title: Photochemical removal of NO(2) by using 172-nm Xe(2) excimer lamp in N(2) or air at atmospheric pressure.
abstract: Photochemical removal of NO(2) in N(2) or air (5-20% O(2)) mixtures was studied by using 172-nm Xe(2) excimer lamps to develop a new simple photochemical aftertreatment technique of NO(2) in air at atmospheric pressure without using any catalysts. When a high power lamp (300 mW/cm(2)) was used, the conversion of NO(2) (200-1000 ppm) to N(2) and O(2) in N(2) was >93% after 1 min irradiation, whereas that to N(2)O(5), HNO(3), N(2), and O(2) in air (10% O(2)) was 100% after 5s irradiation in a batch system. In a flow system, about 92% of NO(2) (200 ppm) in N(2) was converted to N(2) and O(2), whereas NO(2) (200-400 ppm) in air (20% O(2)) could be completely converted to N(2)O(5), HNO(3), N(2), and O(2) at a flow rate of 1l/min. It was found that NO could also be decomposed to N(2) and O(2) under 172-nm irradiation, though the removal rate is slower than that of NO(2) by a factor of 3.8. A simple model analysis assuming a consecutive reaction NO(2)-->NO-->N+O indicated that 86% of NO(2) is decomposed directly into N+O(2) and the rest is dissociated into NO+O under 172-nm irradiation. These results led us to conclude that the present technique is a new promising catalyst-free photochemical aftertreatment method of NO(2) in N(2) and air in a flow system.
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan. tsuji@cm.kyushu-u.ac.jp
authors.forename: Masaharu
authors.initials: M
authors.lastname: Tsuji
authors.forename: Masashi
authors.initials: M
authors.lastname: Kawahara
authors.forename: Kenji
authors.initials: K
authors.lastname: Noda
authors.forename: Makoto
authors.initials: M
authors.lastname: Senda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sako
authors.forename: Naohiro
authors.initials: N
authors.lastname: Kamo
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawahara
authors.forename: Khairul Sozana Nor
authors.initials: KS
authors.lastname: Kamarudin
mesh_terms: D000388:Air; D001274:Atmospheric Pressure; D054018:Lasers, Excimer; D009584:Nitrogen; D009585:Nitrogen Dioxide / Q000302:isolation & purification*; D010777:Photochemistry
chemical_list: D009584:Nitrogen; D009585:Nitrogen Dioxide