Kinetics study of the MO adsorption and photocatalytic degradation using an effectively engineered HF photocatalyst

In this study, copper decorated photocatalysts (Degussa P25), were shaped in the form of ceramic hollow fibers (HFs) and their photocatalytic properties were investigated using Methyl Orange (MO), a prototype anionic pollutant. The abatement of the dye was tested in dark and under UV irradiation by means of batch experiments and a possible mechanism was proposed for the MO photodegradation. The photocatalysts were subjected to a series of MO adsorption experiments at variable initial concentrations, while the adsorption data were interpreted using different models. In general, the data analysis implied favorable MO physisorption on photocatalyst under the conditions used in this work. Furthermore, the adsorption kinetics of the photocatalysts was studied using pseudo-first and pseudo-second order kinetic equations, as well as Bangham, Elovich and Weber-Morris kinetic models. For further elucidation of the photocatalytic mechanism, experiments were performed with either O2 or inert gas sparged MO solutions. It was concluded that the MO degradation rate followed the Langmuir-Hinshelwood (L-H) model. In order to explore the stability of the derived ceramic HFs, their photocatalytic efficiency was investigated in successive cycles of batch photocatalytic experiments. Finally, a simple regeneration process revealed that the efficient photocatalysts could be reused without severe deactivation of their performance.