Little or no increase in SO4*- emissions occurred when an Ope1 diesel vehicle was equipped with an oxidation catalyst. This is consistent with the low exhaust gas temperatures and already existing knowledge of the temperature dependence of SO2 oxidation rate over automotive catalysts. (The overall feasibility of catalytic treatment of diesel exhaust has not been addressed.) Acknowledgme,rzts
(12) Springer, K. 3.; Stahman, R. C. SAE Tech. Pap. 1977, 770258. (13) Springer, K. J.; Baines, T. M. SAE Tech. Pap. 1977, 770818.
(14) Pierson, W. R.; Brachaczek, W. W.; Hammerle, R. H.; McKee, D. E.: Butler. J. W. J. Air Pollut. Control Assoc. 1978,28, 123. (15) Pierson, W. R.; Hammerle,R. H.; Kummer, J. T. S a Tech.Pap. 1974, 740287; SAE Trans. 1974,83, 1233. (16) , ~,Travser. D. A,: Blosser. E. R.: Creswick. F. A.: Pierson. W. R. SAE Tkch.‘Pap. 1975,750091; SAE Trans.’ 1975,’84, 462. ’ (17) Creswick, F. A.; Blosser, E. R.; Trayser, D. A.; Foster, J. F. SAE ~
Tech. Pap. 1975, 750411.
The authors wish t o thank F. C. Ferris for technical assistance and t h e Chemical Analysis Laboratory of the Ford Research Staff for performing the S042-analyses. Literature Cited (1) Shelton, E. M. “Diesel Fuel Oils, 1977”, Petroleum Products
Survey BERC/PPS-77/5, U S . Energy Research and Development Administration, Bartlesville Energy Research Center, Nov 1977, and previous publications of the same series. (2) Shelton, E. M. “Motor Gasolines, Summer 1977”, Petroleum Products Survey BERC/PPS-78/1, Jan 1978, and previous publications of the same series. (3) Begeman, C. R.: Jackson, M. W.; Nebel, G. J. SAE Tech. Pap. 1974,741060
(4) Bradow, R. L.; Moran. J. B. SAE Tech. Pap. 1975,7Fj0090; SAE Trans. 1975,822, 451.
(5) Braddock, J. N.; Bradow, R. L. SAE Tech. Pap. 1975, 750682; SAE Trans. 1975.84. 1603. (6) Holt, E. I.,.; Bachman, K. C.; Leppard, W. R.; Wigg, E. E.; Somers, J. H. SAE Tech. Pap. 1975,750683; SAE Trans. 1975,84, 1620. (7) Ingalls. M. N.: Swinger. K. J. “Measurement of Sulfate and Sulfur Dioxide in Automotice Exhaust”, EPA-460/3-76-015, Southwest Research Institute, Aug 1976. (8) General Motors “Advanced Emission Control System Development Progress”, annual status report submitted to EPA, Dec 16, 1976. (9) Somers, J. H.; Garbe, R. J.; Lawrence, R. D.; Baines, T. M. SAE
(18) Griffing,M. E.; Gilbert, L. F.; Ter Haar, G. L.; Immethun, P. A.; Zutaut, D. W. SAE Tech. Pap. 1975,750697; SAE Trans. 1975,84, 1715. (19) Pierson. W. R. Chem. Tech. 1976.6, 332. (20) Motor Vehicle Manufacturers’ Assosiation, “Motor Vehicle Facts & Figures ’76”, tables on pp 32,68. (21) McKee. D. E. SAE Tech. Pao. 1977,770167. (22) Goksayr, H.; ROSS, K. J. Insi. Fuel 1962,35, 177. (23) Lisle, E. S.; Sensenbaugh,J. D. Combustion 1965,36, 12. (24) Maddalone, R. F.; Newton, S. F.; Rhudy, R. G.; Statnick, R. M. J. Air Pollut. Control. Assoc. 1979,29, 626. (25) Fritz, J. S.; Yamamura, S. S. Anal. Chem. 1955,27, 1461. (26) Fielder, R. S.; Morgan, C. H. Anal. Chim. Acta 1960,23, 538. (27) Butler, J. W.; Locke, D. N. J. Enuiron. Sci. Health-Environ. Sei. Eng. Ser. A 1976, Zl(l),79. (28) Hare, C. T.; Baines, T. M. SAE Tech. Pap. 1979,790424. (29) Novakov, T.; Chang, S.-G.; Harker, A. B. Science 1974, 186, 259. j30) Barbaray, B.; Contour, 75%) as insoluble species (4-71, identified ( 4 ) as BaS04. Some work (IO),however, indicates as much as 80% of t h e emitted Ba is soluble in 0.1 N HCl, at least a t high additive levels ( 7 ) ;the inference is drawn ( I O ) that the Ba is not chiefly BaS04. T h e ratio between insoluble B a s 0 4 and Ba compounds soluble in 0.1 N HC1 (said ( 4 )to be mostly BaC03) in the exhaust particulate is reported t o increase with increasing fuel sulfur level (6) and to decline with increasing Ba content in the fuel ( 6 , 7 ) . Elemental analyses of diesel particulate generated with and without the use of a Ba/Ca fuel additive (9) show (a) that the additive increases the sulfur content and decreases the carbon and hydrogen content of the diesel particulate in comparison to levels found without the additive; and (b) t h a t the emitted SOez- tends to be ap-
1980 American Chemical Society
Volume 14, Number 9, September 1980
1121
The effects of a barium fuel additive and of fuel sulfur level on diesel particulate emissions have been investigated. The Ba fuel additive results in a 30-40% decrease in exhaust opacity as measured by a smokemeter. The opacity reduction does not result from a reduction in total particulate mass emission rate, which is relatively unaffected by the Ba additive. There is, however, an -30% reduction in the mass emission rate of carbonaceous material. More than 90% of the Ba introduced with the fuel can be accounted for in the vehicle exhaust. In the presence of the Ba additive, the amount of emitted s04'- is approximately equimolar with the Ba, and
+
proximately stoichiometric with the sum of the Ba Ca whenever there is enough fuel sulfur. In this paper we present results on the effect of a Ba fuel additive on particulate mass emission rate and particulate chemical composition using a passenger car. The effect of fuel sulfur level on total particulate and sulfate emissions has been investigated as well. Experimental Methods A 1974 Mercedes 240D diesel-powered passenger car was used for all testing. The fuel used was a specially blended low-sulfur no. 2 diesel fuel. The base stock, which contained 0.0087 w t % S, was doped with di-tert-butyl disulfide to two additional fuel sulfur levels: 0.110 and 0.190 wt % S. Each fuel sulfur level was tested with and without the additive manufacturer's recommended level of 0.25 vol % of Lubrizol 556 (which, by fuel analysis, gave 0.058 wt % Ba in the fuel) to give the following six fuel sulfur/barium additive combinations: fuel S level, wt 70
fuel Ba level, wt %
0.0087 0.0087 0.110 0.110 0.190 0.190
0.0 0.058 0.0 0.058 0.0 0.058
electron spectroscopy shows that both the Ba and the SO4'are wholly in the form of BaS04-provided that the amount of sulfur in the fuel is sufficient to react with all of the Ba. This Bas04 represents a substantial increase in diesel particulate S042- emission rate compared to that observed without the Ba additive. The level of fuel sulfur does not have a significant effect on total particulate mass emission rate. In the absence of the Ba additive, the diesel sod2-emission rate is related to fuel sulfur level, but not linearly; the percent of sulfur converted to sulfate decreases as the fuel sulfur level is increased. fiber filters. Vehicle preconditioning for each experiment consisted of 1-h driving a t 80 km/h followed by an overnight soak. Testing with each fuel included a 1974 FTP-cold start followed by two 1974 FTPThotstart tests. For the cold start and the first hot start test, the vehicle exhaust was passed through a Celesco Model 107 smokemeter for measurement of opacity prior to injection into the dilution tube. During the second hot start, the exhaust was injected directly into the dilution tube. Total mass particulate emissions were determined by filter weighing a t constant temperature and humidity. Barium analyses were done by inductively coupled argon plasma atomic emission spectroscopy after leaching the samples in HCl/HNO3. Sulfate (Sod2-) analyses of samples not containing Ba were done by Ba(C104)' titrimetry and ion chromatography of water-leached samples. The SO4'- in the Bacontaining samples, where incomplete leaching of Sod2precluded Sod2analysis by titrimetry or ion chromatography, was determined by combustion analyses for total sulfur. Carbon (C), hydrogen (H), and nitrogen (N) analyses were performed by Spang Microanalytical Laboratories, Eagle Harbor, Mich. Results and Discussion
All measurements were made using the chassis dynamometer/dilution tube system previously described (11,12). The dilution tube flow rate was approximately 17 m3/min (600 cfm) for all experiments. Particulate samples were collected under isokinetic sampling conditions on 20 X 25 cm quartz
The effects of fuel S level and Ba fuel additive on particulate mass emission rate and opacity of the vehicle exhaust are shown in Table I. The effect of fuel S level on both particulate mass emissions and opacity appears to be small; there is perhaps a slight decrease in particulate emissions and opacity with increasing fuel S level in the tests without Ba additive and the opposite effect in the presence of the Ba additive. If
Table 1. Effect of Fuel S and Ba Levels on Total Particulate Mass Emission and Opacity; 1974 Mercedes 240D test type
fuel S, wt %
cold start-FTP hot start-FTP hot start-FTP cold start-FTP hot start-FTP hot start-FTP cold start-FTP hot start-FTP hot start-FTP cold start-FTP hot start-FTP hot start-FTP cold start-FTP hot start-FTP hot start-FTP cold start-FTP hot start-FTP hot start-FTP
0.0087 0.0087 0.0087 0.110 0.110 0.110 0.190 0.190 0.190 0.0087 0.0087 0.0087 0.110 0.110 0.110 0.190 0.190 0.190
fuel Ba,
wt Yo
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.058 0.058
0.058 0.058 0.058 0.058 0.058 0.058 0.058
particulate ma88 emlssion rate ( M ) , rnglkm
518 36 1 399 453 348 385 440 320 362 472 242 339 794c 286 454 469 283 355
% opaclty a
17 15
b 14 13
b 14 13
b 9.5 7.8
b 15c 7.1
b 11 10
b
a Average percent opacity of peak heights in smokemeter traces. Smokemeter measurements not taken: exhaust injected directly into dilution tube. Modal analysis of the test showed a disproportionate level of particulate emissions during the early stages of the run, indicating a possible engine malfunction or sudden release of stored particulate.
1122
Environmental Science & Technology
fuel S level does not affect the combustion process, one should not expect a significant change in mass particulate emissions with changes in fuel S level since sod2-is the only significant particulate species derived from fuel S and it represents only a few percent of the total particulate mass (see below). The Ba fuel additive caused a substantial reduction in the opacity of the diesel exhaust-on the average, 30-40% of the reading. The Ba effect on particulate mass emission rate was much smaller-only -2% for the cold-start tests (the anomalous results with the 0.110 wt % S/0.058 w t % Ba fuel were not included in thir, average) and -10% for the hot-start tests. These reductions in mass particulate are obviously not large enough to account for the observed reductions in opacity. The smoke suppression by Ba therefore must result from changes in chemical composition and/or size distribution (and/or other optical properties) of the particulate emissions. Samples collected during those hot start-FTP tests in which the exhaust was injected directly into the dilution tube were subjected to de tailed chemical analyses. Chemical analyses were not performed on samples collected downstream of the smokemeter, since it was noted that the measured particulate mass emission rates (Table I) were consistently lower when the exhaust was passed through the smokemeter-indicating particulate loss in the smokemeter that might influence the chemical composition. Results of Ba and S042-analyses on the particulate emissions are given in Table 11. The S04?--emissions, both with and without the Ba fuel additive, increased with increasing fuel S levels, though not linearly in either case, so that the % S SO4?--conversion declined as the fuel S level was increased. When the Ba additive was present, the S042- emission rate increased with increasing fuel S level until the amount of emitted S042- was equimolar with the emitted Ba. Photoelectron spectroscopy (ESCA) analysis showed that the Ba and S lines in the particulate samples were identical with those of BaS04. At the lowest fuel S level (0.0087 wt %), the fuel Ba/S molar ratiio was 1.56 and most (63%) of the fuel S was converted to so42-,yielding an exhaust-particulate Ba/S0d2molar ratio of 2.6 (Table 11);the excess Ba is presumably the soluble form(s) of Ba described by previous workers (4-7).
The fact that the particulate Ba/S04?-- ratio stops at -1.0 as the fuel S level is increased implies that the driving force for sod2-formation in the presence of the Ba additive is the formation of BaS04. The notable comparison of Table I1 is the five- to eightfold increase in SO42- emission rate or % S S042- conversion with the use of the Ba fuel additive. The increase is a consequence of B a s 0 4 formation which, as already stated, is evidently the driving force for S042-formation when the additive is present. Not explained, but certainly worth pointing out, is the curious fact that the multiplication factor between the emission rate or % S Sod2- conversion without Ba and that with Ba is essentially constant a t 6.9 f l.O(a)-fold. I t should be mentioned that the formation of S042- in the presence of the Ba additive and that in its absence probably are unrelated processes. The S S042- conversion in the absence of Ba is far short of the thermodynamic equilibrium value. Since equilibrium is not attained, the Ba cannot be acting simply by shifting the equilibrium to the right by removing product. The Ba emission rates in Table I1 account for >90% of the Ba consumed in the fuel. This is consistent with previously published work (5, 9). Carbon, hydrogen, and nitrogen analyses presented in Table I11 reveal some substantial effects of Ba fuel additive. The additive brought about an average 28% reduction in carbon content, 190% increase in hydrogen content, and 42% reduction in nitrogen content of the particulate matter. (Use of a Ba/Ca-containing fuel additive is reported (9) to have given a similar decrease in carbon but a decrease in H as well.) The average C/H mole ratios from Table I11 are 3.6 without Ba additive and 0.95 with it. These results suggest a significant effect of the Ba additive during the carbonaceous particulate formation process. This deduction, which also was advanced by other investigators ( 8 ) ,suggests that it is worthwhile to pursue the mechanism of the involvement of Ba in the formation of particulates on a more fundamental level. The reduction in carbonaceous content of the particulate emissions through the use of the Ba additive is enough to make plausible the large reduction in exhaust opacity in the face of negligible effect on total particulate mass emission rate. The
-
-
-
-
Table II. Ba and SO4*- Analyses of Particulate Emissions a fuel S, wt %
fuel Ea, wt %
partlcuiate mass ernlsslon rate ( M ) , mglkm
0 0 0
0.0087 0.110 0.190 0.0087 0.110 0.190
ernlsslon rate, mglkm Ba
399 385 362 339 454 355
0.058 0.058 0.058
s
~ 0 4 ~ -
-
1.9 5.4
a Analyses performed on samples collected during hot start-FTP tests v S emitted as S04*-.
mole ratlo
8.6 1.8 0.96 62.7 10.5 7.3
5.0 53 44 56
B~/so~'-
%
conversion
14.5 29.5 36.5
2.6 1.o 1.1
?re the vehicle exhaust was injected directly into the dilution tube.
Percent of
el
Table 111. Carbon, Hydrogen, and Nitrogen Analyses of Particulate Emissions a -
elemental analyses hydrogen rng/krn % 01 M b
particulate mass emisslon rate ( M ) , mg/km
rng/krn
0
399 385 36 2
31 1 278 336
78 72 93
7.9 7.4 6.2
0.058 0.058 0.058
339 454 355
204 263 201
60 58 57
22.2 18.6 18.8
fuel S, wt %
fuel Ea, wt %
0.0087 0.110 0.190
0
0.0087 0.110 0.190
0
carbon % of M b
2.0 1.9 1.7 6.5 4.1 5.3
nitrogen rnglkm % 01 M b
4.3
1.2
2.3
0.7
a Analyses performed on samples collected during hot start-FTP tests where the vehicle exhaust was injected directly into the dilution tube. of total particulate mass emissions.
Weight percent
Volume 14, Number 9, September 1980
1123
lack of change in total mass comes about because the carbon decrease caused by the Ba additive is offset by the additional Ba and s04'-. As indicated earlier, the exhaust opacity should be a function of the total particulate concentration in the exhaust, the chemical composition of the particulate, and the particulate size distribution. Particulate size distributions were not measured in this study, but Kittelson et al. (13)report that use of a Ba fuel additive results in a decrease in particle size, which may also be influencing the opacity. Conclusions
The Ba fuel additive caused a 30-40% decrease in opacity and a commensurate (-30%) decrease in the concentration of carbonaceous particulate in the diesel exhaust. Howeyer, this decrease in carbon was offset by Bas04 emissions deriving from the additive Ba and its reaction with fuel-derived sulfur, so that the total particulate mass emission rate was essentially unaffected by the additive. Therefore, the reduction in exhaust opacity was not a consequence of any reduction in total particulate mass, but rather may have been related to compositional change from highly absorbing carbonaceous particulate matter to relatively nonabsorbing Bas04 particles. Fuel S level had no significant effect on the total particulate mass emission rate. Fuel S level did affect the sod2-emission rate, but the effect was not linear. In the no-additive case, the % S S042- conversion of the fuel S was highest at low levels of fuel S and declined steadily with increasing fuel S level. In the presence of the Ba additive, the Sod2- emission rate (and % S sod2-conversion) was many times larger, and all in the form of BaS04. The Ba, through Bas04 formation, governed the SO4'- emission rate; the Ba/S04'- molar ratio was approximately 1.0 when the amount of fuel S was adequate to permit it. In all cases, better than 90% of the fueladditive Ba consumed was emitted.
-
-
The Ba additive caused a great increase in particulate H content and in particulate H/C ratio. This, and the reduction in carbonaceous particulate emissions, suggests a significant effect by the additive during the carbonaceous particulate formation process. Whatever the mechanism for the action of the Ba fuel additive, it must account for the compositional changes, including the prominence of BaS04. Acknowledgments
We wish to thank Fred C. Ferris for technical assistance in conducting the vehicle experiments, William Okamoto and E. H. Schanerberger for preparation of the fuels, and John S. Hammond for conducting the ESCA experiments. The Ba and sod2-analyses were performed by the Chemical Analysis Laboratory of the Ford Research Staff. Literature Cited (1) Cotton, D. H.; Friswell, N.'J.; Jenkins, D. R. Combust. Flame
1971,17, 87. (2) Jenkins, D. R. Combust. Sci. Technol. 1972,5, 245. (3) Glover, I. J . Inst. Petrol. 1966,52, 137. (4) Miller, C. 0. SAE Tech. Pap. 1967,670093. (5) Saito, T.; Nabetani, M. SAE Tech. Pap. 1973, 730170. ( 6 ) Golothan, D. W. SAE Tech. Pap. 1967,670092. ( 7 ) Turley, C. D.; Brenchley, D. L.; Landolt, R. R. J. Air Pollut. Control Assoc. 1973,23, 783. (8) Apostolescu, N. D.; Matthew, R. D.; Sawyer, R. F. SAE Tech. Pap. 1977, 770828. (9) Hare, C. T.; Springer, K. J.; Bradow, R. L. SAE Tech. Pap. 1976, 760130. (10) Gutwein. E. E.: Landolt, R. R.: Brenchlev, D. L. J . Air Pollut. Control Assoc., 1974,24, 40. (11) McKee, D. E. SAE Tech. Pap. 1977, 770167. (12) McKee, D. E.; Ferris, F. C.;Goeboro,R. E. SAE Tech. Pap. 1978, 780592. (13) Kittelson. D. B.: Dolan. D. F.: Diver, R. B.: Aufderheide. E. SAE Tech. Pap. 1978, 780789.
Receiued for review January 23, 1980. Accepted May 12,1980.
Fate of Selected Herbicides in a Terrestrial Laboratory Microcosm Jay D. Gile,' James C. Collins, and James W. Gillett Terrestrial Division, Corvallis Environmental Research Laboratory, U S . Environmental Protection Agency, Corvallis, Oregon 97330
The transport and metabolism of 1%-labeled herbicides (simazine, bromacil, trifluralin, and 2,4,5-T) applied as a foliar spray (0.28 kg/ha) was examined in a terrestrial microcosm chamber (TMC). These chemicals were compared to a reference compound, the insecticide dieldrin. The TMC contained a synthetic soil medium, Douglas fir and red alder seedlings, rye grass, numerous invertebrates, and a gravid gray-tailed vole (Microtus canicaudus). By 20 days posttreatment, total soil residues (parent and metabolites and bound residues) averaged 0.14 ppm for all chemicals. Except for dieldrin little extractable parent material was detected for any of the
chemicals in the soil. Concentrations of 14Cmaterial in the rye grass shoots ranged from an average of 2.5 ppm for 2,4,5-T to 16.8 ppm for simazine. 2,4,5-T and trifluralin were more rapidly degraded than the other chemicals with 2,4,5-T present primarily as extractable metabolites. 14Cmaterial of dieldrin was accumulated to a much greater extent than any of the herbicides in the invertebrates. While concentrations of all chemicals in the vole were low, 14Cmaterial from dieldrin and simazine was present at levels approximately twice those of the other chemicals. None of the chemicals could be detected in the ground water.
Introduction
duced cost in comparison to field studies. The utility of a microcosm rests on its adaptability to studying a wide variety of chemicals in different types of ecosystems. The TMC has previously been used to study insecticides and fungicides in an agricultural ecosystem. In this study herbicide application in a nonagricultural system is examined. Douglas fir reforestation practices have dictated the widespread use of selective herbicides to control red alder and
This is the third in a series of experiments in which representatives from broad categories of pesticides were examined in a terrestrial microcosm chamber (TMC) developed at the U.S. EPA's Corvallis Environmental Research Laboratory (CERL), as described earlier (1,2).Microcosms allow the investigator to examine materials that may be environmentally harmful with little risk to the environment and at a much re1124
Environmental Science & Technology
This article not subject to U.S. Copyright. Published 1980 American Chemical Society
