A study of sorption and decomposition of ozone on microfibrous filtering materials

Article abstract of DOI:10.1134/S1070427208040113

Decomposition of ozone on commercial and pilot filtering microfibrous materials based on polymers, glass fibers, and carbonized polymeric fibers was studied.

Full text of DOI:10.1134/S1070427208040113

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 4, pp. 630 634.
Original Russian Text A.I. Klimuk, L.A. Obvintseva, A.D. Shepelev, V.L. Kuchaev, M.P. Dmitrieva, E.N. Ushakova, A.K. Avetisov, 2008, published
in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 4, pp. 593 597.
Pleiades Publishing, Ltd., 2008.
PHYSICOCHEMICAL STUDIES
OF SYSTEMS AND PROCESSES
A Study of Sorption and Decomposition
of Ozone on Microfibrous Filtering Materials
A. I. Klimuk, L. A. Obvintseva, A. D. Shepelev, V. L. Kuchaev,
M. P. Dmitrieva, E. N. Ushakova, and A. K. Avetisov
Karpov Research Physicochemical Institute, Moscow, Russia
Received October 3, 2007
Abstract Decomposition of ozone on commercial and pilot filtering microfibrous materials based on
polymers, glass fibers, and carbonized polymeric fibers was studied.
DOI: 10.1134/S1070427208040113
In view of the wide use of ozone in chemical and
pulp-and-paper industries, microelectronics, water
treatment, and medicine, a topical issue is develop-
ment of methods for decomposition of excess ozone,
including those to be used in individual and collective
means for protection of the human respiratory system
in those case when the maximum permissible concen-
tration (MPC) of ozone in air is exceeded. Ozone is
commonly decomposed with heterogeneous catalysts
containing metals, such as Cu, Mn, Co, Fe, Ni, Ti,
and Ag, and their oxides in various ratios [1]. Com-
bined filters have also received recognition. These
filters contain, in addition to catalysts, various sor-
bents and fibrous materials: glass fibers, carbon fibers
[2, 3], and polymeric materials used both as porous
supports and as active ozone-binding reagents [4 7].
Ozone is bound with various cyclic polymers: poly-
arene esters and sulfur-containing polymers [4], thio-
esters [5, 6], unsaturated polycycloolefins, and non-
bornene and its higher homologues: nonbornodiene
and dicyclopentadiene [5, 6]. An ozone-binding poly-
mer can be used in a combined filter as a powder,
grains, films, coatings, and finely fibrous materials.
An advantage of fibrous materials is their low hydro-
dynamic resistance, developed surface equally acces-
sible to ozone molecules, and room working tempera-
tures. At present, fibrous filtering materials are ef-
ficiently used to catch aerosol particles. Industrially
manufactured polymeric microfibrous materials, Pet-
ryanov filters (PF), are in common use [8, 9]. These
materials are readily available and inexpensive.
and gaseous impurities. So far, several brands of ma-
terials for catching of radioactive iodine and oxidation
of carbon monoxide have been developed and studies
are being performed to develop new sorption-filtration
materials [10 12]. It is of interest to find out whether
PF and other fibrous filtering materials can be used
to bind ozone. A separate issue is a search for ozone-
resistant filtering materials for air purification to re-
move aerosol impurities in the presence of high con-
centrations of ozone.
The aim of this study was to examine decomposi-
tion of ozone on microfibrous filtering materials of
various types in the context of the problems men-
tioned above. As objects of study served commercial
filtering materials and pilot materials synthesized at
the laboratory of aerosols at Karpov Research Phys-
icochemical Institute.
EXPERIMENTAL
Industrial Petryanov filters [FPA-15-2.0,1 FPP-70-
0.5 (EKhMZ, Elektrostal’, Moscow oblast); FPSAN-
70-0.5 (Esfil, Simolaye, Estonia)], pilot materials
(FPAN-10-3.0, FPF42-10-3.0, FPS-15), ultrathin glass
fibers, and carbonized microfibers were studied.
All the FP samples, except glass fibers, were fab-
ricated by electroforming [8, 9, 13]. Carbonized fi-
brous materials were produced by carbonization of
1
The first figure in the designation of a filter is the average
fiber diameter in tenths of a micrometer, and the second fig-
A topical task is to create fibrous filtering materials
for air purification to simultaneously remove aerosols
ure is the resistance to an air flow in millimeters of water
1
at a flow velocity of 1 cm s
.
630

A STUDY OF SORPTION AND DECOMPOSITION OF OZONE
Table 1. Parameters of the microfibrous filtering materials under study
631
Average fiber
Packing
density, %
Specific surface
Material
Composition
1
diameter,
m
area, m2 g
FPP-70-0.5
FPA-15-2.0
FPAN-10-3.0
FPF42-10-3.0
Chlorinated polyvinyl chloride
Cellulose diacetate
Polyacrylonitrile
Copolymer of tetrafluoroethylene with
vinylidene fluoride
5 7
1.4
1.0
1.0
2.5
2.5 3
3 4
0.7
1.3
Not measured
3 4
Glass fibers
Silicon, boron, aluminum, and calcium
oxides
0.2
5
FPSAN-70-0.5
FPS-15 (pilot sample)
Carbonized fibers
Copolymer of styrene wit acrylonitrile
Polystyrene
Carbon
5 7
1.5
2.0
2 4
3
4 5
0.67
1.83
1.56
microfibers composed of a phenol-formaldehyde resin
by iodometric titration, with optical UV spectroscopy
used in separate experiments.
[12]. The specific surface area of the samples was
determined by the BET method on the basis of ad-
sorption of krypton, using the standard procedure
[14]. Some parameters of the materials are listed in
Table 1.
The experimental setup used in the study is sche-
matically shown in Fig. 1. Electrolyzer 1 is made of
molybdenum glass. As electrolyte 2 serves a NaClO4
solution. Pt-electrode 3 serves as the anode, and
Ni-electrode 4, as the cathode. Ozone-containing ox-
ygen is liberated at the Pt-electrode, and hydrogen, at
the Ni-electrode. The anode and cathode spaces are
separated by ion-exchange membrane 5. To prevent
warming-up of the electrolyte, the electrolyzer is
cooled with tap water (jacket 6). Ozone-containing
oxygen is delivered from the electrolyzer into fluoro-
plastic tube 9 packed with the material under study,
passes optical cuvette 10, and comes to a flask with
a KI solution 11. The parts of the setup are connected
by fluoroplastic tubes. The loss of ozone on this ma-
The decomposition of ozone on microfibrous ma-
terials was studied using the flow-through method
[15]. A gas with a known content of ozone was passed
through a tube with a material under study. The change
in the content of ozone after passing the gas through
the tube was used to find the amount of bound ozone.
The initial mass of the samples under study was 0.2 g.
A tube with an inner diameter of 0.4 cm was densely
packed with the material, with a 5 7-cm-long layer
obtained. Ozone was produced by the electrolysis
method [16]. The concentration of ozone was found
Fig. 1. Schematic of the experimental setup. (1) Electrolyzer, (2) 6 N solution of NaClO electrolyte, (3) Pt-electrode,
4
(4) Ni-electrode, (5) MF4SK (perforated ion-exchange membrane), (6) jacket, (7) O + O (gas), (8) H (gas), (9) fluorio-
3
2
2
plastic tube with a material under study, (10) optical cuvette, (11) 0.05 N solution of KI, and (12) power unit.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 4 2008

632
KLIMUK et al.
The content of ozone in oxygen increases with
the current through the electrolyzer. The electrolyzer
can produce and ozone oxygen mixture containing
3
20.6 to 33.2 g m of ozone as the current strength
is varied from 296 to 550 mA. The corresponding
flow rate of the ozone oxygen mixture varies within
1
the range 1.22 2.27 ml min . The experiments were
performed at a current strength of 510 mA. In this
case, the flow rate of the ozone oxygen mixture was
1
2.0 0.1 ml min . The electrolyzer was calibrated by
measuring the amount of ozone absorbed by the KI
solution at the outlet of an empty fluoroplastic tube
of the same size as that with the material under study.
The amount of ozone absorbed at this current in
the course of 30 min in each of the several runs cor-
3
responded to an ozone concentration of 30 2 g m
or to a content of about 1.5 vol %. The error in deter-
mining the ozone concentration is due to a minor insta-
bility in the current through the electrolyzer at a sta-
bilized voltage across the electrodes. On absorbing
ozone, the KI solution became first yellow, and then
brown. In the course of the experiments, the solution
was titrated, with monitoring by changes in coloration.
Fig. 2. UV absorption spectrum of ozone produced by
electrolysis of a NaClO solution. (D) Optical density
4
and ( ) wavelength.
Figure 3 shows how the average concentration of
ozone (during sampling) at the tube outlet varies with
time. Straight line 1 shows the ozone concentration
at the outlet of an empty tube. It can be seen in Fig. 3
that, with FPSAN-70-0.5 (points 6) and FPS-15
(points 5) filters, there is no ozone at the tube outlet
for 6 7 h. For glass fibers (points 7) and FPF42-10-
3.0 (points 9) and FPAN-10-3.0 (points 4) filters,
the ozone concentration at the tube outlet is the same
as that in the case of an empty tube. For FPP-70-0.5
(points 2) and FPA-15-2.0 (points 3) filters and car-
bonized fibers (points 8), a noticeable concentration
of ozone is observed at the tube outlet, but this con-
centration is considerably lower than that observed
with an empty tube.
Fig. 3. Ozone concentration c after passing ozone-con-
taining oxygen trough the layer of a material vs. time
.
(1) Empty tube, (2) FPP-70-0.5, (3) FPA-15-2.0,
(4) FPAN-10-3.0, (5) FPS-15, (6) FPSAN-70-0.5, (7) glass
fibers, (8) carbonized fibers, and (9) FPF42-10-3.0.
On the basis of the data presented, all the materials
studied can be divided into three groups: (i) materials
inert toward ozone, on which the conversion of ozone
is lower than 10% during a whole day of operation;
(ii) active materials providing an ozone conversion
exceeding 90%; and materials with an intermediate ac-
tivity. On the materials of the third group the ozone
conversion decreases during the first hours of opera-
tion.
terial is insignificant because it has a small coefficient
of heterogeneous decomposition of ozone [1, 17].
The tubes used in the experiments were treated with
ozone for 1 h for passivation.
A UV spectrum of the ozone being formed, mea-
sured with a Perkin Elmer UV spectrometer in
the range 2000 4000 , is shown in Fig. 2. In this
spectral range, only the characteristic absorption band
The most active in ozone decomposition are poly-
styrene-containing materials: FPSAN-70-0.5 and
FPS-15. These materials were used in experiments
in which their activity was studied as a function of
the duration of treatment with ozone. The results
of seven successive runs with FPS-15 are shown in
of ozone, peaked at 2540
present. It also follows from Fig. 2 that no chlorine
dioxide (absorption band peaked at 3600 [18]) is
formed in electrolysis of the NaClO4 solution.
(Hartley band [18]), is
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 4 2008

A STUDY OF SORPTION AND DECOMPOSITION OF OZONE
Fig. 4. The experiments were carried out during
633
a working day, with intervals between the runs equal
to 12 to 48 h. It can be seen that, during the first three
runs, the filter bound the whole amount of ozone de-
livered to the filter. At the end of run no. 4, a mea-
surable ozone concentration appeared at the tube out-
let (curve 4). At the beginning of run no. 5, the ozone
conversion was about 100% during 4 h and decreased
to 80% by the end of the day (curve 5). A similar
behavior was also observed in the subsequent runs. By
the end of run no. 7, the conversion decreased to 50%.
Similar results were obtained with FPSAN-70-0.5
filter, but its activity decreased considerably faster
than that of FPS-15 filter, which may be due both
to the lower specific surface area of FPSAN-70-0.5
(Table 1) and to the presence of acrylonitrile inert
toward ozone in this filter. The results obtained dem-
onstrate that the activity of the polymer with respect
to ozone decomposition decreases (poisoning) both
irreversibly and reversibly. The irreversible poisoning
occurs via chemical reactions between a polymer and
ozone, with chemical bonds in the polymer ruptured
[15, 19]. The reversible poisoning may be due to for-
mation of intermediate oxygen-containing compounds
on the surface, which prevent adsorption of ozone.
In a break in operation, these compounds partly de-
compose.
Fig. 4. Ozone concentration c after FPS-15 filter vs. time .
Digits at points are run numbers.
Fig. 5. Ozone concentration c after a layer of carbonized
fibers vs. time . Digits at points are run numbers.
On the materials with an intermediate activity,
the ozone decomposition was studied in detail on car-
bonized microfibers of phenol-formaldehyde resin.
Four successive runs were made. Their results are
shown in Fig. 5. In run nos. 1 and 2, the conversion
decreased from 100 to 30% in 2 h of operation (curves
1, 2), but in run no. 2, the conversion gradually in-
creased to 50% in the following 4 h. After a break of
4 days in run no. 3, a strong increase in activity was
observed, so that the conversion was close to 100%
during 7 h and then decreased to 80% (curve 3).
The next day, such a decrease in conversion occurred
earlier (curve 4). Thus, a complicated variation of ac-
tivity was observed on carbonized fibers: under the ac-
tion of ozone, the material of the filter is first deac-
tivated and then activated. Possibly, the activation is
partly due to loosening of the carbonized filter under
the action of ozone and to an increase in its specific
surface area.
90% (inlet concentration 1.5%), with 0.15 g of ozone
decomposed. The concentration of ozone in air at
an MPC exceeded by an order of magnitude [19] is
5
4
10 %, i.e., a value four orders of magnitude
lower than that in the experiments performed in this
study. Under these conditions, the filter will provide
a high conversion during a virtually unlimited time.
This also refers to FPSAN-70-0.5 and FPA-15-2.0
filters.
Table 2. Experimentally observed efficiency of ozone
catching by the materials under study
Mass of ozone
bound by
Duration of
filter operation,*
h
Material
a sample,*
g
Table 2 summarizes the results obtained in a study
of the ozone treatment of microfibrous filtering ma-
terials with high and medium activity: data on the
amount of ozone bound by a filter until its conversion
decreases to below 90% and the corresponding dura-
tion of filter operation. A 0.2-g sample of FPS-15
filter worked for 40 h until the conversion reached
FPS-15
FPSAN-70-0.5
FPA-15-2.0
0.144
0.088
0.0066
0.0018
40
25
2
Carbonized fibers
18
*
At an ozone conversion exceeding 90%.
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634
KLIMUK et al.
rialy FP (FP Fibrous Filtering Materials), Moscow:
CONCLUSIONS
Znanie, 1968.
(1) Analysis of the ozone decomposition on com-
mercial and pilot filtering materials shows that filters
based on polystyrene (FPS-15, FPSAN-70-0.5) ex-
hibit a high activity in ozone binding; FPF42-10-3.0
and FPAN-10-3.0 filters and glass fibers are inert
toward ozone; FPP-70-0.5 and FPA-15-2.0 filters
and carbonized microfibers possess an intermediate
activity.
9. Filatov, Yu.N., Elektroformovanie voloknistykh mate-
rialov (EVF-protsess) [Electroforming of Fibrous
Materials (EVF Process), Moscow: Neft’ i gaz, 1997.
10. Basmanov, P.I., Kirichenko, V.N., Filatov, Yu.N.,
and Yurov, F.L., Vysokoeffektivnaya ochistka gazov
ot aerozolei fil’trami Petryanova (High-Efficiency
Purification of Gases To Remove Aerosols with
Petryanov Filters), Moscow: Nauka, 2003.
11. Koshcheev, A.P., Serzhantov, A.E., and Shepe-
lev, A.D., Tret’i Petryanovskie chteniya, 19 21
iyunya 2001 g., Trudy (Proc. of Third Petryanov
Readings, June 19 21, 2001), Moscow: RITs MGIU,
pp. 148 154.
(2) The activity of the polymeric filters decreases
under the action of ozone and is partly restored in
its absence. The activity of carbonized filters increases
upon treatment with ozone.
12. Budyka, A.K., Polevov, V.N., and Shepelev, A.D.,
Abstracts of Papers, Mezhdunarodnaya nauchno-prak-
ticheskaya konferentsiya Aerozoli i bezopasnost’
2005 , Obninsk, 24 28 oktyabrya 2005 g. (Int. Sci.-
Pract. Conf. Aerosols and Safety 2005, Obninsk,
October 24 28, 2005), Obninsk: FGOU GTsIPK,
2005.
13. Filatov, Yu., Electrospinning of Micro- and Nano-
fibers: Fundamentals and Applications in Separation
and Filtration Processes, Budyka, A. and Kirichen-
ko, V., Eds., New York: Begell House, 2007.
(3) Carbonized fibers show a complicated varia-
tion of activity in ozone binding.
ACKNOWLEDGMENTS
The authors are grateful to E.M. Kasatkin and
N.F. Potapova for the provided technique for produc-
tion and titration of ozone and for detailed consulta-
tions in the course of the study and to N.V. Kozlova
for measuring the UV absorption spectrum of ozone.
14. Braude, G.E., Semenova, T.A., and Markina, M.I.,
Khimiya i tekhnologiya azotnykh udobrenii, Vypusk 12
(Chemistry and Technology of Nitrogen Fertilizers,
Issue 12), Moscow: Goskhimizdat, 1961, pp. 67 75.
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aktsii s organicheskimi soedineniyami (kinetika i
mekhanizm) [Ozone and Its Reactions with Organic
Compounds (Kinetics and Mechanism)], Moscow:
Nauka, 1974.
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et al., Sensors, 2003, vol. 3, p. 504.
18. Okabe, H., Photochemistry of Small Molecules,
The study was financially supported by the Interna-
tional Scientific-Technological Center (grant no. 3288).
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