Multi-component behavior of fixed-bed adsorption of dioxins by activated carbon fiber.
The multi-component behavior of fixed-bed adsorption of dioxins (DXNs) was examined through detailed analyses of the concentration profiles of isomers in fixed-bed activated carbon fiber (ACF). Regularities in both adsorption rates and strengths were clarified. (1) The rate of transfer in the adsorption of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCCDs/DFs) tends to increase with decreasing number of chlorine substituents. Axial dispersion also tends to increase with a decreasing number of chlorine substituents under our experimental conditions. (2) Homologues with the same number of chlorine substituents in PCDDs/DFs have similar adsorption strengths. The adsorption strength of PCDD/DF isomers is probably greater than that of co-planar polychlorinated biphenyls (co-PCB) isomers when the number of chlorine substituents is identical. (3) The adsorption strength of isomers depends on their molecular structure. In PCDDs/DFs the toxic isomers, all of which have vicinal chlorine substituents at the 2, 3, 7 and 8 positions, are relatively strong. It is clear, especially in TeCDDs, that isomers with vicinal chlorine substituents are stronger than isomers without. In co-PCBs, isomers without chlorine substituents at ortho positions are stronger than those with, and (4) A close analogy exists between the adsorption strength order for ACF and the elution order in gas chromatography (GC).
Mori
Kozo
K
Advanced Material Business Promotion Department, Osaka Gas Company Ltd., Torishima, Osaka 554-0051, Japan. kmori@osakagas.co.jp
Matsui
Hisaji
H
Yamaguchi
Naoki
N
Nakagawa
Yoshiteru
Y
D000327:Adsorption; D000393:Air Pollutants / Q000302:isolation & purification*; D000397:Air Pollution / Q000517:prevention & control; D001572:Benzofurans / Q000737:chemistry / Q000302:isolation & purification*; D002244:Carbon / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated; D017745:Incineration; D015394:Molecular Structure; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000302:isolation & purification*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D018505:Waste Management / Q000379:methods
D000393:Air Pollutants; D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D002713:Chlorine; D002244:Carbon; D011078:Polychlorinated Biphenyls