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Anal. Chem. 1964, 56, 1625-1628
Steam Distillation, Solvent Extraction, and Ion Exchange for Determining Polar Organics in Shale Process Waters J o h n J. Richard a n d Gregor A. Junk* Ames Laboratory-USDOE,
Iowa State University,Ames, Iowa 5001 1
Steam dlstlllatlon, solvent extraction, and ion exchange procedures have been employed to isolate volatile organlc ackls, bases, and neutral compounds from process waters generated durlng the retortlng of oil shale. Gas chromatography was used for the analysis of the Isolated components and for the dlrect analysis of the process waters. The use of these multiple isolation and analyses procedures has resulted In the determlnatlon of the foilowlng compounds wlth the amounts In ug/mL given in parentheses: 12 C2 to C,o aliphatlc acids (26 to 450); phenol (21); pyridine (5); five methyl substttuted pyrldlnes (3 to 19); aniline (2); isoquinoline (2); four C, to C, n-alkylamlnes ( 2 to 10); three C, to C, n-aikylnltriies ( 1 to 21); benzonltrlie (3); formaldehyde (500); acetaldehyde (2); propanone (16); and butanone (6). The advantages of steam dlstiliatlon and ion exchange for the isolation and eventual anaiysls for water containlng complex mixtures of volatile acidic, basic, and neutral organlc components are described.
The retorting of oil shale leads to a process water containing a complex mixture of acidic, basic, and neutral organic compounds. Raphaelian and Harrison ( 1 ) have identified 160 different components and Pellizzari and his colleagues (2,3) have reported qualitative and quantitative data for 97 organic compounds in oil shale process waters. These researchers used solvent extraction and purge and trap procedures to isolate the organic compounds from the process water. These procedures are efficient for nonpolar, low solubility compounds ( 4 5 ) but are less effective for polar components especially those having high solubility in water. These hydrophilic compounds are frequently isolated by less general, but potentially more efficient procedures, such as distillation (6-1l ) and ion exchange (12,13). Steam distillation, using standard procedures (6, 7), has been investigated thoroughly for the isolation of fatty acids and phenols from wastewaters and other aqueous samples. It has also been shown to be efficient for neutral hydrophilic compounds (8,9).Direct distillation of aqueous samples has also been successful for neutral components (10) and for volatile amines ( 1 1 ) . Other basic components have not been investigated but distillation procedures should be generally applicable to all polar, acidic, and basic organic compounds of reasonable volatility. Polar organic compounds that form anions and cations in water can also be isolated by ion exchange procedures and recent reports (12,1#3)suggest general applicability to organic acids and bases. An alternative to isolating the organic compounds is the direct analysis of process water using gas chromatography (GC) with stationary phases that are tolerant of the water matrix. This procedure is effective if the concentrations of the organic compounds are near or above 1 ppm and other organic and inorganic components in the water do not cause rapid deterioration of the GC column used for the separation. Our analysis of oil shale process waters using the isolation procedures of solvent extraction, ion exchange, and steam
distillation for the volatile polar organic compounds prior to determinations by GC and gas chromatography/mass spectrometry (GC/MS) and our direct analyses of the waters by gas chromatography are presented and discussed in this paper. EXPERIMENTAL SECTION Oil Shale Process Waters. Two process waters were used in these studies. The first was obtained from the Laramie Energy Technology Center, Laramie, WY. This simulated in situ retort (SISR) water was produced during run 17 of a 150-ton capacity retort designed to mimic the in situ processing of oil shale. The Paraho retort (PR) process water was obtained from the Paraho Development Corp., Rifle, CO. It was also produced by aboveground retorting of oil shale. Solvent Extraction. The pH of 50 mL of process water was adjusted to -11 with 6 N NaOH and extracted three times with 25-mL portions of methylene chloride. This base/neutral extract was concentrated to 10 mL and the extract was analyzed by GC. The pH of the water was readjusted to 2 with 6 N H2S04and the extraction and concentration process was repeated to yield an acidic extract. If the reverse pH sequence is used in the extraction procedure to give acid/neutral and base fractions, the pH must be 90% efficiency in the first two 50-mL portions of the distillate and only acetic acid was recovered poorly at 62%. Ethylamine, pyridine, 2,6-dimethylpyridine1 aniline, and isoquinoline were all collected with 89 to 100% efficiency in the first 50-mL portion of the distillate. In separate tests, the bases were completely collected in the first 25 mL of the distillate so a concentration factor of at least 2 could be achieved in the distillation of volatile basic components. Process Waters. Steam distillation, ion exchange, and solvent extraction procedures were used to determine several acidic, basic, and neutral components present in either the SISR or the P R shale process water. Direct injections of these process waters were also employed to establish the probable upper concentration limit. However, direct GC analysis is not generally useful for monitoring purposes because the extraneous inorganic and nonvolatile organic components in the process waters cause very rapid deterioration of the GC columns, usually within five injections. Acids. Aliphatic acids and phenols were determined in the SISR process water by using steam distillation and solvent extraction for their isolation prior to GC analyses and by direct GC analysis of the process water. The analytical results are given in Table V. Good agreement for the three procedures is obtained for all components, except acetic and propanoic acids. This observation was predictable based on interpretation of the recovery test data given in Table 11. The anion exchange procedure was used to determine aliphatic acids and phenol in the P R process water. For comparison, this water was also analyzed by direct GC to ascertain the efficacy of anion exchange for a wastewater having high concentrations of a complex mixture of both organic and inorganic components. The results of these analyses are given in Table VI. The anion exchange procedure gives excellent agreement to direct analyses and it is the only one of three isolation procedures that gives complete recovery, plus an appreciable concentration factor, for all of the aliphatic acids and phenol. Aromatic Bases. Aromatic bases were determined in the SISR process water using steam distillation, solvent extraction, and cation exchange for their isolation prior to analyses by GC. Reasonable agreement for the three procedures was obtained as shown by the results listed in Table VII. However, the steam distillation procedure was superior since it also isolated conveniently the aliphatic amines and several neutral components of interest as discussed in the following section. Amines and Neutral Components. Steam distillation was used to isolate C& aliphatic amines, C2-C4aliphatic nitriles, c1-C~aldehydes, and C& ketones from SISR process water. The results of the GC analyses of this steam distillate and the
I
TIME-
Figure 1. Capillary gas chromatogram of volatile fatty acids in acid fraction of steam dlstlllate of SISR shale process water. Splitless Injection onto OV-351 at 90 O C with 1 min hold, temperature programmed to 220 'C at 5 'Clmin. Acids peak assignments: (1)acetic, (2) propanoic, (3)methylpropanolc, (4) butanoic, (5) 3-methylbutanoic, (6) pentanoic, (7) hexanoic, (8) heptanolc, (9) phenol, (10) octanoic, (1 1) nonanoic, (12) decanoic.
direct GC analyses of the process water are listed in Table
VIII. The aliphatic amines and formaldehyde have not been reported previously to be present in oil shale process waters. This may be due to the solvent extraction (1-3) and purge and trap procedures (2,3)used by others to isolate the organic components from the process waters. The solvent extraction, used by Raphaelian and Harrison (I), may have resulted in loss of the volatile aliphatic amines, carbonyls, and nitriles during the concentration step. Pellizzari et al. (2,3)reported the presence of aliphatic nitriles and carbonyls by use of purge and trap but this procedure probably did not isolate the aliphatic amines and formaldehyde. One might also speculate that these components were detected and not reported or that they were not present in the particular process waters used at other laboratories (1-3). These explanations seem improbable in view of the very high level of formaldehyde. Failure of the isolation procedures seems more probable and is supported by three independent investigations (2,14,15) where elevated temperatures, long purge times, and high flow rates were needed to recover reasonable amounts of volatile polar organic compounds. Even if conditions can be adjusted to isolate volatile amines and neutral components by other procedures, the convenience and effectiveness of steam distillation suggest that it is the best procedure. Capillary Column GC. Direct injection of the oil shale process water onto capillary columns leads to very rapid loss of resolving power and the irreversible sorption of some components. However all the steam distillates, with the neutral components in either the acid or base fractions, can be injected repeatedly onto capillary columns with no deleterious effects. The pH sequence in the steam distillation does not affect the recovery efficiencies of the acids, bases, and neutrals so that pH adjustment can be chosen to achieve the two fractions which are best accommodated to the chromatographic separation. For the SISR process water, pH fractionation to yield base/neutral and acid fractions, as opposed to acid/neutral and base fractions, results in slightly better chromatographic separations. The two chromatograms from these fractions are shown in Figures 1and 2 where the
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ANALYTICAL CHEMISTRY, VOL. 56, NO. 9, AUGUST 1984
help of L. Jackson, Laramie Energy Technology Center, and the participants in the DOE/NBS Analytical Characterization Group, H. Hertz and G. Goldstein, chairman, are acknowledged. Registry No. Methylamine, 74-89-5; ethylamine, 75-04-7; pyridine, 110-86-1;2,6-dimethylpyridine, 108-48-5;aniline, 62-53-3; isoquinoline, 119-65-3;acetonitrile, 75-05-8;propionitrile, 107-12-0; formaldehyde, 50-00-0; acetaldehyde, 75-07-0;propanone, 67-64-1; butanone, 78-93-3; acetic acid, 64-19-7;propanoic acid, 79-09-4; methylpropanoic acid, 79-31-2; butanoic acid, 107-92-6; 3methylbutanoic acid, 503-74-2;pentanoic acid, 109-52-4;hexanoic acid, 142-62-1;heptanoic acid, 111-14-8; octanoic acid, 124-07-2; nonanoic acid, 112-05-0;decanoic acid, 334-48-5;phenol, 108-95-2; 2-methylpyridine, 109-06-8;4-methylpyridine, 108-89-4;2,4-dimethylpyridine, 108-47-4; 2,4,64rimethylpyridine, 108-75-8; propylamine, 107-10-8;butylamine, 109-73-9;butyronitrile, 10974-0; benzonitrile, 100-47-0; water, 7732-18-5.
LITERATURE CITED I TIME-Flgure 2. Capillary gas chromatogram of aromatic bases in base/ neutral fraction of steam distillate of SISR shale process water. Spliless Injection onto a CAM column at 60 O C with 2 min hold, temperature programmed to 220 O C at 5 OC/min. Peak assignments: (1) pyrldlne, (2) 2-methylpyridine, (3) 2,6-dimethylpyrldine, (4) 3methylpyridlne,(5)4-methylpyrldlne, (6)2,5dimethylpyridine, (7) 2,4dimethylpyridine, (8) 3,5dImethylpyrldlne,(9)2,4,6trimethylpyrMine,(10) 3,4dimethylpyrMlne, (11) C3- and C4-pyrldlnes,(12) aniline, (13) qulnollne, (14) isoquinoline.
identified components are numbered and listed in the captions. These capillary column separations are a great aid to identification work and they can be used for quantitative purposes when specific detectors are not available to reduce the probability of interferences. For some wastewaters having high concentrations of neutral components and low concentrations of either acids or bases, the convenience of steam distillation coupled to the proper pH adjustment may be necessary for both identification and quantitation purposes. The inherent disadvantage of this approach is the time necessary to do the distillation and the possible acid and base catalyzed hydrolysis of certain components. This same problem exists in p H adjusted solvent extractions although to a lesser degree because of the lower temperature in solvent extraction. In some cases, the sample volume may be diluted in the distillation to effect quantitative recovery of components such as acetic acid but a concentration factor of at least 2 X can be achieved for many volatile components.
ACKNOWLEDGMENT The authors appreciate the GC/MS analyses provided by M. Avery and the administrative assistance of V. Fassel and R. Fisher, Ames Laboratory program directors. The outside
Raphaellan, L. A,; Herrlson, W. “Organic Constltuents in Process Water from the In-situ Retorting of 011from 011-Shale Kerogen: Occidental Oil Shale, Inc., Logan, Wash. No. 6 Retort Experiment”; Argonne National Laboratory Report ANL/PAG5, 1981. Pellizzarl, E. D. “Identiflcetlon of Components of Energy-Related Wastes and Effluents”, NTIS Publlcatlon No. PB-280.203, 1978. Pelllzari, E. D.; Castlllo, N. P.; Wlllls, S.; Smlth, D.; Bursey, J. T. I n ”Measurements of Organic Pollutants in Water and Wastewater, ASTM STP686”; Van Hall, C. E., Ed.; American Society for Testing and Materials: Philadelphia, PA, 1979; pp 256-274. Mleure, J. P. €nv/ron. S d . Techno/. 1980, 74, 930-935. Garrison, A. W.; Alford, A. L.; Craig, J. S.; Ellington, J. J.; Haeberer, A. F.; McGuire, J. M.; Pope, J. D.; Shackelford, W. M.; Peillzzarl, E. D.; Gebhart, J. E. I n “Advances in Identlfication and Analysis of Organic Pollutants in Water”; Keith, L. H., Ed.; Ann Arbor Science: Ann Arbor, MI. 1981; Voi. 1, Chapter 2. “Standard Methods for the Examination of Water and Wastewater”, 14th ed.; American Public Health Associatlon: Washington DC, 1976; pp 529-531. ”Officlal Methods of Analysis”, 1I t h ed.; AOAC: Washington DC, 1970; Sections 11.036 and 18.026. Peters, T. L. Anal. Chem. 1980, 52, 211-213. Yasuhara, A.; Shiraishl, H.; Tsuji, M.; Okuno, .7’ Mvlmn. Sc/. Techno/. 1981, 15, 570-573. Kuo, P. P. K.; Chian, E. S. K.; DeWalle, F. 8. Water Res. 1977, 7 7 , 1005- 10 11. “Official Methods of Analysls”, 1l t h ed.; AOAC: Washington DC, 1970; Section 34.056. Richard, J. J.; Fritz, J. S. J. Chrmtogr. Scl. 1980, 78, 35-38. Kaczvinsky, J. R.; Salto, K.; Frltz, J. S. Anal. Chem. 1983, 55, 1210- 1215. Mleure, J. P.; Mappes, G. W.; Tucker, E. S.; Dletrich, M. W. I n “Identlficatlon and Analysis of Organic Pollutants in Water”; Keith, L. H., Ed.; Ann Arbor Science: Ann Arbor, MI, 1978; Chapter 8. Kuo, P. P. K.; Chlan, E. S. K.; DeWalle, F. B.; Kim, J. H. Anal. Chem. 1977, 49, 1023-1028.
RECEIVED for review October 18,1983. Accepted April 2,1984. This work was performed in the laboratories of the US. Department of Energy and supported under Contract No. W-7405-Eng-82. The work was supported by the Office of Health and Environmental Research, Office of Energy Research, and the Assistant Secretary for Fossil Energy, Division of Coal Utilization, through the Laramie Energy Technology Center.
