( : ] I ) \Veiser, H. H., "Colloid Chemistry", Wiley, Kew York, 19:i9, 1) AT,. ( 3 2 ) Stumm. Li',, hlorgan. ,J. .J.. "Aquatic Chemistry". \\-iley-Interscience, New York, 1970, p 193. (:],'j)
Rartell. F. E,, Fu, Y,, J . Ph>,s. C'hetn., XI, 1758 (19299).
(:M)\Veher. \V, .I.. dr., "Physiochemical Processes for Li'ater Quality ('ontrol", \Viley-Intel.scierice, New York. 1972. 11 240. (:I,;) Parks, C,. A,. in "Chemical Oceanography". Riley. .I. P.. Skirr()\\. G.,Eds., 2nd ed., Vol. I . Academic Pr i;ifi Somasiindaran, P.. Fuerstenari, D. I . , 70, 90 (1966). (:K) (;audin. A. XI., Fuerstenau, I). LV,,T r a m Am. In.\t. Miti., .ifetail. /'cat. E n g . , 202, $158(1955).
i:M) XIacRitchie, F.,J . C'olioid 1ntrJrfaac.eS c i . . 38, 184 i1972), (39) hlatijevii.. E., Kolak, N.. Catone, D. L., J . Hi>,,\. Cht~m..i:i, :3%6 (1969). (40) Kennedy. 1). C.. Stevens, R.. Kerner, .I. LV.,:In1 D . ~ c > . s iR. v p . , 6:1(8). 2 2 il97-l). ( 1 1 ) Chu, T. Y.J . . Steiner. (;. R., XIcEiityre, (1. I,.. ./. lt'ntvr Poiiiii. ('ciniroi Fcjd., 50, 2157 (1978i.
ficPac.(,ii,cdf o r rci.ic,ic J a n u a r y 22. 1979. Accepted Octobpr 12. 1979. This rcwurcii ii,ori: ii oh ,\upported h>,u grant (6.\(;7i-27:179) friim iirces, 1 'rbun a n d E~r~~~ircintiic~rital Enginc>c.ritiq/ ' r w tional .S(~ic,nac.c~ Foundation.
Estimation of OH Radical Concentration in a Propylene-NO, -Dry Air System Hajime Akimoto", Fumio Sakamaki, Gen Inoue, and Michio Okuda Division of Atmospheric Environment, The National Institute for Environmental Studies, P.O. Tsukubagakuen, Ibaraki, 305 Japan
T h e maximum concentration of OH radical, [OH],,,, was estimated from the dissipation rate of C3H6 in the photooxidation of a CaH,-NO,-dry air ( H 2 0 less than 1ppm) system. The experiments were performed using an evacuable and bakable smog chamber with a volume of 6065 L. T h e [OH],,, values obtained were in the range of (1-6) X IOfimolecule cm-j with an error of f30ct under the experimental conditions of [C:jH6]0 = 0.1-0.5 ppm and [NO,]o = 0.04-0.29 ppm, and h l = 0.13-0.37 min-l. The [OH],,, was found to be proportional to light intensity. I t was also shown that [OH],,, was independent of [ C : , H B ]when ~ [CJH&/[NO,]O 1 2 3, and the dependence of [OH],,, on [NO,]o was obtained.
-
In recent years the importance of OH radicals in the polluted atmosphere has been stressed, since the reaction of OH with hydrocarbons drives the chain reactions which result in the conversion of NO t o NO*, and the subsequent formation of ozone (1-8). Estimation of time-averaged O H Concentrations in ambient polluted atmospheres has been attempted based on the rates of removal of hydrocarbons. By this method, Calvert ( 8 )deduced the average ambient concentration of OH radical in the morning hours of a specific November day in Los Angeles to be (1.0 f 0.8) X ppm, or (2.5 f 2.0) X loBmolecule cm-', while the direct measurements made by Wang et al. (9) in Dearborn, Mich., in August gave values between 1and 5 x 10' molecule em-' during the daytime. In spite of the importance of O H in atmospheric chemistry, no systematic laboratory study t h a t gives the estimation of O H concentration under simulated atmospheric conditions has been made. Under specific experimental condition in the photooxidation of the hydrocarbon-NO,-air system, Wu e t al. ( 1 0 ) measured t h e OH concentration directly by the laser-induced fluorescence technique and compared it with a n estimated value based on the hydrocarbon dissipation rates. T h e average value obtained was typically (1.5 f 0.7) x 107 molecule em-'. I n the present study, hydrocarbon dissipation rates were observed in the photooxidation of the CjH~-No,-dry air system under various light intensities and initial concentrations of NO, and C:jH6. T h e average concentrations of O H radical were estimated from t h e dissipation rates of C ~ H F , ascribed to OH, which was obtained by subtracting the calculated disappearance rate due to ozone from the total decay rate. An attempt was made to correlate the estimated O H 0013-936X/80/0914-93$01.00/0
@ 1980 American
Chemical Society
concentrations to the light intensity and the initial concentrations of NO, and CsH6. Experimental T h e evacuable and bakable photochemical smog chamber and the experimental procedure have been previously described (11, 12).T h e purified dry air used in t h e experiment contained less than 1 ppm of HzO and COZ. All experiments were performed at 30 f 2 "C. Propylene was analyzed either by a n in situ long-path Fourier transform infrared spectrometer (LP-FTIR) or a FID gas chromatograph with a technique of low-temperature condensation. T h e concentrations of 0 and NO, were monitored continuously by commercial chemiluminescent analyzers. T h e absolute calibrations of the ozone analyzer were made against IR photometry using t h e L P - F T I R and described elsewhere (13). Data Reduction In this study, the dissipation rate of C3H6 was analyzed in each run of the C,H,-NO,-dry air system, for which photochemical 0 3 formation has been reported previously (12). The CjH6 and 0 7 concentrations used in the calculation have appeared elsewhere ( 1 4 ) . An experimental run (run 28) with higher concentrations of C& (3.0 ppm) and NO (1.50 pprn), which is not included in the previous report (12, 1 4 ) ,was also analyzed. In the photooxidation of the C'HG-NO,-air system, CxHc, is attacked by a species such as OH, 0 3 , 0, HOr, NO,, etc. (2-5). T h e relative rate of attack on C3HG by the individual species has been estimated in computer modeling studies by several investigators (2-5). According to these studies, the sum of the OH and 0 3 rates seems to amount to more than 90%of the total decay rate of C3Hs. Therefore, neglecting the reaction of C:jH6 with species other than OH and 03,the decay of C:jH6 can be given by:
where hp and k 3 are the rate constants of the reaction of C3H6 with 0 3 and OH, respectively. Integrating and rearranging Equation 1,the following equation can be derived:
+
it
In [C3H61t h 2 [O:,]d t = -h3[OH],,t (2) [C3H610 where [OH].. is the average concentration of O H radical be~
Volume 14, Number
l , January
1980
93
010
-&
2
-
1
0
007-
005
0" . 003 r"
I
002
I
1
(a)
-
L
I
1
001
120
-12t
I
120
240
360
480
600
'
Irradiation Time ( m i d Figure 1. (a) Time variations of the concentration of C3H6 and O3 after irradiation: [CsHs]o = 0.10, [N02]o = 0.021, [ N o l o = 0.005 ppm; kl = 0.16 min-'. (b) The plot of Equation 2 for the above run
94
Environmental Science & Technology
4Bo
600
Figure 2. (a) Time variations of the concentration of C3Hs and O3after irradiation: [C3Hs10= 0.10, [N02]0 = 0.001, [NO10 = 0.033 ppm; kl = 0.16 min-'. (b) The plot of Equation 2 for the above run "IO? 'O
tween t = 0 and t . T h e left-hand side (1.h.s.) of Equation 2 represents the difference between the total amount of decay and the decay due to the reaction with 03,and should be equal to the decay due to OH. T h e slope of the plot of the 1.h.s. vs. time should give the average decay rate of C3H6 attacked by OH radicals. In our calculation, the rate constant, k 2 = (13.0 f 0.1) X cm3 molecule-1 s-l, obtained by Japar, Wu, and Niki ( 1 5 ) was used. Figures l a and 2a show the typical profiles of the formation of O3 and the disappearance of CzHfi when C3H6 was irradiated with NO2 and NO, respectively. T h e concentration of C3H6 decays nearly exponentially with time under our experimental conditions when the initial constituents of NO, were mainly NO2, although a short induction period was observed for some of the runs. When the initial constituents of NO, were mainly NO, a slow initial decay was followed by a faster nearly exponential decay as shown in Figure 2a. Figures l b and 2b show the plot of Equation 2 corresponding to the data shown in Figures l a and 2a, respectively. T h e slope of the plot decreases monotonically with time for C3H6-N02 mixtures, whereas the slope increased with time initially and then decreased a t the later stage for C ~ H G - N O mixtures as typically shown in Figures I b and 2b, respectively. T h e results suggest that the OH radical concentration is high a t the beginning of irradiation and gets lower as the photooxidation proceeds for C3Hfi-NO2 mixtures, while it has a maximum during the irradiation for CsHfi-NO mixtures. T h e latter behavior has been predicted well in the computer modeling studies (2, 3 , 5 ) . In this study, the average total decay rate, (-d[C~Hfi]/ [ C ~ H f i l d t was ) ~ , obtained from the apparent linear plot of log [CsHfi]vs. t as shown typically in Figures l a and 2a. The decay rate due t o OH, (-d[C3Hfi]/[C3H~]dt)o~, was obtained from the slope of the linear part of the plot of Equation 2 as indicated typically in Figures l b and 2b. T h e O H concentration was then calculated from the decay rate using the value of h3 = (2.51 & 0.25) x 10-l' cm3 molecule-'^-^ reported by Atkinson and Pitts (16). Since the maximum slope of the plot was used for the calculation, the OH concentrations obtained
360
240
Irradiallon Time (min)
7 A A
A
would correspond to their maximum values when radical chain oxidations are occurring most actively in the photooxidation process. T h e OH concentration thus obtained is designated as [OH],,, in this study.
Results Table I summarizes the reduced experimental results along with data on the initial concentrations of the reactants and light intensity. T h e initial concentrations of C3H6 and NO, were varied in a systematic manner. T h e initial NO, concentration was varied from 0.020 to 0.063 ppm, and from 0.045 to 0.290 ppm, while the initial C 3 H ~concentration was maintained constant a t 0.10 and 0.50 ppm, respectively. Then, the initial C3H6 concentration was varied from 0.05 to 0.40 ppm and from 0.20 to 0.50 ppm, while the initial NO, concentration
Table I. OH Concentrations Determined from the Decay Rate of C3H6
2 3 4
5 6 7 8 10 11 13 14 15 16 17 19 20 21 22 23 24 25 26 27 28 a
0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.50 0.50 0.50 0.50
0.0196 0.0255 0.0342 0.0359 0.0430 0.0516 0.0630 0.0452 0.0896 0.0901 0.187 0.290 0.0382 0.0393 0.0391 0.0393 0.0863 0.0912 0.0850 0.0900 0.0830 0.0881
0.50 0.05 0.15 0.30 0.40 0.20 0.33
0.50 0.50 0.50 0.50 0.50 3.02
0.0154 0.0046 0.0329 0.0040 0.0217 0.0488 0.0478 0.0040 0.0082 0.0818 0.01 10 0.255 0.0035 0.0035 0.0049 0.0046 0.0092 0.0077 0.0115 0.0120 0.0094 0.0087 0.0068 1.477
0.0889 1.500
0.0042 0.0209 0.0013 0.0319 0.0213 0.0028 0.0152 0.0412 0.0814 0.0083 0.176 0.036 0.0347 0.0359 0.0341 0.0347 0.0771 0.0835 0.0735 0.0780 0.0736 0.0794 0.0821 0.0023
Run numbers are in common to those in ref 20. The values are based on
0.16c 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.367 0.308 0.247 0.189 0.130 0.27 k3
2.49 3.38 3.85 3.76 4.30 4.68 4.93 3.74 4.96 5.44 7.83 11.0 1.91 4.88 4.98 4.93 6.07 6.86 10.1 8.38 7.36 6.27 5.41 15.8
2.00 2.81 2.60 3.36 3.14 2.78 3.38 3.00 3.45 2.63 3.97 4.46 1.51 2.54 2.47 2.50 3.54 3.42 8.93 7.04 5.00 4.42 2.86 10.0
1.3 1.9 1.7 2.2 2.1 1.8 2.2 2.0 2.3 1.7 2.6 3.0 1.o 1.7 1.6 1.7 2.4 2.3 5.9 4.7 3.3 2.6 1.9 6.6
’
= 2.51 X lo-’ cm3 molecule-’ s-’ (ref 25). k , = 0.16 f 0.02 min-’ for runs
2-22
Y
I C1
I
I
J
32
03
04
03
02
01
k,
04
(miri’)
Figure 5. Dependences of the decay rates of on the k , value: [CsHs]o = 0.50, [NO,] = 0.09 ppm; ( - d [ C 3 H s ] / [ C ~ H s ] d f ) ~(0); (-d[&Hsl /[C3Hsldt)o~( 0 )
was held constant a t about 0.04 and 0.09 ppm, respectively. Light intensity was varied from 0.13 to 0.3’7 min-l for a fixed initial concentration of NO, (-0.09 p p m ) and CjHe (0.50 ppm). T h e statistical error associated with the values of (-d[c~HG]/[C3HG]dt)rgiven in Table I was typically d ~ l 0 % . T h e error associated with (-d[C {He]/[C1 H f i ] d t ) 0was ~ estimated to be &20% from the plot of Equation 2. T h e errors for the relative amount of [OH],,, are the same as for -(d[C,iHs]/[CjHs]dt)o~,but taking into consideration the error of h.3, the error f‘or [OH],,, would be estimated to be f30%. T h e effects of the initial concentration of C ~ H on G the total
decay rate and the decay rate due to O H radical are shown in Figure 3. T h e variations with the initial concentration of NO, and with light intensity, as expressed as values of h l (the photodissociation rate of NOp), are shown in Figures 4 and 5 , respectively. Discussion Since the critical role of O H in photochemical air pollution has been generally recognized ( I - 3 ) , it would be of great interest t o establish the dependence of O H concentrations on the reaction parameters such as light intensity and initial Volume 14, Number 1, January 1980
95
concentrations of NO, and C ~ H Iin; the photochemical oxidation of t h e C3H6-NOX-air system. T h e dependence of O H radical concentration on light intensity appears to be most straightforward as shown in Figure 5. Thus, although the total decay rate of C3H6 is not proportional to the k 1 value, the decay rate of C3H6 due to OH, Le., [OH],,,, is proportional to the k 1 value. This evidence of the proportionality of [OH],,, to light intensity is the counterpart of the experimental observation that the NO photooxidation rates for various hydrocarbons are all proportional to light intensity ( 2 7 ) .These facts suggest t h a t the concentration of OH and that of RO2, which converts NO to NOz, are in proportion to each other. It is thought to be reasonable that the concentrations of O H and ROz radicals, both of which are essentially supplied by atonis produced by t h e photolysis of NOz, are proportional to light intensity. T h e nonproportionality of the total decay of C3H6 reflects the different contributions of the 0 3 reaction a t different light intensities. In our previous work (12 j on photochemical ozone formation in the C:IH6-NO,-dry air system, [ 0 3 l r n a x ,t h e ultimate maximum concentration of 03,was found to increase first with increasing [ C ~ H G and ] O then level off. T h e similar behavior of (-d[C:iH&[C:iHe]dt)o~, Le., [OH],,,, is seen in Figure 3. A C:JHe-excessregion where the [OH],,, is not dependent on [C:lH& may be defined as [C2Hc,]o/[N0,y]o> 2 3. I t is interesting to note that this region is about the same as the CaHe-excess region ([C:jH~]o/[NO,](~ Z 3) as defined by the leveling off of [03],,,. In the C3He-excess region, the decay rate of C3H6 increased with [NO,]o, but seems to be independent of [C3&]0 as shown in Figure 3. Figure 6 shows the replot of t h e total decay rate against J[NO,l0 for the data shown in Figure 4. In Figure 6, the runs with different initial constituents of NO, are discriminated. Thus, the total decay rate of C3H6 is shown to be proportional to \/[NO,lo and is not affected by the difference in t h e initial NO, contents. These observations of (-d[C3He]/[C3He]dt)~behavior are in accord with that of [031max, as shown in our previous paper (11).It can be deduced that differences in the initial NO, constituents only affect the time for OH and 0 3 to reach their maximum concentration, but do not appreciably affect the [OH],, and [03],,, realized in the photooxidation process. T h e dependence of the decay rate of C3He due to OH on [NO,]() is somewhat different from that of the total decay rate as shown in Figure 4. Figure 7 shows a log-log plot of [OH],,, values for the run where different k l values were adjusted to the value a t k l = 0.16 min-l using the proportional relationship between [OH],,, and hl. Run 16 in Table I was excluded from the plot since C3H6 concentration was apparently not in the C3H6-excess region for this run. It is interesting to note that the [OH],,, for the high concentration run (run 28) is in accord with that for lower concentration runs within experimental error. The combination of the dependence of [OH],,, on [NO,]o as shown in Figure 7 and t h e dependence on light intensity discussed before yields the relationship:
I
[NOxIo
(pprn)
Figure 6. Plot of ( - ~ [ C ~ H S ] / [ C ~ H vs. S ] ~\/[NO,l0 ~)T . T h e abscissa is in a square root scale. k l = 0.16 min-'. Initial composition of NO,
is mainly NO2 (O,A), half and half (A), and mainly NO (.,A). The circles and triangles are for [C3H6I0 = 0.50 and 0.10 ppm, respectively
-
[OH],,,
= (2.39 f 0.50) X 1 0 ' h ~ [ N 0 , ] ~ 0 ~ 2 2 * 0 ~ 0(3) 1
which should hold in the C3Hs-excess region. The errors correspond to a 95% confidence limit. Wu e t al. (10) reported the concentration of O H as (1.5 f 0.7) X IO7 molecule cm-3 for [C3H& = 0.97-1.45 ppm, [NO,]o = 3.2-4.1 ppm, and h l = 0.22 min-l. Their value was based on h3 = 1.7 X lo-" rather than the 2.51 X lo-" cm3 molecule-l s-l value used in this work, and would reduce to (1.0 f 0.5) X lo7 molecule cmV3on our basis, which may be compared to our predicted value of (7.0 f 1.8) X IO6molecule cmW3 obtained by Equation 3. Although the value is in fair agreement within experimental error, detailed comparison is not 96
Environmental Science & Technology
I
. [NOxlo
Figure 7. Log-log plot of [OH],,, to k , = 0.16 min-'
(ppm)
vs. [NO,]o. All values are adjusted
possible since their experimental condition did not fall into the C3H6-excess region. For ambient air containing 0.02-0.3 ppm of NO, and for sunlight intensity of h l = 0.40 min-l, our study predicts t h e OH concentration in the range of (4.0-7.3) X lofi molecule ern-,'. This is in fair agreement with the value of (2.5 f 2.0) X lofimolecule cm-3 estimated by Calvert (8) for the air in Los Angeles, while the (1-5) X lo7 molecule cmT3 measured by Wang et al. ( 9 )in Dearborn seems to be a little too high. Before further comparison of O H concentrations obtained from the smog chamber studies and ambient air can be made, the effect of humidity and the reactivity of ambient air in terms of the capacity for O H generation should be studied. Such studies are in progress in our laboratory. Literature Cited (1) Heicklen, J., Westberg, K., Cohen, N., "Chemical Reaction in Urban Atmospheres", Tuesday, C. S., Ed., American Elsevier Press, New York, 1971, p 55. (2) Niki, H., Daby, E. E., Weinstock, B., Adu. Chem. Ser., No. 113, 16 (1972). ( 3 ) Demerijian, K. L., Kerr, J. A,, Clavert, J. G., Adu. Enuiron. Sci. Techno/., 4, l(1974). (4) . , Dovle. G. J.. Llovd. A. C.. Darnall. K. R.. Winer. A. M.. Pitts. J. N., JI., knuirbn. .'5k.'Techhol., 9, 2j7 (1975). (5) Calvert, J. G.. McQuigg, R. D., Int. J . Chem. Kinet. Symp., 1,113 (1975). (6) Darnall, K. R., Lloyd, A. C., Winer, A. M., Pitts, J. N., Jr., Enuiron. Sei. Technol , 10,692 (1976). (7) Wu, C. H., Japar, S. M., Niki, H., J . Enuiron. Sei. Health, Ser. A, 11, 191 (1976). (8) Calvert, J. G., Enuiron. Sci. Technol., 10, 257 (1976).
\Vanp, C. C., Davis. L. I., -Jr., LVu, C. H.. dapar, S.. Niki. H.. \Veinstock, H., S'cic>ric,c, 189, 797 (19751. ( 10) LVu. C. H.. LVang, C. C.. .Japar, S. M., Davis, I,. I.. -Jr., Hanahusa. hl.. Killinger. D.. Niki, H., \Veinstock. €3., I n t . J . Chc>ni.K i n e t . , 8 , 765 (1976). (11) Akimoto. H.. Sakamaki. F.. Hoshino. M., Inoue. G.. Okuda, M., E n r i r o n . Sci. Techno/., 13, 53 (1979). (12) Akimoto, H., Hoshino. M., Inoue. G., Sakamaki, F., Washida, N.. Okuda, M.,Enriron. S e i . Techno[., 13, 471 (1979). (13) Akimoto. H.. Inoue. G.. Sakamaki, F., Hoshino, M., Okuda, M., (9)
J . J p n . Soc. Air Poilut., 13, 266 11978). (14) Research Report from the National Institute for Environmental
Studies, Tsukuba, Ibaraki, ,Japan, R-4-78, Aug 1978, pp 67-93, .Japar. S.hl., \Vu. ('. H.. Niki, H., J . P h p ('hcrn., 78, 2;118
(161
(19741. ( 1 6 ) Atkinson, I?.. Pitts. .J. h'.,.Jr.. ,/. ('hcn7. f ) / i > s . ,63, :3591 ( l 9 7 5 ) , ( 1 7) (;laSSlJn. LV. A,, Tuesday, [:, s., J . ,Air P(Ji/l!t.( ' ( J r l t / ' l J / A.S.\rJ('..20,
239 (1970).
Hecpiced f o r r e t ~ i e uA p r i i 6 , 1979. Accepted October L'I, 1979
Analysis of Stack Gases Using a Portable Gas Chromatographic Sampling and Analyzing System Donald L. Miller", John S. Woods, Kenneth W. Grubaugh, and Linda M. Jordon Michigan Division Analytical Laboratories, Dow Chemical U.S.A., Midland, Mich. 48640
w EPA method No. 5 for the determination of particulate emission requires the dry molecular weight of the gas. A gas chromatographic (GC) technique has been developed as a substitute for the chemical ORSAT technique. T h e GC technique has several advantages: one, the stack gas can be analyzed rapidly for Cog, 0 2 , CO, and Ng directly; two, the sample for the GC analysis is obtained via an on-stream sampling system, thus reducing potential contamination as opposed t o the necessary "grab" samples and containers for the ORSAT analyzer; three, the analog signal from the GC is interfaced simultaneously to a recorder and integrator, thus giving a graphical and digital readout. T h e GC sampling and analysis system is described, and a procedure for preparing gas mixtures is presented. Data showing the correlation among t h e theoretical composition, GC analysis, and ORSAT analyses of gas mixtures and stack gases are presented. T h e majority of the commonly used sampling procedures (EPA,ASME, and ASTM) for determining particulate matter in incinerator stack gas also requires the determination of its gaseous components, namely Cog, 0 2 , CO, and nitrogen by difference ( I , 2). T h e sampling procedures also state that the gaseous components be determined by the ORSAT analyzer ( 3 )or comparable apparatus. it'e have developed an on-stream gas chromatographic (GC) gas sampling and analyzing system that we think is not only comparable but better than the ORSAT analyzer for the following reasons: First, the stack gas can be analyzed much faster than by the ORSAT analyzer. During the 15 to 20 min it takes to collect samples and determine C O Y ,0 2 , and CO by t h e ORSAT analyzer, five samples can be analyzed for t h e above components and nitrogen by the on-stream GC system. Second, the GC analysis is much more representative of the actual gas composition than is the ORSAT analysis. T h e gas composition can change drastically during the 15 min required for ORSAT analysis on grab samples. Third, since there are no hottles of absorbing solutions in the GC system, there will be no breakage of bottles or mixture or contamination of solutions. This GC system is portable. All of t h e components are mounted on a 2 ft X 3 ft laboratory cart, and the entire assembly can he taken to the gas source for rapid, repetitive analysis. There are several portable gas chromatographs t h a t are commercially available, including the portable GC manufactured hy the Carle Co., the portable gas chromatograph made by Analytical Instrument Development Inc., and the 0013-936X/80/0914-97$01 .OO/O
@ 1980 American Chemical Society
Model T C D 1010 produced by Baseline Industries. Also, other gas chromatographic techniques have been used to determine the above components in gas streams. Beke ( 4 ) separated N2, O., and CO from mixtures containing Con, NO?, and SF,; using a series-parallel combination of Porapak-Q a t 25 "C and moNZ, and lecular sieve 5A a t 82 "C. Swan (S)determined HZ, o:?, CO in CO2 by passing the mixture through a precolunin of porous polymer material, which absorbed the COP preferentially. T h e other components passed through and were separated on a molecular sieve column and detected by a helium ionization detector. Golden and Yeung ( 6 )determined trace amounts of O:j, N.0, COZ, CHJ. H2O. and CO in gases using long-path absorption infrared techniques. However, our system is not only a gas chromatograph hut a gas chromatograph sampling and analyzing system with several advantageous features which are as follows: (1)I t contains an Alltech concentric column, which allows the gas mixture to be analyzed for COZ, 0 2 , N., and CO a t ambient temperature in less than 3 min without temperature programming, valve switching, or column back flushing. (2) T h e GC detector is connected to an integrator that measures and prints out the peak areas instantaneously, and the actual percentages of the components can be calculated immediately on the site. (3) A stainless steel or quartz glass probe can he placed in the incinerator hot zone and the gas can be either pumped through a valving system and sample loop into the chromatograph or it can bypass it. (4) The valves can he switched and a standard gas mixture passed into the GC allowing for instant calibration. In the following section of the paper the system will be described in detail, and accurate methods for making u p standard mixtures will be presented along with the analysis of the mixture by both GC and ORSAT. Also, the analysis of the stack gas from a waste incinerat,or will he discussed.
Experimental Description of the Apparatus. A diagram of the assembled apparatus is shown in Figure 1. T h e chromatograph is a Gow Mac dual column unit equipped with a concentric column and a thermal conductivity detector. Helium is the carrier gas. T h e detector is wired in parallel to both a recorder and integrator (Hewlett Packard Model 3370A). The data are presented simultaneously as a chromatogram and a digital printout of the peak areas. T h e GC column is a stainless steel concentric column with the following dimensions: inner column, '/x in.; outer column, '/A in.; column length, 6 f t . T h e inner column is packed with Volume 14, Number 1, January 1980
97
