Kinetics of Ti02 Photocatalytic Decomposition

Abstract

<p> Our work demonstrates the decomposition results obtained using Ti02 coated paper at different pH, ionic strength, UV intensities, temperature and flow rates. A kinetic model ofTi02 photocatalytic decomposition of reactive azo dye (RBS) was developed for the different conditions. </p> <p> Ti02 coated paper was developed by simply spraying Ti02 suspension on the filter paper. The stability of the Ti02 coated paper was studied and the environment where Ti02 coated paper can be used is under pH 7. The stability of Ti02 attached on the paper surface is determined by the property of the polymeric retention aids and the adsorption of reactive azo dye (RB5) is dependent on the electrostatic attraction. </p> <p> Ti02 photocatalytic decomposition mainly occurs at the surface of Ti02. So the adsorption of RBS molecules is considered to be one of the most important factors, which can affect the decomposition rate. Other factors, such as UV intensity and temperature, can also change the decomposition rate by affecting the formation of free radicals. </p> <p> New discovery of intermediate products can make the mechanism of the photocatalytic decomposition more clear, although the specific information about the intermediate products is not available yet. The adsorption and decomposition of intermediate products provide useful information for developing the decomposition kinetic model. </p> <p> Langmuir adsorption model is fit for the adsorption of RB5 and its degradation intermediate products at Ti02 surface. Our kinetics model combines the principles of Langmuir-Hinshelwood model and two-step first order model. It can describe the change of the RB5 concentration in the bulk and predict the desorption of intermediate products. </p>