n
a P mI N
z o_
Figure 11. Hydrogen sulfide levels in Cincinnati
5.0
O-SA','PLER NO 1 0 - S A I l P L E R NO 2
4.0
3.3
t-
E
2.0
2
1.0
o
n 12
1 2 p.m.
12
12
12 3.m.
12 P.T.
l i
12 P.m.
SAMPLIUG PERIOD. 5 days
of less than 0.75. A ratio of 0.5 causes a 25% decrease in response. N o mercaptan interference is noted when the HzS to mercaptan ratio is greater than 1. Because the atmospheric concentration of HnS is usually greater than that of CH3SH, interference from CHsSH would not ordinarily pose a problem. Interference from chlorine is not considered serious because chlorine levels in the atmosphere are generally below the level that would cause interference (Figure lo). Reproducibility of Instrumental Method
Two tape samplers were operated simultaneously for 5 days in Cincinnati, Ohio, under field operating conditions to determine the reproducibility of the instrumental method. Data obtained are plotted in Figure 11. The average difference in 2-hr. concentrations over the 5-day period was calculated to be 0.09 p.p.b. with a standard deviation of 1 0 . 3 0 p.p.b., which is within the experimental error of the method.
pollution studies. The sampling instrumentation used has the advantages of low cost and simplicity of operation and maintenance. Acknowledgment
The authors thank Peter Formica and David Norris for their assistance in conducting the experimental work. Mention of company or product name does not constitute endorsement by the National Air Pollution Control Administration.
Concbsions
Literature Cited Bamesberger, W. L., Adams, D. F., Tappi 52, 1302 (1969). O'Keeffe, A. E., Ortman, G. C., Anal. Chem. 38,760 (1966). Park, J. P., J . Air Pollut. Control Assoc. 16, 325 (1966). Sanderson, H. P., Thomas, R., Katz, M., J . Air Pollut. Control Assoc. 16, 328 (1966). Sensenbaugh, P. J., Hemeon, W. C. L., Air Repair 4, 1 (1954). Smith, A. F., Jenkins, D. G., Cunningworth, D. C., J. Appl. Chem. 11, 317 (1961).
The results obtained indicate that the mercuric chloride paper tape method can be used for measurement of H2S in the range of concentration normally encountered in air
Receiued for reciew October 9, 1969. Accepted March 12, 1970. Presented at the Diuision of Water, Air, and Waste Chemistry, 157th Meeting, ACS, Minneapolis, Minn., April 1969.
Ultraviolet Spectrophotometric Determination of Nitrite-Nitrate in KOH John C. MacDonald and Louis Haddad Department of Chemistry, Fairfield University, Fairfield, Conn. 06430
w A method for the simultaneous ultraviolet spectrophotometric determination of NOe- and NOa- in aqueous KOH was developed. The molar absorptivities of NOnand NO3- at the analytical wavelengths of 301 and 356 nm. are solvent dependent; the absorptivities of NOz- and NO3- at 301 nm. decrease linearly with KOH concentration; the absorptivity of NOe- at 356 nm. increases linearly with KOH concentration. Accurate analyses require the correct molar absorptivities and the KOH concentration must be known. Equations for the determination of NO*and of NOs- are presented which require the determination of KOH concentration and the absorbances of the nitritenitrate in 1-cm. cell at 301 and 356 nm. The method was applied successfully to synthetic solutions, ranging from 0.5 to 7 M in KOH.
T
he most prominent air pollutants containing nitrogen are NO and NOz;the ratio of NO to NOz emitted from automobile exhausts is generally 99 :1 (Campau and Neerman, 1966). The methods that have been used for quantitatively determining this NO are: mass spectroscopy (Campau and Neerman, 1966), nondispersive infrared analysis (Huls and Nickol, 1967), oxidation to NOz (Nicksic and Harkins, 1962; Singh, Sawyer, et al., 1968), gas chromatography of NO is also plausible (Dietz, 1968). This laboratory has been studying the possibility of determining NO by absorption in KOH solution according to the equation (Taylor, 1960): 4N0 20H- += Nz0 2N0z Hz0 (1) and then analyzing for nitrite using absorption spectroscopy. A similar method has been applied to NO2 (Altshuller and Wartburg, 1960):
+
2N02 676 Environmental Science & Technology
+ 20H-
+
+=
NOz-
+
+ NOS- f HzO
(2)
0.7
-> -
).
c
c P
a
YI
U
0
z
2 0.6
kn
rp
7.5
U
Y
0 VI
m
m
U 4
U
0
I
0.5 344
352
360
I
5 .5 0
368
W A V E L E N G T H , nm
21 12
8
4
KOH
, MIL
Figure 1. Hypsochromic shift of 0.03 M nitrite at KOH concentrations of 0 (highest absorbance), 4.9 M , and 8.5 M (lowest absorbance)
Figure 2. Rlolar absorptivities of nitrite and nitrate cs. KOH concentration. Left ordinate is at 301 nm. Right ordinate is at 356 nrn.
Reaction 2 is also investigated. These reactions and the possibility of simultaneously determining NO and NOz have required a study of the electronic absorptions of nitrite and nitrate as functions of wavelength, temperature, possible effects of nitrite-nitrate interactions upon absorption characteristics, and KOH concentration. These electronic absorptions were found to be significantly dependent upon the KOH concentration, and analysts who may use this absorption technique for NO2 should have access to these data while our investigation of Reaction 1 is continuing.
pared and absorbances were measured cs. distilled water and also cs. the nitrite or nitrate blank of Table 1. The constancy o f A g i o a as nitrite is increased (column 4, upper half) and Ag&o1as nitrate is increased (column 4, lower half), indicates no measurable interference effects. KOH Concentration. The effects of KOH concentration upon nitrite and nitrate molar absorptivities are significant as shown in Figure 2. The plots are linear and follow the equations :
Results and Discussion Wavelength. The nitrate ion in aqueous solution shows electronic absorption bands centered at about 301 and 203 nm. with molar absorptivities of about 7,000 and 9,500 l./mol. cm., respectively. The higher wavelength maximum used here is solvent dependent (Rotlevi and Treinin, 1965) but does not shift wavelength here with KOH concentration up to 9 M , the highest concentration investigated. The nitrite ion in aqueous solution shows electronic absorption bands centered at about 356,280, and 210 nm. with molar absorptivities of about 23,000,9,000, and47,OOO l./mol. cm., respectively. These bands are also solvent dependent (Strickler and Kasha, 1963). There is a hypsochromic shift of the high wavelength band as the KOH concentration is increased as shown in Figure 1. All subsequent measurements were made arbitrarily at 356 nm. No effect was noted on the much broader 280 nm. band. The 210 nm. band was not investigated. Temperature. The absorption of the nitrogen oxides by KOH solutions was investigated at several temperatures, and the possible effect of change in solvent structure upon electronic absorption was studied. No temperature effects were evident in our experimental range, 2.5" to 45" C. Nitrite-Nitrate Interactions. Since the projected simultaneous analyses required the molar absorptivities of nitrite and nitrate in the presence of each other, possible interaction effects were investigated. The solutions of Table 1 were pre-
&yo' E&?'' E & ; ' '
=
7.09
- 0.18 (KOH)
(3)
=
9.02 - 0.28 (KOH)
(4)
=
23.4
+ 0.48 (KOH)
(5)
Although much data are available on the effects of different solvents on the energy (wavelength) and intensity of these absorptions of nitrite (Strickler and Kasha, 1963) and nitrate
Table I. Investigation of Possible Effects of Nitrite-Nitrate Interactions upon Electronic Transition at 301 nm. 1
2
4
3 A?", "". ~
KNOz
0 0.0120 0,0360 0.0600
Solvent blank 0.150 0.246 0.445 0.650
0.360 0.360 0.360 0.360
0.330 0.459 0.700 0.970
(M/l.)
0.0197 0.0197 0.0197 0,0197
Nitrate 0.165 0.153 0.138 0.151 Nitrite
0 0.0197 0.0591 0.0985
0.315 0.315 0.320 3.316
Volume 4, Number 8, August 1970 677
Table 11. Simultaneous Ultraviolet Spectrophotometric Analyses of Synthetic Nitrite-Nitrate Solutions 30 1 ‘KN02
KOH (M/l.j
,301
(l./Mcrn.j
0.468 0.936 1.40 1.87 3.74 4.41 4.68 7.02
KNOa
(1.lMcm.j
8.89 8.75 8.62 8.49 7.95 7.77 7.69 7.03
7.03 6.92 6.84 6.75 6.41 6.29 6.24 5.82
356
23.3 23.8 24.1 24.2 25.2 25.5 25.6 26.8
(Rotlevi and Treinin, 1965), our knowledge of the effects of solute-solvent interactions upon oscillator strength (and therefore absorptivities) is insufficient to rationalize the positive or negative trends of Figure 2. In any case the ultraviolet spectrophotometric determination of nitrite and nitrate, either separately or simultaneously, requires the determination of (KOH). The method was applied to the simultaneous determination of nitrite and nitrate. Synthetic solutions were prepared. Absorbances at 356 and 301 nm. were determined as well as (KOH). The nitrite is determined from the equation (NO*-)
=
A356
[23.4
+ 0.48 (KOH)]
The nitrate is determined by rearranging Equations 3 and 4,
(Nos-)
=
KNOi
‘KNOi
(I./M cm.)
x [9.02 - 0.28 (KOH)]] (7) [7.09 - 0.18 (KOH)]
A3O1 - [(NOz-)
The application of this procedure is shown by the data for the synthetic solutions shown in Table 11. The solutions are arranged in order of increasing (KOH) to emphasize the positive or negative effects upon the absorptivities. These effects of KOH are most important in the case of analyzing
KNOa (WI.1
(W.1
Added 0,0240 0,0120 0.0360 0.0240 0.0240 0,0240 0.0120 0,0360
Found 0.0236 0.0120 0.0361 0.0244 0.0248 0,0249 0.0121 0,0360
Added 0.0591 0.0393 0,0197 0.0787 0.118 0,0591 0.118
0,0393
Found 0.0586 0,0397 0.0203 0.0805 0.117 0,0608 0.120 0.0421
nitrate in the presence of nitrite in KOH solution; the failure to correct for (KOH) may contribute a large error to the calculation of Equation 7, if two relatively small numbers are involved. Acknowledgment The authors express appreciation to the Connecticut Research Commission for sponsoring this research. Literature Cited Altshuller, A. P., Wartburg, A. F., Anal. Chem. 32, 174 (1960). Campau, R. M., Neerman, J. C., paper no. 660116, SAE Automotive Engineering Congress, Detroit, Mich., January 1966. Dietz, R. N., Anal. Chem. 40, 1576 (1968). Huls, T. A., Nickol, H. A., paper no. 670482, SAE Spring Meeting, May 1967. Nicksic, S. W., Harkins, J., Anal. Chem. 34, 985 (1962). Rotlevi, E., Treinin, A., J. Phys. Chem. 69, 2645 (1965). Singh. T.. Sawver. R. F.. Starkman. E. S.. Caretoo. L. S.. J . k‘CA.’lI, 162 (l968).~ Strickler, S. J., Kasha, M., J . A m . Chem SOC.84,2899 (1963). Tavlor. F. S.. “Inorganic and Theoretical Chemistrv.” 10th Ed., Longmans, GTeen, London, 1960, p. 528. Receiced for reciew Nocember 28, 1969. Accepted March 24, 1970.
A Study of Jets of Electrically Charged Suspensions Yong N. Lee1 and Shao L. So0 Department of Mechanical Engineering, University of Illinois, Urbana, Ill. 61801. Experiments were conducted on jets of charged suspensions of glass and alumina particles. The Reynolds numbers based on the orifice diameter and gas velocity ranged from 300 to 3494. The charge to mass ratios were from to 10-3 C. per kg. Even a small charge markedly altered the radial position of jet boundary of the particulate phase.
P
rocessing streams in various air pollution control systems (Sargent, 1969) may take the form of jets of particulate suspensions. Knowledge of transport and diffusion of particulate matters in these jets is therefore useful in designs. I n a gas these suspensions tend to become electrically Present Address: Roy C . Ingersoll Research Center, BorgWarner Corp., Des Plaines, Ill. 60018. 678 Environmental Science & Technology
charged by surface contact during handling or by collecting charges from an ionized gas (Soo, 1967). Hence, laminar and turbulent jets of suspensions of particles charged to various magnitudes were studied. They constitute unique examples of electrohydrodynamics (Soo, 1969a). Experimental
For conducting experiments at conditions where Reynolds numbers based on orifice diameter were as low as 300, a n orifice diameter of 0.1 in. was used. The jet chamber (1) and the blow-down system including the vacuum tank (2) and filter (3) for collecting particles are shown in Figure 1. The air flow through the orifice ( 5 ) and the dryer (13) was measured by a calibrated orifice meter (4); also shown is the probe holder with screws (7) for horizontal and (8) for vertical traverse. The belt-type particle feeder was driven by a motor (9), moving the particles from the hopper (10) through the gate (11) into the
