プラズマ照射水中のros/rnsの生成特性€¦ · プラズマ照射水...
TRANSCRIPT
平成27年 プラズマ・放電・パルスパワー合同研究会平成27年6月6日(土) 北海道大学情報科学研究科
高橋 一弘* 佐藤 孝紀 伊藤 秀範 川口 秀樹(室蘭工業大学)Igor Timoshkin Martin Given Scott MacGregor(ストラスクライド大学)
Kazuhiro Takahashi*, Kohki Satoh, Hidenori Itoh and Hideki Kawaguchi (Muroran Institute of Technology)
Igor Timoshkin, Martin Given and Scott MacGregor (University of Strathclyde)
Generation characteristics of ROS/RNS in plasma-exposed water
MURORAN INSTITUTEOF TECHNOLOGY
プラズマ照射水中のROS/RNSの生成特性
PST-15-030
ED-15-048
PPT-15-030
in Ar
in Ar/O2 = 80/20 in N2/O2 = 60/40
Ar
Plasma jetPulsed
corona PB-DBD
プラズマ照射水
放電プラズマ中で生成される様々な種(ROS/RNSの前駆体含む)が水に溶け込み,水中にROS/RNS(H2O2やNOx
-)を生成
プラズマ照射水の応用に関する研究
目的パルス放電,コロナ放電,プラズマジェットおよびパックトベッド放電を用いたときの水中のROS/RNSの生成特性の解明
佐藤ら[1]L アルゴンプラズマ流を照射した水に大腸菌を不活化する作用があることを報告
高木[2]L照射水中のNO3-が植物の生長促進に寄与することを報告
照射水を効率よく使用するためには,水中で生成される活性な種の種類および量の制御が不可欠
[1]佐藤 他:日本機械学会熱工学コンファレンス 講演論文集,09-33, 101 (2009)
[2]高木: J.HTSJ, 51, 216, 64 (2012)
R
P M+
R : radical
water H2O2, NOx-
plasma
P : precursor
M+ : ion
Water
MURORAN INSTITUTEOF TECHNOLOGY
背景および目的
実験装置および実験条件(パルス放電)
150
100
50
0
curren
t [A]
543210
time [s]
30
25
20
15
10
5
0
-5
volt
age
[kV
]
Ig
Vg25 kV
140 A
2.0
1.5
1.0
0.5
0.0
elec
tric
po
wer
[M
W]
543210
time [s]
Pg
0.23 J/pulse
in Ar
Gap length
(4 mm)
Ar, O2, N2
Ar/O2 = 80/20, 60/40, 40/60, 20/80 %
N2/O2 = 80/20, 60/40, 40/60, 20/80 %
N2/Ar = 80/20, 60/40, 40/60, 20/80 %
ガス流量: 5.0 L/min
ガス条件
MURORAN INSTITUTEOF TECHNOLOGY
充電電圧: 14.14 kV
パルス繰り返し周波数: 20 pps
deionised water(100 mL)
in Ar
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar N2
Ar:O2 = 80:20 N2:O2 = 80:20
Ar:O2 = 60:40 N2:O2 = 60:40
Ar:O2 = 40:60 N2:O2 = 40:60
Ar:O2 = 20:80 N2:O2 = 20:80
O2
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
Ar
O2
N2
N2を含むガス中では...
H2O2の生成量が著しく低下&
NO2-およびNO3
-が生成
NO2-の生成量は微量
パルス放電による水中のROS/RNS生成
MURORAN INSTITUTEOF TECHNOLOGY
H2O2
NO2-
NO3-
w/o N2
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar Ar:O2 = 80:20
O2 Ar:O2 = 60:40
N2 Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar Ar:O2 = 80:20
O2 Ar:O2 = 60:40
N2 Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar N2
Ar:O2 = 80:20 N2:O2 = 80:20
Ar:O2 = 60:40 N2:O2 = 60:40
Ar:O2 = 40:60 N2:O2 = 40:60
Ar:O2 = 20:80 N2:O2 = 20:80
O2
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
Ar
O2
N2
H2O2の生成
パルス放電による水中のROS/RNS生成
MURORAN INSTITUTEOF TECHNOLOGY
H2O2
NO2-
NO3-
w/o N2
NO2 + OH → HNO3
HNO3 → NO3- + H+ (in water)
OH + OH→ H2O2
H2O + e → OH + O + e
NO3-の生成
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar N2
Ar:O2 = 80:20 N2:O2 = 80:20
Ar:O2 = 60:40 N2:O2 = 60:40
Ar:O2 = 40:60 N2:O2 = 40:60
Ar:O2 = 20:80 N2:O2 = 20:80
O2
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
Ar
O2
N2
H2O2の生成
パルス放電による水中のROS/RNS生成
MURORAN INSTITUTEOF TECHNOLOGY
H2O2 NO3-
NO2 + OH → HNO3
HNO3 → NO3- + H+ (in water)
OH + OH→ H2O2
H2O + e → OH + O + e
NO3-の生成
in O2in N2/O2 = 20/80
10 ~ 15分経過後
15 min
15 mm
印加電圧: +15 kV
放電電流: 0.4 mA
注入電力: 6 W
ガス条件
Ar/O2 = 80/20, 60/40, 40/60 %
N2/O2 = 60/40, 40/60 %
ガス流量:2.0 L/min
実験装置および実験条件(コロナ放電)
MURORAN INSTITUTEOF TECHNOLOGY
deionised water(100 mL)
aluminium foil
• 櫛歯状電極 : 櫛歯26本で1つのクラスターを形成クラスターを4箇所に分散配置
• イオン交換水 : 100 mL
• 電極-水面間の距離 : 15 mm
Cluster(13 x 2)
40 mm20 mm
40
30
20
10
0
con
cen
trat
ion
[p
pm
]
86420input energy [kJ]
Ar:O2 = 80:20
Ar:O2 = 60:40 N2:O2 = 60:40
Ar:O2 = 40:60 N2:O2 = 40:60
40
30
20
10
0
con
cen
trat
ion
[p
pm
]
86420input energy [kJ]
40
30
20
10
0
con
cen
trat
ion
[p
pm
]
86420input energy [kJ]
O2混合比が高い→H2O2生成量低下
N2-O2中ではAr-O2中に比べてH2O2の生成量が低下
&NO2
-およびNO3-が生成
コロナ放電による水中のROS/RNS生成
MURORAN INSTITUTEOF TECHNOLOGY
H2O2
NO2-
NO3-
60:40
80:20
40
30
20
10
0
con
cen
trat
ion
[p
pm
]
86420input energy [kJ]
Ar:O2 = 80:20
Ar:O2 = 60:40 N2:O2 = 60:40
Ar:O2 = 40:60 N2:O2 = 40:60
40
30
20
10
0
con
cen
trat
ion
[p
pm
]
86420input energy [kJ]
O2混合比が高い→H2O2生成量低下
N2-O2中ではAr-O2中に比べてH2O2の生成量が低下
&NO2
-およびNO3-が生成
コロナ放電による水中のROS/RNS生成
MURORAN INSTITUTEOF TECHNOLOGY
H2O2 NO3-
Ar/O2 N2/O2
40:6040:60
60:40
N/A
10 mm
coppertube
(f 3 x 2 mm)
aluminiumsheet
実験装置および実験条件(プラズマジェット)
MURORAN INSTITUTEOF TECHNOLOGY
deionised water(200 mL)
65 mm
Autosampler
印加電圧 : AC 12 - 14 kVp-p
周波数 : 17 kHz
注入電力 : 4 - 8 W
N2/O2
(0 or 0.1 L/min)N2/O2 mixture ratio:
100/0, 80/20, 60/40,
40/60, 20/80, 0/100
Ar (10 L/min) or He (5 L/min)
glass tube
(f 6 x 3 mm)
放電の様子
Ar, d = 65 mm
15 mm
10 mm
coppertube
(f 3 x 2 mm)
aluminiumsheet
実験装置および実験条件(プラズマジェット)
MURORAN INSTITUTEOF TECHNOLOGY
deionised water(200 mL)
15 mm
glass tube
(f 6 x 3 mm)
Autosampler
N2/O2
(0 or 0.1 L/min)N2/O2 mixture ratio:
100/0, 80/20, 60/40,
40/60, 20/80, 0/100
Ar (10 L/min) or He (5 L/min)印加電圧 : AC 12 - 14 kVp-p
周波数 : 17 kHz
注入電力 : 4 - 8 W
放電の様子
Ar, d = 65 mm
Ar, d = 15 mm
15 mm
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
3020100
input energy [kJ]
Ar (65 mm) Ar + N2/O2 (80/20)
Ar + N2 Ar + N2/O2 (60/40)
Ar + O2 Ar + N2/O2 (40/60)
Ar (15 mm) Ar + N2/O2 (20/80)
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
3020100
input energy [kJ]
Ar (65 mm) Ar + N2/O2 (80/20)
Ar + N2 Ar + N2/O2 (60/40)
Ar + O2 Ar + N2/O2 (40/60)
Ar (15 mm) Ar + N2/O2 (20/80)
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
3020100
input energy [kJ]
Ar (65 mm) Ar + N2/O2 (80/20)
Ar + N2 Ar + N2/O2 (60/40)
Ar + O2 Ar + N2/O2 (40/60)
Ar (15 mm) Ar + N2/O2 (20/80)
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
3020100
input energy [kJ]
He (65 mm) He + N 2/O2 (80/20)
He + N 2 He + N 2/O2 (60/40)
He + O 2 He + N 2/O2 (40/60)
He (15 mm) He + N 2/O2 (20/80)
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
3020100
input energy [kJ]
He (65 mm) He + N 2/O2 (80/20)
He + N 2 He + N 2/O2 (60/40)
He + O 2 He + N 2/O2 (40/60)
He (15 mm) He + N 2/O2 (20/80)
プラズマジェットによるROS/RNS生成
MURORAN INSTITUTEOF TECHNOLOGY
H2O2
NO2-
NO3-
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
3020100
input energy [kJ]
He (65 mm) He + N 2/O2 (80/20)
He + N 2 He + N 2/O2 (60/40)
He + O 2 He + N 2/O2 (40/60)
He (15 mm) He + N 2/O2 (20/80)
ArプラズマジェットH2O2LO2混合により減少NO2
-Lガス種により増減NO3
-LN2混合により増加
Heプラズマジェット生成物への影響なし
ガス混合の影響
短ギャップ:H2O2濃度の増加
OH + OH →H2O2
H2O + e → H + OH + e
H2O + e → H2O+ + e
H2O + H2O+ → H3O
+ + OH
etc...(電気学会技術報告 第1339号, (2015))
水面までの距離の影響
Ar He
glass ball(f 3.0 mm)
mesh
rod(f 2 mm)
glass tube
実験装置および実験条件(パックトベッド放電)
印加電圧: AC 8 - 26 kVp-p
周波数: 11 kHz
注入電力 : 6 - 15 W
Ar, O2, N2
Ar/O2 = 80/20, 60/40, 40/60, 20/80 %
N2/O2 = 80/20, 60/40, 40/60, 20/80 %
N2/Ar = 80/20, 60/40, 40/60, 20/80 %
ガス流量: 2.0 L/min
ガス条件
(100 mL)
MURORAN INSTITUTEOF TECHNOLOGY
オフガス中(in Ar/O2)および水中の生成物
MURORAN INSTITUTEOF TECHNOLOGY
水中にH2O2およびNO2-は生成されない
O2を含むガス中でO3が生成される
O3は水中のROS/RNSの生成に寄与しない
N2-O2混合ガスでは水中にNO3-が生成
オフガス中にNO3-の生成に係る種が存在
4
3
2
1
0
abso
rban
ce [
a.u.]
2400 2200 2000 1800 1600 1400 1200 1000 800
wavenumber [cm-1
]
Ar/O2 = 80/20 O3(1000ppm)
O3 (1000ppm)
200
150
100
50
0
concentr
ati
on [
ppm
]
50403020100input energy [kJ]
Ar
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
Ar:O2 = 20:80
O2
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
NO3-
0.8
0.6
0.4
0.2
0.0
ab
sorb
an
ce [
a.u
.]
2400 2200 2000 1800 1600 1400 1200 1000 800
wavenumber [cm-1
]
N2/O2 = 80/20
before sparging
バブリング前のオフガス中の生成物(in N2/O2)
O3
N2O5N2OO3
オフガス中の生成物
N2O(亜酸化窒素), HNO3(硝酸), N2O5, O3
MURORAN INSTITUTEOF TECHNOLOGY
HNO3
HNO3,N2O5
0.8
0.6
0.4
0.2
0.0
ab
sorb
an
ce [
a.u
.]
2400 2200 2000 1800 1600 1400 1200 1000 800
wavenumber [cm-1
]
N2/O2 = 80/20
before sparging after sparging
バブリングによる水中のNO3-生成
HNO3 とN2O5が減少
NO3-の生成に寄与
オフガス中の生成物
N2O(亜酸化窒素), HNO3(硝酸), N2O5, O3
N2O5 + H2O → 2HNO3
HNO3 + H2O → H3O+ + NO3
-
MURORAN INSTITUTEOF TECHNOLOGY
O3
N2O5N2OO3
HNO3,N2O5 HNO3
15
10
5
0100806040200
300
250
200
150
100
50
0
conce
ntr
atio
n [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
N2:O2 = 60:40
N2:O2 = 40:60
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
6004002000input energy [kJ]
Ar (65 mm) He (65 mm)
Ar + N2 He + N2
Ar + N2/O2 (80/20) He + N2/O2 (80/20)
Ar + N2/O2 (60/40) He + N2/O2 (80/20)
Ar + N2/O2 (40/60) He + N2/O2 (80/20)
Ar + N2/O2 (20/80) He + N2/O2 (80/20)
Ar + O2 He + O2
Ar (15 mm) He (15 mm)
5
4
3
2
1
0200150100500
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar Ar:O2 = 80:20
O2 Ar:O2 = 60:40
N2 Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
300
250
200
150
100
50
0
concentr
ati
on [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar Ar:O2 = 80:20
O2 Ar:O2 = 60:40
N2 Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
H2O2生成濃度(効率)の比較
コロナ放電
パックトベッド放電プラズマジェット
パルス放電
1 g/J H2O2濃度(最高生成効率)
パルス放電(1 g/J)
コロナ放電(0.26 g/J)
プラズマジェット(0.05 g/J)
>>
MURORAN INSTITUTEOF TECHNOLOGY
12
10
8
6
4
2
0
conce
ntr
atio
n [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
N2:O2 = 60:40
N2:O2 = 40:60
12
10
8
6
4
2
0
concentr
ati
on [
ppm
]
6004002000input energy [kJ]
Ar (65 mm) He (65 mm)
Ar + N2 He + N2
Ar + N2/O2 (80/20) He + N2/O2 (80/20)
Ar + N2/O2 (60/40) He + N2/O2 (80/20)
Ar + N2/O2 (40/60) He + N2/O2 (80/20)
Ar + N2/O2 (20/80) He + N2/O2 (80/20)
Ar + O2 He + O2
Ar (15 mm) He (15 mm)
12
10
8
6
4
2
0
concentr
ati
on [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar Ar:O2 = 80:20
O2 Ar:O2 = 60:40
N2 Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
12
10
8
6
4
2
0
concentr
ati
on [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar Ar:O2 = 80:20
O2 Ar:O2 = 60:40
N2 Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
NO2-生成濃度(効率)の比較
0.27 g/J NO2-濃度
(最高生成効率)
パルス放電(0.27 g/J)
コロナ放電(0.1 g/J)
プラズマジェット(0.025 g/J)
MURORAN INSTITUTEOF TECHNOLOGY
>>
コロナ放電
パックトベッド放電プラズマジェット
パルス放電
200
150
100
50
0
conce
ntr
atio
n [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
N2:O2 = 60:40
N2:O2 = 40:60
200
150
100
50
0
concentr
ati
on [
ppm
]
6004002000input energy [kJ]
Ar (65 mm) He (65 mm)
Ar + N2 He + N2
Ar + N2/O2 (80/20) He + N2/O2 (80/20)
Ar + N2/O2 (60/40) He + N2/O2 (80/20)
Ar + N2/O2 (40/60) He + N2/O2 (80/20)
Ar + N2/O2 (20/80) He + N2/O2 (80/20)
Ar + O2 He + O2
Ar (15 mm) He (15 mm)
5
4
3
2
1
0200150100500
200
150
100
50
0
concentr
ati
on [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
Ar:O2 = 20:80
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
Ar
O2
N2
200
150
100
50
0
concentr
ati
on [
ppm
]
6005004003002001000specific energy [kJ/L]
Ar
Ar:O2 = 80:20
Ar:O2 = 60:40
Ar:O2 = 40:60
Ar:O2 = 20:80
O2
N2:O2 = 80:20
N2:O2 = 60:40
N2:O2 = 40:60
N2:O2 = 20:80
N2
N2:Ar = 80:20
N2:Ar = 60:40
N2:Ar = 40:60
N2:Ar = 20:80
NO3-濃度
(最高生成効率)
パックトベッド放電(0.66 g/J)
コロナ放電(0.64 g/J)
パルス放電(0.36 g/J)
プラズマジェット(0.05 g/J)
=>
>
NO3-生成濃度(効率)の比較
MURORAN INSTITUTEOF TECHNOLOGY
0.66 g/J
コロナ放電
パックトベッド放電プラズマジェット
パルス放電
まとめ
MURORAN INSTITUTEOF TECHNOLOGY
パルス放電,ストリーマコロナ放電およびプラズマジェットを水に照射,あるいはパックトベッド放電のオフガスを水にバブリングした水中のH2O2, NO2
-
およびNO3-の濃度を調査し,それぞれの生成効率を比較した
•パックトベッド放電のオフガス(N2O5およびHNO3)をバブリングすることでNO3
-のみを効率良く生成でき,O3はROS/RNSの生成に寄与しない
•放電を水に照射することでH2O2, NO2-(微量)およびNO3
-が生成される
•パルス放電およびコロナ放電を用いた場合,N2を含むガス中ではNO2-お
よびNO3-が生成され,H2O2の濃度が低下する
•プラズマジェットでは,H2O2, NO2-およびNO3
-の生成量は極めて小さい
•NO3-の生成過程においてH2O2の生成を抑制する反応がある
•本研究で得られた生成効率の最高値は,H2O2 :1 g/J(パルス放電)NO2
- :0.27 g/J(パルス放電)NO3
- :0.66 g/J(パックトベッド放電)である