Envlron. Scl. Technol. 1903, 17, 760-762
chi, John Foor, Jr., John R. Foor, John A. Hook, Warren H. Kipp, the crew a t Allegheny under the late Robert J. Hauger, and the Executive Director of the Pennsylvania Turnpike Commission, James B. Wilson. Registry No. Ammonia, 7664-41-7; ammonium, 14798-03-9.
Literature Cited (1) Magee, P. N.; Montesano, R.; Preussmann, R. In “Chemical
Carcinogens”;Searle, C. E., Ed.; American Chemical Society: Washington, DC, 1976; ACS Monogr. No. 173, Chapter 11. (2) Fine, D. H.; Rounbehler, D. P.; Belcher, N. M.; Epstein, S. S. Science (Washington, D.C.) 1976, 92, 1328-1330. (3) Shapley, D. Science (Washington,D.C.) 1976,191,268-270. (4) Pellizzari, E. D. U.S. Environmental Protection Agency, 1977, Report EPA-60017-77-055, P B 269582. (5) Urban, C. H.; Garbe, R. J. SAE Tech. Pap. Ser. 1979, No. 790696, SAE Trans. 1979,88, 2402-2419. (6) Slone, R. J.; Scheffel, R. W.; Shahed, S. M.; Petersen, B. SAE Tech. Pap. Ser. 1980, No. 801375. (7) Smith, L. R.; Urban, C. M.; Baines, T. M. SAE Tech. Pap Ser. 1982, No. 820967. (8) Goff, E. U.; Coombs, J. R.; Fine, D. H.; Baines, T. M. SAE Tech. Pap. Ser. 1980, No. 801374. (9) Hare, C. T.; Baines, T. M. SAE Tech. Pap. Ser. 1977, No. 770719. (10) Hurn, R. W.; Allsup, J. R.; Cox, F. U.S. Environmental Protection Agency, 1975, Report EPA-65012-75-014, P B 253782. (11) Hurn, R. W.; Cox, F.; Allsup, J. R. U.S. Environmental Protection Agency, 1976, Report EPA-60012-76-026, P B 254238. (12) Zweidinger, R. B.; Tejada, S. B.; Sigsby, J. E.; Bradow, R. L. In “Ion Chromatographic Analysis of Environmental Pollutants”; Sawicki, E.; Mulik, J.; Wittgenstein, E., Eds.; Ann Arbor Science Publishers: Ann Arbor, MI, 1978; Vol. 1, Chapter 11. (13) Cadle, S. H.; Nebel, G. J.; Williams, R. L. SAE Tech. Pap. Ser. 1979, No. 790694; SAE Trans. 1979, 88, 2381-2401. (14) Urban, C. M.; Garbe, R. J. SAE Tech. Pap. Ser. 1980, No. 800511. (15) Smith, L. R.; Black, F. M. SAE Tech. Pap. Ser. 1980, No. 800822. (16) Cadle, S. H.; Mulawa, P. A. Environ. Sci. Technol. 1980, 14, 718-723.
(17) Smith, L. R.; Carey, P. M. SAE Tech. Pap. Ser. 1982, No. 820783. (18) Robinson, E.; Robbins, R. C. “Sowces, Abundance, and Fate of Gaseous Atmospheric Pollutants”; Stanford Research Institute, Menlo Park, CA, 1969; report to American Petroleum Institute, Supplement June, p 5. (19) Kamin, H. et al. “Ammonia”; N.A.S.-N.R.C., Committee on Medical and Biologic Effects of Environmental Pollutants, Subcommittee on Ammonia; University Park Press: Baltimore, MD, 1979; pp 130, 131, 138. (20) Magill, P. L.; Benoliel, R. W. Ind. Eng. Chem. 1952, 44, 1347-1351. (21) Harkins, J. H.; Nicksic, S. W. Enuiron. Sci. Technol. 1967, 1, 751-752. (22) Hunter, J. E., Jr. Central States Section Meeting, Combustion Institute, Ann Arbor, MI, 1971, General Motors Research Publication GMR-1061. (23) Gentel, J. E.; Manary, 0. J.; Valenta, J. C. Enuiron. Prot. Agency Publ., APTD Ser. (US.) 1973, APTD-1567. (24) Henein, N. A. SAE Tech. Pap. Ser. 1975, No. 750931. (25) Bradow, R. L.; Stump, F. D. SAE Tech. Pap. Ser. 1977, No. 770369. (26) Braddock, J. N. SAE Tech. Pap. Ser. 1981, No. 810280. S. A. Anal. Chem. 1977,49,401-403. (27) BOU~OUCOS, (28) Chladek, E.; Marano, R. S.; Kelly, M., Ford Motor Company, unpublished data, 1982. (29) Truex, T. J.; Pierson, W. R.; McKee, D. E. Enuiron. Sci. Technol. 1980,14, 1118-1121. (30) Pierson, W. R.; Brachaczek, W. W.; Hammerle, R. H.; McKee, D. E.; Butler, J. W. J . Air Pollut. Control Assoc. 1978, 28, 123-132. (31) Chang, T. Y.; Modzelewski, S. W.; Norbeck, J. M.; Pierson, W. R. Atmos. Environ. 1981, 15, 1011-1016. (32) Pierson, W. R.; Gorse, R. A., Jr.; Szkarlat, A. C.; Brachaczek, W. W.; Japar, S. M.; Lee, F. S.-C.; Zweidinger, R. B.; Claxton, L. D. Environ. Sci. Technol. 1983, 17, 31-44. (33) Gorse, R. A., Jr., submitted for publication in Environ. Sci. Technol. (34) Harvey, C. A.; Garbe, R. J.; Baines, T. M.; Hellman, K. H.; Somers, J. H.; Carey, P. M. SAE Tech. Pap. Ser. 1983, No. 830987. Received for review February 15, 1983. Revised manuscript received June 10, 1983. Accepted July 11, 1983.
CORRESPONDENCE The following proportionality constants (K,) were derived by Sakamaki, Akimoto, and Okuda:
Comment on “Photochemical Reactivity and Ozone Formation in I-Olefin-Nitrogen Oxide-Air Systems” SIR: Sakamaki, Akimoto, and Okuda (1)have presented a methodology for quantifying the relationship between precursor NO, and ozone under conditions of excess hydrocarbon. They note that for a given initial concentration of NOz at a particular NO2 photolysis rate constant (KJ there exists a photostationary concentration of ozone, [O,],. In a series of experiments involving terminal olefiis under conditions of hydrocarbon excess, maximum Oswas found to be proportional to [O,],,. Sakamaki, Akimoto, and Okuda note that since [O,],, [(K1/K3)[N0~111/z (where K3 = rate of reaction between O3 and NO), [O,], is approximately proportional to the square root of initial [NO21* 760 Environ. Sci. Technol., Voi. 17, No. 12, 1983
KP
hydrocarbon
9.93 9.21 8.45 8.24
C,H, C3H6 l-C,H, 1-C,H,o
We have extended this analysis to some of the data obtained from the University of California, Riverside (UCR), smog chamber (2). Although the UCR experiments typically use a mixture of NO and NO2 as the initial NO,, the measured NOz peak can be used to calculate [O,],, (see Figure 1). The UCR experiments show greater variability than those of Sakamaki, Akimoto, and Okuda. Some of the variance in the Kp for each hydrocarbon may be due to reaction products formed prior to the NOz peak. Changes
0013-936X/83/09 17-0760$01.50/0
0 1983 American Chemlcal Society
I/ IO
\
I
0
c TIME OF DAY Flgure 3. Propene plus toluene photooxldlzed in the UNC outdoor smog chamber. Initlal condltions of propene and NO, identical wlth those shown In Flgure 2; 0.45 ppm of toluene added. All other experimental conditions Identical wlth those of Figure 2. Note reduced ozone peak. Solld lines Indicate slmulatlon results (5).
I -
.-
,
\
n
O
n 4
no,
PO1
OD,
DO4
DO,
007
001
001
001
P I
IWP,
Figure 1. Calculations of Kp([03]mx/[03]ps). [O,],. Is calculated at the NO2peak for data obtalned in the UCR evacuable smog chamber (2). Data for o-xylene experlmsnt EC-291 is from ref 3. Abbreviations: E = ethene; = propene; B = butane; T = toluene; A = acetaldehyde; F = formaldehyde; D = 2,ddimethylbutane; TB = toluene plus benzaldehyde; M = m-xylene; 0 = o-xylene. (asterisk) No added NO,; background NO, only.
oDo5 6
7
8 % 9
1>12
13
TIME OF DAY
I5 16
17
Flgure 2. Propene photooxidized in the UNC outdoor smog chamber. Lines indicate slmulation results (5).
in chamber conditions and analytical procedures might also be responsible. Some of the propene experiments were probably performed at a HC/NO, ratio that was less than optimum, and the extended time to peak O3 may have been long enough for heterogeneous losses of 0,and NO, to become a factor. A t low concentrations of NO,, the UCR chamber ppb/min) becomes a factor. emission rate of NO, (~~0.1 This is one reason for the slope of the Kp/ [03],, curves at low [O,],, in Figure 1. Two indicated experiments for formaldehyde and acetaldehyde were performed without added NO,; the [O,],, was calculated from the measured NOz background in the chamber. Despite these caveats, the UCR data supports the conclusions of Sakamaki, Akimoto, and Okuda in that (1) ozone formation is roughly proportional to [NOz]1/2and (2) ethene is more efficient than propene as a generator of O3per NO, consumed. These results also indicate that butane may be more efficient than propene in generating O3 a t high HC/NO,. The parameter Kpis also a function of temperature since many NO, sinks, especially PAN, are temperature sensitive. Thus, the direct calculation of K for an outdoor smog chamber is impractical. However, is an indication of NO, sink strength, and relative differences in Kpamong different compounds do have an observable effect, even under diurnally varying conditions. An experiment that clearly demonstrates this effect is shown in Figures 2 and 3. It was predicted ( 4 ) that the addition of toluene to a propene system would result in
4
a reduced ozone peak. In a dual experiment performed at the University of North Carolina (UNC) outdoor chamber, the propene plus toluene experiment produced ozone at a faster initial rate than the propene-only experiment, yet the experiment with toluene reached a peak value that was 30% less than the experiment without toluene. Thus, the low Kp shown by toluene is in agreement with previous analyses that indicate the existence of strong NO, sinks in toluene photochemistry. It is interesting to note that a mixture of toluene and benzaldehyde has a lower Kp than toluene itself. Undoubtedly this is due to the additional NO, sink that benzaldehyde oxidation produces (6). Since benzaldehyde is also a radical scaveenger, it is evident that the addition of this compound to a smog system can both retard ozone formation (because of the radical sink effect) and reduce the ozone maximum (because of the NO, sink effect). Unfortunately, benzaldehyde is the direct precursor of peroxybenzoyl nitrate, a powerful eye irritant (7). Practical use of benzaldehyde to reduce ozone formation is therefore contraindicated. Our analysis also indicates what may be an important difference in the chemistries of m- and o-xylene. The Kp for m-xylene appears to be fairly high, similar to that for propene. However, o-xylene seems to have a low K,, similar to that of toluene. Mechanistically, this may be interpreted as the result of a high rate of o-tolualdehyde formation. The fraction of H atom abstration by OH vs. OH addition to the aromatic ring has been measured as 0.2 for o-xylene and 0.04 for m-xylene (8). Dimitriades et al. (9) reported a high rate of NO-to-NO2 conversion for o-tolualdehyde, coupled with a low ozone-forming potential. This indicates a high radical initiation reactivity coupled with a strong NO, sink. The large difference in Kp between o-xylene and mxylene may have important implications regarding the development of generalized mechanisms for the atmospheric photooxidation of aromatic hydrocarbons. Registry No. Nitrogen oxide, 11104-93-1;ozone, 10028-15-6.
Literature Cited (1) Sakamaki, F.;Akimoto, H.; Okuda, M. Environ. Sci. Technol. 1981, 15, 665. (2) Pitts, J. N., Jr.,.et al. U.S. Environ. Prot. Agency 1979, EPA-600/3-79-1IO. (3) Carter, W. P. L.,personal communication, 1983. (4) Killus, J. P.; Whitter, G. Z. Atrnos. Environ. 1982, 16, 8. (5) Whitten, G. Z.; Killus, J. P.; Hogo, H. U.S. Environ. Prot. Agency 1980, EPA-600/3-80-028a. (6) Niki, H., et al. “Nitrogenous Air Pollutants, Pollutants, Chemical and Biological Implications”; Ann Arbor Science: Ann Arbor, MI, 1979. (7) Heuss, J. M.; Glasson, W. A. Environ. Sci. Technol. 1968, 2,1109-1116. Environ. Sci. Technol., Vol. 17, No. 12, 1983 761
Envlron. Sei. Technol. 1983, 77,762-762
(8) Atkinson, R.; Darnall, K. R.; Lloyd, A. C.; Winer, A. M.; Pitts, J. N., Jr. Adv. Photochem. 1979, 11, 375-488. (9) Dimitriades, et al. “Development and Utility of Reactivity Scales from Smog Chamber Data”; U.S.Department of the Interior: Washington, DC, 1975.
James P. Killus,” Gary 2. Whltten
Systems Application, Inc. San Rafael, California 94903
SIR: We have been interested in establishing general relationships between photochemical ozone formation and the initial concentrations of hydrocarbons (HC) and NO, so as to enable inter-smog chamber comparison more quantitatively and get guidelines for ozone control strategy (1-4). We introduced “ozone formation potential (P)” defined as [O,],,/[O,],, as a measure of ultimate maximum concentration of ozone after prolonged irradiation. Here [O,],, was defined by -kl
[O,l,, =
+ (kL2 + 4k1k2[N0,]o)’/2 2k2
(1)
where kl and k2 are the rate constant of NOz photolysis and the NO-0, reaction, respectively. The basis for our proposal to use the nondimensional parameter was that P is approximately a constant which is determined specifically for each hydrocarbon in HC-excess region as revealed from our experimental (1-3) and computer simulation ( 4 ) studies. Killus and Whitten plotted K (which corresponds to our P) against [O,],, for the UCR chamber data in their comment on our previous paper (I). The constancy of Kp against [O,],, does not seem to be verified in Figure 1 of their comment. Although the experimental conditions ([HC],/[NO,], ratio) of the UCR chamber data employed are not specified, those experiments would not have always been performed at the HC-excess region. The tendency that the P value decreases as the [HC]o/[NO,]o ratio decreases has been predicted in our computer simulation for
782
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propylene (4) and also verified experimentally (5). Thus, the decreasing trend of Kp as [O,],,increases depicted in the figure would be due to a lower [HC],/[NO,], ratio for the runs with higher [O,],,. Also, the definition of [O,],, by Killus and Whitten is somewhat different from that we are using conventionally. They used a NO2 peak concentration instead of initial NO, concentration in eq 1. The use of NOz peak concentration might give more consistent results when comparing runs with different NO-to-N02 initial ratios, while the use of [NO,], is more versatile when comparing smog chamber experiments for which only a chemiluminescent NO, analyzer is employed and no “NO2” data are supplied. The use of NO2 peak concentration instead of [NO,], value would increase slightly a value of Kp as compared to a value of P. Our recent experimental results (5) revealed that the ozone formation potential as defined in the HC-excess region is the highest for paraffins, the lowest for aromatics, and intermediate for olefins. Further, m-xylene has a higher P value than toluene but lower than propylene. These trends agree fairly well with the results given by Killus and Whitten. The details of our study on the ozone formation potential for various hydrocarbons will be published elsewhere (6). Registry No. Nitrogen oxide, 11104-93-1;ozone, 10028-15-6.
Literature Cited (1) Sakamaki, F.; Akimoto, H.; Okuda, M. Environ. Sci. Technol. 1981, 15, 665.
(2) Akimoto, H.; Sakamaki, F.; Hoshino, M.; Inoue, G.; Okuda, M. Enuiron. Sci. Technol. 1979, 13, 53. (3) Sakamaki, F.; Akimoto, H.; Okuda, M. Enuiron. Sci. Technol. 1980, 14, 985. (4) Sakamaki, F.; Okuda, M.; Akimoto, H.; Yamazaki, H. Enuiron. Sci. Technol. 1982, 16, 45. (5) Samakaki, F.; Akimoto, H.; Okuda, M.; presented at the 22nd Annual Meeting of Japan Society of Air Pollution, Akita, Japan, Oct 7-9, 1981. (6) Sakamaki, F.; Akimoto, H., manuscript in preparation for publication.
Fumio Sakamaki, Hajlme Akimoto” The National Institute for Environmental Studies P.O. Tsukuba-gakuen, Ibaraki 305,Japan
0013-936X/83/0917-0762$01.50/0
0 1983 American Chemical Society
