Photocatalytic kinetics kinetic expression

An extension of tlie Turchi and Ollis (1990) kinetic scheme for photocatalytic reactions involving hydroxyl radical attack. In this work the precise evaluation of the photon-solid catalyst interaction and the proper knowledge of theLVRPA [c (x, C p)] were incorporated into the kinetic expression. The final result can be applied to any photocatalytic reactor regardless of its irradiation level. 

The photocatalytic degradation of PCE was studied in the laboratory photoreactor depicted in Figure 5, for differenf values of PCE inlef concenfrafions, relative humidities, and irradiation levels (Imoberdorf et al., 2005). It was experimentally found that the PCE reaction rate shows (i) first-order kinetics with respect to the PCE concentration in the gas phase, (ii) linear dependence with respect to the irradiation level, and (iii) site-competitive kinetics for the dependence with the relative humidity. Thus, Equation (7) is reduced to a rather simple analytic expression ... 

Generally first-order kinetics with respect to the concentration of the pollutant is observed for most AOPs in water. The compounds, which exhibit non-first-order kinetics also show quantum yields greater than one. These apparent higher quantum yields are due to sensitized oxidations. The kinetics for photocatalytic oxidation (PCO) can be expressed as one of Langmuir-Hinshelwood type, thus depending on both the degradation rate and the adsorption rate constant of the pollutant. 

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