Photochemical Removal of N₂O in N₂ or Air Using 172 nm Excimer Lamps

Abstract

N 2 O removal was investigated in N 2 or air using 172 nm Xe 2 excimer lamps (50 or 300 mW/cm 2 ) without using any expensive catalysts. The residual amount of N 2 O and the formation ratios of products were measured as functions of photoirradiation time, N 2 O concentration, and O 2 concentration. N 2 O (100 ppm) was completely converted to N 2 and O 2 without NO x emission in N 2 at atmospheric pressure after 30 min photoirradiation using a high-power Xe 2 excimer lamp (300 mW/cm 2 ). 76% of N 2 O (100 ppm) was also converted to N 2 , O 2 , and HNO 3 in air (20% O 2 ) after 30 min photoirradiation using the high-power lamp. We concluded that N 2 O is dominantly decomposed by 172 nm photolysis in N 2 and by the O( 1 D) þ N 2 O reaction in air, where O( 1 D) atoms dominantly arise from the 172 nm photolysis of O 2 . The conversion of N 2 O in air increased more than twofold by decreasing the total pressure from atmospheric pressure to 20 kPa by suppressing the collisional quenching of O( 1 D) by N 2 and O 2 buffer gases. In a flow experiment, the conversion of N 2 O in N 2 was only 6 -18% in the total flow rate range of 0.1-1 L/min owing to the short residence time of N 2 O in the photolysis chamber.

Degradation of a Model Naphthenic Acid, Cyclohexanoic Acid, by Vacuum UV (172 nm) and UV (254 nm)/H2O2

“…The naturally dissolved oxygen was not removed from solutions because oxygen quenched the formation of H • . Contrary to γ-radiolysis, N 2 O cannot be added to scavenge H • in a VUV system because N 2 O undergoes photolysis to N 2 and singlet oxygen. , …”

“…Contrary to γ-radiolysis, N 2 O cannot be added to scavenge H • in a VUV system because N 2 O undergoes photolysis to N 2 and singlet oxygen. 24,25 The main light emission of the low pressure lamp is at 254 nm. A radiometer (International Light Inc. Model IL 1400A) equipped with a UV detector (International Light Inc. Model SED240) and a neutral density filter (Model QNDS2), calibrated at 5 nm intervals in the range of 200-400 nm, was used to measure the irradiance at the surface of the water samples.…”

Sustainable removal of N2O by mediated electrocatalytic reduction at ambient temperature electro-scrubbing using electrogenerated Ni(I) electron mediator

“…was identified as an additional product to N2 and O2 [54] via OH and NO2 as potential intermediates. To investigate this further, the GC column temperature was reduced to 100°C, resulting in a decrease in NO2 peak intensity (Fig.3 curve b).…”

Photochemical Removal of SO2 and CO2 by 172 nm Xe2 and 146 nm Kr2 Excimer Lamps in N2 or Air at Atmospheric Pressure

“…Among these reactions, two-body reaction (17) and threebody recombination reactions ( 12) and ( 19) are more significant than reactions (18) and (20), because the rate constant of reaction ( 18) is very small and the relative concentration of CO 2 is lower than those of N 2 and O 2 .…”

“…It was applied to the photochemical removal of NO and NO 2 in N 2 or air in our previous studies. [18][19][20] In this study, we investigated the photochemical removal of SO 2 and CO 2 using a 172 nm Xe 2 excimer lamp. In addition, we also used a 146 nm Kr 2 excimer lamp as a new VUV source for the removal of these molecules.…”