Environmental Letters
ISSN: 0013-9300 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/lesa17
Detection and Determination of Sulfuric Acid Aerosol - Difficulties in Trapping J. W. Robinson & W. M. Reid To cite this article: J. W. Robinson & W. M. Reid (1975) Detection and Determination of Sulfuric Acid Aerosol - Difficulties in Trapping , Environmental Letters, 8:4, 361-369, DOI: 10.1080/00139307509437446 To link to this article: http://dx.doi.org/10.1080/00139307509437446
Published online: 02 Sep 2009.
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Citing articles: 1 View citing articles
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Date: 06 November 2015, At: 05:51
ENVIRONMENTAL LETTERS, 8(4), 361-369 (1975)
Detection and Detednation of Sulfuric Acid Aerosol
-
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
Difficulties in Trapping.
J. W. Robinson and W. M. Reid Chenistry Deparhnent Louisiana State University Baton Rouge, Louisiana 70803
Beginning with the 1975 model year, most American-made automobiles were fitted with a catalytic converter primarily using platinum as the catalyst.
The purpose of the converter was to oxidize completely all
unburned hydrocarbons and carbon monoxide issuing from the automobile cylinders, thus reducing atmospheric pollution by these species. One of the difficulties associated with the use of this device was that any sulfur in the gasoline was oxidized to sulfur dioxide in the auto engine and any sulfur dioxide reaching the platinum catalyst was converted to sulfur trioxide. After combination with water which is formed during combustion in the engine, the sulfur trioxide forms sulfuric acid.
Sulfuric
acid tends to form aerosols and these aerosols can linger in the atmosphere for considerable time periods.
Studies of the health effects of sulfuric
acid are not very complete but certainly sulfuric acid is very deleterious to such tender tissue as lung tissue and the delicate membranes of the mouth and throat and would represent a severe hazard to anyone breathing this material even in low concentrations for extended periods of tine.
361 Copyright 0 1975 by hlarcel Dekker, Inc. All Rights Reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher.
ROBINSON AND REID I n o r d e r t o c o n t r o l p o l l u t i o n by s u l f u r i c a c i d a e r o s o l generated from automotive exhausts, i t is a b s o l u t e l y e s s e n t i a l t h a t t h e amount of s u l f u r i c acid being produced i n t h i s fashion be p r e c i s e l y known.
However,
t h e amount of s u l f u r i c a c i d which may be generated i n catalyst-equipped c a r s is, a t p r e s e n t , uncertain.
Assuming 0.0%
s u l f u r f u e l , i t has been
estimated that a catalyst-equipped c a r may produce up t o
0.3 grams of
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
s u l f u r i c acid p e r m i l e traveled.% This, however i s an estimate based on a r e l a t i v e l y low average value f o r s u l f u r content of f u e l and on preliminary d a t a which has proven t o be i n c o n s i s t e n t .
The v a r i o u s procedures t h a t
have been used f o r exhaust monitoring have produced d i f f e r e n t r e s u l t s . = A l l of t h e s e techniques have u t i l i z e d t r a p p i n g techniques and involve
a n a l y s i s f o r e i t h e r s u l f a t e o r a ~ i d . ~The, inconsistency ~ ~ ~ of t h e reported r e s u l t s i n d i c a t e s t h a t t h e r e i s some fundamental problem with t h e techniques being used.
Experimental observations have led u s t o b e l i e v e t h a t t h e
problem l i e s i n t h e t r a p p i n g techniques.
I t w i l l a l s o be r e c a l l e d t h a t
t h e c a t a l y t i c technique used f o r t h e manufacture of s u l f u r i c a c i d from sulfur utilized a platinun catalyst.
One of t h e major problems with t h i s
method w a s t h a t t h e s u l f u r i c a c i d formed became a n aerosol very d i f f i c u l t t o c o l 1 e c t ; m i l l i o n s of d o l l a r s were spent i n developing aqueous trapping methods,none of which were s a t i s f a c t o r y . i n s t r o n g s u l f u r i c acid.
The problem was solved by t r a p p i n g
It seems l i k e l y t h a t t h e s e problems w i l l p e r t a i n
t o any a n a l y t i c a l technique t h a t involves t r a p p i n g and t h a t low r e s u l t s would n e c e s s a r i l y be obtained. was warranted.
I t was f e l t t h a t a'study of t h e phenomenon
The o b j e c t i v e of t h i s work was t o measure t h e e f f i c i e n c i e s
of v a r i o u s f i l t e r i n g agents used f o r t h e determination o f s u l f u r i c a c i d a e r o s o l a s generated from a p l a t i n t n c a t a l y s t .
362
SULmRIC ACID AEROSOL Experimental The t r a p p i n g e f f i c i e n c i e s of Fluoropore f i l t e r m a t e r i a l (0.5 micron pore s i z e ) , water, s o d i m carbonate s o l u t i o n , and s o d i m hydroxide solut i o n f o r f r e s h l y generated s u l f u r i c a c i d were i n v e s t i g a t e d .
The a n a l y t i c a l
technique enployed w a s a r a d i o - t r a c e r technique u t i l i z i n g l i q u i d s c i n t i l l a t i o n counting as t h e measurement.
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
Generation of S u l f u r i c Acid S u l f u r dioxide was generated by t h e r e a c t i o n of hydrochloric a c i d w i t h sodium s u l f i t e i n aqueous s o l u t i o n t o which a small amount of sodium s u l f i t e l a b e l l e d w i t h sulfur-35 was added. radioactive isotope of.sulfur,
Sulfur-35 i s n beta-emitting
The s u l f u r dioxide was converted t o sul-
f u r i c a c i d by passing i t over platinum c a t a l y s t (obtained from General Motors Corporation) heated t o @O°C vapor.
along with a i r s a t u r a t e d with water
This was a n attempt t o simulate t h e conditions of a n automobile
exhaust system.
The experimental arrangement for t h e generation of t h e
s u l f u r i c a c i d i s shown i n Figure 1. Trapping o f S u l f u r i c Acid The e f f l u e n t from t h e platinum c a t a l y s t was passed s e q u e n t i a l l y through a Fluoropore f i l t e r , 101111. o f 0.1 molar s o d i m t e t r a c h l o r m e r c u r a t e ( I 1 )
s o l u t i o n , l h l . of water, lhl. of 0.1 molar Na,C03 of 0.1 molar NaOH s o l u t i o n .
s o l u t i o n , and l h l .
Sodium t e t r a c h l o r m e r c u r a t e ( I 1 ) i s t h e s u l f u r
d i o x i d e - s p e c i f i c absorbing agent used i n t h e West-Gaeke t e s t f o r s u l f u r dioxide.6
I t s purpose as a t r a p was to remove any s u l f u r d i o x i d e t h a t
passed through t h e c a t a l y s t unoxidized and thence through t h e f i l t e r , so t h a t a c o r r e c t i o n f o r t h e amount of s u l f u r i c a c i d generated could be made, A s i t turned o u t , t h e c a t a l y s t w a s e s s e n t i a l l y 10%
efficient for the
conversion of s u l f u r dioxide t o s u l f u r t r i o x i d e and s u l f u r i c a c i d a t bO°C
363
ROBINSON AND REID
f)
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
a
Figure 1.
a.
Air
b.
NapS03 -F Na,35S03
c.
HCl
d.
Platinm
e.
Heater
EXPERIMENTAL A W G P I E N T FOR GENERATION
OF SULFURIC ACID AEROSOL
as shown by the absence of sulfur dioxide in the sodium tetrachloromercurate(I1) trap.
Gas dispersion tubes and glass beads were used to maximize the contact
of the gas with the trapping solution. The trapping arrangement is shown in Figure 2. The Fluoropore filter was located lt feet from the catalyst. Analysis of the TraE. Sulfur-35, with an
87 day half-life, decays to chlorine-35 by emission
of a 0.167 MeV beta particle.
The low energy of this radiation required I
that liquid scintillation counting be the measurement technique anployed. A liquid scintillation cocktail consisting of
6 grams of 2,5-diphenyloxazole
(PPO), 0.25 grams of 1,4-di-2( 5-phenyl-oxazolyl)-benzene (POPOP), and 100
364
SULFURIC ACID AEROSOL
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
m a
d
Figure 2.
e a.
Fluoropore f i l t e r
b.
Gas dispersion tube
c.
Glass beads
d.
Na2HgC14 solution
e.
H$
f.
Na2C0, s o l u t i o n
g.
NaOH solution
f
SULFURIC ACID TRAPPING ARRANGEXENT
g r m s o f naphthalene i n a l i t e r of p-dioxane was prepared and used for the counting medium.
365
ROBINSON AND REID One ml. of solution was taken from the reaction vessel both before and after the reaction and was placed in a counting vial with 18ml. of coctail. After the reaction, the Fluoropore filter was placed totally in a counting vial with 18nl. of cocktail, and lml. from each of the traps was similarly treated. The volume of solution in each vial was increased to -1.
by addition of distilled water to help solubilize the sample.
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
The radioactivity of the solution in each vial was then measured by the liquid scintillation counting technique with a counting time of 10 minutes. Quench correction factors were determined and applied to each of the solutions involved in the scintillation counting in order to normalize the data.
The results are shown in Tabie 1. In order to see the effect of increased distance of the traps from the catalyst, the transfer line from the catalyst to the Fluoropore filter was lengthened to
5 feet and the experiment repeated. The results are shown
in Table 2. These experiments were repeated several times with essentially the same results being obtained each time. Discussion. The startling result of this experiment was that the Fluoropore filter (which has been recomended as a filter device for ranoving sulfuric acid aerosol from the atmosphere) was only able to scrub out approximately ldp of the sulfuric acid which passed through it.
Clearly any method using
this filter as the scrubbing device would be totally unacceptable as an analytical technique for the determination of sulfuric acid aerosol in the atmosphere. The data also clearly showed that sulfuric acid was extremely difficult to trap in simple aqueous solutions.
The results merely confirmed the
empirical data which had been achieved through much hard work when the
366
SULFLRIC ACID AEROSOL
TABLE I Radioactivities and Trapping Efficiencies of the Various Sulfuric Acid Traps
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
(1% Foot Transfer Line) cpm/mt sample
cpm/total solution*
Before reaction
4220.6
108385
After reaction
3299.4
99509
f
of trapped
H&O&**
Filter
28.2
Na2%C14
47.6
500
5.6
H20
28.1
281
3*3
Na2C0,
445.4
4677
52.8
NaOH
321.1
3368
38.0
*Total activity lost
28.2
=
**Totnl activity trapped
0.3
8876 cpm
=
8854 cpm
catalytic process for the manufacture of sulfuric acid was set up comercially many years ago.
It would seem that simply filtering out sulfuric acid aerosol from the air by any of the solutions or the Fluoropore filter would not be satisfactory.
It is possible that the sulfuric acid can be changed to another chemical form such as by the addition of Emrmonia or some other reagent.
The dif-
ficulty involved with this technique is that now the technique measures total sulfate rather than sulfuric acid.
If we are prepared to say that
the sulfuric acid and total sulfate in the atmosphere are synonymous or
367
ROBINSON AND REID TABLE 2 Radioactivities and Trapping Efficiencies of the Various Sulfuric Acid Traps
(5 Foot Transfer Line)
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
cpm/total solution* Before reaction
3790.3
95195
After reaction
2803.3
85275 0.8
81.0
Na2%c14
61.9
651
6.7
H,&
42.0
420
Na,C03
443.2
4740
4.3 48.7
NaOlI
366.8
3850
39.5
81.0
activity lost = 920 cpm
**Total so
of trapped
HrSOa*
Filter
*Total
are
46
activity trapped =
9742 cpm
close to each other that the error involved is uniuportant then
the data would be valid, but under all other circumstances sulfate would be a direct interference to such a technique. CONCLUSIONS The data clearly calls for some other method of analysis which does not involve collecting or scrubbing of the sulfuric acid aerosol from the atmosphere.
Such a method would be the use of laser induced infrared
fluorescence. In an effort to develop such a technique, preliminary experiments have been carried out and rep~rted.~
368
SULFURIC ACID AEROSOL The results obtained by this method indicated that a fluorescence
technique was feasible but using the equipment at a laser power of 30 watts, the sensitivity was about one order of magnitude too low.
The results
justify further development of the IR fluorescence technique which we are currently undertaking. REFERENCES
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
1. Russell E. Train, Before the Committee on Public Works of the United States Senate, Nw. 2.
6, 1973.
Russell E. Train, op. cit.
3. B. T. Conmius, Analyst, 88, 364 (1963). 4. J. F. Raesler, J. J. R. Stenenson and J. S. Nador, J. Air Pollut. Contr. Assoc.,
3,576 (1965).
5. P. W. West, A. D. Shendrikes and Nicholas Herrara, Anal. Chim. Acta.,
as
111 (1974).
6. P. W. West.and G.
C. Gaeke, Anal. Cha., Vol.
7. J. W. Robinson and W. M. Reid, Env. Letters,
28, No.
12, 1816 (1956).
m, 195-236 (1974). Accepted January 22, 1975
369
ISSN: 0013-9300 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/lesa17
Detection and Determination of Sulfuric Acid Aerosol - Difficulties in Trapping J. W. Robinson & W. M. Reid To cite this article: J. W. Robinson & W. M. Reid (1975) Detection and Determination of Sulfuric Acid Aerosol - Difficulties in Trapping , Environmental Letters, 8:4, 361-369, DOI: 10.1080/00139307509437446 To link to this article: http://dx.doi.org/10.1080/00139307509437446
Published online: 02 Sep 2009.
Submit your article to this journal
Article views: 2
View related articles
Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=2esa20 Download by: [NUS National University of Singapore]
Date: 06 November 2015, At: 05:51
ENVIRONMENTAL LETTERS, 8(4), 361-369 (1975)
Detection and Detednation of Sulfuric Acid Aerosol
-
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
Difficulties in Trapping.
J. W. Robinson and W. M. Reid Chenistry Deparhnent Louisiana State University Baton Rouge, Louisiana 70803
Beginning with the 1975 model year, most American-made automobiles were fitted with a catalytic converter primarily using platinum as the catalyst.
The purpose of the converter was to oxidize completely all
unburned hydrocarbons and carbon monoxide issuing from the automobile cylinders, thus reducing atmospheric pollution by these species. One of the difficulties associated with the use of this device was that any sulfur in the gasoline was oxidized to sulfur dioxide in the auto engine and any sulfur dioxide reaching the platinum catalyst was converted to sulfur trioxide. After combination with water which is formed during combustion in the engine, the sulfur trioxide forms sulfuric acid.
Sulfuric
acid tends to form aerosols and these aerosols can linger in the atmosphere for considerable time periods.
Studies of the health effects of sulfuric
acid are not very complete but certainly sulfuric acid is very deleterious to such tender tissue as lung tissue and the delicate membranes of the mouth and throat and would represent a severe hazard to anyone breathing this material even in low concentrations for extended periods of tine.
361 Copyright 0 1975 by hlarcel Dekker, Inc. All Rights Reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher.
ROBINSON AND REID I n o r d e r t o c o n t r o l p o l l u t i o n by s u l f u r i c a c i d a e r o s o l generated from automotive exhausts, i t is a b s o l u t e l y e s s e n t i a l t h a t t h e amount of s u l f u r i c acid being produced i n t h i s fashion be p r e c i s e l y known.
However,
t h e amount of s u l f u r i c a c i d which may be generated i n catalyst-equipped c a r s is, a t p r e s e n t , uncertain.
Assuming 0.0%
s u l f u r f u e l , i t has been
estimated that a catalyst-equipped c a r may produce up t o
0.3 grams of
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
s u l f u r i c acid p e r m i l e traveled.% This, however i s an estimate based on a r e l a t i v e l y low average value f o r s u l f u r content of f u e l and on preliminary d a t a which has proven t o be i n c o n s i s t e n t .
The v a r i o u s procedures t h a t
have been used f o r exhaust monitoring have produced d i f f e r e n t r e s u l t s . = A l l of t h e s e techniques have u t i l i z e d t r a p p i n g techniques and involve
a n a l y s i s f o r e i t h e r s u l f a t e o r a ~ i d . ~The, inconsistency ~ ~ ~ of t h e reported r e s u l t s i n d i c a t e s t h a t t h e r e i s some fundamental problem with t h e techniques being used.
Experimental observations have led u s t o b e l i e v e t h a t t h e
problem l i e s i n t h e t r a p p i n g techniques.
I t w i l l a l s o be r e c a l l e d t h a t
t h e c a t a l y t i c technique used f o r t h e manufacture of s u l f u r i c a c i d from sulfur utilized a platinun catalyst.
One of t h e major problems with t h i s
method w a s t h a t t h e s u l f u r i c a c i d formed became a n aerosol very d i f f i c u l t t o c o l 1 e c t ; m i l l i o n s of d o l l a r s were spent i n developing aqueous trapping methods,none of which were s a t i s f a c t o r y . i n s t r o n g s u l f u r i c acid.
The problem was solved by t r a p p i n g
It seems l i k e l y t h a t t h e s e problems w i l l p e r t a i n
t o any a n a l y t i c a l technique t h a t involves t r a p p i n g and t h a t low r e s u l t s would n e c e s s a r i l y be obtained. was warranted.
I t was f e l t t h a t a'study of t h e phenomenon
The o b j e c t i v e of t h i s work was t o measure t h e e f f i c i e n c i e s
of v a r i o u s f i l t e r i n g agents used f o r t h e determination o f s u l f u r i c a c i d a e r o s o l a s generated from a p l a t i n t n c a t a l y s t .
362
SULmRIC ACID AEROSOL Experimental The t r a p p i n g e f f i c i e n c i e s of Fluoropore f i l t e r m a t e r i a l (0.5 micron pore s i z e ) , water, s o d i m carbonate s o l u t i o n , and s o d i m hydroxide solut i o n f o r f r e s h l y generated s u l f u r i c a c i d were i n v e s t i g a t e d .
The a n a l y t i c a l
technique enployed w a s a r a d i o - t r a c e r technique u t i l i z i n g l i q u i d s c i n t i l l a t i o n counting as t h e measurement.
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
Generation of S u l f u r i c Acid S u l f u r dioxide was generated by t h e r e a c t i o n of hydrochloric a c i d w i t h sodium s u l f i t e i n aqueous s o l u t i o n t o which a small amount of sodium s u l f i t e l a b e l l e d w i t h sulfur-35 was added. radioactive isotope of.sulfur,
Sulfur-35 i s n beta-emitting
The s u l f u r dioxide was converted t o sul-
f u r i c a c i d by passing i t over platinum c a t a l y s t (obtained from General Motors Corporation) heated t o @O°C vapor.
along with a i r s a t u r a t e d with water
This was a n attempt t o simulate t h e conditions of a n automobile
exhaust system.
The experimental arrangement for t h e generation of t h e
s u l f u r i c a c i d i s shown i n Figure 1. Trapping o f S u l f u r i c Acid The e f f l u e n t from t h e platinum c a t a l y s t was passed s e q u e n t i a l l y through a Fluoropore f i l t e r , 101111. o f 0.1 molar s o d i m t e t r a c h l o r m e r c u r a t e ( I 1 )
s o l u t i o n , l h l . of water, lhl. of 0.1 molar Na,C03 of 0.1 molar NaOH s o l u t i o n .
s o l u t i o n , and l h l .
Sodium t e t r a c h l o r m e r c u r a t e ( I 1 ) i s t h e s u l f u r
d i o x i d e - s p e c i f i c absorbing agent used i n t h e West-Gaeke t e s t f o r s u l f u r dioxide.6
I t s purpose as a t r a p was to remove any s u l f u r d i o x i d e t h a t
passed through t h e c a t a l y s t unoxidized and thence through t h e f i l t e r , so t h a t a c o r r e c t i o n f o r t h e amount of s u l f u r i c a c i d generated could be made, A s i t turned o u t , t h e c a t a l y s t w a s e s s e n t i a l l y 10%
efficient for the
conversion of s u l f u r dioxide t o s u l f u r t r i o x i d e and s u l f u r i c a c i d a t bO°C
363
ROBINSON AND REID
f)
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
a
Figure 1.
a.
Air
b.
NapS03 -F Na,35S03
c.
HCl
d.
Platinm
e.
Heater
EXPERIMENTAL A W G P I E N T FOR GENERATION
OF SULFURIC ACID AEROSOL
as shown by the absence of sulfur dioxide in the sodium tetrachloromercurate(I1) trap.
Gas dispersion tubes and glass beads were used to maximize the contact
of the gas with the trapping solution. The trapping arrangement is shown in Figure 2. The Fluoropore filter was located lt feet from the catalyst. Analysis of the TraE. Sulfur-35, with an
87 day half-life, decays to chlorine-35 by emission
of a 0.167 MeV beta particle.
The low energy of this radiation required I
that liquid scintillation counting be the measurement technique anployed. A liquid scintillation cocktail consisting of
6 grams of 2,5-diphenyloxazole
(PPO), 0.25 grams of 1,4-di-2( 5-phenyl-oxazolyl)-benzene (POPOP), and 100
364
SULFURIC ACID AEROSOL
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
m a
d
Figure 2.
e a.
Fluoropore f i l t e r
b.
Gas dispersion tube
c.
Glass beads
d.
Na2HgC14 solution
e.
H$
f.
Na2C0, s o l u t i o n
g.
NaOH solution
f
SULFURIC ACID TRAPPING ARRANGEXENT
g r m s o f naphthalene i n a l i t e r of p-dioxane was prepared and used for the counting medium.
365
ROBINSON AND REID One ml. of solution was taken from the reaction vessel both before and after the reaction and was placed in a counting vial with 18ml. of coctail. After the reaction, the Fluoropore filter was placed totally in a counting vial with 18nl. of cocktail, and lml. from each of the traps was similarly treated. The volume of solution in each vial was increased to -1.
by addition of distilled water to help solubilize the sample.
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
The radioactivity of the solution in each vial was then measured by the liquid scintillation counting technique with a counting time of 10 minutes. Quench correction factors were determined and applied to each of the solutions involved in the scintillation counting in order to normalize the data.
The results are shown in Tabie 1. In order to see the effect of increased distance of the traps from the catalyst, the transfer line from the catalyst to the Fluoropore filter was lengthened to
5 feet and the experiment repeated. The results are shown
in Table 2. These experiments were repeated several times with essentially the same results being obtained each time. Discussion. The startling result of this experiment was that the Fluoropore filter (which has been recomended as a filter device for ranoving sulfuric acid aerosol from the atmosphere) was only able to scrub out approximately ldp of the sulfuric acid which passed through it.
Clearly any method using
this filter as the scrubbing device would be totally unacceptable as an analytical technique for the determination of sulfuric acid aerosol in the atmosphere. The data also clearly showed that sulfuric acid was extremely difficult to trap in simple aqueous solutions.
The results merely confirmed the
empirical data which had been achieved through much hard work when the
366
SULFLRIC ACID AEROSOL
TABLE I Radioactivities and Trapping Efficiencies of the Various Sulfuric Acid Traps
Downloaded by [NUS National University of Singapore] at 05:51 06 November 2015
(1% Foot Transfer Line) cpm/mt sample
cpm/total solution*
Before reaction
4220.6
108385
After reaction
3299.4
99509
f
of trapped
H&O&**
Filter
28.2
Na2%C14
47.6
500
5.6
H20
28.1
281
3*3
Na2C0,
445.4
4677
52.8
NaOH
321.1
3368
38.0
*Total activity lost
28.2
=
**Totnl activity trapped
0.3
8876 cpm
=
8854 cpm
catalytic process for the manufacture of sulfuric acid was set up comercially many years ago.
It would seem that simply filtering out sulfuric acid aerosol from the air by any of the solutions or the Fluoropore filter would not be satisfactory.
It is possible that the sulfuric acid can be changed to another chemical form such as by the addition of Emrmonia or some other reagent.
The dif-
ficulty involved with this technique is that now the technique measures total sulfate rather than sulfuric acid.
If we are prepared to say that
the sulfuric acid and total sulfate in the atmosphere are synonymous or
367
ROBINSON AND REID TABLE 2 Radioactivities and Trapping Efficiencies of the Various Sulfuric Acid Traps
(5 Foot Transfer Line)
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cpm/total solution* Before reaction
3790.3
95195
After reaction
2803.3
85275 0.8
81.0
Na2%c14
61.9
651
6.7
H,&
42.0
420
Na,C03
443.2
4740
4.3 48.7
NaOlI
366.8
3850
39.5
81.0
activity lost = 920 cpm
**Total so
of trapped
HrSOa*
Filter
*Total
are
46
activity trapped =
9742 cpm
close to each other that the error involved is uniuportant then
the data would be valid, but under all other circumstances sulfate would be a direct interference to such a technique. CONCLUSIONS The data clearly calls for some other method of analysis which does not involve collecting or scrubbing of the sulfuric acid aerosol from the atmosphere.
Such a method would be the use of laser induced infrared
fluorescence. In an effort to develop such a technique, preliminary experiments have been carried out and rep~rted.~
368
SULFURIC ACID AEROSOL The results obtained by this method indicated that a fluorescence
technique was feasible but using the equipment at a laser power of 30 watts, the sensitivity was about one order of magnitude too low.
The results
justify further development of the IR fluorescence technique which we are currently undertaking. REFERENCES
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1. Russell E. Train, Before the Committee on Public Works of the United States Senate, Nw. 2.
6, 1973.
Russell E. Train, op. cit.
3. B. T. Conmius, Analyst, 88, 364 (1963). 4. J. F. Raesler, J. J. R. Stenenson and J. S. Nador, J. Air Pollut. Contr. Assoc.,
3,576 (1965).
5. P. W. West, A. D. Shendrikes and Nicholas Herrara, Anal. Chim. Acta.,
as
111 (1974).
6. P. W. West.and G.
C. Gaeke, Anal. Cha., Vol.
7. J. W. Robinson and W. M. Reid, Env. Letters,
28, No.
12, 1816 (1956).
m, 195-236 (1974). Accepted January 22, 1975
369
