EO – 24/06/2008 1 Département Energie Workshop on Information, Energy and Environment Princeton University, Supélec, Ecole Centrale Paris and Alcatel-Lucent

EO – 24/06/2008 1

Département Energie

Workshop on Information, Energy and Environment

Princeton University, Supélec, Ecole Centrale Paris and Alcatel-Lucent Bell Labs


Environmental Applications of Environmental Applications of Atmospheric Pressure Atmospheric Pressure Non-Thermal PlasmasNon-Thermal Plasmas

Emmanuel Odic, Michael J. Kirkpatrick, Ange MfoparaPower & Energy Systems Department, SUPELEC, Gif-sur-Yvette

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St-Elmo’s fireLightning

Atmospheric phenomena

Introduction

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Hall 1MV LGE EDF les Renardières (1997)

280 cm

Ground plate

HV transport line losses

Introduction

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Introduction

W. V Siemens Ozonizer (1857)water treatmentdisinfection paper bleaching

Electrostatic Precipitator (1890)dust removal

Early application of electrical discharges for environmental applications

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1. Fundamentals on non-thermal plasmasElectrical dischargePlasma typesSource of active species

2. Flue gas treatmentdilute VOC treatment

Energy cost considerationsSolid by-product treatment

3. Surface treatmentbio-decontamination / sterilization

Outline

Environmental Applications of Atmospheric Pressure Non-Thermal Plasmas

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E+

+

-

E

E

+

*

+

Ionizationavalanche

Electron attachment

Photo-ionizationSecondary electrons

d EV

Air, atm. press., room temp. ne ~ 106 m-3 N ~ 2.1025 m-3 ~ 1 µm

d = 1 cm V = 32 kVEq

Mean electron energy

Electrons density ne

Eqnj e

1. Electrical discharges : fundamentals

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0 10 20 30We (eV)

dn/n

(2)(1) (3) (5)(4)

Electron energy distribution function (air, atm. press.)

Species First electronic excitation (eV)

Dissociation (eV) Ionization (eV)

H2 11,47 4,477 15,422

O2 1,635 (1) 5,115 (2) 12,2 (3)

O3 - 6,17 -

N2 5,23 9,762 (4) 15,576 (5)

NO 5,38 6,507 9,25CO 6,04 11,111 14,00CO2 10,0 5,46 13,7

H2O 7,6 9,511 12,6

N2O - - 11,0

OH 4,06 4,45 12,9Loeb 1965

1. Electrical discharges : fundamentals

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HV Transformer

Gas inletGas outlet

HV connection

Stainless steel mesh

DBD discharge in airDBD discharge in air

• Active length of discharge: 150 mm• Gap: 1.5 mm• Reactor volume: 14.5 ml• Residence time @ 5L/min: ~170 µs

Co-axial dielectric barrier discharge reactor

(1)

(3)

(2)

(2)

(3)

(4)

(4) gas

gas

(1)

(3)

(2)

(2)

(3)

(4)

(4) gas

gas

(1) High voltage electrode : ext. diam. 19 mm

(2) Dielectric barrier (Al2O3 ceramic / Pyrex )

(3) Counter electrode (mesh electrode)

(4) Gas gap : 1,5 mm

2. Pollution control

VOC treatment

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isopropanol removal rate as a function of the energy density for thermal oxidation treatment and for NTP treatment. Initial isopropanol concentration: 1000 ppmv (3000 ppm Ceq) in dry air, gas flow: 300 L/h

Energy cost considerations

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400 1600 1800

Energy Density (J/l)

Isop

ropa

nol C

onve

rsio

n R

ate

(%)

TO

NTP


VOC treatment

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Non-thermal plasma : low temperature oxidation

ISOPROPANOL BY-PRODUCTS (ppmv)

CH4 C2H4 C3H6 CH3CHO CH3CO CH3 CH3CHOHCH3 CO CO2

42 30 64 26 182 222 1139 399

- - traces traces 214 146 1298 622

Example 1 : Isopropanol (3000 ppm Ceq)thermal oxidation treatment of 1000 ppmv isopropanol in air at 650°C (tr = 1 s ; R = 78% ; S = 26%)NTP treatment of 1000 ppmv isopropanol in air ( tr ~ 10 ms ; R = 85.5% ; S = 32.5%)

TOLUENE BY-PRODUCTS (ppmv)

CH4 C2H4 C3H6 C4H8 C4H10 HCOOH C6H6 C7H8 C6H5OH C6H5CHO CO CO2

75 139 21 3.6 2.6 139 9 363 28 26 2022 630

- - - - - traces 8 255 traces traces 2894 2223

Example 2 : Toluene (7000-9100 ppm Ceq)thermal oxidation treatment of 1000 ppmv toluene in air at 650°C (tr = 0.5 s ; R = 64% ; S = 24%) NTP treatment of 1300 ppmv toluene in air ( tr ~ 10 ms ; R = 80.5% ; S = 43.5%)

Parissi L., Odic E., Goldman A., Goldman M., Borra J-P.: "Temperature effects on plasma chemical reaction. Application to VOC removal ", contribution for a chapter 11 to "Electrical Discharges for Environmental purposes : background and

applications", E.V. Veldhuizen ed., Nova Science Publisher, New York, 2000, pp. 279-313.


VOC treatment

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Successful VOC treatment means

Total conversion in gas phase

Total carbon recovery

But …

Background2. Pollution control

VOC treatment

benzene (0.5%)

toluene (19.5%)

CO (32%)CO2 (24.5%)

missing C(23.5%)

DBD treatment of toluene in dry air

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Simplest PAH – relatively lowtoxicity for lab safety concerns

High conversion in gas phasebut very low carbon balance

Model compound: naphthalene C10H8

Polycyclic Aromatic Hydrocarbons (PAH) are particulate precursors Automotive aim: cold start application Public Health: some PAH are known or suspected carcinogens


VOC treatment

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Naphthalene removal

0

10

20

30

40

50

60

0 50 100 150Specific Energy Density [J/L]

Nap

hth

alen

e [p

pm

]

0

50

100

150

200

250

300

CO

, CO

2 [

pp

m]

Naphthalene CO2 CO

0

20

40

60

80

100

120

140

160

180

0 50 100 150 200

Specific Energy Density [J/L]

Nap

hth

alen

e [p

pm

]

0

40

80

120

160

200

240

280

320

360

CO

2, C

O [

pp

m]

Naphthalene CO2 CO

90% conversion @ 100J/L

90% conversion @ 60J/L

[C10H8]in = 50 ppm [C10H8]in = 160 ppm

• Major byproducts: CO and CO2

• CO below the detection limit for lower naphthalene concentration• Minor byproducts: phthalic anhydride and naphthalenedione


VOC treatment

A. Mfopara Ph.D. 2006-2008

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Carbon recovery

0

20

40

60

80

100

0 50 100 150 200Specific Energy Density [J/L]

Co

ut/

Cin

[%

]

160 ppm 50 ppm

100*][*10

][*10][][%

810

8102

in

outoutin HC

HCCOCOCC

• Better carbon balance with less naphthalene• Deposit located at gas inlet

HV electrode after 2h of C10H8 introduction

Gas inlet Gas outlet


VOC treatment


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0

10

20

30

40

50

60

0 25 50 75 100 125 150

Time [min]

Nap

hth

alen

e [p

pm

]

0

20

40

60

80

100

120

CO

2, C

O [

pp

m]

naphthalene CO2 CO

Rea

cto

r o

pen

C10H8 offdischarge on discharge on

‘Cleaning’ of solid deposit, ~150 J/L

[C10H8]in = 50 ppm


VOC treatment


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Concluding remarks

• DBD reactor effective for HCs removal from gas phase• Two major byproducts : CO2 and CO• Low carbon balance explained by deposit formation• Possible storage and post-treatment of solid by-products

Industrial applicationsautomotive application (cold start)paint industrystationary emission source (factory, …)


VOC treatment

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Workshop on Information, Energy and Environment3. Surface treatment

Bio-decontamination

More and more polymeric parts in surgical / medical tools (e.g. endoscope) Wet heat (reference treatment : 121-134°C - 2.2 bar) treatment not applicable

for sterilization Need of a « low » temperature sterilization process

Potential technology: non-thermal plasma process

Atmospheric pressure non-thermal plasmas for surface sterilization

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Droplets (dried or not) containing bacteria: 10μL, 104-107 bacteria total

Quantified using a direct plate counting method

Pyrex ®

Gas mixture

HV

Non-thermal plasma source

Treated surface

3. Surface treatment

Bio-decontamination

B. Dodet Ph.D. 2003-2005

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a. Dried spore samples submitted to a wet air discharge effluentb. Liquid spore samples submitted to a dry air discharge effluentc. Dried spore samples submitted to a dry air discharge effluent

1,E+00

1,E+01

1,E+02

1,E+03

1,E+04

1,E+05

1,E+06

1,E+07

0 2 4 6 8 10Time (minutes)

Surv

ivor

s

(a) Dried spore samples submitted to awet air discharge effluent (90% RH)(b) Liquid spore samples submitted to adry air discharge effluent (RH<15%)

(c) Less than 1 Log population reduction after a 10 minute treatment time

Only wet samples efficiently decontaminated

B. Subtilis


Bio-decontamination

B. Dodet Ph.D. 2003-2005

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1 – 1.5 µm

Exosporium

Core

Coats

CortexDNA

Protein shell

nucleic acid

model DNA : plasmid PET9SnI (ring double string molecule – 4285 base pairs)

protein

model protein : RNAse A (thermo resistant, 124 AA, 13.7 kDa)

Interaction of the DBD effluents with

Scanning electron micrograph of Bacillus Subtilis spores


Bio-decontamination

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10 min

C C C CCM

Dry gas

5 min 20 min 5 min2 min

Humid gasDry gas

1 85 76432 9 10 11

Dried sampleLiquid sample

10 min

C C C CCM

Dry gas

5 min 20 min 5 min2 min

Humid gasDry gas

1 85 76432 9 10 11

Dried sampleLiquid sample

Lane 1: molecular weight marker (M) Lanes 3, 5, 7, 9, 11: Controls (C)

Liquid sample / dry Ar/O2 : Lane 2: 10 minute treatment time Lane 4: 5 minute treatment time Lane 6: 2 minute treatment time

Dried sample / dry Ar/O2 : Lane 8: 20 minute treatment time

Dried sample / humid Ar/O2 : Lane 10: 5 minute treatment time

PET9SnI agarose gel electrophoresis of plasmid for different treatments

DNA treatment

1. Plasmid incubated 10 minutes in HNO3 sol. (pH 1.8)

→ no modification of migration bands

2. 10 minutes treatment → negative PCR test

3. Strong decay of the 260 nm absorption band → bases degradation

4. Aqueous phase is required for DNA fragmentation


Bio-decontamination

B. Dodet Ph.D. 2003-2005

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C M

N2 / O2 Ar / O2Acid

1 85 76432

C M

N2 / O2 Ar / O2Acid

1 85 76432

Lane 1: Control

Lane 3: molecular weight marker

Lane 2&4: N2/O2 discharge treatment

Lanes 5&6: Acid control

Lanes 7&8: Ar/O2 discharge treatment

RNAse A SDS-PAGE for different treatments (20 minutes)

Protein treatment

1. RNAse A incubated 20 minutes in HNO3 sol. (pH 1.8)

→ no modification of migration bands

2. RNAse degradation with and without HNO3 formation

3. Aqueous phase is required for protein degradation


Bio-decontamination

B. Dodet Ph.D. 2003-2005

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CONCLUSION

For the plasma process under investigation i.e. interaction of the biologic material with an atmospheric pressure DBD effluent :

Spore bacteria D = 1 (12 minute sterilization time) for B. SubtilisD = 2.3 (28.6 minute sterilization time) for B. Stearothermophilus

Work in progress : application to biofilmssearch for “soft” operating conditionsapplication to Prion


Bio-decontamination

THANK YOU

Documents

EO – 24/06/2008 1 Département Energie Workshop on Information, Energy and Environment Princeton University, Supélec, Ecole Centrale Paris and Alcatel-Lucent