Contribution of UV light to the decomposition of toluene in dielectric barrier discharge plasma/photocatalysis system

Abstract

The contribution of UV light from plasma and an external UV lamp to the decomposition of toluene in a dielectric barrier discharge (DBD) plasma/UV system, as well as in a plasma/photocatalysis system was investigated. It was found that UV light from the DBD reactor was very weak. Its contribution to the removal of toluene in the plasma/photocatalysis system could be ignored. Whereas, the introduction of external UV light to the plasma significantly improves the removal efficiency of toluene by 20%. The removal efficiency of toluene in the plasma/photocatalysis system increased about 22% and 16% when compared with a plasma only system and plasma driven photocatalyst system, respectively. The increased toluene removal efficiency was mostly attributed to the contribution of the synergy between plasma and UV light, but not to the synergy between plasma and photocatalysis. The synergetic effect between plasma and photocatalysis was not significant.

Isovaleraldehyde degradation using UV photocatalytic and dielectric barrier discharge reactors, and their combinations

“…This observation was supported by the work of Cal and Schluep [38], that studied two different gap distances (3 and 5 mm) between electrodes and observed that the reactor with the 5 mm gap spacing required about three times the amount of power compared to the reactor with the 3 mm gap to achieve a benzene RE of 95%. the RE of isovaleraldehyde, also seen for similar catalysts elsewhere [39]. These results…”

Nonthermal plasma activates catalyst: from current understanding and future prospects

“…Comparison of these two design parameters clearly indicates the potential of PDC process for the VOC removal. Recent studies, however, provided several experimental evidences that the role of UV in the PDC process is minor due to the low UV dose [45,46]. UV dose in photocatalytic process is in the order of several mW cm −2 , whereas it is only in the order of several μW cm −2 in nonthermal plasma in air.…”

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

“…Several studies suggested that photocatalysis using ozone-generating short-wavelength UV light [16][17][18][19][20] or in combination with atmospheric non-thermal plasma [21][22][23][24] can be suitable alternatives for indoor air cleaning. These radiation sources present the additional advantage of generating excess ozone, as well as other potentially harmful, reactive species that should be prevented from being introduced into occupied spaces.…”

“…The lifetime of toluene due to this reaction is likely similar to the short reactor residence time. Due to the generation of ozone in this process, photocatalytic oxidation under 185 + 254 nm is often termed UV/TiO 2 /O 3 [17,[18][19][20][21][22][23][24][25][26][27] .…”

“…Previous reports on the photocatalysis of VOCs under ozone-generating radiation used target pollutant concentrations 1 to 3 orders of magnitude higher than those that could be typically encountered in a building air cleaning system [17,[20][21][22][23][24][25][26][27][28][29][30], and experimental conditions leading to unrealistically high O 3 concentrations (e.g., 3-15 ppm) [19]. Here, we investigated the reaction of toluene in the low ppb range, in conditions that generate ≤ 300 ppb ozone, analyzing the effect of the residence time and the reactor length on the toluene removal and formaldehyde formation.…”