OZONE CHEMISTRY AND TECHNOLOGY

Chemical Reaction in Silent Discharge MOMOTARO

SUZUKI, SATIKO OKAZAKI, and TATSUO

YAMAMOTO

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 27, 2016 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch044

Defense Academy, Obaradai, Yokosuka, Japan

The high frequency oscillatory current during the silent electrical discharge in an ozonizer affects the chemical reaction in some way. A parallel relation exists between the high frequency current a n d the yield of hydrogen peroxide from hydrogen a n d oxygen, but not between the low frequency base current a n d the yield.

T h e s i l e n t e l e c t r i c a l d i s c h a r g e i n a n o z o n i z e r i s a l w a y s a c c o m p a n i e d b y s o m e s o r t of high frequency electrical oscillations. T h e phenomenon has been pointed out b y v a r i o u s a u t h o r s (1-3, 6, 7). T h e r e i s a n o s c i l l a t i o n w i t h a f r e q u e n c y of s e v e r a l h u n d r e d kilocycles w h i c h c a n easily be detected b y a n o r d i n a r y wave meter o r w i t h a n oscilloscope. A c c o r d i n g t o t h e a b o v e a u t h o r s , t h e o s c i l l a t i o n h a s b e e n e x p l a i n e d as d i s p l a c e m e n t c u r r e n t , w h i c h is p r o d u c e d i n t h e o z o n i z e r c i r c u i t i n a c c o r d a n c e w i t h t h e t i m e c o n s t a n t of t h e c i r c u i t i t s e l f . T h i s h i g h f r e q u e n c y c u r r e n t , t h o u g h i t s a m p l i t u d e i s c o n s i d e r a b l e , s u p p o s e d l y does n o t h a v e a n y a p p r e c i a b l e effect o n c h e m i c a l r e a c tions w h i c h m a y occur i n the discharge. T h e reaction is controlled r a t h e r b y the e n e r g y c o n s u m e d w h e n l o w f r e q u e n c y c u r r e n t of 50 o r 60 cycles is u s e d f o r t h e i n i t i a t i o n of t h e e l e c t r i c a l d i s c h a r g e . T h e m o s t d i r e c t m e a s u r e of t h e process of c h e m i c a l r e a c t i o n is f u r n i s h e d b y t h e e n e r g y c o n s u m p t i o n i n a n o z o n i z e r ; t h i s e n e r g y is simply that measured b y a low frequency wattmeter or similar equipment. N e v e r t h e l e s s , t h e series of i n v e s t i g a t i o n s u n d e r t a k e n i n t h i s i n s t i t u t e s h o w s t h a t t h e h i g h f r e q u e n c y o s c i l l a t o r y c u r r e n t affects i n some w a y t h e c h e m i c a l r e a c t i o n s i n t h e s i l e n t d i s c h a r g e . T h e h i g h f r e q u e n c y c u r r e n t of s e v e r a l h u n d r e d k i l o c y c l e s p l a y s a m o r e i m p o r t a n t role t h a n t h e l o w f r e q u e n c y base c u r r e n t . W i t h a w a v e m e t e r i t i s p o s s i b l e t o d e t e c t g e n e r a l l y t w o sorts of h i g h f r e q u e n c y o s c i l l a t i o n — o n e of s e v e r a l h u n d r e d k i l o c y c l e s , m e n t i o n e d a b o v e , a n d a n o t h e r of s e v e r a l k i l o c y c l e s , w h i c h c o r r e s p o n d s t o t h e n u m b e r s of pulses of d i s c h a r g e s t a k i n g p l a c e o n t h e s u r f a c e of t h e o z o n i z e r electrode d u r i n g a p e r i o d of one c y c l e of l o w f r e q u e n c y base current. T h e latter oscillation has n o t h i n g to do w i t h the chemical reaction (4). Results

and

Conclusions

A h y d r o g e n - r i c h gas m i x t u r e of h y d r o g e n a n d o x y g e n w i l l p r o d u c e h y d r o g e n p e r o x i d e u n d e r s i l e n t e l e c t r i c a l d i s c h a r g e i n a n o z o n i z e r (4). I n t h i s case i f t h e y i e l d of h y d r o g e n p e r o x i d e is p l o t t e d a g a i n s t t h e v o l u m e p e r c e n t of o x y g e n i n t h e gas m i x t u r e , a c u r v e is o b t a i n e d w i t h a m i n i m u m y i e l d a t 3 . 5 % of o x y g e n . O n t h e o t h e r h a n d , i f t h e v a l u e s of h i g h f r e q u e n c y o s c i l l a t o r y c u r r e n t a n d of l o w f r e q u e n c y base 331

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

332

A D V A N C E S IN

CHEMISTRY SERIES

c u r r e n t , are p l o t t e d a g a i n s t t h e v o l u m e p e r cent of o x y g e n , t h e n a t 3 . 5 % of o x y g e n t h e r e is a m i n i m u m i n t h e h i g h f r e q u e n c y c u r v e a n d a m a x i m u m i n t h e l o w f r e q u e n c y curve, respectively. T h u s , a p a r a l l e l r e l a t i o n is o b t a i n e d b e t w e e n t h e y i e l d of h y d r o g e n peroxide a n d the high frequency current, but not between the y i e l d a n d low frequency current. I n a n o s c i l l o g r a m of c u r r e n t of a silent d i s c h a r g e i n a n o z o n i z e r , t h e r e is a h a i r l i k e p u l s e c u r r e n t i m a g e o n t h e w a v e f o r m of 5 0 - c y c l e base c u r r e n t w h i c h we m a y c a l l " h a i r " (5). I n a n e x p e r i m e n t of ozone f o r m a t i o n i n a n o z o n i z e r , t h e m e a n s q u a r e l e n g t h , V s ô , w h e r e a is t h e l e n g t h of e a c h h a i r i n t h e o s c i l l o g r a m , c o r r e s p o n d s t o the m e a n h i g h frequency current w h i c h accompanies the pulse i n a n ozonizer. By m e a n s of a n a p p r o p r i a t e w a v e f i l t e r c i r c u i t i t w a s possible t o s e p a r a t e t h e c u r r e n t whose f r e q u e n c y was m o r e t h a n 200 k c . T h i s h i g h f r e q u e n c y c u r r e n t w a s m e a s u r e d w i t h a h e l p of t h e r m o c o u p l e - t y p e a m m e t e r . T h e e x p e r i m e n t a l results ( F i g u r e 1) s h o w


2

x CD

Ο

X

Figure 1.

20

/ Σ α

40 2

Relation

60

80

100

(ARBITRARY UNITS) of

high

frequency

current

to

t h a t t h e h i g h f r e q u e n c y c u r r e n t is r e l a t e d l i n e a r l y t o V%a . T h e t o t a l q u a n t i t y of elec t r i c i t y t r a n s f e r r e d f r o m one e l e c t r o d e t o t h e o t h e r d u r i n g one p e r i o d of 5 0 - c y c l e a l t e r n a t i n g c u r r e n t is expressed b y t h e t o t a l l e n g t h of t h e h a i r s i n t h e o s c i l l o g r a m . I f t h e y i e l d of ozone is p l o t t e d a g a i n s t t h e t o t a l l e n g t h of t h e h a i r s , a l i n e a r c u r v e is o b t a i n e d ( F i g u r e 2 ) . T h e s e e x p e r i m e n t a l results s h o w g o o d a g r e e m e n t w i t h t h e previously developed theory. 2

T h o u g h t h e m e c h a n i s m of t h e influence of h i g h f r e q u e n c y c u r r e n t o n c h e m i c a l r e a c t i o n s is n o t y e t f u l l y e l u c i d a t e d , i t is possible t o p e r c e i v e some s o r t of effect of t h e h i g h l y oscillating current a c c o m p a n y i n g the silent discharge on the discharge reaction. F u r t h e r r e s e a r c h is i n progress i n t h i s l a b o r a t o r y . P a r t of t h i s e x p e r i m e n t was c a r r i e d o u t i n t h e c h e m i c a l l a b o r a t o r y of T o k y o M e t r o politan U n i v e r s i t y , Setagaya, T o k y o , J a p a n . Literature

Cited

(1) Harries, W. L., Engel, A. von, Proc. Phys. Soc. (London) 6 4 B , 916 (1951). (2) K l e m e n c , Α., H i n t e n b e r g e r , H., Höfer, Η., Z. Elektrochem. 4 3 , 708 (1937).


SUZUKI, OKAZAKI A N D Y A M A M O T O - R E A C T I O N IN SILENT DISCHARGE


50

0

200

Σ α Figure 2.

(3) (4) (5) (6) (7)

400

600

800

(ARBITRARY UNITS)

Relation of hair length to ozone yield

Manley, T. C., Trans. Electrochem. Soc. 84, 83 (1943). Suzuki, M., Proc. Japan Acad. 26, 20 (1950). Suzuki, M., Naito, Y . , Ibid., 28, 469 (1952). Warburg, Ο., Z. tech. Physik 4, 450 (1923). Warburg, O., Leithäuser, Ann. Physik 28, 1 (1923). RECEIVED

for review M a y 27, 1957.

Accepted June 19, 1957.


333

OZONE CHEMISTRY AND TECHNOLOGY

Recommend Documents