Composition, Treatment Efficiency, and Environmental Significance of Dye Manufacturing Plant Effluents Larry M. Games and Ronald A. Hltes" Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02 139
Extraction of the organic compounds from a dye manufacturlng plant wastewater with methylene chloride revealed the presence of several chemicals, some of whlch may be potentially toxic. Qualitativeresults of composlte sampling over a 2.5-month period indicated that grab sampling techniques would have been misleading In assesslng envlronmental Impact. Semiquanttlatlon of the compostles from both treated and untreated effluents Indicated that some compounds, 1,3,3-trimethyloxlndole for example, were actually /ncreas/ng in concentratlon as a result of reactions occurrlng during treatment. One of the compounds identified, 5-chloro-3phenyl-l,2,4-thiadiarole, has been patented as a nematoclde and seems to result from an impurity in a raw material. The lack of relevant toxicity data about most of the compounds found in thls study emphaslres the need for methods of determlnlng the effects of chronic low level exposures to water pollutants.
Synthetic chemicals associated with various types of industries have been shown to be the cause of tumor formation leading to increased incidence of cancer among industrial workers employed in these operations. A notable, fairly recent example is the clustering of rare liver cancer cases among employees of plants producing or utilizing vinyl chloride. In the late 1800's, dye manufacturing plant employees were found to be victims of increased incidence of bladder cancer, later traced to the use of benzidine and 2-naphthylamine in dye synthesis ( 1 ) . Some dyes, such as Red Dye No. 2, have also been shown to be carcinogenic ( I ) . Because of these previous findings concerning the dye industry, and because dye manufacturing in general involves the use of rather complex and sophisticated chemicals of various kinds, we chose a dye manufacturing plant a t which to conduct an in-depth study of the types and amounts of synthetic organic compounds being released into the environment. The only previous study of a dye plant effluent of which we are aware was a rather cursory study done by the EPA (2), even though a rather large quantity of dyes are produced annually in the United States, about 3 x 10' lb (3). Since some dye intermediates are known to be toxic, an extensive study seemed to be desirable. This report includes (a) an identification and semi-quantitation of the dichloromethane extractable organic compounds present in the dye plant effluent, (b) an assessment of the abatement efficiency of the wastewater treatment plant on the basis of individual compounds versus COD or BOD measurements, and (c), from the analysis of receiving water and sediment samples, an evaluation of the environmental significance or hazard associated with the particular plant studied. Plant Characteristics and Geography. The geographical layout of the plant is shown in Figure 1. The plant utilizes an average of 3 x lo6 gallons/day process water drawn from the fresh water Back River and released after treatment into the brackish water Cooper River which flows directly into the Atlantic Ocean. The flow of the Cooper River is such that the final effluent is diluted by a factor of lo3;this reduces the
concentration of any compound present from 1 ppm to 1 ppb upon release. The plant wastewater treatment system is shown in Figure 2. Total residence time (by volume) is about 19 days, but in practice, flow patterns can sometimes reduce this to 6 days. The acidic raw effluent is neutralized following the equalization pond and then mechanically stirred in the aeration lagoons to accelerate aerobic biological degradation. Two large settling ponds, which make up -80% of the total system volume, complete the treatment. Preliminary studies indicated that the water from the Back River was unpolluted so work was concentrated at the Points A and B, representing the raw and final effluent. Because the dye plant operates in the batch mode, changing product mix often, a complete picture of the effluent could be obtained only by composite sampling. For a 21/2 month period, composites were collected weekly, sampling over the whole 168-h period on a flow-adjusted basis. The plant wastewater after treatment is gray in color with no visible suspended matter and no noticeable odor. The reduction of COD and BOD in the treatment plant averages about 70% and 85%, respectively; normal effluent values are 200 mg/L and 60 mg/L. Based on the average COD value, the plant dischargesapproximately 920 tons of organics yearly. Identifications. Although many ancillary techniques are used, the heart of the analytical methodology is gas chromatographic mass spectrometry. Since very few of the more complex compounds identified were listed in mass spectral compilations such as the Eight Peak Index ( 4 ) or the computerized Mass Spectral Search System (5),we were forced to rely heavily upon high resolution mass spectrometry, a priori spectral interpretation, synthesis and purchase of standards, and reference material such as the Trade Commission Report ( 3 ) for identification purposes. The rather secretive nature of the dye industry meant that the mass spectra of many of the compounds found had not been published even though in common use. Although the company involved was very willing to accommodate our work and to aid in sampling, we wish to emphasize that they did not furnish us with any information about their chemical processes. The two exceptions to this were their willingness to confirm the reasonable presence of several of the more complex molecules after identification was complete and to specify the correct isomer in some ambiguous substitution cases. Substitution patterns are nearly impossible to discern from mass spectrometric data alone without standard spectra for comparison. Even if standards are available, it is not always possible to choose, for instance, between a meta- and parasubstituted aromatic ring. As a result, many of the compounds identified in this work, unless we know or have good reason to suspect the substitution pattern, are reported without a specified substituent relationship. In the case of the aromatic amines, this may be particularly important, since N-substituted compounds can be inherently more toxic than ringsubstituted ones (1).
EXPERIMENTAL Sampling. D y e Plant. Preliminary grab samples were col-
lected in 1-galamber glass bottles with Teflon-lined caps. These ANALYTICAL CHEMISTRY, VOL. 49, NO. 9,AUGUST 1977
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MPRSHLAND
Y6h
DAM
(/
TO C H A R L E S T O N BPY
Flgure 1. Geographical location of the dye manufacturing plant and locations of the river water (0)and sediment ( x ) sampling sites
.
COOPER RIVER
BACK RIVER TO C H A R L E S T O N BAY
Figure 2. Diagram of the dye manufacturing plant wastewater treatment system. Composite sample collection points are designated A (raw effluent) and B (final effluent)
bottles were carefully pre-cleaned by detergent washing, followed by rinsing in distilled water, nanograde methanol, and nanograde methylene chloride. Samples were preserved during air shipment to the laboratory by the addition of reagent grade HC1 to lower the pH to 2 and addition of 250-300 mL of CH2C12. Addition of the organic solvent also started the extraction. Composite samples of the raw and final effluent were also collected in pre-cleaned glass bottles. Compositing was done on a variable flow-adjusted basis for the raw effluent and the final effluent. River Water and Sediment. River water and sediment samples were collected during July 1976,and sampling locations are shown in Figure 1. These locations were chosen (on the basis of local knowledge about current patterns in the area) as places where the effluent stream might pool. Both sets of samples were obtained by a scuba diver operating from a small boat. The sediment samples were collected using a small, pre-cleaned garden spade. Most of the samples were predominantly mixed grades of sand, two were hard clay, and three contained mostly soft mud, as specified in Figure 1. The samples were placed in acid-cleaned jars and returned to the laboratory within five days where they were frozen until analysis. River water was collected in 1-gal bottles at or near mid-depth of the river. Workup and preservation was identical to that for the effluent samples. Extraction. Water. The acidic samples were extracted immediately upon arrival at the laboratory. While this extraction should collect all neutral and acidic species, many amines are present in dye plant effluents, so the water was adjusted to pH 10 with reagent grade KOH and a second extraction was carried out to isolate basic species. 1434
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Both the acid and base extracts were highly colored, the hue of which changed with each composite sample. Two-dimensional thin-layer chromatography of one of these extracts showed over 50 colored spots which were presumed to be dyes. Sediment. Approximately 150-g sediment samples were Soxhlet-extractedwith 60/40 benzenemethanol. Extraction with other solvents such as methylene chloride or isopropanol/benzene did not appear to improve extraction speed or efficiency. All solvents used were nanograde quality purchased from Mallinckrodt. For all samples, extracting solvents were removed by distillation at reduced pressure using a commercially available rotary evaporator equipped with Teflon seals. Temperatures were kept at 40 "C or below to minimize sample loss through volatilization during this step. Analysis. Preliminary gas chromatographic analysis of the sample extracts was done on a 2-mm i.d., 1/4-incho.d., 6-foot glass column packed with 3% SP-2100 on 80/100 mesh Supelcoport. The column was normally temperature-programmed from 70 to 310 "C at 8"/min in a HP-5730A gas chromatograph equipped with a flame ionization detector. If preliminary gas chromatographic analysis indicated the presence of a large unresolved "hump" of alkanes, as in most of the sediment samples, open column liquid chromatography with deactivated silica gel (10% water added) was used to separate the alkanes. Elution with hexane removed most of the alkane material, and subsequent elution with benzene and methanol allowed recovery of the dye-plant-derived compounds. Gas chromatographic mass spectrometry (GC/MS) was done on a HP-5982A quadrupole instrument operated under computer control (HP-2100s) in the continuous scanning mode. The same gas chromatographic column described earlier was utilized. Although the instrument has a dual chemical ionization/electron impact source,all spectra reported here are electron impact spectra obtained at -70 eV ionization energy. Because of the complexity of the samples, some of the gas chromatographic analysis was done on high resolution open tubular glass capillary columns. The liquid phase was SE-52, a methyl phenyl silicone; it was coated by a static coating method (6)on columns varying in length from 15 to 30 m with inner diameters of approximately 0.27 mm. GC/MS using the capillary column was helpful in many cases to obtain cleaner spectra with less interference from adjacent gas chromatographic peaks. Since standard spectra of most of the more complex compounds from the dye manufacturing industry were not available, high resolution mass spectrometry was utilized to aid in the identification by providing molecular formulas. Unresolved whole samples were analyzed, and matching of individual peaks in the high resolution mass spectrum to specific compounds was done by use of low resolution mass chromatograms. This technique is obviously useful only when the compound under study has a unique fragment or molecular ion. Data were obtained on a DuPont 21-llOB double focusing mass spectrometer located in the laboratory of K. Biemann (7). Selected ion monitoring is a technique which increases mass spectrometric sensitivity by a factor of lo3 (in some cases) by observing only a limited number of masses rather than the whole spectrum (8,9). The HP-5982A GC/MS system is provided with software to allow monitoring of up to four masses at any given time with variable dwell times. This methodology was used extensively in the studies of the sediment and river water samples, since concentrations of dye-plant-derived compounds were too low to detect by standard GC/MS procedures.
RESULTS AND DISCUSSION Results of the 21/2-monthcompositing study for both the treated and untreated plant effluent are shown in Table I. Structures for a selected group of the compounds listed in Table I are illustrated in Figure 3 and identified by number. Several of these will be discussed in more detail. The numbers in parentheses in Table I refer to the frequency of presence, that is, the number of composite samples in which the particular compounds were found. The concentration range may be somewhat misleading since in some cases only one or two samples contained the compound in question. The number
WCH3 a,cH2 CH3
15
CH3
21
23 R = H 2 6 R = C$
CH3
24
I158
CH3
41 R = N H 2
0 N = N 0 ° C H 3
8 39
H 0 II
42
40
$a
60
120
148
:E!
160
S2C
C?2
C H \ C /IIH
0
CH3
45
,CH2CH20CH2CH2
CH2CH0
OH
HRMS A = .7mmu 0
--fNYaH9
I
117 132
1160
i,
0
1175(Mt)
40
52
NHCOCH3
49 R:OCzHs 50 R = O C H 3
Flgure 3. Structures for some of the compounds found in the dye plant wastewater. Numbers refer to compounds as listed in Table I
Figure 5. Mass spectra of compounds labeled A , B, C, and E in Figure 4. The HRMS A refers to the difference in mmass units between the measured exact mass and that calculated from the molecular formula
min
6
10
20
30
1 ASTRAPHLOXIN (RED D Y E )
FF
Flgure 6. Summary of reactions involving 1,3,3-trimethyl-2-methyleneindoline ( 7 7 , 23, 24). The earliest reference to this compound, called Fischer's Base, is found in a paper from 1887 (25) and E were obtained from high resolution data, and the structures in Figure 5 were hypothesized by analogy, but positive identification was difficult. A search of the Trade Commission report on synthetic organic chemicals produced in the United States in 1973 (3) revealed that compounds B and E were in fact manufactured by the company which operated the plant we were investigating. A knowledge of mass spectral fragmentation patterns partially confirmed the identification, and purchase of the compound B , 1,3,3-trimethyl-2-methyleneindoline(from Aldrich Chemical Co.), enabled a positive identification by mass spectrometry and GC retention time. The indolineacetaldehyde, compound E , ANALYTICAL CHEMISTRY, VOL. 49, NO. 9, AUGUST 1977
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Table I. List of Compounds Found in the Composite Samples Collected from the Dye Manufacturing Planta Final Raw wastewater, Raw wastewater, Compound effluent ppb Compound PPb PPb 27. Dinitrophenol 1. Chlorobenzene 90-530 ( 8 ) b 400-3200 (8) NDC 28. Dichloronaphthalene ND 95-180 (2) 2. Bromoaniline 3 (1) 29. Bromodiethylaniline 23-120 (3) 30. Bromonitrobenzene 37-190 ( 5 ) 3. Anisole 5-71 (4) ND 31. Nitroaniline 270 (1) 3 2. Tribromoaniline 4. Phenol 110-910 (8) ND 54-87 (3) 33. N-Hydroxyethyl-NND 5. Aniline 36-480 (6) 10-96 ( 7 ) butyl-p-bromo6. 4,4-Dimethylpentene 38-420 (8) ND aniline 34. Bromodinitro120 (1) benzene 7. Dichlorobenzene 90-380 (8) 5-32 (3) 35. Bromonitroaniline ND 36. N-Hydroxyethyl-N36-330 (4) 8. Nitrobenzene 15-240 (3) bu tylaniline 23 (1) 37. 1,3,3-TrimethylND oxindole + C,H,e 9. C, aniline 8-15 ( 4 ) 38. N-Hydroxyethyl-N54 (1) ND 10. Chloroaniline 7-12 (5) ND cyanoethyl aniline 11. C, aniline 15-30 (2) 7-24 ( 2 ) 39. Methoxyazobenzened ND 12. c 40. N-Butyl-N-p-(p28-250 (3) hydroxyethoxy)12. C, aniline ND ethyl anilined 4 (1) 41. 5-Amino-3-phenyl5-46 ( 4 ) 13. Anisidine 29-84 ( 2 ) ND 1,2,4-thiadiazoled 42. 1,3,3-Trimethyl-A 3-52 (6) 14. Nitrochlorobenzene indolineacet87 ( 38 (1) 15. 2-Methylindolined 26-400 28-610 ( 6 ) aldehyded 43. Anthraquinone 49-110 ( 6 ) 44. Bromodinitroaniline 50-120 (5) *P45. 3,3-Dimethyl-l,~ ND 16. C, aniline 95-170 19-22 (2) indolinediacetaldeh y ded 46. HydroxyanthraND quinone 17. Caprolactam ND 36-150 ( 2 ) 47. DihydroxyanthraND quinone 18. Methylmethoxy22-55 ( 12-40 ( 5 ) 48. Aminoanthraquinone 69-160 ( 2 ) aniline 49. N-Acetyl-"-ethylND N'-cyanoethyl19. Dichloroaniline ND 57 (1) ethoxyphenylenediamined 20. Trimethylindole ND 13-72 (7) 50. N-Acetyl-"-ethyl21. 1,3,3-Trimethyl-2320 (1) 3-130 (7) N'-cyanoethylmethylene inme thoxyphenyldolined enediamined 22. Dibromoaniline 42-66 (2) 51. HydroxyaminoND 23. 3-Phenyl-1,2,4anthraquinone thiadiazoled 52. Bromoamino170-200 ( 2 ) 24. 1,3,3-Trimethyl65-510 ( 8 ) 10-3600 ( 9 ) hydroxyanthraoxindoled quinoned 25. Dimethyl phthalate 38-130 ( 4 ) ND 53. Dibromoamino92-170 ( 4 ) 26. 5-Chloro-3-phenylND anthraquinone 1 5 (1) 1,2,4-thiadiazoled
Final effluent ppb 42-2700 (5) ND 43 (1) 12 (1) ND 5-72 (6) 7-34 (2) ND 12-48 ( 4 ) 16-32 (2) 27-78 ( 7 ) 68-86 ( 2 ) 52-150 (2) ND 19-230 (7) 14-440 ( 7 ) ND 8-42 (7) 9-460 (4) 5-8 ( 3 ) 5-44 ( 3 ) 5-29 ( 5 ) 13-44 ( 4 )
1.5-220 ( 6 )
1.5-27 (4) 16-75 ( 3 ) ND
a The raw effluent refers t o Point A (Figure 2) and the final effluent to Point B (Figure 2). Where substitutional isomers are designated, they are based, for the most part, on information other than mass spectra interpretation. Number in parentheses refers to the total number of composites in which the compound was found. The raw effluent is based on eight total samples and the final effluent on nine total samples. ND means "not detected". Refers to compounds whose and high resolustructures are shown in Figure 3. e This compound has a similar mass spectrum to 1,3,3-trimethyloxindole, tion mass mectrometrv indicated that i t has two additional CH, units.
was synthesized [for synthetic route, see (11) and Figure 61 in our laboratory from B , and it had a mass spectrum and GC retention time identical with the unknown. The purchased standard of 1,3,3-trimethyl-2-methyleneindoline contained small quantities of compound A , and the similarity of its mass spectrum with that of compound B , except for a 2 mass unit shift, led to the assignment of the saturated analogue, 1,2,3,3-tetramethylindoline. During work with the 1,3,3-trimethyl-2-methyleneindoline, i t was noted that colorless standard solutions (in methylene chloride) turned dark red after a short time. Tests indicated that this occurred even in the dark so that no photochemical 1436
ANALYTICAL CHEMISTRY, VOL. 49, NO. 9, AUGUST 1977
reaction was taking place. Since this compound has been used extensively in the dye industry, we searched through the literature very carefully for reports of this phenomenon. Figure 6 summarizes the reactions which are apparently occurring. If the red dye i s being formed, some methylene donor like formic acid must be present, but we have not pursued the reaction sequence as i t occurs in methylene chloride any further. Gas chromatographic and GC/MS analyses clearly show, however, that the indoline is being slowly converted to the oxindole over a period of several days. As will be discussed later, this reaction assumes some importance when considering the efficiency of the waste
22 I CH3D
/C2H4CN
NHCOCH3 p C
192
&
246
261 ( M ' )
235
N H COC H g
206
Figure 7. Mass spectra of two related compounds found In the dye plant effluent. These two compounds appear in Table I as entries 49 (bottom) and 50 (top). The ethoxy compound elutes first from an SP-2100 gas chromatographic column
I48 ,CzH4CN
pH5 I 120
91
CH3
173
I
C p Hq CN
/
PH40H I20
I
Figure 8. Mass sDectra of two standard comDounds for comDarlson to those in Figure 7. The top compound Is N-ethyl-N-cyanoethyl-m-toluidine and the bottom Is N-cyanoethyl-N-hydroxyethyl-m-toluidine'
treatment system presently employed by the dye plant. The two related mass spectra shown in Figure 7 were even more difficult to interpret. Although high resolution data indicated a molecular formula of CI4Hl9N3O2for one and C15H21N302 for the other, thus confirming the interpretation that the compounds differed only by one CH2 unit, little information that might give an idea about the structures of the two compounds could be found in the literature. The peaks at m l e 221 and 235, respectively, correspond to the loss of CH2CN from the molecular ions which clearly is more favorable than the loss of methyl, mle 246 and 260. A small loss of 42 mass units, CH,CO, also occurs in both compounds, indicating the possible presence of an N-acetyl group. Based on such considerations, the structures shown in Figure 7 were
assigned by a priori interpretation of the spectra. Confirmation of these structures was not possible by reference to the literature, and synthesis appeared to be a rather involved procedure; thus, the mass spectra of model compounds which had similar structural features and which could be purchased commercially were obtained for comparison purposes. In particular, the presence of the ethoxy and methoxy groups in the compounds shown in Figure 7 was deduced mainly because OCH3and OC2H6were parts of the compounds remaining after mass spectral assignment of the fragment losses observed. However, the presence of N-hydroxyethyl groups in two of the other compounds (numbered 33 and 36, Table I) indicated that this particular structural moiety was a common one, and it seemed important to rule out its ANALYTICAL CHEMISTRY, VOL. 49, NO. 9, AUGUST 1977
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Table 11. Concentration of Various Individual Compounds in Both the Raw and Final Effluent for Each of the Dates That Composites were Collected. 1,3,3-TrimethylAniline 2-Methylindoline oxindole Dinitrophenol Final Raw Final Final Raw Date Raw Final Raw -b 240a 2300 160 49 3122-31 26 N.D. N.D. 340 N.D.C -b 3124-413 N.D. lost 300 52 lost 16 lost lost 415-419 120 1000 480 N.D. N.D. 140 320 160 4/19-4123 240 3200 680 82 510 4/26-4130 480 10 400 2700 2100 3600 48 24 26 610 160 513-517 510 660 660 56 110 5110-5114 N.D. 54 N.D. 42 1400 740 36 39 N.D. 28 310 5/17-5121 N.D. 400 150 N.D. 130 5 124-5 / 2 8 370 17 99 N.D. 100 600 N.D. 96 N.D. N.D. 65 611-614 5-Amino-3-phenyl1,2,4-thiadiazole Raw Final 3/22-31 26 3124-413 415-41 9 4/19-4123 4/26-4130 513-517 5110- 5 114 5/17-5121 51 24- si 28 611-614
16
lost N.D. N.D. N.D. N.D. 46 18 5
1,3,3-Trimethyl-AZicYindolineacetaldehyde Raw Final
~
58 230 33 19 48 42 84 N.D. N.D.
27
-
lost 36 52 N.D. N.D. 20 18 3
57 440 14 14 33 55 16 N.D. N.D.
-
Bromodinitroaniline Raw Final 69
lost 110 120 100 N.D. 50 N.D. N.D.
-
42 38 30 13 30 N.D. 8 15 N.D.
3/22 to 3/26, only raw composite collected; 3/24 to 413, only final composite a Concentrations in parts per billion, collected. N.D. means “not detected”. presence. The two standards shown in Figure 8 were purchased (Aldrich Chemical Co.) and analyzed for this purpose. As one can see from the mass spectrum of N-hydroxyethyl-N-cyanoethyl-rn-toluidine, competition between loss of CH2OH (31 mass units) and loss of CHzCN (40 mass units) clearly favors CH20H. Since no fragment corresponding to this loss was present in the mass spectra of the N-substituted phenylenediamines (Figure 7), it was ruled out of consideration. The spectrum of the N-ethyl-N-cyanoethyl-rn-toluidine, conversely, shows almost exactly the same proportional loss of CHzCN and CH3 seen for the phenylenediamines. Although, for a variety of reasons, we believe the structures we have deduced for these phenylenediamines (see Figure 7) are correct, structural proof must await comparison with authentic compounds. In addition, the exact substitution pattern of the three groups around the ring, which cannot be determined from the mass spectra alone, must be fixed based on other spectral, synthetic, or circumstantial data. Sediment a n d River Water Samples. Because the sensitivity limits of the standard workup and identification procedures we about 1 ppb for the water samples and because the dilution effect of the river is so large, only a few of the compounds present in the final effluent were expected to be detected by standard gas chromatographic mass spectrometry done on 1-gal river water extracts. In fact, none were detected in this manner. Selected ion monitoring of the predominant mass fragments associated with 1,3,3-trimethyloxindole( m / e 160), dinitrophenol ( m l e 184), and 5-amino-3-phenyl-1,2,4thiadiazole (rnle 177) gave positive results, but only the oxindole appeared to be present in anything but ultra-trace quantities (
