Chemosphere, Vol.13, No.3, P r i n t e d in G r e a t B r i t a i n
pp
421-426,
1984
0 0 4 5 - 6 5 3 5 / 8 4 $ 3 . 0 0 + .OO © 1 9 8 4 P e r g a m o n P r e s s Ltd.
ADSORPTION AND CHLORINATION OF DIBENZO-P-DIOXIN AND I-CHLORODIBENZO-P-DIOXIN ON FLY ASH FROMMUNICIPAL INCINERATORS H. O. Rghel and G.A. Eiceman* Department of Chemistry New Mexico State University Las C r u c e s , NH 88003 U.S.A. ABSTRACT A d s o r p t i o n and c h l o r i n a t i o n r e a c t i o n s f o r d l b e n z o - p - d l o x l n (DO) and 1 - c h l o r o d i b e n z o - p d l o x l n (1-MCDD) on f l y a s h were c h a r a c t e r i z e d q u a n t i t a t i v e l y u s i n g l a b o r a t o r y - b a s e d s i m u l a t i o n o f s t a c k e m i s s i o n s w i t h a i r and H C l - a l r a t m o s p h e r e s . I n f l u e n c e s o f c o n t a c t t i m e and t e m p e r a t u r e were s t u d i e d and r e s u l t s showed b e h a v i o r o f DD and I-MCDD c o n s i s t e n t w i t h t h a t for ],2,3,4-tetrachlorodlbenzo-p-dloxln. D i - , t r i - , and t e t r a - c h l o r l n a t e d d l o x l n s were m a j o r compounds p r o d u c e d f r o m h e t e r o g e n o u s p h a s e r e a c t i o n s o f DD and I-MCDD w l t h HCI i n a i r . Total c o n v e r s i o n t h r o u g h r e a c t i o n s a l o n e were a s h i g h a s 81~ and 58% r e s p e c t i v e l y . INTRODUCTION Polychlorlnated dibenzo-p-dloxlns (PCDD) have been found amongst a complex mixture of organic compounds on fly ash produced in municipal incinerators during combustion of refuse (I-4).
Origins, routes for entry, and fate of PCDD in the atmospheric environment have become
major concerns due to potentially serious human health effects through exposure to PCDD (5-7). In prior work, a model PCDD (I,2,3,4-TCDD) was found to be reactive toward HCI in air with the TCDD adsorbed on fly ash.
Furthermore, fly ash was not an inert substrate and 1,2,3,4-TCDD
was irreversibly adsorbed or decomposed in part at temperatures as low as 150°C (8,9).
These
experiments were started in an attempt to determine the possibility of a chemical, rather than physical, basis for Townsend's hypothesis (I0,11).
Townsend concluded after examination of
extensive envlronmental-analytlcal data collected by Dow Chemical Co. (12) that PCDD underwent reactions on hot particulate matter during release into the environment.
Ratios of various
cogeners were not constant but varied as a function of distance from point source and finally reached an equilibrium value at some unspecified distance. used neither to prove nor disprove Townsend's model.
Results from our prior work may be
However, reactions seen with 1,2,3,4-
TCDD provide limited evidence for a chemical basis under conditions used in those studies.
421
422
Similar heterogenous phase reactions between chlorinated organic compounds, other than PCDD, on fly ash and other inorganic matrices have been reported (13-15).
Moreover, recent
kinetic studies by Shaub et al. (16-17) showed that gas phase reactions alone are insufficient to account for observed levels of PCDD in fly ash and gas-solid reactions may also be significant not only during transport but also during formation processes. Immediate objectives of work reported here include:
a) determination if reactions of
1,2,3,4-TCDD on fly ash seen earlier are general in nature for DD and I-MCDD, and b) collection of further quantitative data of PCDD behavior on fly ash toward a more complete understanding of possible sample transformations during release and transport of the fly ash into the atmosphere. EXPERIMENTAL Nearly all details on procedures, reagents, and instrumentation were identical to those in prior similar studies (8,9,18).
However, the solvent (benzene) used in extraction of fly
ash was replaced with an isotropic mixture of acetone and hexane.
In addition, a Durabond
(Alltech Associates, Inc., Deerfield, IL) fused silica column containing OV-101 was used instead of a regular coated fused silica column.
Procedure blanks were always low in residue
contamination or artifacts. As before, all final quantitative measurements on fly ash extracts were made using selected ion monitoring (SIM) analysis in gas chromatography/mass spectrometry (GC/MS) methods. RESULTS AND DISCUSSION Adsorption Extraction of DD and I-MCDD from fly ash and condensation of extracts resulted in loss of analyte as was also seen with 1,2,3,4-TCDD (8).
Moreover, percent recovery of DD and I-MCDD
through flash evaporation from inlet to reaction tube, extraction, and condensation was only 52% and 56% respectively.
Since flash evaporation was roughly 100% efficient, all mass lost
was lost during handling of the extract.
Although losses through use of a rotary evaporator
may be expected, and similar losses were also seen for 1,2,3,4-TCDD,
such values for DD and
MCDD were large and were due possibly to higher volatility of DD and MCDD compared to that for 1,2,3,4-TCDD.
In all further studies, results were corrected for loss in efficiency from f
sample preparation. Trends in adsorption of DD and I-MCDD as irreversible loss (or unrecovered mass) to fly ash are shown in Figures I and 2.
The behavior was similar to that seen for 1,2,3,4-TCDD with
increased degree of loss with increased temperature and with little effect from time between
423
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Figure 2. Irreversible loss or decomposition (expressed as percent adsorption) of l-chlorodlbenzo-p-dioxln on fly ash in air atmosphere. At temperatures of 50 and IO0°C, recovery was complete within experimental errors corrected for sample preparation.
Figure I. Irreversible loss or decomposition (expressed as percent adsorption) of dlbenzo-p-dioxln on fly ash in alr atmosphere. At temperatures below 100 to 150°C, recovery was complete within experimental errors corrected for sample preparation.
120-
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Figure 3. Results from SIM analysis of fly ash extract from chlorination of DD on fly ash using HC1 in air. Peak areas are from raw data and are useful for relative comparison.
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Figure 4. Results from SIM analysis of fly ash extract from chlorination of I-MCDD on fly ash using HCl in air. Peak areas are from raw data and are useful for relative comparison.
424
2.5 to I0 mln.
Maximum losses to irreversibly bonded products or to products not seen through
GC and GC/MS analysis amounted to roughly 49% for DD and 27% for I-MCDD at 200°C.
Behavior
at temperatures greater than 200°C was not studied and products of decomposition were never detected in a cold trap for reaction tube effluent.
Data for recovery from the fly ash at
temperatures of 100°C and below were erratic with recovery efflclencles near or above 100%. This behavior with standard deviations as large as 30% was believed also due to difficulties from volatility during sample preparation of samples and standards.
Nevertheless,
irreversible loss outside experimental error was seen only at 150 and 200°C as shown in Figures I and 2.
No lower or higher chlorinated PCDD were detected in extracts from these
studies. Chlorination Reactions Results from chlorination of DD and I-MCDD on fly ash using 5 to 10% (Vol/Vol) HCI in air at temperatures between 50 to 250°C are shown in Figures 3 and 4.
Plots of peak area
from SIM analysis for each cogener detected showed chlorination of DD to MCDD, dichloro(DCDD), trlchloro- (T3CDD), and tetrachloro- (T4CDD) dibenzo-p-dioxin. chlorinated under identical conditions to DCDD, T3CDD, and T4CDD.
Similarly, I-MCDD was
Chlorinated dioxins with
5 to 8 chlorine atoms were detected at very low levels relatively in both chlorination of DD an MCDD.
As seen before with chlorination of 1,2,3,4-T4CDD, effects of temperature on chlori-
nation were dramatic with a maximum conversion of starting material to higher chlorinated species at 150°C.
Although attempts have not been made for absolute quantification of
cogeners in extracts, plots of detector response for direct comparisons show differences in relative abundances at each temperature in both chlorination studies.
For example in
chlorination of DD, MCDD was the predominant species between 50 to 150°C, where as DCDD was the predominant PCDD at 200°C.
As before with 1,2,3,4-TCDD, the higher the temperature of the
fly ash the greater the production of higher chlorinated cogeners up to 2000C, where percent conversion and yield for higher chlorinated cogeners decreased. percent conversion of DD were:
Approximate values for
50=C, 12%; 100°C, 30%; 150°C, 81%; 200~C, 56% and 2500C, 48%.
Similar though not identical trends were seen for chlorination of MCDD as shown in Figure 4. Values for percent conversion of MCDD were also a function of temperature as:
50°C, 9%;
lO0°C, 14%; 150°C, 29%; 200°C, 58% and 250°C, 49%. Since values for conversion were corrected for irreversible adsorption, losses in conversion efficiency may be due to presence of DD or MCDD as an unreactive but reversibly adsorbed species.
No other data or theories regarding this behavior
exist presently apart
425
from earlier studies using 1,2,3,4-TCDD (9).
Production of higher chlorinated cogeners may
be expected to proceed through consecutive chlorination reaction as seen in Figures 3 and 4 through comparison of relative abundance of each cogener.
Highly chlorinated organic
compounds such as CCI 4 have been used as chlorinating reagents in heterogenous reactions (19) at temperatures of 500°C.
Moreover, Karasek et al. (20) reported a correlation between PCDD
and other chlorinated organic compounds.
Use of CCI 4 and octachlorodlbenzo-p-dloxin
in the
reaction tube as chlorinating reagents showed no noticeable effects on DD or MCDD and no higher chlorinated species were detected using such chlorinating agents under conditions for these studies. CONCLUSIONS Several conclusions can be made from results presented above. a)
Chlorination of chlorinated dloxins on fly ash is common to DD, MCDD, and
1,2,3,4-TCDD. b)
These include:
This type of heterogenous reaction may reasonably be expected for other PCDD,
At temperatures above 150°C, DD and MCDD (and 1,2,3,4-TCDD) were adsorbed irrever-
sibly or decomposed on fly ash.
Further processing of fly ash at temperatures above 200°C in
actual incinerators may lead to reduced levels in particulate emissions unless other undefined variables influence reactivity, c)
HCI is an effective chlorinating agent while CCI 4 and OCDD were not successful for
chlorination between 50 to 400°C, and d)
Disproportionatlon reaction of MCDD was not evident.
ACKNOWLEDGEMENT Although the research described in this article has been funded wholly by the United States Environmental Protection Agency under assistance agreement number R809084-02-0 to G.A. Eiceman, it has not been subjected to the Agency's required peer and administrative review and, therefore, does not necessarily reflect the view of the Agency and no official endorsement should be inferred.
REFERENCES I.
Olie, K., Vermulen, P.L., and Hutzinger, O., Chemosphere 6, 455 (1977).
2.
Buser, H.R., Bosshardt, H.-P., and Rappe, G., Chemosphere 7, 105 (1978).
3.
Eiceman, G.A., Clement, R.E., and Karasek, F.W., Anal. Chem. 51, 2343 (1979).
4.
Lahaniatis, E.S., Parlar, H., and Korte, F., Chemosphere 6, 11 (1977).
426
5.
Tsushimoto, G.; Matsumura, F.; 5ayo, R., Environ. Toxicol. Chem., 1, 61 (1982).
6.
Weber, H.; Poiger, H.; Schlatter, C., Xenobiotica, 12, 6 (1982).
7.
Phillpp, M.; KrasnobaJew, V.; Zeyer, J.; Huetter, R., FEMS Symp., Vol. 12 (1981).
8.
Rghei, H.O. and Eiceman, G.A., Chemosphere, Ii, 569 (1982).
9.
Eiceman, G.A. and Rghei, H.O., Chemosphere, II, 833 (1982).
I0.
Townsend, D.I., "The Use of Dioxin Isomer Group Ratios to Identify Sources and Define Background Levels of Dioxins in the Environment", Abstract 80, Pesticide Division, National Meeting American Chemical Society, Washington, D.C., September I0, 1979, and reprint of that lecture dated December 6, 1979 from the author.
ii.
Townsend, D.I., Chemosphere, 12, 4/5, 637 (1983).
12.
The Chlorinated Dioxin Task Force, "The Trace Chemistries of Fire - A Source of and Route for the Entry of Chlorinated Dioxins into the Environment", Dow Chemical Company, Midland, Michigan (1978).
13.
Gaurey, J., Simont, J., Electro. Chim. Acta., 24 (a), 1039 (1979).
14.
Evdokimova, A.S.; Shuten Kova, T.V.; Rufikov, S.R.; Bikkulor, A.Z.; Volitor, R.B., Otkrytiya, Ozobret. prom. obraztsy Toverney Zmaki, 32, 84 (1979).
15.
Eiceman, G.A. and Rghei, H.O., Environ. Sci. Technol., 16, 53 (1982).
16.
Shaub, W.M. and Tsang, W., Environ. Sci. Technol. In Press.
17.
Shaub, W.M. and Tsang, W., to appear in the proceeding of the symposium on the Origins and Fate of Dioxins and Dibenzo Furans in the Total Environment, II., American Chemical Society Meeting, Washington, D.C. (1983).
18.
Eiceman, G.A. and Rghel, H.O., to appear in the proceeding of the symposium on the Origin and Fate of Dioxlns and Dibenzo Furans in the Total Environment, II., American Chemical Society Meeting, Washington, D.C. (1983).
19.
Dorrepaal, W. and Lauw, R., Int. J. of Chemical Kinetics, I0, 249 (1978).
20.
Karasek, F.W. and Viau, A.C., J. Chromatogr., 265, 79 (1983).
( R e c e i v e d in T h e N e t h e r l a n d s
12 N o v e m b e r
1983)