationship of catalytic activity with Fe configuration over bentonite, three kinds of Fe-pillared bentonites were prepared by pillaring the bentonite with different Fe configurations (Fe-polycation, alpha-Fe2O3 and alpha-FeOOH). The characteristics of Fe-pillared bentonites were detected by N-2 adsorption/desorption, XRF, XRD, FTIR, AFM and UV-vis. Their catalytic activities were compared by discoloration and mineralization of Orange II in the presence of UV light and H2O2. The order of catalytic activity of Fe-pillared bentonites for dye discoloration was alpha-Fe2O3-pillared bentonite (alpha-Fe2O3-PB)>hydroxyl-Fe-pillared bentonite (H-Fe-P-B) >alpha-FeOOH-pillared bentonite (alpha-FeOOH-P-B). And that for dye mineralization was alpha-Fe2O3-P-B=H-Fe-P-B >>alpha-FeOOH-P-B. A possible catalytic mechanism was proposed for surface and solution reactions to discuss the difference in their catalytic activities. The rate constants of UV-Fenton reaction decreased but the catalytic activities of Fe-pillared bentonites for H2O2 became more obvious when the UV light wavelength increased. Furthermore, the reaction activation energy of UV-Fenton reaction was 18.6 kJ mol(-1), 20.1 kJ mol(-1) and 23.9 kJ mol(-1) with catalyst of H-Fe-P-B, alpha-Fe2O3-P-B and alpha-FeOOH-P-B, respectively. The results showed that both alpha-Fe2O3-P-B and H-Fe-P-B were promising catalysts for UV-Fenton system because of its physical and chemical stability and highly catalytic activity. (C) 2009 Published by Elsevier B.V.