title: Removal efficiencies for 136 tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofuran congeners with activated carbons.
abstract: In this study, the removal efficiency of 136 tetra- to octa-chlorinated dibenzo-p-dioxin (CDD)/furan (F) congeners from a nitrogen + oxygen carrier gas was studied using a laboratory-scale, fixed bed adsorption system. Two kinds of activated carbon with dissimilar pore structures were used as adsorbents. The total concentration of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) in the source gas was 541 ng/Nm(3) and that of the 17 toxic 2,3,7,8-substituted PCDD/Fs 96.35 ng/Nm(3), accounting for 17.8% of the total original weight amount. Their toxic equivalent quantity (TEQ) was 8.31 ng I-TEQ/Nm(3). For both activated carbons, the removal efficiencies of the ten PCDD/F homologue groups rise with chlorine substitution number. The removal efficiencies vary approximately as a power function of vapor pressure (correlation coefficients r(2) = 0.93 and 0.81, respectively). Competitive adsorption and desorption occur as adsorption time went on, causing elution of the lower chlorinated homologues, i.e. tetra-CDD/F and Penta-CDD/F congeners. In addition, there are significantly different concentration distributions for isomers in the same homologue groups. However, their removal efficiencies have weak correlation with their initial concentrations. The correlation coefficients are from -0.47 to 0.32 and from -0.57 to 0.46 respectively for the two kinds of activated carbons.
authors.affiliation: State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Zheda Road 38#, Hangzhou, 310027, China.
authors.forename: Xu-Jian
authors.initials: XJ
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Zheda Road 38#, Hangzhou, 310027, China. lixd@zju.edu.cn.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Li
authors.affiliation: State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Zheda Road 38#, Hangzhou, 310027, China.
authors.forename: Ming-Jiang
authors.initials: MJ
authors.lastname: Ni
authors.affiliation: State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Zheda Road 38#, Hangzhou, 310027, China.
authors.forename: Ke-Fa
authors.initials: KF
authors.lastname: Cen
mesh_terms: D000327:Adsorption; D001572:Benzofurans / Q000302:isolation & purification*; D002606:Charcoal / Q000737:chemistry; D004147:Dioxins / Q000302:isolation & purification*; D004785:Environmental Pollutants / Q000302:isolation & purification*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000302:isolation & purification*
chemical_list: D001572:Benzofurans; D004147:Dioxins; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D002606:Charcoal; C023614:dibenzofuran; C020887:dibenzo(1,4)dioxin
keywords: Activated carbon; Adsorption; Initial concentration; PCDD/Fs; Removal efficiency; Vapor pressure