title: Catalytic oxidation of gaseous PCDD/Fs with ozone over iron oxide catalysts.
abstract: Catalytic oxidation of PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) with ozone (catalytic ozonation) over nano-sized iron oxides (denoted as FexOy) was carried out at temperature of 120-180 degrees C. The effects of operating temperature, ozone concentration, space velocity (SV) and water vapor contents on PCDD/F removal and destruction efficiencies via catalytic ozonation were investigated. High activity of the iron oxide catalyst towards PCDD/F decomposition was observed even at low temperatures with the aid of ozone. The PCDD/F removal and destruction efficiencies achieved with FexOy/O3 at 180 degrees C reach 94% and 91%, respectively. In the absence of ozone, the destruction efficiencies of all PCDD/F congeners are below 20% and decrease with increasing chlorination level of PCDD/F congener at lower temperature (120 degrees C). However, in the presence of ozone, the destruction efficiencies of all PCDD/F congeners are over 80% on FexOy/O3 at 180 degrees C. Higher temperature and ozone addition increase the activity of iron oxide for the decomposition of PCDD/Fs. Additionally, in the presence of 5% water vapor, the destruction efficiency of the PCDD/Fs is above 90% even at lower operating temperature (150 degrees C). It indicates that the presence of appropriate amount of water vapor enhances the catalytic activity for the decomposition of gas-phase PCDD/Fs.
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, Chungli 320, Taiwan.
authors.forename: Hou Chuan
authors.initials: HC
authors.lastname: Wang
authors.forename: Shu Hao
authors.initials: SH
authors.lastname: Chang
authors.forename: Pao Chang
authors.initials: PC
authors.lastname: Hung
authors.forename: Jyh Feng
authors.initials: JF
authors.lastname: Hwang
authors.forename: Moo Been
authors.initials: MB
authors.lastname: Chang
mesh_terms: D000397:Air Pollution / Q000032:analysis / Q000517:prevention & control; D001572:Benzofurans / Q000032:analysis* / Q000737:chemistry; D002384:Catalysis; D000072338:Dibenzofurans, Polychlorinated; D005290:Ferric Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000032:analysis* / Q000737:chemistry; D011078:Polychlorinated Biphenyls / Q000032:analysis* / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D013696:Temperature; D014835:Volatilization
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D005290:Ferric Compounds; D000072317:Polychlorinated Dibenzodioxins; C000499:ferric oxide; D010126:Ozone; D011078:Polychlorinated Biphenyls