Photocatalytic oxidation of toluene at indoor air levels (ppbv): Towards a better assessment of conversion, reaction intermediates and mineralization

Effect of key parameters on the photocatalytic oxidation of toluene at low concentrations in air under 254+185nm UV irradiation

“…The photocatalytic oxidation of toluene at 500 ppb and 290 ppb was shown to peak for ~2000 ppm H 2 O (equivalent to ~ 10%RH) [43]. Sleiman et al [15] observed the same inhibition of toluene photocatalytic oxidation at high RH using TiO 2 supported in a paper matrix, with ~100% conversion for all experiments performed at RH < 20%. Van Durme et al [44] described a maximum degradation rate for 500 ppb of toluene vapor at 26% RH for its oxidation by non-thermal plasma (an emerging, complementary technology for gas phase photocatalytic air purification), but the processes under dry air and higher humidity conditions were less efficient.…”

“…In that range, the toluene conversion efficiency increased from ~ 30 to 90%, indicating that, under all the experimental conditions, the system did not achieve complete conversion. Previous studies showed that at such low toluene concentrations, the removal efficiency was shown to be independent of the initial concentration [13,15] which suggested low coverage of the catalyst surface and first-order dependence on toluene concentration. In our case, for a given flow rate, the removal efficiency observed at the longest reactor length (L = 10 cm) was significantly higher than that observed for L = 5 cm (Figure 3-A).…”

“…Formaldehyde is produced as a partial oxidation byproduct in the photocatalytic oxidation of toluene [12,15]. However, experimental conditions may be conducive to very different formaldehyde yields.…”

“…Recently, a few studies investigated the removal performance of UVPCO at low VOC concentrations comparable to those encountered in buildings [11][12][13][14][15]. With VOC concentrations in the ppbv range, the low catalyst surface coverage led to different kinetics and mechanisms with respect to reactions using high gas phase concentrations (in the ppmv range), and the competition between different VOCs for reactive surface sites was shown to be insignificant.…”

Design and performance evaluation of the functional coating for air purification under indoor conditions

“…Photocatalytic oxidation (PCO) technology is considered as one of the potentially very efficient advanced oxidation processes for the improvement of the air quality by degrading inorganic and organic air pollutants [3][4][5][6]. The most used photocatalyst -titanium dioxide (TiO 2 ) (pure or modified) -has received considerable attention in the past decade due to its high PCO activity, high chemical stability, low toxicity and low cost [7,8].…”