Coupling of Adsorption on Zeolite and V-UV Irradiation for the Treatment of VOC Containing Air Streams: Effect of TiO₂ on the VOC Degradation Efficiency

Abstract

We have investigated the efficiency of the coupling of adsorption on a zeolite material (DAY) and UV or V-UV irradiation for the treatment of VOC containing air streams. We have compared the efficiency of photodegradation of two pollutants (1-butanol and toluene) in the absence and in the presence of TiO2 deposited on DAY (DAY/TiO₂). Irradiation was performed with two different excimer lamps emitting in the V-UV at 172 nm and in the UV at 308 nm. The gaseous effluent was analyzed on-line at the exit of the photochemical reactor by GC and FTIR. The adsorbents (DAY and DAY/TiO₂) were analyzed before and after irradiation by solid state NMR, and the residual organic products remaining on the solids by GC-MS after extraction. The results show that the coupling of adsorption on DAY/TiO₂ and V-UVirradiation is highly efficient both for VOC mineralization and adsorbent regeneration. This efficiency results from the synergy between the important contribution of VUV photolysis to the oxidative degradation of the VOC and the photocatalytic effect of TiO₂ under V-UV irradiation at the DAY/TiO₂ surface, preventing adsorbent fouling as observed in the absence of TiO₂. The contribution of TiO₂ was particularly remarkable in the case of toluene.