OZONE CHEMISTRY AND TECHNOLOGY

Nonaqueous Colorimetric Method for Determination of Ozone A. D. DELMAN, A. E. RUFF, Β. B. SIMMS, and A. R. ALLISON

Downloaded by CORNELL UNIV on October 10, 2016 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch016

Material Laboratory, New York Naval Shipyard, New York, Ν. Y.

A new colorimetric procedure has been developed for the quantitative measurement of atmospheric ozone. The specific, sensitive, and reproducible non aqueous method utilizes the rate of color produced on ozonization of o-dichlorobenzene solutions of N-phenyl-2-naphthylamine. The color reaction con forms to Beer's law a n d has a practical sensitivity of ±1.8 X 10-3 mg. of ozone. O x y g e n a n d oxides of nitrogen, in concentrations greater than those nor mally occurring in the atmosphere, do not interfere with the chromogenic reaction.

Investigation of t h e d e g r a d a t i v e effects of ozone o n e l a s t o m e r i c m a t e r i a l s h a s necessi t a t e d d e v e l o p i n g t e c h n i q u e s t o m e a s u r e ozone c o n c e n t r a t i o n p r e c i s e l y . T h e l i t e r a t u r e (2-4, 7, 9, 10, IS) h a s p r e s e n t e d t h e efforts of s e v e r a l w o r k e r s . H o w e v e r , t h e t e c h n i q u e s u s e d c o s t l y e q u i p m e n t s u c h as i n f r a r e d a n d u l t r a v i o l e t s p e c t r o p h o t o m e t e r s , aqueous c o l o r i m e t r i c m e t h o d s i n v o l v i n g t h e f o r m a t i o n o r d e s t r u c t i o n of fluorescence o r dyes, a n d i o d o m e t r i c p r o c e d u r e s . A q u e o u s c o l o r i m e t r i c m e t h o d s g i v e e r r a t i c r e s u l t s , because t r a c e a m o u n t s of s u c h o x i d i z i n g agents as oxides of n i t r o g e n i n t e r f e r e . I n t h e i o d o m e t r i c p r o c e d u r e s (2-4), t h e r e a c t i o n of ozone w i t h p o t a s s i u m i o d i d e is s i g n i f i c a n t l y affected b y t h e p H of t h e reacting m e d i u m a n d is t r u l y quantitative only i n n e u t r a l solution. D u r i n g the analysis of a i r c o n t a i n i n g h i g h ozone c o n c e n t r a t i o n s , f o r e x a m p l e , t h e p o t a s s i u m i o d i d e s o l u t i o n s t e n d t o increase i n a l k a l i n i t y r e s u l t i n g f r o m t h e f o r m a t i o n of p o t a s s i u m h y d r o x i d e , a n d the results become m o r e inaccurate w i t h increasing absorption time. H o w e v e r , the i o d o m e t r i c p r o c e d u r e agrees o v e r a n ozone c o n c e n t r a t i o n range f r o m 24 t o 160 m g . p e r l i t e r (2, 3, 8), w i t h a b s o l u t e m e t h o d s b a s e d o n gas d e n s i t y m e a s u r e m e n t s . I t is ac c u r a t e t o 0.06 m g . p e r l i t e r i f p r e c a u t i o n s a r e t a k e n t o c o n t r o l p H a n d a v o i d loss of iodine b y vaporization. T h e a u t h o r s i n v e s t i g a t e d b y v i s c o m e t r i c t e c h n i q u e s (5, 6) t h e p o t e n t i a l s u i t a b i l i t y of s e v e r a l c o m m e r c i a l l y a v a i l a b l e c h e m i c a l s as i n h i b i t o r s of o z o n e - i n d u c e d p o l y m e r c h a i n scission. C o l o r changes w e r e o b s e r v e d d u r i n g t h e o z o n i z a t i o n of e l a s t o m e r s o l u t i o n s c o n t a i n i n g s u c h p r o t e c t a n t c h e m i c a l s as i V ^ A f ' - d i - s e c - b u t y l - p - p h e n y l e n e d i a m i n e , nickel dibutyldithiocarbamate, a n d 6-ethoxy-l,2-dihydro-2,2,4-trimethylquinoline, re s p e c t i v e l y . T h e c h r o m o g e n i c r e a c t i o n s of these a n d o t h e r c h e m i c a l s i n d i c a t e d t h a t t h e c o l o r c h a n g e v a r i e d w i t h ozone c o n c e n t r a t i o n , a n d of t h e c h e m i c a l s e x a m i n e d , i V - p h e n y l 2 - n a p h t h y l a m i n e e x h i b i t e d s u p e r i o r b e h a v i o r . T h i s p a p e r r e p o r t s i t s use as a c o l o r i m e t r i c reagent f o r d e t e r m i n i n g ozone c o n c e n t r a t i o n s . 119

OZONE CHEMISTRY AND TECHNOLOGY Advances in Chemistry; American Chemical Society: Washington, DC, 1959.

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Reagents and

CHEMISTRY SERIES

Apparatus

C O L O R I M E T R Y . A 0 . 0 1 M s o l u t i o n of i V - p h e n y l - 2 - n a p h t h y l a m i n e is p r e p a r e d b y d i s s o l v i n g 0.439 g r a m of c h e m i c a l , E a s t m a n K o d a k N o . 2767 o r e q u i v a l e n t , i n 200 m l . of redistilled o-dichlorobenzene. I O D O M E T R I C C A L I B R A T I O N . P o t a s s i u m i o d i d e ( c r y s t a l l i n e p o w d e r , reagent g r a d e ) , 0.002iV s o d i u m t h i o s u l f a t e , 0 . 0 2 5 N p o t a s s i u m d i h y d r o g e n p h o s p h a t e , 0.025iV d i s o d i u m h y d r o g e n p h o s p h a t e , 0 . 0 0 2 N i o d i n e , 5 0 % s u l f u r i c a c i d ( b y v o l u m e ) , a n d 2 % soluble s t a r c h ( b y w e i g h t ) are r e q u i r e d . O X I D E S O F N I T R O G E N . T O d e t e r m i n e t h e i r c o n c e n t r a t i o n , 0.0IN p o t a s s i u m p e r m a n g a n a t e a n d s u l f u r i c a c i d (specific g r a v i t y 1.84 a t 15.6° C . ) are r e q u i r e d . A 0.005iV s o d i u m c a r b o n a t e s o l u t i o n c o n t a i n i n g 0.1 m o l e of p o t a s s i u m p e r m a n g a n a t e (11) is u s e d as a n a b s o r b a n t f o r oxides of n i t r o g e n . O Z O N I Z A T I O N . T h e a p p a r a t u s u s e d t o ozonize a l l s o l u t i o n s has b e e n d e s c r i b e d i n d e t a i l (6"). COLORIMETRY M E A S U R E M E N T S . A K l e t t - S u m m e r s o n photoelectric colorimeter, M o d e l M 3 8 9 6 , e q u i p p e d w i t h a N o . 42 filter h a v i n g a n a p p r o x i m a t e s p e c t r a l r a n g e f r o m 400 to 465 ιημ, was u s e d f o r c o l o r i m e t r i c m e a s u r e m e n t s . Experimental A n i n v e s t i g a t i o n of t h e effects of reagent c o n c e n t r a t i o n o n t h e i n t e n s i t y of c o l o r p r o d u c e d d u r i n g t h e c h r o m o g e n i c r e a c t i o n b e t w e e n ozone a n d 7 V - p h e n y l - 2 - n a p h t h y l amine i n o-dichlorobenzene i n d i c a t e d t h a t the o p t i m u m solution concentration was 0.01M. Reaction Rate. T h e i n t e n s i t y of c o l o r p r o d u c e d d u r i n g o z o n i z a t i o n of i V - p h e n y l 2 - n a p h t h y l a m i n e i n o - d i c h l o r o b e n z e n e s o l u t i o n w a s d e t e r m i n e d . A s t r e a m of o z o n i z e d a i r o r o z o n i z e d o x y g e n , flowing a t a r a t e of 0.05, 0.10, 0.15, a n d 0.20 c u b i c m e t e r p e r h o u r , r e s p e c t i v e l y , w a s b u b b l e d t h r o u g h 200 m l . of a s o l u t i o n c o n t a i n i n g 0.01 m o l e of reagent a t r o o m t e m p e r a t u r e a n d a t m o s p h e r i c p r e s s u r e . A l i q u o t s of t h e o z o n i z e d s o l u t i o n s were r e m o v e d a t preselected t i m e i n t e r v a l s f o r c o l o r i m e t r i c m e a s u r e m e n t . T h e r e s u l t s o b t a i n e d f o r e a c h of t h e flow rates w e r e i d e n t i c a l f o r t h e r e s p e c t i v e o z o n i z e d gases. T h e d a t a are p l o t t e d i n F i g u r e 1. T h e results of t h e c h r o m o g e n i c r e a c t i o n v a r y w i t h t h e c o n c e n t r a t i o n of ozone i n a c c o r d a n c e w i t h B e e r ' s l a w . Calibration. T h e ozone e q u i v a l e n c y of c o l o r i m e t e r scale r e a d i n g s , i n t e r m s of m i l l i g r a m s of ozone, w a s c a l c u l a t e d f r o m i o d o m e t r i c m e a s u r e m e n t s (12) of ozone

700

r

REACTION TIME-MINUTES Figure 1.

Rate of color formation


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c o n c e n t r a t i o n . T h e o z o n i z e d gas w a s passed t h r o u g h a s o l u t i o n c o n t a i n i n g 2 0 g r a m s of p o t a s s i u m i o d i d e a n d 5 0 m l . e a c h of 0.002iV s o d i u m t h i o s u l f a t e , 0.0257V p o t a s s i u m d i h y d r o g e n p h o s p h a t e , a n d 0.0257V d i s o d i u m h y d r o g e n p h o s p h a t e f o r p r e d e t e r m i n e d time intervals at r o o m temperature a n d atmospheric pressure. T h e unreacted s o d i u m thiosulfate was titrated w i t h a standardized 0.002^ iodine solution, using freshly pre p a r e d s o l u b l e s t a r c h s o l u t i o n as t h e i n d i c a t o r . T h e v o l u m e of effluent gas w a s c o r r e c t e d f o r t e m p e r a t u r e a n d p r e s s u r e t o 2 5 ° C . a n d 7 6 0 m m . T h e ozone c o n c e n t r a t i o n was c a l c u l a t e d as f o l l o w s : Ozone concentration, mg. per liter —


ml. of iodine (blank — sample) Χ Ν of iodine X 24 corrected volume

. .

A p l o t of c o l o r i m e t e r scale r e a d i n g s a g a i n s t m i l l i g r a m s of ozone g a v e a s t r a i g h t - l i n e curve. F i g u r e 2 presents t h e ozone c o n c e n t r a t i o n m e a s u r e m e n t s of o z o n i z e d a i r a n d o z o -

OZONIZED

FLOW

RATE

METER

Figure 2.

PER

-

OXYOEN

CUBIC HOUR

O z o n e concentration by iodometry

n i z e d o x y g e n . T h e ozone c o n c e n t r a t i o n w a s i n v e r s e l y p r o p o r t i o n a l t o t h e r a t e of flow of effluent gas. I n a d d i t i o n , t h e q u a n t i t y of ozone p r o d u c e d b y t h e g e n e r a t o r r e m a i n s r e l a t i v e l y c o n s t a n t f o r e a c h of t h e gases s t u d i e d . T h e c a l i b r a t i o n r e l a t i o n s h i p , c o l o r i m e t e r scale r e a d i n g vs. m i l l i g r a m s of ozone, m a y be u s e d t o d e t e r m i n e t h e ozone c o n c e n t r a t i o n of u n k n o w n s p e c i m e n s . Ozone concentration (mg. per liter) = colorimeter scale reading X mg. of ozone equiv. corrected volume

^

Effects of Oxygen. T h e effects of o x y g e n a l o n e o n o - d i c h l o r o b e n z e n e s o l u t i o n s of i V - p h e n y l - 2 - n a p h t h y l a m i n e were d e t e r m i n e d b y r e p e a t i n g t h e p r o c e d u r e w i t h u n o z o n i z e d o x y g e n . A s n o s i g n i f i c a n t c o l o r change w a s o b s e r v e d i n t h e r e a g e n t s o l u t i o n a f t e r 6 h o u r s , o x y g e n a l o n e h a s n o effect o n t h e c h r o m o g e n i c r e a c t i o n . Effects of Oxides of Nitrogen. T o d e t e r m i n e t h e effects of oxides of n i t r o g e n o n the chromogenic reaction investigated, the ozonization procedure was repeated after p a s s i n g t h e o z o n i z e d a i r t h r o u g h a p p r o x i m a t e l y 2 0 m l . of p o t a s s i u m p e r m a n g a n a t e absorbant.


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T h e results were i d e n t i c a l w i t h those f o r o z o n i z e d a i r ( F i g u r e 1 ) . T h e r e f o r e , t h e oxides of n i t r o g e n a r e c o m p l e t e l y r e m o v e d b y t h i s a b s o r b a n t w i t h o u t affecting t h e ozone c o n c e n t r a t i o n . T h e c o n c e n t r a t i o n of oxides of n i t r o g e n i n o z o n i z e d a i r w a s d e t e r m i n e d b y b u b b l i n g a s t r e a m of gas, flowing a t 0.05, 0.10, 0.15, a n d 0.20 c u b i c m e t e r p e r h o u r , r e s p e c t i v e l y , t h r o u g h 50 m l . of c o n c e n t r a t e d s u l f u r i c a c i d f o r 2 h o u r s a t r o o m t e m p e r a t u r e a n d a t m o s p h e r i c p r e s s u r e . T h e a c i d c o n t a i n i n g t h e a b s o r b e d oxides of n i t r o g e n w a s a d d e d s l o w l y t o 50 m l . of d i s t i l l e d w a t e r i n a n ice b a t h , so as t o f o r m t w o l a y e r s . T h e c h i l l e d l i q u i d w a s t h e n t i t r a t e d w i t h O.OliV* p o t a s s i u m p e r m a n g a n a t e s o l u t i o n , w i t h g r a d u a l stirring to m i x the t w o layers slowly, u n t i l a faint p i n k color persisted for 1 m i n u t e . T h e v o l u m e of o z o n i z e d a i r w a s c o r r e c t e d f o r t e m p e r a t u r e a n d p r e s s u r e t o 25° C . a n d 760 m m . T h e v a l u e of oxides of n i t r o g e n , d e t e r m i n e d as n i t r o g e n d i o x i d e , were c a l c u l a t e d .


Concentration of oxides of nitrogen (mg. per liter) = ml. of K M n Q Χ Ν of K M n Q X 46 corrected volume 4

4

( 3 )

R e s u l t s of these m e a s u r e m e n t s a r e p r e s e n t e d i n F i g u r e 3. T h e s e c o n c e n t r a t i o n s of oxides of n i t r o g e n , g r e a t e r e v e n t h a n t h e 0.7 X 1 0 - m g . p e r l i t e r e n c o u n t e r e d i n a i r 3

FLOW RATE-CUBIC METER PER HOUR Figure 3.

Concentration of oxides of nitrogen in ozonized air

s a m p l e s d u r i n g s m o g i n L o s A n g e l e s (1), h a v e n o effect o n t h e i n t e n s i t y of c o l o r p r o d u c e d i n t h e reagent s o l u t i o n d u r i n g o z o n i z a t i o n . A p p l i c a b i l i t y o f M e t h o d . T h e p o t e n t i a l s u i t a b i l i t y of t h e c o l o r i m e t r i c t e c h n i q u e , f o r use i n m e a s u r i n g a t m o s p h e r i c ozone c o n c e n t r a t i o n , w a s d e t e r m i n e d b y r e p e a t i n g t h e o z o n i z a t i o n p r o c e d u r e w i t h u n o z o n i z e d a i r flowing a t 0.40 c u b i c m e t e r p e r h o u r . I o d o m e t r i c m e a s u r e m e n t s of a t m o s p h e r i c ozone c o n c e n t r a t i o n were m a d e s i m u l taneously. T h e r e s u l t s of c o l o r i m e t r i c m e a s u r e m e n t s a r e g i v e n i n F i g u r e 4. T h e ozone c o n c e n t r a t i o n of t h i s a i r s p e c i m e n w a s , u s i n g E q u a t i o n 2, a p p r o x i m a t e l y 1.8 Χ 1 0 mg. p e r l i t e r . T h i s v a l u e is e q u i v a l e n t t o 9 p . p . h . m . ( b y v o l u m e ) , w h i c h is i d e n t i c a l w i t h that determined iodometrically. -

Recommended

4

Procedure

A s t h e chromogenic reaction presented follows Beer's l a w , the recommended c e d u r e i s as f o l l o w s :


pro

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B u b b l e a s t r e a m of a i r t h r o u g h t h e reagent s o l u t i o n u n t i l a c o l o r change is o b s e r v e d . M a k e a single c o l o r i m e t r i c m e a s u r e m e n t of t h e o z o n i z e d reagent. Determine t h e v o l u m e of effluent gas u s e d , c o r r e c t i n g f o r t e m p e r a t u r e a n d p r e s s u r e . C a l c u l a t e t h e ozone c o n c e n t r a t i o n , u s i n g E q u a t i o n 2.

24

r


ο

REACTION TIME-HOURS Figure 4. Precision of

Rate of color formation by atmospheric ozone

Method

B e c a u s e t h e p r e c i s i o n of m e a s u r e m e n t is a p p r o x i m a t e l y 0.1 d i v i s i o n a t t h e m i d p o i n t of t h e c o l o r i m e t e r scale, i n t h e w o r k i n g r a n g e u s e d , t h e s e n s i t i v i t y of t h e c o l o r i m e t r i c t e c h n i q u e is e q u i v a l e n t t o a p p r o x i m a t e l y ± 1 . 8 X 1 0 m g . of ozone. - 3

Acknowledgment T h e a u t h o r s g r a t e f u l l y a c k n o w l e d g e t h e i n t e r e s t a n d s p o n s o r s h i p of t h i s w o r k b y T . A . W e r k e n t h i n , h e a d of t h e E l a s t o m e r s B r a n c h , B u r e a u of S h i p s , N a v y D e p a r t m e n t , Washington, D . C. Literature (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

Cited

Air Pollution Control Dist., C o . of Los Angeles, Calif., Ann. Rept. 1950-51. Birdsall, C. M., Jenkins, A. C., Spadinger, E., Anal. Chem. 24, 662-4 (1952). Briner, E., Paillard, H., Helv. Chim. Acta 18, 234-7 (1935). Crabtree, J., Kemp, A. R., Ind. Eng. Chem., Anal. Ed. 18, 769-74 (1946). Delman, A. D., Ruff, A. E., Simms, Β. B., Allison, A. R., Advances in Chem. Ser. N o . 21, 176 (1958). Delman, A. D., Simms, Β. B., Allison, A. R., Anal. Chem. 26, 1589-92 (1954). Eberhardt, W. H., Shand, W., Jr., J. Chem. Phys. 14, 525-30 (1946). K i r k , R. E., Othmer, D. F., eds., "Encyclopedia of Chemical Technology," V o l . IX, pp. 375-53, Interscience, New York, 1952. Prudhomme, Α., Ann. univ. Lyon Sci. Sect. Β 4 (3), 36-45 (1948). Teichert, F., Z. Meteorol. 7, 33-4 (1953). University of Alaska, Geophys. Inst. Rept. AD2950, Sci. Rept. N o . 1 (1952). Ibid., Chap. 1. Vassy, E., Vassy, Α., O.N.E.R.A. Rapp. tech. No. 42 (1948).

RECEIVED for review April 22, 1957. Accepted June 19, 1957. The opinions or asser tions contained in this paper are the private ones of the authors and are not to be con strued as official or reflecting the views of the Navy Department or the Naval Service a t large.


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