Environmental Engineering Reference
In-Depth Information
Table 4.2 Emissions of dioxins and furans under control [
24
]
No
IUPAC name
Common abbreviation
I-TEQ
1.
2,3,7,8 Tetrachlorodibenzodioxin
TCDD
1.000
2.
1,2,3,7,8 Pentachlorodibenzodioxin
PeCDD
0.500
3.
1,2,3,4,7,8 Hexachlordibenzodioxin
HxCDD
0.100
4.
1,2,3,7,8,9 Hexachlordibenzodioxin
HxCDD
0.100
5.
1,2,3,4,6,7,8 Heptachlorodibenzodioxin
HpCDD
0.010
6.
Octochlordibenzodioxin
OCDD
0.001
7.
2,3,7,8 Tetrachlorodibenzofuran
TCDF
0.100
8.
2,3,4,7,8, Pentachlorodibenzofuran
PeCDF
0.500
9.
1,2,3,7,8 Pentachlorodibenzofuran
PeCDF
0.050
10.
1,2,3,4,7,8 Hexachlorodibenzofuran
HxCDF
0.100
11.
1,2,3,6,7,8 Hexachlorodibenzofuran
HxCDF
0.100
12.
1,2,3,7,8,9 Hexachlorodibenzofuran
HxCDF
0.100
13.
2,3,4,6,7,8 Hexachlorodibenzofuran
HxCDF
0.100
14.
1,2,3,4,6,7,8 Heptachlorodibenzofuran
HpCDF
0.010
15.
1,2,3,4,7,8,9 Heptachlorodibenzofuran
HpCDF
0.010
16.
Octochlorodibenzofuran
OCDF
0.001
The largest amounts of polychlorinated dioxins and furans are produced mainly
through the combustion of wood fuel, coal and many other organic substances with
different, generally halogenated functional groups. For temperatures between
250 and 800
C, the process is called “cold combustion” and releases dioxin
compounds through intermediates resulted from the combustion of lignin or tan-
nin—for wood, or intermediaries produced by cyclic and aromatic compounds—for
coal [
22
,
23
] (Figs.
4.3
,
4.4
, and
4.5
).
Conversion through combustion of organic compounds with aromatic cycles to
dioxins and furans is possible in the presence of any Cl
-
ion donor, the reaction
being catalyzed by some heavy metal ions, of which Cu
2+
is mentioned most
frequently [
22
,
24
,
26
].
If fuel and fuel oil combustion generally produces small specific amounts of
dioxins, chloride-containing organic compounds generate dioxins and furans
directly in the flame, for which reason they are known as
polychlorinated organic
compounds
(POPs) and their use is strictly controlled or forbidden according to
international conventions concerning pollution control [
25
].
This category includes biphenyls or polychlorinated terphenyls (PCB or PCT).
Owing to their dielectric and thermo-mechanical properties, in the past they were
largely used in high-voltage transformers and condensers. Currently, PCB or
PCT-containing oils are forbidden in any field of activity, because they are dioxin
precursors and very toxic. Besides these polynuclear compounds, the POPs list
