Variation of Langmuir adsorption constant determined for TiO2-photocatalyzed degradation of acetophenone under different light intensity

The Langmuir-Hinshelwood (L-H) kinetic model has been used to describe semiconductor photocatalysis. In this report, the GH rate constant (k(L-H))and the Langmuir adsorption constant (K) have been determined under different light intensity for the photocatalytic degradation of poorly adsorbed acetophenone over TiO2 of Degussa P25 in aqueous medium (pH 6.2). The result shows that K decreases when the irradiation is performed at higher light intensity, while k(L-H) increases expectedly. It is also demonstrated that the initial time interval selected for the initial rate calculation is quite critical to the final determination for the constants. (C) 2000 Elsevier Science S.A. All rights reserved.