Content uploaded by Sergei Preis
Author content
All content in this area was uploaded by Sergei Preis on Aug 02, 2014
Content may be subject to copyright.
Provided for non-commercial research and educational use only.
Not for reproduction or distribution or commercial use.
This article was originally published by IWA Publishing. IWA Publishing recognizes
the retention of the right by the author(s) to photocopy or make single electronic
copies of the paper for their own personal use, including for their own classroom use,
or the personal use of colleagues, provided the copies are not offered for sale and
are not distributed in a systematic way outside of their employing institution.
Please note that you are not permitted to post the IWA Publishing PDF version of
your paper on your own website or your institution’s website or repository.
Please direct any queries regarding use or permissions to wst@iwap.co.uk
Pulsed corona discharge: the role of ozone and hydroxyl
radical in aqueous pollutants oxidation
S. Preis, I. C. Panorel, I. Kornev, H. Hatakka and J. Kallas
ABSTRACT
Ozone and hydroxyl radical are the most active oxidizing species in water treated with gas-phase
pulsed corona discharge (PCD). The ratio of the species dependent on the gas phase composition
and treated water contact surface was the objective for the experimental research undertaken for
aqueous phenol (fast reaction) and oxalic acid (slow reaction) solutions. The experiments were
carried out in the reactor, where aqueous solutions showered between electrodes were treated with
100-ns pulses of 20 kV voltage and 400 A current amplitude. The role of ozone increased with
increasing oxygen concentration and the oxidation reaction rate. The PCD treatment showed energy
efficiency surpassing that of conventional ozonation.
S. Preis (corresponding author)
I. C. Panorel
H. Hatakka
J. Kallas
Laboratory of Separation Technology, LUT
Chemistry,
Lappeenranta University of Technology,
P.O. Box 20,
Lappeenranta 53851,
Finland
E-mail: sergei.preis@lut.fi
I. Kornev
High Technology Physics Institute,
Tomsk Polytechnic University,
2A Lenin Ave.,
Tomsk,
Russia
Key words |electric discharge, energy efficiency, oxalate, phenol, water treatment
INTRODUCTION
An interest towards intense cost-effective technologies
able to oxidize refractory pollutants in water/wastewater
treatment is growing due to accumulation and diversifica-
tion of hazardous substances in the environment, and
tightening standards for water supply and wastewater dis-
posal. Advanced oxidation processes (AOPs) are
powerful, human-friendly and effective means for water
treatment, although the excessively expensive character
of ozone production and application makes it a privilege
of industrially developed countries. The way to promote
AOPs in water treatment technology is the substantial
improvement of their cost efficiency. One of the AOPs is
the application of electric discharges to oxidation–
reduction reactions with short-living powerful oxidants,
such as hydroxyl radical (OH), ozone (O
3
)andatomic
oxygen (O), generated directly in the treated water or at
the gas–liquid interface. Previous studies (Yavorovsky
et al.;Chauhan et al.;Hoeben et al.;
Kornev et al.) showed the concentration of gas-
phase discharges in close vicinity of the gas–liquid inter-
face, where the short-living oxidants generated in the
discharge react with pollutants in the boundary layer of
water. Various discharge systems were proposed and are
still under study: spark discharge in gas bubbles (Anpilov
et al.), pulsed streamer discharges in liquid and gas-
bubbled reactors with pulses at micro-second diapason
(Shih & Locke ;Ruma et al.), gas-phase dielectric
barrier discharge of various configurations (Yavorovsky
et al.;Malik & Schoenbach ;Marotta et al.
), plasmotrons utilizing gliding arc discharge for bom-
bardment of treated surfaces with ionized gas (Locke &
Thagard ;Benstaali et al.;Merouani et al.),
pulsed corona discharge (PCD) over the water surface
(Grabowski et al.;Magureanu et al.), flash
corona over the water surface (Aristova & Piskarev
), and PCD in water aerosol (Pokryvailo et al.).
The authors earlier proposed PCD (Panorel et al.),
where water was dispersed in gas in the form of droplets,
jets and films sized up to a few millimetres, forming a suf-
ficient interface treated with PCD in a cost-effective
manner.
The described method showed the energy efficiency
exceeding that of traditional ozonation by a few times
(Panorel et al.) using simple equipment: the pulsed dis-
charge, unlike ozone synthesis in conventional ozone
generators, is insensitive towards gas humidity; the reactor
closed compartment, in which the treatment takes place,
makes the residual ozone destruction minor, if air is used,
or unnecessary with an oxygen-enriched gas.
The PCD treatment of water is often offering an energy-
efficient alternative to conventional ozonation forming
ozone and OH radicals in humid air (Ono & Oda )
1536 © IWA Publishing 2013 Water Science & Technology |68.7 |2013
doi: 10.2166/wst.2013.399
and most likely on the treated water surface thus involving
water itself in the oxidation:
eþH2O>
eþHþOH(1)
Hydroxyl radicals and ozone may directly oxidize aqu-
eous pollutants in the vicinity of the gas–liquid interface.
In the bulk of water the dissolved ozone contributes to oxi-
dation directly or decomposes via formation of OH radical
(von Gunten ). The ratio of ozone and direct OH radical
contributions may determine the oxidation chemistry and
kinetics and the choice of treatment parameters, i.e. pulse
repetition frequency and the gas composition, resulting ulti-
mately in the treatment cost. The present research had an
objective of establishing the ratio of contributions of ozone
and OH radicals directly formed from water to oxidation
of rapidly reacting phenol and slowly reacting oxalate.
MATERIALS AND METHODS
The experimental system consists of a PCD reactor and a
high voltage (HV) pulse generator shown in Figure 1. The
reactor utilizes wire-plate corona geometry: horizontal elec-
trode wires are placed between vertical earthed plate
electrodes. The electrodes’geometry parameters determin-
ing the pulse characteristics (Briels et al.)were
chosen for the maximum pulse energy; the electrodes were
made of stainless steel wire of 0.5 mm diameter, positioned
at 17 mm from the vertical grounded plate electrodes with
the distance of 30 mm between the HV electrodes. The
total length of the HV electrodes was 32 m in 0.5-m sections,
i.e. 64 electrodes were positioned between two plates sized
0.5 ×2.0 m. The volume of the discharge zone of the reactor
thus was 34 L. Water is fed to the top of reactor, where it is
dispersed through a perforated plate producing jets, droplets
and films. Water showers between electrodes to the zone of
gas-phase PCD formation, where the treatment with oxi-
dants takes place. The power supply generates the
discharge pulses of voltage pulse amplitude of 18–20 kV,
current of 380–400 A, and 100 ns duration at pulse rep-
etition frequency from 100 to 840 pulses per second (pps)
(see Figure 2). The pulse parameters were registered with
the Agilent 54622D oscilloscope. The energy delivered to
the reactor, calculated as an integral product of voltage
and current peak areas, was 0.30–0.33 J per pulse. The
energy consumption efficiency of the pulse generator was
67%.
The experiments were performed using 50-L samples of
circulating solutions, if not stated otherwise. Oxygen and
nitrogen were delivered to the reactor using the port in the
tank cover. Oxygen content in the gas phase was measured
using a Servomex 570A oxygen analyzer.
Phenol and oxalate were dissolved in water at ambient
temperature remaining at 18–20 WC in experiments; the
temperature of the solution stabilized at about 20–22 WCin
equilibrium with the ambient temperature. pH was adjusted
with sodium hydroxide. The operating parameters included
Figure 1 |Experimental setup outline.
1537 S. Preis et al. |Pulsed corona discharge: ozone and hydroxyl radical Water Science & Technology |68.7 |2013
the phenol content of 100 mg L
1
and oxalic acid content
from 100 to 1,000 mg L
1
, oxygen concentration in air
from 0 to 90% vol., circulating water flow rate 3, 5, 7, 10
and 15 L min
1
. The gas–liquid contact surface was
measured at corresponding water flow rates by the classical
method of sulphite oxidation with air oxygen in the presence
of cobalt sulphate catalyst.
The reactor was open to the atmosphere through a 5-mm
port for the pressure equalization. This port showed
negligible impact when no reaction took place: water circu-
lation in the reactor filled with 90% oxygen showed no
change in oxygen content for 6 h. The replacement of
oxygen consumed in reaction with ambient air allows pre-
cise calculation of oxygen consumption using the reading
of an oxygen gas analyzer.
Ozone concentration in the gas was measured iodo-
metrically by blowing the exact amount of the gas, 1 L,
from the reactor through a Drexel trap filled with acidified
potassium iodide solution. The free iodine was titrated
with 0.1-N sodium thiosulphate solution. Ozone concen-
tration in water was also measured iodometrically.
Attempts to measure the content of hydrogen peroxide
were also undertaken using the titanyl sulphate method
described by Eisenberg (). The results of analysis,
however, showed negligible contents, in amounts smaller
than 1 mg L
1
, of ozone and hydrogen peroxide in samples
taken immediately from the bottom of the reactor even in
Millipore water.
Phenol was chosen as the reference substance for the
energy efficiency analysis as there is substantial literature
to support its use (Grabowski et al.;Marotta et al.
). Oxalate is known to be a refractory compound with
slow oxidation rate. Phenol concentration was determined
by the 4-nitroaniline method (Leithe ), oxalate concen-
tration was matched with the total organic carbon (TOC)
determined using a Shimadzu 5050 TOC analyzer. Chemi-
cal oxygen demand (COD) was measured by the
potassium dichromate closed reflux colorimetric method
(Standard Methods ).
RESULTS AND DISCUSSION
Energy efficiency in oxidation
The oxidation efficiency of phenol, zero in 100% nitrogen,
increased with oxygen volumetric concentration, approxi-
mating to a constant level at 60% vol. with further oxygen
concentration growth at about 120 g phenol per 1 kWh of
delivered energy at 840 pps and 140 g kWh
1
at 100 pps in
alkaline solutions with starting pH 11 (Figure 3). The effi-
ciency in air at oxygen concentration of 20.5% vol. ranged
from 55 to 88 g kWh
1
at 840 and 100 pps respectively,
noticeably surpassing conventional ozonation efficiency
(Krichevskaya et al.). These numbers were obtained
for 50% degradation of phenol in 100-ppm solutions. The
effect of the reduced frequency diminishes with the
increased oxygen concentration indicating probably a
Figure 3 |Oxidation efficiency of phenol vs oxygen content in the gas phase: phenol
initial concentration 100 mg L
1
, initial pH 11, efficiency assessed at 50%
phenol removal.
Figure 2 |Voltage and current oscillograms of the pulse.
1538 S. Preis et al. |Pulsed corona discharge: ozone and hydroxyl radical Water Science & Technology |68.7 |2013
bigger contribution of ozone in oxygen-enriched gas. Ozone,
however, plays a more significant role in air observed in the
noticeable improvement in PCD efficiency at decreased fre-
quency: lower pulse repetition frequency likely allows
longer-living ozone to participate in oxidation between
pulses. Pulse parameters did not vary with the variation of
pulse repetition frequency.
Alkaline medium, as expected, was more beneficial
than acidic (initially neutral pH decreased during the
course of the treatment from 6.5–7.0 to about 4.0) in
phenol oxidation by a factor of about two. The efficiency
in mineralization of phenol, i.e. in TOC degradation
ranged from 5 g C kWh
1
in air to about 10 g C kWh
1
in
90% oxygen in alkaline solutions.
Oxidation efficiency of oxalate in air under the
described conditions was independent of pH from 3 to 11
showing the mineralization efficiency of about 5–10 g C
kWh
1
dependent on the oxalate initial concentration
(100–800 mg L
1
). The energy efficiency of oxalate oxi-
dation was invariant with the pulse repetition frequency,
indicating possibly a minor role of longer-living ozone in
the reaction.
Contact surface and efficiency correlation
The flow rate of treated phenolic solution was varied from 3
to 15 L min
1
, which, relating to the cross-section of the
PCD zone, corresponds to the surface velocity from 10.4
to 52.9 m h
1
. The contact surface determined by the sul-
phite method (Danckwerts ) was showing linear
growth with the flow rate from 9 to 43 m
1
respectively.
The phenol oxidation efficiency reaches its maximum at
20 m
1
, remaining constant with further growth of circulat-
ing water flow and the contact surface (Figure 4). This
indicates the discharge power, not the contact surface,
being a restraining factor in oxidation kinetics over the con-
sidered surface limit.
The pulse parameters practically did not change with
variation of wetting density. The detailed study of the
impact of wetting with conductive solutions on the pulse
parameters can be found in Kornev et al.().
Surface reaction
The immediate mineralization of phenol, i.e. TOC degrada-
tion, was observed from the start of treatment, witnessed
indirectly by the surface character of the oxidation reaction
(Figure 5): immediate mineralization is not characteristic of
phenol oxidation in a bulk solution with ozone. The hypoth-
esis of the surface reaction was also supported by the role of
OH-radical scavenging agents added to the treated solution.
The addition of the well-known OH-radical scavenger tert-
butyl alcohol (TBA) to the treated solution did not have an
effect even at the TBA concentration exceeding that of
phenol by a factor of 10. At the same time, the addition of
a non-ionic surfactant, igepal C-630 (2-[2-(4-nonylphenoxy)
ethoxy] ethanol, C
19
H
32
O
3
) in concentration equimolar
with phenol, resulted in a noticeable slowdown of oxidation
in neutral–acidic solutions (Figure 6). This indicates the sur-
face character of radical attack screened by the surfactant.
None of the used radical scavengers is oxidized by PCD.
The role of ozone and OH radical in oxidation
Phenol oxidation
Oxygen in the gas space of the reactor is mostly consumed
in the synthesis of ozone with the further reaction of the
Figure 4 |Oxidation efficiency of phenol vs gas–liquid contact surface: phenol initial
concentration 100 mg L
1
, initial pH 11, efficiency assessed at 50% phenol
removal, pulse repetition frequency 840 pps. Figure 5 |Mineralization of phenol: initial pH 11, applied power 250 W.
1539 S. Preis et al. |Pulsed corona discharge: ozone and hydroxyl radical Water Science & Technology |68.7 |2013
latter. If oxidation takes place on account of ozone only, the
COD degradation should be equal to oxygen consumption
from the reactor’s gas phase. The authors, however,
observed a misbalance between these two values: COD
degraded substantially faster than oxygen was consumed.
The misbalance between oxygen consumption in the reac-
tor and the decreasing COD showed a substantial contribution
of OH radicals produced from water molecules. The exper-
iment was carried out with 700 L of phenolic solution
treated in air (20.5% vol. of O
2
) and oxygen-enriched gas
(78.5% vol. O
2
). The big volume of solution was applied to
minimize the influence of changing phenol concentration,
keeping it close to uniform for a longer time, and to minimize
the gas volume in the reactor, 50 L, for noticeable oxygen gas
phase concentration change. The COD decrease, i.e. oxygen
introduction to the solution, surpassed the oxygen decrease
in the gas phase in the reactor 1.9 and 1.3 times in air and
in the oxygen-enriched gas respectively. The contribution of
OH radicals at low concentrations of oxygen thus was substan-
tially bigger: the radicals’share in phenol oxidation decreased
with increasing oxygen concentration. Negligible oxidation of
phenol at zero oxygen concentrationmaybeexplainedbythe
absence of oxygen-scavenging H radicals formed simul-
taneously with the OH radical at the interface with their
recombination, or the OH radical formation reaction being
more complex than the one described in Equation (1).
Oxalate oxidation
Slow oxidation of oxalic acid showed substantial contribution
of OH-radicals to oxidation. The drastic difference in oxi-
dation rate was observed in experiments, in which solutions
were treated with PCD and solely with ozone at the same
ozone gas-phase concentrations. The experiments were
carried out in air atmosphere with the equilibrium gaseous
ozone concentration maintained at 5 mg/L for identical
periods of time. The ozone concentration in the reactor with-
out PCD application was maintained by ‘blinking’switching
the pulse generator on for 5 s with 10-s intervals; the treated
solution flow was turned off for the time PCD was applied.
The oxidation rate with ozone alone was about five times
lower than with the PCD application. The oxidation reaction
with ozone thus contributed, under the experimental con-
ditions, about 20% of the total oxidation rate.
Phenol oxidation kinetics: practical description
The degradation rate coefficients at the initial stage of reac-
tion (50% degradation), within which degradation followed
the linear pattern, were determined. The reaction rate coef-
ficients were determined assuming that the combined effect
of the OH-radicals and ozone results in a second order reac-
tion rate, the first order relative to the target pollutant and
the first order towards the oxidant. The second reaction
order is attributable to the majority of aqueous ozonation
reactions, proceeding via ozone decomposition in water
(Hoigné & Bader ;von Gunten ).
The description of the reaction kinetics is complicated
due to the unknown sum of oxidants’concentration and
their share in the reaction: the short-living OH-radicals pre-
sumably formed at the surface of treated water are difficult
to quantify; ozone formed in the discharge is present in
dynamic equilibrium established between the formation
and consumption rate. The indifference of the discharge treat-
ment efficiency towards the hydrodynamics of water flow and
the contact surface of treated solutions observed earlier
(Panorel et al.) and in this work indicates a constant
amount of oxidants available momentarily in the discharge
zone. Therefore, the sum concentration of oxidants taking
part in the reaction could be characterized with an accuracy
sufficient for practical applications by the power Pdelivered
to the volume of the discharge zone V, and so used with the
second order reaction rate constant k
2
:
dC=dt¼k2CPV1(2)
where k
2
is the second order reaction rate constant, m
3
J
1
;C
is the concentration of the pollutant, mol m
3
;Pis the pulsed
power delivered to the reactor, W; Vis volume of the dis-
charge zone, m
3
, in the experimental device: 0.034 m
3
.
The second order reaction rate coefficients calculated for
the initial period of treatment are given in Table 1. One can
Figure 6 |Phenol degradation in presence of igepal C-630 surfactant radical scavenger:
air; initial pH 6.0; legend gives concentration of surfactant; phenol initial
concentration 1 mM, applied power 150 W.
1540 S. Preis et al. |Pulsed corona discharge: ozone and hydroxyl radical Water Science & Technology |68.7 |2013
see the oxidation rate coefficients expectedly growing with
the content of oxygen: ozone equilibrium concentration is
higher in oxygen-rich atmosphere. The second order reaction
rate coefficient decreases with the pulse repetition frequency
due to the increased ozone impact at lower frequency.
The proposed kinetic approach appears to be of practi-
cal value and the numerical values obtained for phenol
may be used for further references. The higher reaction
rate in oxygen media shows the increasing role of ozone
in oxidizing phenol.
CONCLUSIONS
The PCD method appeared to be highly effective in oxi-
dation of phenol, surpassing the closest competitor,
conventional ozonation, in energy efficiency.
The short-living oxidants formed at the water surface
treated with the PCD contribute to oxidation of organic pol-
lutants. The contribution of short-living oxidants decreases
with the increased reaction rate and, for fast oxidation reac-
tions, the oxygen concentration in the gas phase.
Oxidation of slowly oxidized refractory pollutants may
benefit from high pulse repetition frequencies, whereas
with rapidly reacting substances low frequency treatment
is beneficial for a larger contribution of ozone participating
in oxidation between pulses, although the oxidation rate
also decreases.
The mass transfer showed minor impact to the oxidation
efficiency; the process rate is determined primarily by the
pulsed power delivery rate.
ACKNOWLEDGEMENTS
This study was supported by Finnish Funding Agency for
Technology and Innovation (Tekes), projects 40418/06
and 40131/08, the Academy of Finland, and the Ministry
of Education and Science of the Russian Federation, project
No. 14.B37.21.1244.
REFERENCES
Anpilov, A. M., Barkhudarov, E. M., Bark, Y. B., Zadiraka, Y. V.,
Christofi, M., Kozlov, Y. N., Kossyi, I. A., Kop’ev, V. A.,
Silakov, V. P., Taktakishvili, M. I. & Temchin, S. M.
Electric discharge in water as a source of UV radiation,
ozone and hydrogen peroxide. J. Phys. D: Appl. Phys.34 (6),
993–999.
Aristova, N. A. & Piskarev, I. M. Kinetics of phenol oxidation
under flash corona electric discharge. Russ. J. Appl. Chem.75
(1), 86–89.
Benstaali, B., Al-Bastaki, N., Addou, A. & Brisset, J. L.
Plasma-chemical and photo-catalytic degradation of methyl
orange. Int. J. Environ. Waste Manage. 11 (2), 158–177.
Briels, T. M. P., Kos, J., Winands, G. J. J., van Veldhuizen, E. M. &
Ebert, U. Positive and negative streamers in ambient air:
measuring diameter, velocity and dissipated energy. J. Phys.
D: Appl. Phys. 41 (23), article no. 234004.
Chauhan, S., Yankelevich, E., Bystritskii, V. & Wood, T. K.
Degradation of 2,4,5-trichlorophenol and 2,3,5,6-
tetrachlorophenol by combining pulse electric discharge with
bioremediation. Appl. Microbiol. Biotechnol.52 (2), 261–266.
Danckwerts, P. V. Gas–Liquid Reactions. McGraw-Hill, New
York, p. 276.
Eisenberg, G. M. Colorimetric determination of hydrogen
peroxide. Ind. Eng. Chem. Analy.15 (5), 327–328.
Grabowski, L. R., van Veldhuizen, E. M., Pemen, A. J. M. &
Rutgers, W. R. Corona above water reactor for
systematic study of aqueous phenol degradation. Plasma
Chem. Plasma Process.26 (1), 3–17.
Hoeben, W. F. L. M., van Veldhuizen, E. M., Rutgers, W. R. &
Kroesen, G. M. W. Gas phase corona discharges for
oxidation of phenol in an aqueous solution. J. Phys. D: Appl.
Phys.32 (24), L133–L137.
Hoigné, J. & Bader, H. Ozonation of water: selectivity and
rate of oxidation of solutes. Ozone: Sci. Eng. 1(1), 73–85.
Kornev, J., Yavorovsky, N., Preis, S., Khaskelberg, M., Isaev, U. &
Chen, B.-N. Generation of active oxidant species by
pulsed dielectric barrier discharge in water-air mixtures.
Ozone: Sci. Eng.28 (4), 207–215.
Kornev, I., Osokin, G., Galanov, A., Yavorovskiy, N. & Preis, S.
Formation of nitrite- and nitrate-ions in aqueous
solutions treated with pulsed electric discharges. Ozone: Sci.
Eng.35 (1), 22–30.
Krichevskaya, M., Klauson, D., Portjanskaja, E. & Preis, S.
The cost evaluation of advanced oxidation processes in
laboratory and pilot-scale experiments. Ozone: Sci. Eng.33
(3), 211–223.
Leithe, W. Die Analyse der Organischen Verunreinigungen in
Trink-, Branch- und Abwasser (Analysis of Organic
Pollutants in Potable, Process and Wastewaters).
Wissenschaftliche Verlagsgesellschaft MBH, Stuttgart,
p. 152.
Table 1 |The second order reaction rate coefficients for phenol degradation in alkaline
solutions
Second order reaction rate constant k
2
,m
3
J
1
Frequency, pps Power, W Air 90% oxygen
100 30 36 ±4×10
–8
58 ±4×10
8
200 60 34 ±4×10
8
57 ±5×10
8
400 120 31 ±3×10
8
54 ±3×10
8
600 180 27 ±3×10
8
52 ±3×10
8
840 250 23 ±3×10
8
50 ±3×10
8
1541 S. Preis et al. |Pulsed corona discharge: ozone and hydroxyl radical Water Science & Technology |68.7 |2013
Locke, B. R. & Thagard, S. M. Analysis and review of
chemical reactions and transport processes in pulsed
electrical discharge plasma formed directly in liquid water.
Plasma Chem. Plasma Process. 32 (5), 875–917.
Magureanu, M., Bradu, C., Piroi, D., Mandache, N. B. &
Parvulescu, V. Pulsed corona discharge for degradation
of methylene blue in water. Plasma Chem. Plasma Process.
33 (1), 51–64.
Malik, M. A. & Schoenbach, K. H. A novel pulsed corona
discharge reactor based on surface streamers for NO
conversion from N
2
-O
2
mixture gases. Int. J. Plasma Environ.
Sci. Technol.5(1), 50–57.
Marotta, E., Ceriani, E., Schiorlin, M., Ceretta, C. & Paradisi, C.
Comparison of the rates of phenol advanced oxidation in
deionized and tap water within a dielectric barrier discharge
reactor. Water Res. 46 (19), 6239–6246.
Merouani, D. R., Abdelmalek, F., Ghezzar, M. R., Semmoud, A.,
Addou, A. & Brisset, J. L. Influence of peroxynitrite in
gliding arc discharge treatment of alizarin red S and
postdischarge effects. Ind. Eng. Chem. Res.52 (4), 1471–
1480.
Ono, R. & Oda, T. Dynamics of ozone and OH radicals
generated by pulsed corona discharge in humid-air flow
reactor measured by laser spectroscopy. J. Appl. Phys. 93
(10), 5876–5882.
Panorel, I. C., Kornev, I., Hatakka, H. & Preis, S. Pulsed
corona discharge for degradation of aqueous humic
substances. Water Sci. Technol.: Water Supply 11 (2),
238–245.
Pokryvailo, A., Wolf, M., Yankelevich, Y., Wald, S.,
Grabowski, L. R., van Veldhuizen, E. M., Rutgers, W. R.,
Reiser, M., Glocker, B., Eckhardt, T., Kempenaers, P. &
Welleman, A. High-power pulsed corona for
treatment of pollutants in heterogeneous media. IEEE
Trans. Plasma Sci. 34 (5), 1731–1743.
Ruma, P., Lukes, P., Aoki, N., Spetlikova, E., Hosseini, S. H. R.,
Sakugawa, T. & Akiyama, H. Effects of pulse frequency
of input power on the physical and chemical properties of
pulsed streamer discharge plasmas in water. J. Phys. D: Appl.
Phys. 46 (12), article no. 125202.
Shih, K.-Y. & Locke,B. R. Chemical and physical characteristics
of pulsed electrical discharge within gas bubbles in aqueous
solutions. Plasma Chem. Plasma Process. 30 (1), 1–20.
Standard Methods for the Examination of Water and Wastewater
(A. D. Eaton, L. S. Clesceri, A. E. Greenberg, eds),
19th edn. American Public Health Association/American
Water Works Association/Water Environment Federation,
Washington, DC, USA, pp. 5–15.
von Gunten, U. Ozonation of drinking water: Part I.
Oxidation kinetics and product formation. Water Res.37 (7),
1443–1467.
Yavorovsky, N., Boev, S., Muratov, E. & Polyakov, N.
Reactor and method of water treatment. Patent of Russian
Federation No. 2136600. 16.12.1997
First received 15 January 2013; accepted in revised form 29 May 2013
1542 S. Preis et al. |Pulsed corona discharge: ozone and hydroxyl radical Water Science & Technology |68.7 |2013
