Basic Study on Simulated Indoor Air Treatment by Atmospheric Microplasma
大気圧マイクロプラズマを用いた模擬室内空気の浄化の基礎研究
Tomoya Kuwabara, Marius Blajan, Kazuo Shimizu
Innovation and Joint Research Center, Shizuoka University, 3-5-1 Jyohoku, Nakaku, Hamamatsu, 432-8561, Japan; E-mail：shimizu@cjr.shizuoka.ac.jp

Microplasma has advantages of reducing
the power and downsizing
the entire
plasma system, compared to otheratmospheric plasmas. It is generated in
atmospheric pressure at only around 1.0
kV since its discharge gap is especiallysmall.

The microplasma reactor is shown in Fig.
1. A pair ofpunching metal plates
covered with dielectric layer are used as
microplasma electrodes.

Maximum removal ratio [%]50

Discharge voltage of maximum
treatment ratio [kV]

1Even at low discharge voltage (600 V,700 V) with very small amount of ozone
production (0 ppm ~ 0.39 ppm) , theremoval ratio was 10.4 % to 14.6 %, theremoval amount of 0.05 ppm to 0.07 ppm
was obtained.

We investigated capability of whether
microplasma can removed volatile organic
compounds (VOCs).

2. ATMOSPHERIC
MICROPLASMA REACTOR

Table 3 Experimental results ofCH3CHO treatment.

Fig. 3 Experimental setup.
Formaldehyde(HCHO)
andacetaldehyde (CH3CHO) are the target as
the typical VOCs gas.

CH3CHO gas flow rate [L/min.]

2.35

HCHO gas flow rate [L/min.]

5.00

CH3CHO and HCHO
Analysis method

DNPH-HPLC
methodTable 4 Experimental parameters.

Ozone Analysis

Ozone monitor

Power supply

Pulse generator andHigh Voltage Amplifier

Discharge gap [um]100fo…

0.8Discharge
0.91.01.1
1.21.3
voltage [kV]Fig. 6 HCHO and O3 concentration atHumidity of 55 %.

The value at 800 V

Humidity [%]0 and 55lower

The process of treatment CH3COOHand HCHO by O3 and OH radical [2, 3]
CH3CHO  OH  CH3CO  H 2O
CH3CO  O2  M  CH3C(O)OO  M
CH3C(O)OO  NO2  M  CH3C(O)OONO2  M
HCHO O  HCO  OH
HCHO OH  HCO  H2O
HCO  O  CO2  H
HCO  O  CO  OH
HCO  OH  H2O  CO
HCO  O3  H  O2  CO2

5. CONCLUSIONS(1)CH3CHO was decomposed byatmospheric microplasma within arange of discharge voltage from600 V to 1000 V at 0um discharge
gap . CH3CHO removal ratio at 600
V was almost 10 % without ozone
production,andat1000
Vreached 50 %.

(2)

HCHO was decomposed byatmospheric microplasma. TheHCHO
concentration
wasdecreased below 0.08 ppm at 1.1
kV without humidity. And HCHO
was decreased below 0.08 ppm at
1.2 kV with humidity at 100 um
discharge gap.

(3)

Atmosphericmicroplasma
technology could treat CH3CHoand HCHO which are typical VOCs
gases with the various radicals. Inthis study, the efficiency ofmicroplasma was shown.

Table 5 Experimental results ofHCHO treatment.
Discharge voltage which HCHO
decrease under 0.08 ppm [kＶ]

Initial concentration ofHCHO concentration [ppm]

10.00
8.00
6.00
4.00
2.00
0.00

Removal of HCHO was slightly
compared to without humidity.

4.2 Treatment of HCHO

Table 1 Parameters of experiments.

0.50
0.40
0.30
0.20
0.10
0.00

O3 concentration [ppm]

3. EXPERIMENTAL SETUPHCHO concentration[ppm]1. INTRODUCTION

1.1 (Hum. 0%)
1.2 (Hum. 55 %)4.3 Analysis of chemical reaction
15000

Neon transformer

Discharge gap [um]0Initial concentration of CH3CHO[ppm]0.48

Humidity [%]55

CH3CHO removal ratio
[%]

60.0
40.02 mmFig. 2 Light emitting of streamers on
microplasma electrode (680 V).
Microplasma is a typical dielectric barrierdischarge. The image of Light emitting ofstreamers is shown in Fig. 2.

a…

O3 concentration [ppm]Fig. 1 Schematic image of
microplasma reactor.

Power supply

10.0

20.0

5.00.00.0
600
800 1000
Discharge voltage [V]Fig. 4 Removal ratio of CH3CHO andO3 concentration at 0 um.

0.60

is10000

15.00
fo…

0.40

10.00

0.20

5.00

0.00

0.00
0.8Discharge
0.9 1.0voltage
1.1 1.2
1.3[kV]

Fig. 5 HCHO and O3 concentration.
at Humidity of 0 %HCHO
wastreatedwithlow
concentration of ozone without humidity.

Intensity (a.u.)

Table 2 Experimental parameters.

Indoorconcentrationof HCHO
regulated to 0.08 ppm by MHLW.

O3 concentration [ppm]

4.1 Treatment of CH3CHOHCHO Concentration[ppm]

4. Results and discussion

5000OH radical

0302 304 306 308310 312 314
Wavelength(nm)316 318

Fig. 7 OH radical peak measured byICCD camera.
CH3CHO and HCHO was treated withvarious radicals (N*, O*, OH*, etc) whichwere produced by microplasma. The peakof OH radical it is shown in Fig.7.
The chemical reaction process which
treat CH3CHO and HCHO are defined by
the following chemical formula.

The process of product O3 and OH
radical [1]O2  e  O  O  e
O  O2  M  O3  M

H 2O  e  OH  H  eO  H 2O  2OH

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