Low temperature atmospheric pressure discharge plasma processing.pdf

7/26/2019 Low temperature atmospheric pressure discharge plasma processing.pdf

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94

T. Oda et aL /Journal of Electrostatics 35 (1995) 93-101

a g a s m i x i n g p o i n t a f te r a c e r a m i c

r e a c t o r a n d g a s m i x i n g s p a c e w i t h

a lo w pr e ss u re l m e r c u r y l am p U V

s o u r c e ) i s n e w l y at t ac h e d . T y p i c a l

e x p e r i m e n t a l p r o c e d u r e i s a s

fo l lows:

a . D I R E C T : p l a s m a p r o c e s s i n g

a f t e r m i x i n g

M i x i n g P o i n t B )

o f c o n t a m i - n a t e d

a i r con tami -

n a n t i s e x p o s e d t o

p l a s m a )

b . I N D I R E C T : m i x i n g o f c o n -

t a m i n a t e d a i r a n d

p l a s m a p r o c e s s e d

c l e a n a i r a t m i x i n g

p o i n t A .

c . U V : p o w e r o n o f a U V

l a m p U V

ir radiat ion) .

The c e r amic r eac to r t e s t ed i s 10

m m i n i n n e r d i a m e t e r a n d 1 1 5 m m

l o n g d r i v e n b y a s t a n d a r d p o w e r

s u p p l y o f 5 K h z .

2 2 S a m p l e G a s e s

As con taminan t s , t yp ica l o rgan ic

m a t e r i a l s d e c o m p o s e d a r e

a

MixingTank Nz

b) total experimental setup

a) cross section o f a reactor

It , UV Lump

,~/Mixing Point A ~

~ e r a m i c Reactor

Fl0wl I Flow[

M et e~ t Mete~

L~

02 Air Tank

F i g . 1 S c h e m a t i c d i a g r a m o f S P C P e x p e r i m e n t a l s e tu p .

t r i ch lo roe thy lene : CICH=CCI2, mo lecu la r w e igh t : 131.39 , spec i f i c g r av i ty : l . 47 , vapor

p ressu re 60 mmHg a t 20 .5~C.

b . t e t r ach lo romethane : CCI4 vapo r p r essu re 89 .5 m m Hg a t 20C. f o rb idden f rom 1996)

c . 1 ,1 ,1 -t r ich lo roe thane : CH3CCI3 , vapo r p r essu re 100 m mH g a t 20C. f o rb idden f rom

1996)

d . 1 ,2 -d ich lo roe thane : CH2CICH2CI va por p r essu re 61 mm Hg a t 20C.

e . d ichlo rom ethan e: CH2C12, 349 m m H g at 20~C

f . ace tone : CH3COCH~, mo lecu la r we igh t :58 .08 , spec i f i c g r av i ty :0 .79 ,

vapor p r essu re :200 mmHg a t 22 .7C.

A g i v e n a m o u n t o f l i q u i d w a s s a m p l e d b y a m i c r o s y r in g e a n d w a s i n j e c t e d i n to a p r e s s u r iz e d

tank con ta in ing d ry compressed a i r was mixed a t up to 6 a tmospher i c p r essu re .

2 3 E x p e r i m e n t a l P r o c e d u r e s

T w o d i f fe r e n t s e r i e s o f e x p e r i m e n t s w e r e d o n e a s f o l l o w s .

2.3.1. Decomposition Mechanism

I n o r d e r t o h a v e a g o o d u n d e r s ta n d i n g o f t h e d e c o m p o s i t io n m e c h a n i s m , a n I N D I R E C T

me thod was n ew ly t e s t ed where the c l ean a ir was in t roduced in to the ce r am ic r eac to r. Af t e r


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1 . Oda e t al . IJourn al of Electrostatics 35 (1995) 93-101 95

plasma processing, the clean air was mixed with other VOC-contaminated air at mixing point

A. A small pen-type low pressure mercury lamp (Hamamatsu Photonics, L937-02, input

power: 5W), is inserted in a mixing gas chamber of contaminated gas and processed air shown

in Fig. 1.

Pure nitrogen or pure oxygen gas are also tested as carrier gas in place of clean dry air.

Trichloroethylene and acetone are tested as contaminants and a large difference of

decomposition performance was recognized. Those data were compared with other typical

data obtained by the standard process (DIRECT method).

2 . 3 .2 A N e w S a m p l e T e s t

Decomposition performance of four new halogenated organic compounds Co, c, d, and e

in 2.) was tested to know the applicability of SPCP for halogenated organic contaminant

decomposition. Especially, the two which will be forbidden in the near future.

3.RESULTS AND DISCUSSIONS

3 .1 D I R E C T a n d I N D I R E C T D e c o m p o s i t i o n T e s t s fo r T r i c h l o r o e t h y l e n e a n d A c e t o n e

3 . 1 . 1 T r i c h l o r o e t h y l e n e

3.1.1.1 DIRECT and INDIRECT Effects

The decomposition rates of trichlo- ~

roethylene in air versus discharge elect-tic ;~

power consumption at the reactor are g.

shown in Figs. 2 and 3. Fig. 2 was

recorded with a low flow rate; that is, a

Ca

flow rate of the 1,000 ppm

trichloroethylene in air at 400 ml/min and ~

Q)

the rate of pure air was 712 ml/min.

In the case of INDIRECT, the time

interval after the plasma processing (gas

flow time from the reactor to the mixing

point A) is 0.24 seconds and the final

concent-ration of the trichloroethylene is

360 ppm. At power consumption of only

1 W, the decomposition rate is already 40 ~ 100

%, but it does not increase at higher o

~.~

electric power. At a power of more than ~

10 or 15 W, it decreases drastically to zero ~

in the case of the INDIRECT method.

This tendency is similar to ozone C~

generation. High power causes high

temperature of the reactor wall and the

produced ozone might be decomposed at ~

high temperature. FAN in Fig. 2 means

fan cooling of the reactor with cooling

fins. Cooling by fan increases the

decomposition rate (Fig.3) occurs. In the

case of DIRECT, more than 90 %

100 f ~ - -

80 / --,,- :DIRECT

-i- :INDIRECT

60 -*-:INDIRECT+FAN

40 r,~'m''~:a- -~'*'--

20 ,

0 ' : '.

----' --

0 10 20 30

Power (W)

Fig.2 Decomposition rate of trichloroethylene

in air for the low flow rate.

80 ~ i =

40 : ,IY

.. .

CT

20 ..~-:INDIRECT

d

- t -. : I N D I R E C T F A N

0 10 20 30

Power (W)

Fig.3 Decomposition rate of vichloroethylene in

air for the high flow rate.


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96 T. Oda et aL /dournal o f Electrostatics 35 (1995) 93-101

o~ 100 F Interval Tim e ~ 100 Interval T im e ~.-:10cm(0.08sec)

~ 80 ~ f/ : ' ' ~ [ -*-:10cm(0'24sec) I ~ I ~

.... :70cm (l.68sec) c~ 80 w. :70cm(0.56sec)

6

~

6

8

20 ~ 20

~

0 10 20 30 ~ 0 10 20 30

Power (W) Power (W)

(a) low flow rate (b) high flow rate

Fig . 4 De com posit ion ra te of 1 ,000 ppm tr ichloroethylene in a ir .

deco mp osit ion occu rs a t only 5 W electr ic p owe r. On the other hand, in Fig .3 a t the high

flow rate (1 ,000 ppm tr ichloroethylene: 1 ,172 ml/min and air : 2 ,000 ml/min, f inal

concentra t ion: 370 ppm), the t ime interval is only 0 .08 seconds, and the decomposit ion ra te

gradua lly increases with e lectric p ow er for DIR EC T and an abrupt decrease o f the

decomposit ion ra te ( the maximum is not so high as that for DIRECT) at h igh e lectr ic power

is not so apparent. A slight FA N effect (a few %) is detected. In the case o f f luorocarbon

decomp os i t ion , no decompos i t ion w as de tec ted b y IND IRE CT o r U V i rrad ia tion . 3~

A t ime interval between the plasm a processing and m ixing with contam inated gas at point

A, m ay a f fec t the decomp os i t ion ra te tha t was sugges ted by Y amam oto . ~} Tw o jo in t p ipes o f

d i f fe ren t leng ths o f 0.1 m o r 0 .7 m be tween the ou t le t o f the p lasma reac to r and the mixing

point A of two gases was tested to check radical species and their li fe times. Results are

show n in Figs. 4 (a) and (b) where the t ime in parenthesis was the e lapsed t ime before m ixing.

In the shortest case , the decomposit ion ra te is the largest which is in good agreement with

the normal radical o r ozo ne li fe t ime effects . Ho we ver , the effect o f longer t ime is not

apparent and the results suggest that the ozone in the a ir created by SPCP may be the main

decomposit ion source.

100

3.1 .1 .2 Carr ier Gas Dependence

In place o f air, pure nitrog en or :=_ 80

oxygen gas was used as the carr ier gas .

E 60

Figures 5 and 6 show such results . In ~ 40

n i t rogen car rier , the DIR EC T method can

eas i ly decom pose t r i-ch lo roe thy lene up to ~ 20

99%, bu t no t r ich lo roe thy lene can be ~ 0 -

d e c o m p o s e d b y I N D I RE C T a t a ll. 0

Ni t rogen rad ica ls o r h igh energy e lec t rons

in t h e p l a s m a p r o d u c e d b y S P CP m a y

des troy trichloroethylene. The ir life time

may be ve ry smal l (o f mi l l i second o rder

- - - - : D I R E C T

- i v : D I R E C T + U V

- - : I N D I R E C I + F A N

- n - : I N D I R E C T + F A N + U V

- ~ . . . . . . . . . ~ . X X . . . . . . X

10 20 30

Power (W)

Fig . 5 Decom pos i t ion o f t r ich lo roe thy lene in N

for the low f low rate .

) and any ( less than a few percent which is the detect ion l imit) decomposit ion is not detected

b y t h e I N D I RE C T m e th o d.

3 .1 .1 .3 UV Irradiat ion Effects

As the mixing cel l contains a UV lamp, the UV irradiat ion effect is a lso shown in Figs.


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7 . Oda et al./Journal of Electrostatics 35 (1995) 93-101 97

5 and 6 with the mark UV. The

decomposition rate of trichloroethylene is

more than 95 for the low flow rate

(1,116 ml/min in total) or 65 for the

high flow rate (3,172 ml/min) with slight

(weak) UV light irradiation without

plasma discharge. The input power of

the low pressure mercury lump ( source as

calibration) is only 5 W and total UV

light intensity (2553A) may be less than 1

(30mW); that is, the UV decomposition

effect is much stronger than SPCP energy.

In the oxygen carrier, the UV effect is

greater and roughly 80 or 100

trichloroethytene are decomposed by the

very weak UV irradiation. Sometimes,

the UV irradiation effects might be

reduced (decomposit ion rate decreases) by

plasma discharge which is assumed to be

ozone and temperature effects. In a

nitrogen carrier, the UV effect is not so

large and constant; that is, the

decomposition rate is 20 for the low

flow rate and 5 for the

high flow rate.

3.1.2 Acetone

3.1.2.1 DIRECT and INDIRECT

The decomposition performance of

acetone in air by DIRECT or INDIRECT

SPCP is shown in Fig.7 where only the

DIRECT method can decompose 90

acetone at 30 W for the low flow rate

(1,000 ppm acetone in air:400 ml/min +

dry air:716ml/min). The maximum

decomposition rate by INDIRECT method

is less than 20 . For the high flow rate

(1,000 ppm acetone air: 1172ml/min,

air:2,000ml/min), the decomposition

rate is very low and the maximum rate is

only 60 at 30W by DIRECT shown in

Fig.8. For the same high flow, the de-

composition rate by INDIRECT is roughly

1oo ~ . . . ~

s

: - - -0 - - : D I R E C T

4o

- . J ,. : I N D I R E C T * F A N

20 - ~ :INDIRECT+FAN+UV

o

0

0 10 20 3o

Power (W)

Fig. 6 Decomposition of trichloroethylene in

oxygen for the high flow rate.

1 0 0

;~ 80

~

6o

~ 4o

N 20

o

~ o

o

o l i

I n ' - a - D I R E C T + U V

t . . b . I N D I R E C T + F A N

/ - ~ - I N D I R E C T F A N + U V

1 0 2 0 3 0

Power (W)

Fig. 7 Decomposition of acetone in air for the

low flow rate.

100

?-2 80

~ 6

~ 4o

~ 20

~ o

: D I R E C T

- t v : D I R E C T + U V

- - t ,- : I N D I R E C T + F A N

- ~ - : I N D I R E C T + F A N + U V ~ ~ ~ - - . - ~ l

. j r ' -

0 10 20 30

Power (W)

Fig. 8 Decomposition of acetone in air for the

high flow rate.

the same as that for the small flow rate, 20 . All decomposition rates of acetone are much

smaller than rates of trichloroethylene at the same conditions indicating hat the decomposition

of acetone is difficult. For the higher flow rate, the maximum decomposition rate is less than

70 by DIRECT. By gas-chromato-analysis, no apparent difference of processed products


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98 T. Oda et al./Yournal of Electrostatics 35 (1995) 93-101

were de tec ted .

100

3 . 1 .2 . 2 C a r r i e r G a s a n d U V E f f e c t s

: 80

W h e n t h e c a r r i e r g a s i s o x y g e n , t h e ~

d e c o m p o s i t i o n r a t e o f a c e t o n e i s v e r y ~ - 6 0

h i g h c o m p a r e d w i t h t h e a i r c a r r ie r w h i c h ~ 4 0

i s show n in F igs . 9 and 10 . Espe c ia l ly , :~

t h e m a x i m u m d e c o m p o s i t i o n r a te s o f ~ 2 0

a c e t o n e b y I N D I R E C T a r e v e r y h i g h , a s ~ 0

60 % fo r the low f low ra te o r 40 % fo r ~ /

t h e h i g h f l o w r a t e c o m p a r e d w i t h t h e

c a s e i n a i r o r n i tr o g e n . O z o n e o r O

s h o u l d b e v e r y e f f e c t iv e i n d e c o m p o s i n g F i g . 9

a c e t o n e . T h e U V i r ra d i a t i o n e f f ec t i s

v e r y s m a l l , s i m i l a r t o t h e a i r c a r r i e r

a l t h o u g h U V i s v e r y e f f e c t i v e i n

d e c o m p o s i n g t r i c h l o ro e t h y l e n e . T h e ~ 1 00

t im e in te rva l e f f ec t i s sho wn in F ig . 11 . o

Fo r the h igh gas f low ra te , the :~ 80

d e c o m p o s i t i o n r a te f o r a s h o r t p a t h a n d ~ - 6 0

l o w e l e c t r i c a l p o w e r i s v e r y h i g h a t 6 0

40

% , b u t i t r e d u c e s t o t h e s a m e l e v e l f o r a

l o n g g a s p i p e w h e n t h e i n p u t e l e c t r ic 8 2 0

p o w e r i s l a rg e . F o r t h e l o w f l o w r a t e ~ 0

o f ca r r i e r gas , 10 o r 20 % h ighe r ~

d e c o m p o s i t i o n r a te ( c o n s t a n t to b e 6 0 % )

o c u r s i n m o s t p o w e r c o n s u m p t i o n r a n g e.

W h e n t h e c a r r i e r g a s i s n i t r o g e n , th e

d e c o m p o s i t i o n r a t e o f a c e t o n e is l o w . F i g .

C o m p a r e d w i t h t h e a i r c a r r i e r , t h e

d e c o m p o s i t i o n r a te i s 5 o r 1 0 % s m a l l e r

b y D I R E C T s h o w n i n F i g . 1 2 f o r t h e l o w ~ 1 00

f low ra te . Th e r a te i s l e s s than 5 %

( w i t h i n e r r o r l e v e l ) w h i c h i s m u c h :~ 8 0

sm al le r tha n tha t fo r the a i r ca r r i e r by ~ - 60

I N D I R E C T . O x i d a t i o n o f a c e t o n e $

s h o u l d b e t h e e s s e n t i a l f o r :~ 4 0

dec om pos i t io n . ~6 20

)

0

e , :

F o u r N e w H a l o ge n a te d V O C s

F i g u r e 1 3 s h o w s o n e e x a m p l e o f

t e t r a c h l o r o m e t h a n e d e c o m p o s i t i o n

p e r f o r m a n c e v e r s u s e l e c t r i c p o w e r

c o n s u m p t i o n w h e r e t h e r e s i d e n c e t im e i s

c a l c u l a t e d a s t h e r e a c t o r v o l u m e d i v i d e d

[

+ : D I R E C T

~ - i - : D I R E C T + U V

- k . : I N D I R E C T + F A N

- ~ - : IN D I R E C T + U V + F

A N

0 10 20 30

Power (W )

A c e t o n e d e c o m p o s i t i o n i n o x y g e n f o r th e

low f low ra te .

Fig. 11

. a / 9 < , - - x

- - Jr - : I I ~ C T + F M q

- - : l l ~ l l ~ f f r + F . ~ q + l J V

0 10 20 30

Power (W )

1 0 A c e t o n d e c o m p o s i t io n i n o x y g e n f o r th e

h igh f low ra te .

Interval Time

--*- : l)cm(0.08sec)

m. :70cm(0.56sec)

_ r . - -

0 10 20 30

Power (W )

A c e t o n e d e c o m p o s i t i o n i n o x y g e n f o r

d i f f e r e n t m i x i n g t i m e i n t e r v a l .

b y t h e g a s f l o w r a te . A v e r y h i g h d e c o m p o s i t i o n r a t e o f m o r e t h a n 9 5 % i s r e a l i z e d a t

e l e c t r ic a l p o w e r c o n s u m p t i o n o f 3 0 - 4 0 W f o r 1 , 00 0 p p m t e t r a c h l o r o m e t h a n e i n a i r. W h e n


7/9

T . O d a e t a l . I J o u r n a l o f E l e c tr o s t a ti c s 3 5 ( 1 9 9 5 ) 9 3 - 1 0 1 99

t h e c o n c e n t r a t i o n o f c o n t a m i n a n t is 1 0 0

p p m , t h e h i g h e r d e c o m p o s i t i o n r a t e

was r eco rded .

T h e n e c e s s a r y e l e c t r i c p o w e r

c o n s u m p t i o n t o d e c o m p o s e o n e

m o l e o f c o n t a m i n a n t s i s sh o w n i n

F i g . 1 4 w h e r e o r i g i n a l c o n t a m i - n a n t

c o n c e n t r a t i o n fo r e a c h o f t e t r a e t h a n e ,

t r i c h l o r o e t h a n e , d i - c h l o r o e t h a n e o r

d i c h l o r o - m e t h a n e , i s 1 ,0 0 0 p p m . I n

e v e r y c a se , t h e m i n i m u m p o w e r i s 2 -

3 X 1 7 J / m o l e o r d e r. H o w e v e r , t h e

d e c o m p o s e d p r o d u c t a n a l y s i s6) sugges ts

t h a t t h e r e a r e m a n y i n t e r m e d i a t e b y -

p r o d u c t s i n c l u d - i n g p o i s o n o u s m a t e r i a l s

w h e n t h e d e c o m p o s i t i o n r a t e i s l e s s

t h a n 6 0 o r 70 % . I n g e n e r a l , w h e n th e

f l o w r a t e i s l a r g e ( s m a l l r e s i d e n c e

t i m e ) , t h e n e c e s s a r y p o w e r t o

d e c o m p o s e o n e m o l e o f V O C i s s m a l l.

A t t h e d e c o m p o s i t io n

r a t e o f 8 0 % , d i c h l o r o e t h a n e i s t h e

e a s ie s t d e c o m p o s e d a m o n g f o u r V O C s

a n d t r i c h l o r o e t h a n e i s t h e m o s t s t a b l e

( t h e m o s t d i f f i c u l t m a t e r i a l t o

d e c o m p o s e ) . H o w e v e r , t h e d i f f e r e n c e

i s o n l y f a c to r o f 2 o r 3 . A t t h e h i g h

d e c o m p o s i t i o n r a t e , N z O i n c r e a s e s i n

the p roduc t gas es .

4 . C O N C L U S I O N S

100

-

o

:~ 80

60

E

o

40

20

0

0

, f i / - I - : D IR E C T + U V

J --~ ,- : INDIR ECT

? - ~ - :INDIE , _ . , . . _ C I + U V. . . . .

10 20 30

P o w e r ( W )

F i g . 1 2 A c e t o n e d e c o m p o s i t i o n i n n i t r o g e n fo r t h e

l o w f l o w r a t e .

100

0

:.-2_- 80

6 0

E

o

40

20

S P C P d e c o m p o s i t i o n p e r f o r m a n c e ~ 1 00

o f 1 ,0 0 0 p p m v o l a t i l e o r g a n i c . ~ 8 0

c o m p o u n d s ) V O C s ) i n a t m o s p h e r ic 8

-~

p r e s s u r e a i r , o x y g e n o r n i t r o g e n w a s E 6 0

t e st e d . O x y g e n i s f o u n d t o b e t h e 8

40

mo s t des t ruc t ive ca r r i e r gas o f d i lu te c3

V O C s . V O C s i n p u r e n i t r o g e n c a r ri e r , ~ 2 0

e s p e c i a l l y t r i c h l o r o e t h y l e n e , c a n b e

d e c o m p o s e d b y S P C P w h e n t h e

c o n t a m i n a t e d g a s i s d i r e c t l y p r o c e s s e d .

H o w e v e r , t h e V O C s d e c o m p o s i t i o n

p e r fo r m a n c e b y t he I N D I R E C T m e t k o d

( p l a s m a p r o c e s s e d n i t r o g e n g a s i s F i g . 1 3

m i x e d w i t h c o n t a m i n a t e d g a s ) , i s v e r y

p o o r i n d i c a t i n g th e l i f e - t im e o f t h e

at g

/ m'

,. .,-

i , Residence Time

; .. --*- :0.3 9s

; - - :0 .76s

.

--- : 1.65s

10 20 30 40

P o w e r ( W )

(a) 100 ppm

~ A _ , _ . A - . . . . . . . . . A ' . - i . . . . . .

m - . l , - -

, / , . .

# A . -

/ J ~ T i m e

t ' J - -- : 0 .3 9 s

i~ J .... :0.76s

~ / - - : 1 .65s

0 10 20 30 40

P o w e r ( W )

(b) 1 ,000 ppm

D e c o m p o s i t i o n o f t e t ra c h l o ro m e t h a n e f o r

1 0 0 a n d 1 , 0 0 0 p p m i n a i r b y S P C P .


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1O0 T O da et al /Journal f Electrostatics 35 (1995) 93-101

n i t ro g e n r a d i c a l o r h i g h e n e r g y e l e c t ro n p r o d u c e d b y t h e p l a s m a w h i c h m a y d e c o m p o s e V O C s

i s a s s u m e d t o b e v e r y sm a l l . O z o n e o r O r a d i c a l s e e m s t o b e v e r y e f fe c t iv e in d e c o m p o s i n g

V O C s a s o p p o s e d t o t h e f l u o r o c a r b o n d e c o m p o s i t i o n t e s t ( w h e r e n o d e c o m p o s i t i o n w a s f o u n d

b y t h e I N D I R E C T m e t h o d ) . F o r a l l 1 ,0 00 p p m c h lo r o - o r g a n ic c o m p o u n d s i n a i r

( t e tr ach lo romethane , t r ich lo roe thane , d i ch lo roe thane o r d i ch lo romethane) , t he necessa ry e l ec t r ic

p o w e r to d e c o m p o s e 1 m o l e o f V O C s i s f o u n d t o b e 2 - 3 X 107 J / m o l e w h e n t h e

d e c o m p o s i t i o n r a te i s 6 0 o r 7 0 % .

Tr i ch lo roe thy lene was found to de com pose w i th a s l igh t ir r ad ia t ion o f UV l igh t , bu t t he

m e c h a n i s m i s n o t y e t u n d e r s to o d .

M uch fu r the r r esea r ch shou ld be done fo r f u r the r p r ac t i ca l app l i ca t ion o f SPC P gas con t ro l .

R E F E R E N E S

1 ) S . M a s u d a N o n - E q u i l i b r i u m P l a s m a C h e m i c a l P r o c e s s P P C P a n d S P C P f o r C o n t r o l o f

NO x, Sox and Other Gaseo us Po l lu t an t s, P roc .4 th In t .Conf .ESP pp .615-623(1990)

2 ) S . M a s u d a

e t a l ,

A C e r a m i c - B i a s e d O z o n i z e r U s i n g H i g h F r e q u e n c y S u r f ac e D i s c h a rg e ,

IEEE Trans . IA-24 , pp .223-231(1988)

3 ) T . O d a et a l , A t m o s p h e r i c P r e s s u r e D i s c h a rg e P l a s m a P r o c e s s i n g f o r G a s e o u s A i r

Con tam inan t s , IEEE Trans . IA-29 , pp .787-792(1993)

4 ) T . O d a e t a l , D e c o m p o s i t io n o f G a s e o u s O r g a n i c C o n t a m i n a n t s b y S u r f ac e D i s c h a r g e

I n d u c e d P l a s m a C h e m i c a l P r o c e s s i n g - S P C P , C o n f . R e c . o f I E E E / I A S 1 99 2 A n n .

M ee t ing pp . 1570-1574(1992) .

5 ) T . Y a m a m o t o : p r i v a t e c o m m u n i c a t i o n .

6 ) t o be p r esen ted in fu tu r e Confe r ence .


9/9

T . O d a e t a l . / J o u r n a l o f E l e c t r o st a t ic s 3 5 ( 1 9 9 5 ) 9 3 - 1 0 1

101

o E 16

~ 14

~ 12

~ : 10

~ . o 6

u ~

2

u ~ 0

o - 6

o - , 1 6

14

~ 12

~ ~0

8

~ . ~ 6

_ 4

o o

ud 2

~

0

~ ..~

Resi.dence Time - --*- 0.39s

"'~" :0.76s

- ~ - : 1 . 6 5 s

~ t

~ , ~ . . . . . A ~ -

Residence Time ~ )

- * - :0.39s

.m . :0.76s ,

- ~ - : l . 6 5 s

~ 1 8

~ 1 6

o x

~ 12

10

~.=__

Z

~ 8

~ . ~ 6

E o

. ak

20 40 60 80 100 0 20 40 60 80

Rate o f Decom posi t ion (%) Ra te of Decom posi t ion (%)

(a) tetrachloromethane (b) trichloroethane

Residence Time

~ - : 0 : 3 9 s

" '~" :0 .76s

- ~ - : 1 . 6 5 s

/,

/ '

/ ' . '

/ ~ ) ' l i . a n

18

~ 1 4

0 X

-

~ 1 2

~ 10

._=

o

g~ 6

~ 4

~ ~ 2

o

100

Residence Time i A

- :0 .39s ,

" '~" :0.76s

- ~ - : 1 .6 5 s , . . i

f

/ .

o 0

o . -

20 40 60 80 100 : ' ~ 0 20 40 60 80

. ~ '

R a t e o f D e c o m p o s i t i o n ( % ) ~ ~ R a te o f D e c o m p o s i t i o n ( % )

(c) 1,2 dichloroethane (d)di-chloromethane

F i g . 1 4 N e c e s s a r y e l e c t r ic a l e n e r g y t o d e c o m p o s e 1 m o l e V O C s i n ai r w h e r e

c o n c e n t r a t i o n i s 1 , 0 0 0 p p m .

100

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