Envlron. Sci. Technol. 1984, 18, 734-739
Nriagu, J. O., Ed. “Zinc in the Environment: Ecological Cycling”; Wiley-Interscience: Toronto, 1980; Part I. Subcommittee on Zincr-National Research Council “Zinc”; University Park Press: Baltimore, MD, 1979. Spear, P. A. “Zinc in the Aquatic Environment: Chemistry, Distribution and Toxicology”;National Research Council: Ottawa, Canada, 1981. Cammarota, V. A., Jr. In “Zinc in the Environment: Ecological Cycling”; Nriagu, J. O., Ed.; Wiley-Interscience: Toronto, 1980; Part I, pp 2-38. Nriagu, J. O.,Ed. “Cadmium in the Environment: Ecological Cycling”;Wiley-Interscience: Toronto, 1980; Part I. Gillespie, J. E.; Acton, C. J. “Soils of Peterborough County”. Ontario Institute of Pedology, University of Guelph, Guelph, Ontario, 1981, Report 45. Jones, R. Water Air Soil Pollut. 1983, 19, 389-395.
(11) Jackson, M.L. “Soil Chemical Analysis”; Prentice-Hall:
Englewood Cliffs, NJ, 1958.
(12) Lindsay, W. L.Adv. Agron. 1972,24, 147-186. (13) Schuman, L. M.In “Zinc in the Environment: Ecological
(14)
(15) (16) (17)
Cycling”;Nriagu, J. O., Ed.; Wiley-Interscience: Toronto, 1980; Part I, pp 40-69. Sims, J. L.; Patrick, W. H., Jr. Soil Sci. SOC.Am. J . 1978, 42, 258-262. Frank, R.; Ishida, K.; Suda, P. Can. J . Soil Sci. 1976,56, 181-196. Kraal, H.; Ernst, W. Environ. Pollut. 1976, 11, 131-135. Harris, T.M.New Phytol. 1946, 45, 50-55.
Received November 15, 1982. Revised manuscript received October 14, 1983. Accepted April 11, 1984. Funding for part of this research was provided by Trent University.
Illinois Basin Coal Fly Ashes. 1. Chemical Characterization and Solubility Wllllam R. Roy,” Robert A. Grlffln, Donald R. Dlckerson, and Rudolph M. Schullert
Geochemistry Section, Illinois State Geological Survey, Champaign, Illinois 6 1820 Twdve precipitator-collected fly ash samples (nine derived from high-sulfur Illinois Basin coals and three from Western U.S.coals) were found to contain a variety of paraffins, aryl esters, phenols, and polynuclear aromatic hydrocarbons including phenanthrene, pyrene, and chrysene but all at very low concentrations. Less than 1% of the organic carbon in the samples was extractable into benzene. Solubility studies with a short-term (24-h) extraction procedure and a long-term (20-week) procedure indicate that the inorganic chemical composition of some types of fly ash effluent is time dependent and may be most toxic to aquatic ecosystems when initially mixed with water and pumped to disposal ponds. Some acidic, highCd fly ashes would be classified as hazardous wastes if coal ash was included in this waste category by future RCRA revisions.
Introduction Coal fly ash research has greatly increased in recent years in response to the anticipated dependence of coal by the electric utilities. The implications of the Resource Conservation and Recovery Act (RCRA) of 1976 have also focused attention on fly ash and its subsequent disposal problems. The environmental impacts of coal fly ash from highsulfur Illinois Basin coals has been investigated previously (I+), but the mobilization of potentially toxic constituents in ash-water interactions has received only limited attention. Natusch et al. (3) concluded that Cd, Co, Mn, P, and Zn were “substantially” extractable from an alkaline fly ash sample. Griffin et al. (6) also found that these constituents were fairly soluble in a laboratory extract of an acidic fly ash but noted that only B, Ca, and SO4 exceeded water-quality limits. In order to gain a greater perspective of ash-water interactions, this study examines the extractability of 24 constituents from different Illinois Basin fly ashes using both short-term and long-term batch extraction techniques. Theis and Richter (5) noted that fly ashes contain little organic matter, but prior to this study there is very little Present address: S.M.C. Martin, Valley Forge, PA. 734
Envlron. Sci. Technoi., Voi.
18, No. 10, 1984
Table I. Summary of the Origin and General Characteristics of the 12 Fly Ash Samples fly location of ash power plant
I1
boiler
type
color of sample’
classificationC
S.W. Illinoisb cyclone
grayish brown, alkaline Modic silt 2.5Y 6f 2 I2 S.W. Illinoisb pulverized very dark acid C-Modic silt loam grayish brown, lOYR 312 I3 E. Illinoisb pulverized gray, 5Y 5f 1 alkaline Modic silt I4 E. Illinoisb pulverized gray, 5Y 5f 1 alkaline Modic silt pulverized grayish brown, alkaline Modic I5 E.Illinois silt 2.5Y 5.512 I6 S.W. Illinois pulverized gray, 2.5Y 5 f0 alkaline Modic silt I7 C. Illinois acid C, cyclone very dark Zn-Fersic grayish brown, silt lOYR 3f 2 alkaline Modic I8 S.E. Illinoisb pulverized gray, 2.5Y 5f 0 silt alkaline Modic I9 S.E.Illinoisb pulverized gray, 2.5Y 5 f 0 silt alkaline w1 S.W. Illinois pulverized gray, lOYR Ba-Modic 711 silt alkaline w 2 Minnesota pulverized light gray, 2.5Y 7f 2 B, Ba, SrCalsialic silt alkaline cyclone gray-light, w3 N. Dakota B, Ba, Sr2.5Y 6.512 Calcic silt
‘Dry Munsell soil colors. Samples indicated were taken from same individual power plant but were derived from different boilers. Classification svstem of Rov and Griffin (8). information concerning the identity and solubility of organic compounds present in precipitator-collected fly ash. The results of this study should be of use in the assessment of possible environmental impacts of fly ash disposal to aquatic ecosystems during the initial sluicing of the ash into retention lagoons and while the effluent is confined in the ash pond.
0013-936X/84/0918-0734$01.50/0
0 1984 American Chemical Society
Materials and Methods
For Chemical Characterization. A summary of the origin and general characteristics of the 12 fly ash samples used in this study is given in Table I; complete chemical characterization is given in Suloway et al. (7). All were grab samples collected from hoppers below electrostatic precipitators at the source power plants. Nine of the fly ashes (11-19) were generated from Illinois Basin coals (predominatly the Herrin No. 6 coal); three Western U.S.fly ashes were studied for comparisons. Fly ash W1 was derived from subbituminous coal from Colorado while W2 and W3 were derived from lignite coal in North Dakota. The proposed U.S.EPA extraction procedure (EP) (9) was used to study the short-term leaching of potential pollutants that may occur during sluicing to ash ponds. Additional solubility characterizations were carried out with four Illinois Basin fly ashes and a western fly ash by using a long-term equilibration procedure (LTE) to suggest the water quality of ponded fly ash leachate. Fly ash ponds may reach steady-state conditions if the rates of the chemical reactions controlling the solubility of the particular mineral phases involved are rapid in comparison with the retention times of the water in the ponds. The LTE procedure involved mixing 3400 g of fly ash with 17 L of deionized water in a 19-L reaction vessel made of Pyrex glass after a procedure designed by Griffin et al. (6). These mixtures were stirred for 30 min, 3 times a week, in order to simulate ash ponding environments. All aqueous solutions derived from extraction experiments were analyzed by inductively coupled argon plasma emission spectrometry (ICAP). The organic material in fly ash (350-550 g) was extracted for 40 h with 1L of benzene by using a large (70 X 300 mm body) Soxhlet apparatus (7). The solvent volume was reduced on a rotary evaporator. Activated copper was used to remove free sulfur from the extracts. The final traces of solvent were removed with gentle heat and a stream of dry nitrogen. The extracts were separated into seven fractions according to the EPA Level One (Revised) Procedure for Organic Analysis (IO). This separation is done by liquid chromatography (LC) on a silica gel column (200 X 10.5 mm i.d.) using a gradual gradient of solvents from nonpolar to polar. An infrared spectrum was run on each extract and on each fraction. For the pyrolysis studies a 10-g sample of fly ash was placed in the bottom of a 300 X 13 mm i.d. Pyrex tube followed by a plug of quartz wool. The tube was then constricted just above the quartz wool retainer. The top of the tube was sealed with a skirted-septum stopper, and the tube was evacuated. The sample end of the tube was heated at 450 "C for 5 min in a tube furnace while the upper end of the tube was cooled with powdered dry ice. The tube was then sealed and separated at the point of constriction, trapping the volatile organics in the upper portion of the tube. The noncondensables were analyzed by GC and the components identified by comparison of retention times with known standards. The condensable portion was analyzed by GC and one sample by gas chromatographymass spectroscopy (GC-MS). Indentification of components was made by comparison to the GS-MS analysis and the the retention times of known standards. A 2 m by 3 mm stainless steel column packed with Chromosorb 102 was used for the noncondensable gas analyses: helium flow 30 mL/min; injection port 125 "C; detector (FID) 200 "C; column oven program 50 "C for 1min; a temperature rise to 170 "C at 10 "C/min and a final hold at 170 "C for 5 min. A 1.25 m by 3 mm stainless column packed with
SP-2100 was found best for the condensables from the pyrolysis and for the extracts and subfractions of the extracts: helium flow 35 mL/min.; injection port 250 "C; detector (FID) 315 "C; column oven program 100 "C for 2 min; a temperature rise rate of 4 "C/min to 260 "C with a final hold of 10 min. An Altex Ultrasphere ODs, 5-m, 4.6 X 250 mm column and UV detection were used for high-performance LC (HPLC). The solvent was 80:20 v/v methanol-water with a 1mL/min flow rate under isocratic conditions. Results and Discussion Inorganic Fly Ash Characterization. Bulk mineralogical, microscopic, and chemical analysis of the Illinois Basin fly ash samples (11-19) indicated that they were essentially spherical particles composed of silicon, aluminum, and iron. Amorphous aluminosilicate glass, quartz (SiO,), magnetite (Fe304),and hematite (Fez03)were found in all nine samples; mullite (Al6SizOl3)was detected by X-ray diffraction in all the samples except fly ashes I2 and 17. A small amount of lime (CaO) was detected in 11,15, 17, and I9 and anhydrite (CaS04) in 17. The complete mineralogical and inorganic chemical composition of the ashes is given elsewhere (7). The general chemical composition of each sample is indicated by the results of a classification system (Table I) proposed by Roy and Griffii (8). Benzene Extractable Organics. Five of the 12 fly ashes were extracted with benzene, and organic analyses of the extracts were carried out and compared to the carbon content of the ashes. In the two western fly ashes, W1 and W2, less than 1% of the organic carbon present in the fly ash was extractable into benzene; in two other fly ashes (I6 and IB), less than 0.1% of the organic carbon was extracted into benzene. The benzene extracts of four of the fly ashes were separated into seven LC fractions according to the EPA level 1procedure (IO). Only 11mg of extract was obtained from fly ash 16, which was insufficient for further analyses. With the exception of the extract from fly ash W1, the major portions of the organics in the extracts were found in fractions LC-1 (n-paraffins; 50%) and LC-6 (phenols; 20%). The infrared spectra of the LC-1 fractions of all the fly ash samples were very similar and typical of aliphatic hydrocarbons. Gas chromatograms of these fractions contained peaks for all n-paraffins from CI1through approximately CS6,as well as numerous peaks due to much smaller concentrations of branched-chain and cyclic hydrocarbons. The infrared spectra of the LC-2 fractions showed them to be highly aliphatic with very weak aromatic absorptions, indicating alkyl-substituted and/or fused ring aromatics, but GC data of these fractions indicated that the major constituents were n-paraffins. The LC-2 fraction of fly ash W1 contained phenanthrene, pyrene, chrysene, and small quantities of other polynuclear aromatic hydrocarbons of lower molecular weight than chrysene, possibly phenols. Phenanthrene and pyrene have also been detected in coal ash in a study discussed in EPRI (11). The infrared spectra of the LC-3 samples exhibited strong aliphatic absorption peaks and weak aromatic peaks expect for the W l LC-3 fraction, which appeared to have more aromatic compounds than the remaining three LC-3 fractions. Strong absorptions were also present in the carbonyl (1750-1700 cm-l) regions due likely to long-chain aliphatic esters or aryl esters. Aryl esters have been detected in a char prepared by heating coal at 350 "C in a fluidized bed (22). The gas chromatograms of the LC-3 Environ. Sci. Technol., Vol. 18, No. 10, 1984
735
Table 11. Hydrocarbons Detected in the Noncondensable Pyrolysates (Pyrolysis at 460 OC except Where Indicated) hydrocarbon
fly ash
proiso- 2-meth- 1- n- 2-meth- iso- 1- 3-meth2-meth- 4-meth- 1- nmeth- ethyl- eth- pyl- pro- but- ylprop- but- but- ylbut- pen- pen- ylbut- n-pen- ylpent- ylpent- hex- hexane ene ane ene pane ane ene ene ane ene tane tene ene tane ene ene ene ene
x x x x x
x x x x x
x x x x x
x x
x x
x x
x x
x x 450OCX w2 x w3 x
x x x x x
x x x x
x x x x
I2 I3 14 I5
I6 I7
X
X
IS I9 w1 300oc 400oc
I'
3000
x x x x x
x x
X
x x x x
x x x x
x
X
X
X
x x x x
1600
2000
x x
x x x x x x x x
x x x x x x x x
X
x
x x x x
x
1200
x x x
x
X
x
x
X X X
X
x x x x
x x x x
X X X
?
X X
X
x x x x
X
X
X
x x x x
X X
x
? X
X X
x x x
X
X X
X
X
x
X
X
x x
x x
x x
800 650
cm-'
Flgu.re 1. Typical Infrared spectra of the (a) LC-4 and (b) LC-6 fraction of the benzene-extracteble organic matter associated with fly ash. (Ruh as a film on NaCl prisms.)
samples showed the presence of 8-10 dominant but unidentified components. Phenanthrene, pyrene, and cbrysene were identified in the LC-3 fraction. The infrared spectra of the LC-4 fractions (Figure 1) show the beginning of major differences in the compositions of the organics derived from the various fly ashes. The LC-3, LC-4, and LC-5 fractions of W1 contained peaks dve to carbonyl absorption that were resolved into at least two distinct peaks indicating the presence of both aliphatic and aryl esters or long-chain aldehydes and ketones. Phenanthrene and pyrene were again identified by HPLC. The infrared spectra of the LC-6 fractions of I5,18, and W2 were quite similar, with strong hydroxyl, carboxyl, and carbonyl absorption (Figure 1). HPLC analysis showed that the sample probably contained a large number of phenolic cornpounda, as well as other polar aromatics. The LC-7 fractions were quite small and appeared to be contaminated with silica gel from the column. Infrared intensities were weak, but the absorptions were esaentially comparable to the absorptions in the respective LC-6 fractions. HPLC showed one major, strongly polar compound. Some of the organics associated with these fly ashes are on the priority pollutant list but present in very small quantities (
