Environ. Sci. Techno/. 1982, 16, 229-232
(12) Stolbunov, A. K. Hydrobiol. J. 1976, 12, 24-9. (13) Borighem, G.; Vereecken, J. Ecol. Modell. 1978, 4 , 51-9. (14)
Buikema, A. L., Jr.; McGuiness, M. J.; Cairns, J., Jr. Mar. Environ. Res. 1979, 2, 87-181.
Received for review June 26,1981. Accepted December 21,1981.
This work was supported by the US Department of Energy, Ecological Research Division, Office of Health and Environmental Research, under Contract DE-ACOG-76RLO 1830 with the Pacific Northwest Laboratory operated by Battelle Memorial Institute. Mention of trade names in this manuscript does not imply endorsement by the Pacific Northwest Laboratory or the U S . Department of Energy.
Effluent Analysis of Wastewater Generated in the Manufacture of 2,4,6-Trinitrotoluene. 1. Characterization Study Ronald J. Spanggord," Bradford W. Glbson, Rodney G. Keck, and David W. Thomas Life Sciences Division, SRI International, Menlo Park, California 94025
Jesse J. Barkley, Jr. US Army Medical Research and Development Command, Fort Detrick, Frederick, Maryland 21 701
rn Wastewaters resulting from the production and purification of TNT were characterized. Over 30 nitroaromatic compounds were identified and quantified over a l-yr sampling period. Sources of the identified compounds were predicted on the basis of the operation of the manufacturing process. This work serves as the primary step in an evaluation program to assess the environmental impact of a complex industrial discharge. The allowable level of chemicals discharged into the environment from an industrial waste stream will depend ultimately on the evaluation of the toxicological properties and the environmental fate of the components in the waste stream. The initial step in these evaluations is the identification of the waste-stream components. Once the components are identified, screening studies in various biological systems and studies of the behavior of the components in regard to environmental transport and transformation can commence. The quantitative distribution of the components in the waste stream also must be determined. This entails detailed sampling programs to identify those components that are being consistently discharged and to determine their relative ratios in the waste stream. By studying mixtures of components representative of the discharge, one may identify synergistic or antagonistic effects, and it may be found that there are advantages to testing mixtures when the toxicological testing advances to the chronic phase, especially if the industrial waste is highly complex. Finally, an understanding of how the identified components arise in the waste stream is critical in providing ways to mitigate their environmental impact. This study was undertaken as the initial phase of a toxicological evaluation of a highly complex industrial wastewater resulting from the production and purification of 2,4,6-trinitrotoluene (TNT). The objectives were to identify the components of the discharge-commonly called condensate water--resulting from the continuous TNT manufacturing process, to identify possible sources of the components, and to determine component ratios that can be considered "representative" of the discharge for toxicological investigations. The latter objective is discussed in the accompanying paper (1). T N T is manufactured by the successive nitration of toluene in a continuous process. The product is purified by sodium sulfite treatment to remove unsymmetrical TNT isomers (Sellite process) and is then subjected to OO13-936X/82/0916-O229$O1.25/O
0 1982 American
water washing, drying, and flaking. The water washes, the Sellite waters, and the neutralized spent acids are combined and routed to settling ponds, remaining there for varying periods. The resulting waste is pumped to an evaporator, where the water is distilled, condensed, and discharged. The organic components are stream distillates or volatiles resulting from this evaporative process. This suggested the use of gas chromatography/mass spectrometry (GC/MS) methods for component identification and GC methods for quantitative analysis. GC methods have been used previously to analyze both crude and purified TNT (2) and to monitor TNT formation in the continuous process (3);the latter study demonstrated the resolution capabilities of GC for mixtures of complex isomeric nitroaromatics. Experimental Section Sampling. Samples of condensate water effluent were collected directly from the effluent pipe. One sample was collected at least once a week at random times over 1 yr (54 samples). The condensate effluent is discharged intermittently, and our sampling frequency was designed to include the manufacturing cycles for that year. Once-aweek sampling was considered sufficient to determine a representative discharge. Samples (100 mL) were collected in glass bottles with Teflon-lined caps by plant personnel and airmailed to SRI. Aliquots (20 mL) were extracted with diethyl ether (2 X 20 mL). The extracts were dried over anhydrous magnesium sulfate, fitered, and rotary-evaporated to about 1mL for GC analysis. Analysis. Sample extracts were analyzed initially by packed-column GC using a Hewlett-Packard Model 5711 gas chromatograph equipped with an on-column injection port and a 1.3 m X 1.3 mm (i.d.) glass column packed with 10% DC-200 on 80/100 Gas Chrom Q. The oven was programmed from 105 to 200 "C at 4 OC/min. Nitrogen was used as the carrier gas at a flow rate of 30 mL/min. Detection was achieved by flame ionization, which was maintained at 300 "C. Benzophenone was used as an internal standard. As the complexity of the sample extracts became evident, glass capillary GC was employed to obtain better resolution of the sample matrix. These analyses were performed on a Varian Model 2740 gas chromatograph modified for capillary GC. A 60-m SE-30 glass column (J & W Scientific) was used at 140 "C for 5 min and then programmed to 220 "C at 4 OC/min, with a nitrogen flow
Chemical Society
Environ. Sci. Tachnol., Vol.
16, No. 4, 1982
229
Table I. Components Identified in Ether Extract of Condensate Water compd N-nitrosomorpholine N-morpholinoacetonitrile 2-nitrotoluene 4-nitrotoluene 1,3-dinitrobenzene 2,6-dinitrotoluene 2,5 -dinitrotoluene 2,4-dinitrotoluene 2,3-dinitrotoluene 3,5-dinitrotoluene 3,4-dinitrotoluene 1,5-dimethyl-2,4-dinitrobenzene 3-methyl-2-nitrophenol 5-methyl-2-nitrophenol 2,4,6-trinitrotoluene 2-amino-3,6-dinitrotoluene 2-amino-4,6-dinitrotoluene 3-amino-2,4-dinitrotoluene 3-amino-2,6-dinitrotoluene 4-amino-2,6-dinitrotoluene 4-amino-3,5-dinitrotoluene 5-amino-2,4-dinitrotoluene toluene 1,3,5-trinitrobenzene 2,3,6-trinitrotoluene 2-amino-4-nitrotoluene 2-amino-6-nitrotoluene 3-amino-4-nitrotoluene 2,4-dinitro-5-methylphenol 3,5-dinitroaniline 4-nitrobenzonitrile 3-nitrobenzonitrile
concn range, mg/L
occurrence rate, %
0.1-0.3 0.02-2.0 0.02-0.14 0.01-0.17 0.20-8.5 0.06-14.9 0.01-0.60 0.04-48.6 0.20-2 .o 0.14-6.48 0.03-1.30 0.01 -0.7 1 0.007-0.034 0.006-0.049 0.10-3.40 0.01 -0.05 0 .oo 1-0.1 0 0.03-1.90 0.01-3.80 0.03-3.30 0.02-0.31 0 .OB -17.7 0.02-1.00 0.06-0.20 0.03-1.00 0.002-0.10 0.005-0 .BO 0.002-0 .O 5 0.008-0.40 0.005-0.30 0 .OO6-0 .O2 0.001-0.03
53.1 86.0 38.0 43.0 97.5 100 70.9 100 72.2 94.9 63.3 68.3 24.1 17.7 20.3 5.1 21.5 98.7 84.8 81.0 67.1 75.9 25.3 3.8 6.3 7.6 12.7 2.5 8.9 7.6 3.8 5.1
source of ref samplea (4)
Aldrich Eastman Matheson Eastman Aldrich ICN ICN Aldrich (5)
Aldrich ( 61 Aldrich Aldrich E. I. du Pont (7) (7) (7)
(7) (7) (7) (7) Mallinckrodt (8) (9)
Pfaltz & Bauer Aldrich b (7)
Aldrich Aldrich Aldrich
a Numbered references denote source of synthetic procedure. Other compounds obtained from indicated commercial Prepared in a bomb reactor at 150 "C from 3,4-dinitrotoluene, ammonium hydroxide, and methanol. source,
-
rate of 0.58 mL/min. Flame ionization was used for detection; 1,4-dinitrobenzene was used as an internal standard. Peak areas were determined with a HewlettPackard 3380A integrator-recorder. Components were identified by using an LKB 9000 GC/MS equipped with a PDP-12 computer and confirmed through standard reference spectra or through authentic samples prepared in our laboratory. The chromatographic column and conditions were identical with those used for the packed-column analysis.
Analytical Quality Assurance To assure the validity of the analytical determinations, daily instrument calibration was performed as well as precision and accuracy studies using actual wastewaters containing low (0.10 ppm), medium (2.30 ppm), and high (11.8 ppm) concentrations of major components. The gas chromatograph was calibrated twice daily by using reference standards, and the calculated response factors relative to the internal standard were found to vary less than f2.0% over the analysis period. The precision of the extraction and gas-chromatographic methods was determined for 13 major components and found to be within f10% at the low concentration level (0.10 f 0.01 ppm), 4~4.1%at the medium concentration level (2.30 f 0.09 ppm), and f1.5% at the high concentration level (11.8 f 0.18 ppm) based on six replications. Accuracy was also determined by spiking known concentrations of the 13 major components into an actual wastewater at twice the concentration of the low and medium levels and at one-half the concentration of the high level. The percent recoveries at the above concentration levels were found to be 89.6 f 4.4%, 97.2 f 1.5%) and 104 f 1.8%, respectively. 230
Environ. Sci. Technol., Vol. 16, No. 4, 1982
Results Identifications. A typical capillary column GC profile of the condensate water extract appears in Figure 1. GC/MS data indicated complex mixtures of isomeric nitroaromatics, including isomeric mono-, di-, and trinitrotoluenes; aminodinitrotoluenes; nitrophenols; nitrobenzonitriles; nitroxylenes; and nitrated benzenes in the ether extract. Positive identification of each component was made by comparing mass-spectral data and GC retention time to those of authentic standards. Table I lists the identified compounds, along with the concentration range observed over a 12-month period, the occurrence rate, and the source of the reference sample. Source of Condensate Components. From the list of compounds in Table I, two compounds-N-nitrosomorpholine (I) and N-morpholinoacetonitrile (11)-were identified that are not directly related to aromatic nitration reactions. Compound I may arise from the nitrosation of morpholine (111), which is used as an algicide in watercooling towers at a munition facility (Betz NA-7 water additive). High concentrations of acids, nitrates, and nitrites in the process streams may provide excellent conditions for nitrosation to occur (eq 1). N-Nitroso-
(1)
I
H (111)
+
"02
(11 I
Ne0
(I)
morpholine, a known carcinogen ( I O ) , should be eliminated by substituting a water additive other than secondary, tertiary, or quaternary amine compounds (nitrosamine
m
on w
N
N N
24 2 N
Flgure 1. Gas-chromatographic profile of the ether extract of condensate water.
precursors). Compound I1 could not be identified in the water additives used at the munition facility; however, compounds of the form IV have been reported (11)to be effective algicides, and 11may result from the decomposition of such analogues (eq 2). 0
/I
Ng CYH-C-NHR
NfCCH2 I
The majority of the remaining components arise through the nitration of toluene or through the chemical or microbial transformation of nitrated toluenes. Toluene (the starting material), the three isomeric mononitrotoluenes, and the six isomeric dinitrotoluenes were observed in the ether extract. All of these compounds are expected from the nitration of toluene. However, the concentration of 3,5-dinitrot~luene(V) always appeared high relative to that of the other isomers, indicating that other processes were contributing to the formation of V besides simple electrophilic substitution of toluene, which should occur only to a very small extent (12). Compound V may also arise from the diazotization and decomposition of 4-amino3,5-dinitrotoluene (VI) in water, a reaction that is commonly used to prepare V (eq 3). Compound VI was CH ,
isomers found in the nitration of toluene, which normally are removed by the Sellite process-a process in which nitro groups ortho or para to each other are displaced readily by sulfite, SO,-, leading to water-soluble sulfonic acids. Ammonia will also displace these labile nitro groups and possibly the sulfonic acid, leading to the formation of the aminodinitrotoluenes. Direct displacement has been used to prepare these compounds in the laboratory (7). Since the wastes reside in open ponds with the potential of supporting life before the evaporation process, the possibility of aminodinitrotoluene formation (from the bacterial conversion of nitrate and nitrite to ammonia and of unreacted TNT isomers) is high. The distribution of the most abundant aminodinitrotoluene isomers parallels the TNT isomer distribution observed in the nitration of toluene. The aminodinitrotoluenes that are not obtained readily by displacement reactions-such as 2-amino-4,6dinitrotoluene and 4-amino-2,6-dinitrotoluene-probably arise from the bacterial reduction of TNT (23). Similarly, the aminonitrotoluenes may result from the bacterial reduction of 2,4- and 2,6-dinitrotoluene. A major component of the discharge (13.8%) was 1,3dinitrobenzene. Although this compound could arise, in part, from the nitration of benzene (an impurity in the toluene, the starting material), it probably results from the oxidation and decarboxylation of 2,4- and 2,6-dinitrotoluene (eq 4). 1,3,5-Trinitrobenzene may arise by a CH 3
HO-C=O
CH.
" 1
(VI)
(V)
consistently found in the discharge. Of the 16 possible isomeric aminodinitrotoluenes, 8 were observed and identified in the discharge. These compounds undoubtedly arise from the unsymmetrical TNT
similar route through the oxidation and decarboxylation of TNT. Environ. Sci. Technol., Vol. 18, No. 4, 1982 231
The formation of 1,5-dimethyl-2,4-dinitrobenzene probably results from the nitration of m-xylene, a common impurity in toluene. One might also expect 1,3-dimethyl-2,4-dinitrobenzeneto be formed (6),but this isomer was not observed in the discharge. The nitrophenols can result from the nitration of 3methylphenol, a toluene impurity, to yield 3-methyl-2nitrophenol, 5-methyl-2-nitropheno1, and a dinitration product, 2,4-dinitro-5-methylphenol (eq 5). The last OH
OH
OH
NO,
NO2
NO s
compound was also found in the synthesis of 5-amino2,4-dinitrotoluene from 2,4,5-trinitrotoluene and may result in the wastewater from this route (eq 5). The occurrence of nitrobenzonitriles is difficult to explain by a mechanism acting directly on TNT waste products. If these compounds arise through the dehydration of oxime intermediates, as has been postulated for the formation of 2,4,64rinitrobenzonitrile in the photolysis of T N T (14), then possibly the nitrobenzonitriles result from the action of benzyl anions and nitrite in a photolytic process (eq 6). This possibility exists due to the holding
NOS
CHINO
CH-N-OH
CaN
NO 1
NO*
NO 2
period and open-trough transport of the wastewaters.
Discussion Although many isomeric components were observed in the discharge, their mass spectra were sufficiently different to allow identification by comparison to authentic standards. (The mass spectrum of any of the condensate components is available on request.) In the case of the aminodinitrotoluenes, where 16 isomers are possible, not all of the isomers could be evaluated by mass spectrometry. However, prior knowledge of the nitration products of toluene suggested the most probable isomers to be present. These isomers were then synthesized or otherwise obtained for comparative analysis, which was based not only on mass-spectral data but also on GC retention time. The GC profiles from the various samplings consistently showed 2,4-dinitrotoluene, 2,6-dinitrotoluene, and 1,3-dinitrobenzene as the major effluent components, with ap-
232 Environ. Sci. Technol., Vol. 18, No. 4, 1982
proximately half of the 32 identified compounds occurring in more than 50% of the analyzed samples. Since the three major compounds represented approximately 75 % by weight of the total component distribution, many of the minor components may have been present below detection limits when the major components were quantified in the parts-per-billion range. Thus, the occurrence rate for each component may be higher than indicated in Table I. An understanding of the formation of the identified components in the initial phase of a wastewater characterization study will allow decisions to be made before subjecting compounds to toxicologicaltesting. Compounds of known toxicity or of potential concern, such as N nitrosomorpholine, can be eliminated by modifying the process stream (substituting a water additive). If they cannot be eliminated, appropriate pollution abatement controls must be applied or environmental fate mechanisms must be established demonstrating that these materials are quickly rendered innocuous to the environment. Acknowledgments
We thank Dr. N. Burlinson of the Naval Surface Weapons Laboratory for contributing some of the analytical measurements. L i t e r a t u r e Cited Spanggord, R. J.; Suta, B. D. Environ. Sci. Technol., following paper in this issue. Gehring, D. G.; Shirk, J. E. Anal. Chem. 1967, 39, 1315. Dalton, R. W.; Kohlbeck, J. A.; Bolleter, W. T. J . Chromatogr. 1970,50, 219. Beilsteins Handbuch der Organischen C h e p i e , 1937,27, 8. Cohen, H.; McCandlish, B. J . Chem. SOC.London 87,1271. Coon, C. S.;Blucher, W. C.; Hill, M. D. J. Org. Chem. 1973, 38, 4243. Coon, C. L.; Spanggord, R. J.; Son, D. U. H. J. Org. Chem. 1979,44,2499. Gilman, H., Ed. ”Organic Synthesis”; Wiley: New York, 1941; Vol. 1, p 541. Dennis, W. H.; Rosenblatt, D. H.; Blucher, W. G.; Coon, C. L. J. Chem. Eng. Data 1975,20, 202. Druckery, H.; Preussmann, R.; Ivankovic, S.; Schmahl, D. Krebsforsch. 1967. 69. 103. Langdon, W. E.; Levis, W. W. U.S.Patent 3 104 199. Urbanski, T. “Chemistry and Technology of Explosives”; Macmillan: New York, 1964; Vol. I. McCormick, N. G.; Fecherry, F. E.; Levinson, H. S. Appl. Environ. Microbiol. 1976, 31, 949. Burlinson, N. E.; Sitzman, M. E.; Kaplan, L. A,; Kayser, L. A. J . Org. Chem. 1977, 44, 3695. Received for review December 15, 1980. Revised manuscript received June 6,1981. Accepted December 22,1981. This work was performed under Contract D A M D 17-76-C-6050 from the US A r m y Medical Research and Development Command.
