Jou nal o Physics: Con e ence Se ies
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Des uc ion o Di ec Blue 106 Dye in Unde wa e
Discha ge
To ci e his a icle: L Nmco á e al 2014 J. Phys.: Con . Se . 516 012008
View he a icle online o upda es and enhancemen s.
Rela ed con en
Unde wa e dc plasma
A Yu Niki o o , Ch Leys, L Li e al.
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Diaph agm discha ge in liquids:
Fundamen als and applica ions
F an isek K cma, Zdenka S a a and Jana
P ochazko a
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Topical Re iew
Pe e B uggeman and Ch is ophe Leys
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Des uc ion o Di ec Blue 106 Dye in Unde wa e Discha ge
L Němco á1, F K čma1, A Niki o o 2, C Leys2
1 Facul y o Chemis y, B no Uni e si y o Technology, Pu kyno a 118, B no
612 00, Czech Republic
2 Depa men o Applied Physics, Ghen Uni e si y, Joze Pla eaus aa 22, Ghen
9000, Belgium
E-mail: xcnemco a@ ch. u b .cz
Abs ac . An applica ion o unde wa e discha ge is one possible way how make he
des uc ion o o ganic dyes. This con ibu ion p esen s esul s o Di ec Blue 106 des uc ion in
discha ge gene a ed in bubbles. The ini ial conduc i i y alue o 30 µS.cm-1 was ob ained using
elec oly e; he s a ing dye concen a ion was 20 mg.l-1. The DC ol age om 1.5 kV o 3.0
kV was applied o gene a e he discha ge a he mean cu en o 10–30 mA. The sys em was
bubbled h ough he high ol age capilla y elec ode by He, A and N2 a he cons an gas
ollow o 200 sccm. The dye des uc ion a e was di ec ly p opo ional o he applied discha ge
cu en , so he highes e iciency was eached a he cu en o 30 mA. The des uc ion a e was
s ongly dependen on he illing gas. While using He and A only 4% des uc ion was ob ained
du ing he 20 minu es ea men a 10 mA o discha ge cu en bu he decomposi ion o 52 %
was eached i ni ogen was in oduced in o he high ol age elec ode. The des uc ion
e iciency o abou 40 % (He, A ) and o e 60 % in ni ogen was eached a discha ge cu en
o 30 mA. This eno mous di e ence was p obably connec ed no only o he p oduc ion o
hyd ogen pe oxide ha seems o be usually he main oxida i e specie in unde wa e
discha ges bu also a omic and exci ed ni ogen pa icles, bo h a omic and molecula , can ha e
e y posi i e e ec in he dye des uc ion. The de ailed s udy o he kine ic mechanisms
leading o he Di ec Blue 106 dye des uc ion will be a subjec o he u he s udies.
1. In oduc ion
Di ec Blue 106 dye belongs unde he g oup o O ganic Syn he ic Dyes. By de ini ion, dyes a e
colo ed, ionizing and a oma ic o ganic compounds which show an a ini y owa ds he subs a e o
which i is being applied. One cha ac e is ic o dye is ha he dyes mus ge comple ely o a leas
pa ially soluble in which i is being pu o. The ule ha we apply o o he chemicals is simila ly
applicable o dyes also. Fo example ce ain kind o dyes can be oxic, ca cinogenic o mu agenic and
can pose as a haza d o heal h. Di ec Dyes a e one o he mos popula dye g oups. They ha e a wide
ange o applica ions because hey a e o en cheap and easy o apply. Thei chemical composi ion
consis s o sal s o complex sul u ic acids. They a e usually soluble in wa e and hey show a good
a ini y o as ib e ypes and hus hey a e applied o nume ous subs a es o example o ex iles,
lea he , plas ic, pape , e c. in liquid o m. Due o hei wide ange o applica ions, he was e wa e
con aining hese dyes can be a g ea en i onmen al p oblem. I is easie o decompose hese dyes
di ec ly in he liquid phase. The dye concen a ion in was e wa e is usually no e y high and hus he
dye decomposi ion should be comple ed in liquid phase di ec ly. Un o una ely, many o o ganic dyes
a e no possible o decompose using mic oo ganisms due o he p esence o mul iple bounds mainly in
4 h In e na ional Wo kshop & Summe School on Plasma Physics 2010 IOP Publishing
Jou nal o Physics: Con e ence Se ies 516 (2014) 012008 doi:10.1088/1742-6596/516/1/012008
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Published unde licence by IOP Publishing L d 1
he benzene ing (see Fig. 1). Thus, and due o he inc easing demand o pu i ica ion o dye
con aining indus ial was ewa e s by ad anced oxida ion p ocesses (AOP), a la ge numbe o pape s
a e published on he subjec s. In AOP, gene ally eac i e, s ongly oxidizing ·OH adicals play he
main ole in des uc ion o he dye molecules. The decolo a ion o he dye is gene ally ollowed by
spec opho ome y a he abso bance maximum be ween 350 and 700 nm [1-2].
Figu e 1. Di ec blue 106 chemical s uc u e
Unde wa e discha ge is a p omising en i onmen al p ocess o wa e ea men . Nowadays he e a e
mo e di e en con igu a ions sui able o he undewa e discha ge igni ion. Besides well desc ibed
pulsed co ona like sys ems in poin o plane [3] and coaxial con igu a ions [4] and so called elec ode
less con igu a ions (diaph agm [5] and capilla y [6]), he discha ge c ea ed in he bubbles in oduced
in o he sys ems can be applied. All hese discha ges gene a e he non he mal plasma e y simila o
gas co ona discha ge bu i p esen s se e al physical di e ences. The e is a lowe ionic mobili y in he
bulk liquid; on he o he hand, he elec on densi y and elec on collision equency a e much highe
han in he gas phase. This unde wa e bubble discha ge con igu a ion is ela i ely new one and ully
combines bo h gas and liquid phase discha ges. The gas bubbles a e in oduced in o he sys em by hin
s ainless s eel capilla y ha play simul aneously a ole o HV pin elec ode. Thus he HV pin elec ode
is co e ed by a hin gas laye and he discha ge is gene a ed in he gas phase in pin o plane
con igu a ion. The discha ge s eame s (plasma channels) gene a ed in he gas phase a e long enough
(up o 1 cm) and hus hey in oduce in o he liquid phase and u he p opaga e in i [7, 8].
2. Expe imen al echnique
The p incipal scheme o he se -up o he gene a ion o he unde wa e discha ge in gas bubbles is
p esen ed in ig. 2.
Figu e 2. Scheme o he expe imen al se -up
4 h In e na ional Wo kshop & Summe School on Plasma Physics 2010 IOP Publishing
Jou nal o Physics: Con e ence Se ies 516 (2014) 012008 doi:10.1088/1742-6596/516/1/012008
2
The discha ge eac o consis ed o pe spex discha ge chambe ( olume o 1 L), on he bo om o
which a glass capilla y ( he inne diame e o 1.2 mm, leng h o 50 mm) is placed. Liquid was
connec ed h ough a shun ing esis ance o 100 Ω o he g ound po en ial by s ainless s eel elec ode
placed a he uppe pa o he chambe . The eac o was wa e cooled in o de o a oid he mal
des uc ion o hyd ogen pe oxide a empe a u es abo e 30 °C [9]. HV elec ode was a s ainless s eel
ube ( he diame e o 0.5 mm) which was placed inside glass capilla y. The gas (A , He o N2) has
been applied h ough his ube in o de o p oduce bubbles. Gas low in he sys em was supplied by
mass low con ol sys em (MKS 4000). Flow a e o used gases was ixed a 200 sccm in all
expe imen s. The elec ic discha ge was loca ed di ec ly on he su ace o he me allic ube inside o
bubbles. The DC powe supply o he discha ge sus aining has been connec ed o he eac o h ough
a ballas esis o 30 kΩ. The applied ol age was a ied om 1.5 o 3.0 kV a mean cu en om 10
mA o 30 mA.
3. Resul s and discussion
The kine ic plo s o discha ge cu en s o 15 and 30 mA a e p esen ed in Figu e 3. Discha ge
gene a ed a 10 mA was no s able and hus he des uc ion o di ec blue dye was no su icien ly
e ec i e as i is demons a ed in Table I. One can see ha in he case o He and A plasmas he
des uc ion e iciency o he di ec blue dye molecules was much lowe han in he case o N2.
Maximal des uc ion o abou 64 % was achie ed in N2 plasma a he highes applied cu en . We
suppose ha his e ec is connec ed o he o ma ion o HNO3 in case o N2 due o oxida ion o N2 ha
leads o he dec ease o solu ion pH down o 2. Used dye has lowe s abili y in acidic solu ions wi h
pH<6 and he oxida i e abili y o plasma is s onge in acidic condi ions (e.g. he oxida i e po en ial o
he hyd oxyl adical is 2.70 V a pH 3.0 and 2.34 V a pH 9.0). A new se o expe imen s will be
a anged o con i m his hypo hesis.
As i was poin ed in In oduc ion, he unde wa e discha ge is a sou ce o di e en eac i e pa icles
(aqueous elec ons, OH, O, H adicals, O3, H2O*, HO2, and many o he eac i e species) as well as UV
adia ion. Besides hem, also he empe a u e in he bubble su ounding should be aken in o accoun .
Gas empe a u e inside he bubble es ima ed by i ing he emission spec a o OH bands can each
1500-2000 K [10] and hus i can in luence he des uc ion o o ganic compounds due o he mal
dissocia ion. In o de o es ima e an impo ance o di e en mechanism in chemical des uc ion o he
dye addi ional expe imen s wi h sca enge o OH adicals [11] ha e been ca ied ou . The ull
unde s anding o he dye des uc ion mechanism and i s kine ic is hus e y complica ed ask ha is
impossible o sol e wi hou u he s udies including he exac analyzes o he discha ge p oduc s by
a ious analy ical echniques.
0 5 10 15 20
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
abso bance (a.u.)
ime (min)
N
2
A
He
I
0 5 10 15 20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
abso bance (a.u.)
ime (min)
N
2
II
A
He
Figu e 3. Kine ic plo s o Di ec Blue 106 dye des uc ion a he cu en o 15 mA (I) and 30 mA (II)
4 h In e na ional Wo kshop & Summe School on Plasma Physics 2010 IOP Publishing
Jou nal o Physics: Con e ence Se ies 516 (2014) 012008 doi:10.1088/1742-6596/516/1/012008
3
Table I. E iciency o he Di ec Blue 106 des uc ion a e 20 minu es plasma ea men .
Cu en [mA] Decomposi ion o he dye [%]
He A N2
10 4 4 52
15 6 15 53
20 21 24 55
25 32 30 59
30 36 43 64
4. Conclusion
This wo k has been ocused on chemical e iciency o he elec ic discha ge in wa e solu ion
gene a ed in gas bubbles. The in luence o he used gas (He, A , N2) was s udied a he cons an gas
low. The des uc ion o Di ec Blue 106 dye was obse ed as a unc ion o applied discha ge cu en .
A g ea di e ence be ween used gases was ound. By using lowe cu en o 10 mA and 15 mA (He,
A ) he plasma was no ully s able and e iciency o decomposi ion was e y low o a ew pe cen s. I
inc eased up o 40 % a he cu en o 30 mA in bo h cases. On he o he hand a 52 % des uc ion o
dye du ing 20 minu es was obse ed in N2 bubbles e en a e y low cu en o 10 mA and i inc eased
up o abou 65 % a 30 mA. The possible explana ion o his g ea di e ence is in he c ea ion o
HNO3 acid molecules when ni ogen is in oduced in o he sys em. These molecules dec ease he pH
o solu ion ha accele a es he dye decolo a ion.
Acknowledgemen
This wo k was pa ially suppo ed by he In e uni e si y A ac ion Poles P og am o he Belgian
Science Policy, p ojec No. PSI-P6/08 and by p ojec o Speci ic Uni e si y Resea ch a B no
Uni e si y o Technology, p ojec No. FCH-S-10-8.
5. Re e ences
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[2] Wa d D B, Tizaoui C and Sla e M J 2006 Chem. Eng. P ocess. 45 124-139
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[4] Šunka P, Babický V, Člupek M,Lukeš P, Šimek M, Schmid J and Če nák M (1999) Plasma
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[5] S a á Z, K čma F, Nejezchleb M and Skalný J D (2009) Desalina ion 239, 283-294
[6] DeBaedemaeke F, Šimek M, Schmid J and Leys C (2007) Plasma Sou ces. Sci. Technol. 16
341-354
[7] Niki o o A Y 2009 IEEE T ans. Plasma Sci. 36 872-876
[8] Malik M A, Gha a A and Malik S A 2001 Plasma Sou ces. Sci. Technol. 10 82-91
[9] Schumb W C, Sa e ield Ch N and Wen wo h R L 1955 Hyd ogen pe oxide, Am. Chem. Soc.
Monog aph Se ., New Yo k
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[11] Nakui H, Oki su K, Maeda Y and Nishimu a R (2007) Ul asonics Sonochem.14 627-632
4 h In e na ional Wo kshop & Summe School on Plasma Physics 2010 IOP Publishing
Jou nal o Physics: Con e ence Se ies 516 (2014) 012008 doi:10.1088/1742-6596/516/1/012008
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