TiO2-mediated photocatalytic degradation of Orange II with the presence of Mn2+ in solution

The photocatalytic degradation of Orange H was investigated in aqueous dispersions of titanium dioxide (TiO2) using UV light as irradiation source. The experimental results demonstrated that the photocatalytic decolorization of Orange II was feasible. The optimum pH value was found to be 7.00. The presence of Mn2+ did not alter its degradation pathways, but it reduced the dye degradation efficiency. Mn2+ at an elevated level had a more significant detrimental effect on the dye degradation efficiency. The atomic absorption spectrometry and X-ray photoelectron spectroscopy (XPS) analyses showed that Mn2+ was adsorbed on the surface of TiO2. This was the reason for the reduced catalytic efficiency of TiO2 with the presence of Mn2+. A modified Langmiur-Hinshelwood model was able to describe the TiO2-mediated photocatalytic kinetics of Orange II appropriately with and without the presence of Mn2+ in solution. (C) 2003 Elsevier B.V. All rights reserved.