Photocatalytic degradation of some VOCs in the gas phase using an annular flow reactor: Determination of the contribution of mass transfer and chemical reaction steps in the photodegradation process

The photodegradation of some VOCs in an annular reactor is chemical step controlled. The limitation due to mass transfer is negligible. The use of a combined plug-flow model shows that the apparent rate constant (k*) is equal to kK representing the Langmuir–Hinshelwood rate constants. So the design of an annular reactor using the L–H model can be considered. The photodegradability of the tested VOCs is strongly dependent on the product kK. Trichloroethylene is the best degraded while toluene is the worst. The study of the mineralization rate, defined as the ultimate degradation phase of the compounds, shows that this last is firstly dependent on the contact time and not on the nature of the VOC. Moreover increasing the inlet VOC concentration leads to a decrease in the mineralization rate.