Radiation-induced degradation of diethylstilbestrol by electron beam irradiation

Article abstract of DOI:10.14233/ajchem.2013.12882

The degradation kinetics and primary radiolytic degradation mechanism of diethylstilbestrol by electron beam irradiation have been investigated. The results show that the electron beam irradiation is an effective method to reduce diethylstilbestrol. The degradation of diethylstilbestrol in acetonitrile/water oxidative system is higher than in methanol/water reductive system at the same absorbed dose. Furthermore, the study indicates that the decomposition rate increased with the addition of H2O2 to the solution. These illustrate hydroxyl radical (OH) might play a crucial role in degradation of diethylstilbestrol. The removal of diethylstilbestrol followed pseudo-first-order kinetic in acetonitrile/water solution and the kinetics rate constant decayed exponentially with increasing initial concentration of diethylstilbestrol. The degradation rate of diethylstilbestrol decreased with increasing absorbed dose in acetonitrile/water solution, which was illustrated by changes in specific reduction efficiency and increased with decreasing initial concentration at a constant absorbed dose. Different systems saturated with O2 or N2 did not lead to an effectively increase in the degradation of diethylstilbestrol. The solution in alkaline condition was benefit for the degradation of diethylstilbestrol. Organic acids produced by the degradation of diethylstilbestrol were identified using ion chromatography, such as acetic acid, formic acid and oxalic acid. Diethylstilbestrol radiolysis may be caused by that OH attacked diethylstilbestrol leading to the open of benzene ring and generation of organic acids.

Full text of DOI:10.14233/ajchem.2013.12882

Asian Journal of Chemistry; Vol. 25, No. 1 (2013), 191-196
http://dx.doi.org/10.14233/ajchem.2013.12882
Radiation-induced Degradation of Diethylstilbestrol by Electron Beam Irradiation
*
LIANG WANG, MINGHONG WU, GANG XU , NING LIU, LIANG TANG, TINGTING BU and JISAN ZHENG
School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P.R. China
*Corresponding author: E-mail: xugang@shu.edu.cn
(Received: 18 October 2011;
Accepted: 16 July 2012)
AJC-11846
The degradation kinetics and primary radiolytic degradation mechanism of diethylstilbestrol by electron beam irradiation have been
investigated. The results show that the electron beam irradiation is an effective method to reduce diethylstilbestrol. The degradation of
diethylstilbestrol in acetonitrile/water oxidative system is higher than in methanol/water reductive system at the same absorbed dose.
Furthermore, the study indicates that the decomposition rate increased with the addition of H2O2 to the solution. These illustrate hydroxyl
radical (·OH) might play a crucial role in degradation of diethylstilbestrol. The removal of diethylstilbestrol followed pseudo-first-order
kinetic in acetonitrile/water solution and the kinetics rate constant decayed exponentially with increasing initial concentration of diethyl-
stilbestrol. The degradation rate of diethylstilbestrol decreased with increasing absorbed dose in acetonitrile/water solution, which was
illustrated by changes in specific reduction efficiency and increased with decreasing initial concentration at a constant absorbed dose.
Different systems saturated with O2 or N2 did not lead to an effectively increase in the degradation of diethylstilbestrol. The solution in
alkaline condition was benefit for the degradation of diethylstilbestrol. Organic acids produced by the degradation of diethylstilbestrol
were identified using ion chromatography, such as acetic acid, formic acid and oxalic acid. Diethylstilbestrol radiolysis may be caused by
that ·OH attacked diethylstilbestrol leading to the open of benzene ring and generation of organic acids.
Key Words: Diethylstilbestrol, Degradation, Electron beam irradiation, Kinetics, Mechanism.
treatment. To resolve this problem, several advanced treatment
processes have been investigated5-7, most of which have
focused on photodegradation process. An investigation into
photocatalytic degradation of diethylstilbestrol published by
Zhou et al.5 showed the photooxidation efficiency of diethyl-
stilbestrol was higher at pH 3.50 0.05 and Fe(III)/oxalate
ratio 10.0/120.0 µmol L-1. Although photodegradation process
is a useful method for the decomposition of contaminants, it
has some obvious disadvantages, such as low efficiency and
long decomposition time. Other physicochemical methods
have also been reported for the degradation of diethylstilbestrol.
For example, Abderrazik et al.6 claimed the degradation rate
of diethylstilbestrol by ultrasound irradiation was significantly
increased with the addition of Fe(II) catalyst. However, physi-
cochemical methods have obvious disadvantages such as high
cost and additional pollution.
INTRODUCTION
In recent years, the increased occurrence of endocrine
disrupting chemicals (EDCs) in the environment has become
a serious social problem. Among compounds associated with
endocrine disruption, diethylstilbestrol (DES) occupied a
prominent place. Diethylstilbestrol was the first synthetic
non-steroid estrogen drug. It was used to prevent from sponta-
neous abortions by millions of pregnant women from 1940 to
1970 in most of countries. However, the use of diethylstilbestrol
for this purpose was banned due to its human carcinogenicity
issues1,2. Compared with natural estrogen, diethylstilbestrol
was more stable and remained longer time in body3 and has
been increasing concerned due to its potential impact on
humans and wildlife.
Although the use of diethylstilbestrol has been banned
for years in the world, it is still illegally used sometimes for
increasing the weight gain of cattle, sheep and fish. Diethyl-
stilbestrol has been encountered in some areas. For example,
Solé et al.4 reported the concentration of diethylstilbestrol were
34 ng L-1 in the effluent and 43 ng L-1 in the influent from
sewage treatment plants in the Catalonian area (N.E. Spain).
Because of the stability and toxicity of diethylstilbestrol,
its wastewaters are resistant to the conventional biological
Radiation processes are classified as advanced oxidation
processes (AOPs), which apply on the decomposition of persis-
tent organic pollutants using electron beam (EB) or γ-radiation.
Compared with other methods, electron beam radiation has
advantages for degrading refractory organic pollutants, such
as high efficiency, short decomposition time and no secondary
pollution. A number of reports have been appeared on the
radiation8-14. An investigation into hexachlorobenzene

192 Wang et al.
Asian J. Chem.
degradation by electron beam radiation showed that the
removal efficiency was 90.2 % with pH 11.8 solution of
acetone/water mixture (20/80, v/v) at 10 kGy15. PCP was
completely decomposed when a 10 kGy absorbed dose was
used together with 20 µM Fe (III)-EDTA or less 1 mmol of
H2O216. However, to the best of our knowledge, no information
is available for diethylstilbestrol degradation with electron
beam radiation.
stilbestrol before and after electron beam irradiation. The
injection volume was 10 µL. The mobile phase was a mixture
of acetonitrile and Milli-Q water (50/50, v/v), with a flow rate
of 1.0 mL min-1. The column temperature was maintained
at 298 K and the wavelength for UV detection was set at
230 nm.
The organic acids, the diethylstilbestrol decomposition
products of the irradiated samples, were analyzed using an
ion chromatograph (IC-Metrohm MIC advanced) with a
METROSEP A SUPP 5-250 (5 mm particle size, 250 mm ×
4 mm) column. The eluent was 3.2 mM Na2CO3 and 1.0 mM
NaHCO3 at a flow rate of 0.7 mL min-1. The injection volume
of the sample was 10 µL.
In this work, radiation induced degradation of diethyl-
stilbestrol under various conditions has been investigated.
Several factors that can influence the degradation efficiency
of diethylstilbestrol were evaluated, such as in oxidation-
reduction conditions, changing the initial concentration of
diethylstilbestrol, adding H2O2, saturating with different gases
and adjusting the pH of the solution. In addition, the degra-
dation products of diethylstilbestrol were analyzed using ion
chromatography. A possible degradation mechanism for the
radiolytic degradation of diethylstilbestrol is also proposed.
The results provided here may be acknowledged with purpose
on providing scientific and technical support of degradation
diethylstilbestrol by electron beam irradiation.
RESULTS AND DISCUSSION
Irradiation of diethylstilbestrol in reductive and oxi-
dative conditions: During electron beam irradiation, water
radiolysis happened within a short time. The radiation tech-
nology used reactive species such as hydrogen atoms (Hˆ),
–
hydrated electrons (eaq ) and hydroxyl radicals (·OH) as well
as less reactive species, such as H2O2, H2 and H3O+, produced
by water radiolysis (eqn. 1) for the decomposition of toxic or
refractory organic compounds, were formed11:
EXPERIMENTAL
Diethylstilbestrol, potassium hydroxide, sodium carbonate
and sodium bicarbonate were purchased from acros organics
(Geel, Belgium) (> 99 % purity). Methanol and acetonitrile of
HPLC grade were acquired from CNW (Düsseldorf, Germany).
30 % H2O2 and perchloric acid (HClO4) were obtained from
Shanghai Chemical Reagent Co. Ltd., which were the highest
purity commercially available. Distilled and deionized water
were produced using a Milli-Q system (R > 18.1 MΩ cm).
Sample preparation: Different solutions containing
diethylstilbestrol were prepared by dissolving diethylstilbestrol
in methanol/water solution (55/45, v/v) and acetonitrile/water
solution (35/65, v/v). Different additives of different concen-
trations were added to the solution of acetonitrile/water
mixture to determine their effect on the degradation of diethyl-
stilbestrol. The pH of the acetonitrile/water solutions was
adjusted by KOH and HClO4. All operations were performed
at ambient temperature.
H2O ~~~~→ (2.7) ˆOH + (2.6) eaq– + (0.55) Hˆ + (0.45) H2
+ (0.7) H2O2 + (2.6) H3O+
(1)
In acetonitrile/water solution, acetonitrile scavenges a
large amount of eaq– and ˆOH is the main reactive species of
diethylstilbestrol decomposition in acetonitrile/water solution:
•
•
ea−q + CH3CN → CH3CH N (or CH3 CNH) + OH−
(2)
In methanol/water solution, ·OH is easily scavenged by
methanol and eaq– is the main reactive specie of diethylstilbestrol
degradation:
•
(3)
CH3CN+⋅OH → CH2OH +H2O
In acetonitrile/water solution, ·OH is the main reactive
species, but the reaction rate of ·OH with acetonitrile is lower
than that of ·OH with other organic pollutants10. Accordingly,
in irradiation of methanol/water solution, the reductive reactions
prevail, while oxidative reactions dominate in irradiating
acetonitrile/water solution.
Irradiation experiments: All irradiation experiments for
the decomposition of diethylstilbestrol were conducted using
an electron accelerator (GJ-2-II accelerator, Xianfeng electrical
plant) belonging to the Institute ofApplied Radiation, Shanghai
University, China. The electron beam energy was 1.8 MeV
and the variable current power was in the range 0-10 mA. The
solutions of diethylstilbestrol were irradiated by transmitting
radiation at a distance of 30 cm from the source. The volume
and thickness of the solutions of diethylstilbestrol in film bag
were 10 mL and 2 mm, respectively. The experiments were
carried with an electron beam current of 1 mA. Samples were
irradiated at absorbed doses ranging from 2 to 50 kGy. Before
analysis, all samples were filtered through 0.45 µm syringe
micro filters.
The effect of different solutions on the degradation of
diethylstilbestrol by electron beam irradiation is shown in
Fig. 1. The results indicate the system could affect the degra-
dation of diethylstilbestrol. The degradation rate in reduction
methanol/water solution is lower than that in the solution of
oxidation acetonitrile/water at the same absorbed dose. For
example, at an absorbed dose of 30 kGy and an initial concen-
tration of 10 mg L-1, the degradation efficiency of diethylstilbestrol
in acetonitrile/water solution was 89.8 %, but only 57.3 % in
methanol/water solution (Fig. 1). Furthermore, it was removed
more rapidly by electron beam radiation as the absorbed dose
increased in acetonitrile/water solution than in methanol/
water solution. These results illustrate that ·OH plays a crucial
role in decomposition of diethylstilbestrol, as reported in Zhang
et al.17 for radiolysis decomposition of CaLS in aqueous
solution. Because of the higher degradation rate in the aceto-
nitrile/water solution, we used it for further investigations.
Analytical methods: A HPLC system (Agilent, USA,
1200 Series high-performance liquid chromatography)
equipped with a XDB-C18 reverse phase column (150 mm ×
4.6 mm2) was used for quantitative determination of diethyl-

Vol. 25, No. 1 (2013)
Radiation-induced Degradation of Diethylstilbestrol by Electron Beam Irradiation 193
It shows that diethylstilbestrol in acetonitrile/water solution
can be efficiently decomposed by electron beam irradiation.
The required absorbed doses to remove 100 % of diethylstil-
bestrol in acetonitrile/water solution were 15, 30 and 50 kGy
at the initial concentration of 2, 5 and 10 mg L-1, respectively.
Even at the higher concentrations of 30 and 100 mg L-1, the
concentration of diethylstilbestrol decreased by more than
90 % when 50 kGy was applied. The results indicate degrada-
tion depends on the initial concentration of diethylstilbestrol
100
80
60
40
20
0
Acetonitrile/water solution
Methanol/water solution
and better decomposition can be achieved with low initial concen-
trations and high applied absorbed doses. It was obvious at
higher concentration of diethylstilbestrol, degradation was
somewhat slower, but the absolute sum of diethylstilbestrol
degradation was higher. Furthermore, with the decrement of
the diethylstilbestrol concentrations, the absorbed dose need
for complete degradation decreased.
0
10
20
30
40
50
Dose (kGy)
Fig. 1. Radiolysis of diethylstilbestrol (10 mg L-1) in different solutions
Kinetics of diethylstilbestrol in acetonitrile/water
solution under electron beam irradiation: The decompo-
sition efficiency of diethylstilbestrol was different from per
unit absorbed dose. The specific reduction efficiency (G) could
be used to express this phenomenon (eqn.4), which was defined
by Zhang et al.15,18 and Mohamed et al.19.
(a)
2
mg
mg
·
·
L-1
L-1
80
40
5
10mg
30mg
100mg
·
L-1
L-1
L-1
·
·
0
3
(b)
∆RNA
D(6.24×1017 )
2
1
0
G =
(4)
where, ∆R is the change in diethylstilbestrol concentration (mol
L-1) at a given absorbed dose, D is the absorbed dose in kGy,
6.24 × 1017 is the conversion constant from kGy to 100 eVL-1
and NA is Avogadro's constant (6.02 × 1023).
0
10
20
30
40
50
Dose (kGy)
0.10
0.08
0.06
(c)
According to eqn. (4), the G values of diethylstilbestrol
in acetonitrile/water solution are shown in Fig. 2. The results
show that G values decreased with increasing absorbed dose,
which is due to the relative concentration of active radicals
being lower at higher absorbed doses20.
0
20
40
60
80
100
Initial concentration (mg· L-1)
Fig. 3. Degradation of diethylstilbestrol for different initial concentrations:
(a) Degradation rate vs. absorbed dose; (b) -ln(C/C0) vs. absorbed
dose; and (c) Pseudo-first-order rate constant k vs. initial
concentration
400
300
200
100
0
A modified pseudo-first-order reaction kinetic model
(eqns. 5 and 6) could be applied expediently to compare the
decomposition rates at various conditions21-23, which can be
expressed as:
CD = C0e−kD
(5)
ln CD = ln C0 − kD
(6)
where, C0 is the initial concentration of diethylstilbestrol (mg
L-1) and CD is the residual concentration of diethylstilbestrol
(mg L-1) at the absorbed dose (D) (kGy), k is the pseudo-first-
order kinetic constant (kGy-1).
0
10
20
30
40
50
Dose (kGy)
Fig. 2. Relationship between specific reduction efficiency (G) and dose of
electron beam radiation for diethylstilbestrol in acetonitrile/water
solution
At initial concentrations of diethylstilbestrol ranging from
2 to 100 mg L-1, all the reactions follow pseudo-first-order
kinetic (R > 0.99) (Fig. 3b). The results illustrate an excellent
agreement with the modified pseudo-first-order reaction
mechanism (eqn. 5 and 6).
Both initial concentration and absorbed dose of diethyl-
stilbestrol are important parameters that effect the radiolytic
degradation of diethylstilbestrol. Acetonitrile/water solutions
having initial concentrations of 2, 5, 10, 30, 100 mg L-1 were
irradiated by 3, 5, 7, 10, 15, 20, 30, 50 kGy electron beam
radiation at room temperature. The influences of these two
factors on diethylstilbestrol degradation are shown in Fig. 3(a).
It is obvious the differences of the pseudo-first-order rate
constants (k) among various initial concentrations are statistically
significant. The k values decrease exponentially with the increment
of initial concentrations. An increment of initial concentration
finally leads to a decrement in k, as shown in Fig. 3(c).

194 Wang et al.
Asian J. Chem.
Effect of H2O2 on the degradation of diethylstilbestrol:
100
80
60
40
20
0
It is well known that H2O2 is an efficient oxidation agent, which
is widely used in wastewater treatment. As shown in Fig. 4(a)
and (b), when the initial concentrations of H2O2 were in the
range of 0-9.8 × 10-2 mmol L-1, removal of diethylstilbestrol
was more effective at a higher initial concentration of H2O2
than at a lower H2O2 level or in pure solvent. For example, the
degradation efficiency of diethylstilbestrol at the absorbed dose
of 15 kGy was 67.4, 79.5 and 87.7 % for H2O2 concentrations
of 0, 9.8 × 10-4 and 9.8 × 10-2 mmol L-1, respectively. The
removal of diethylstilbestrol with adding H2O2 followed pseudo-
first-order kinetic. The kinetic constant k as a function of the
addition of H2O2 decreased in the order of 9.8 × 10-2 mmol L-1 >
9.8 × 10-4 mmol L-1 > 0 mmol L-1. The highest k value reached
0.1386 kGy-1 by adding 9.8 × 10-2 mmol L-1 H2O2 while the
lowest k value was 0.0749 kGy-1 observed without H2O2.
Similar results were discovered in the decomposition of chloro-
phenols21 and dyes24 under irradiation. This can be attributed
O
2
N
2
Air
0
10
20
30
40
50
Dose (kGy)
Fig. 5. Degradation efficiencies of diethylstilbestrol saturated with different
gases
–
to H2O2 reacting with eaq . The degradation mechanisms of
H2O2 are described the reaction25,26 as follows:
91.22, 86.9 and 89.8 % saturated with N2, O2 and air at an
absorbed dose of 30 kGy respectively. It indicated that different
systems saturated with O2 or N2 did not lead to effective incre-
ment of diethylstilbestrol degradation.
H2O2 + eaq– → ˆOH + OH–
(7)
In oxidizing conditions, ·OH was the main reactive species
that degrade diethylstilbestrol in acetonitrile/water solution,
eaq– is scavenged by H2O2 and acetonitrile (eqn. 7 and 2) and
the ·OH radicals are produced (eqn. 7).As a result, the amounts
of ·OH are much larger during electron beam irradiation in
the presence of H2O2 than in the absence of H2O2. This claimed
that ·OH played an important role in degradation of diethyl-
stilbestrol.
Effect of initial pH on diethylstilbestrol degradation:
The initial pH value is an important parameter that might
affect the decomposition efficiency of diethylstilbestrol during
radiolysis. The initial pH values of the diethylstilbestrol solu-
tions were adjusted to 3, 6.27 and 11 by HClO4 and KOH. The
diethylstilbestrol degradation efficiency by electron beam
irradiation with different initial pH values are shown in Fig. 6.
Removal of diethylstilbestrol was generally more effective
under acidic or alkaline conditions than under neutral conditions.
For example, at pH 6.27, a reduction of 78.8 % was achieved
at 20 kGy, while at the same absorbed dose, the degradation
efficiency at pH 11 and 3 were 88.6 and 81.6 %, respectively.
It is known that, the H+ can scavenge a large amount of eaq
and generate Hˆ (with rate constant of 2.3 × 1010 L mol S-1)15,18
so the H+ and acetonitrile (eqn. 2) can scavenge a large amount
of eaq– in acetonitrile/water solution and the ·OH is the main
reactive specie in the degradation of diethylstilbestrol. As a
result, acidic and alkaline conditions could prevent the reaction
of eaq– with other matters, which can promote the reaction of
H2O2 = 9.8× 10-2 mol· L-1
0.9
H O = 9.8× 10-4 mol· L-1
2
2
0.6
0.3
H O = 0 mol· L-1
2
2
–
(a)
,
0.0
0
k = 0.1386 kGy-1 R = 0.9911
k = 0.1065 kGy-1 R = 0.9908
k = 0.0749 kGy-1 R = 0.9987
-1
-2
-3
(b)
100
80
0
10
20
30
40
50
Dose (kGy)
Fig. 4. Effect of H2O2 on diethylstilbestrol degradation in acetonitrile/water
solution: (a) C/C0 vs. absorbed dose; and (b) ln(C/C0) vs. absorbed
dose
60
Effect of saturation with different gases on decompo-
sition of diethylstilbestrol: In order to investigate the effect
of saturation with different gases on decomposition of diethyl-
stilbestrol, new degradation systems were established under
N2, O2 and air -saturated conditions. Decomposition curves of
diethylstilbestrol by electron beam irradiation under N2, O2
and air -saturated conditions are shown in Fig. 5. From the
results obtained in Fig. 5, decomposition of diethylstilbestrol
under these saturated conditions was slightly changed. For
instance, the degradation rate of diethylstilbestrol reached
40
pH = 3
pH = 11
pH = 6.27
20
0
0
10
20
30
40
50
Dose (kGy)
Fig. 6. Decomposition of diethylstilbestrol in different pH solutions

Vol. 25, No. 1 (2013)
Radiation-induced Degradation of Diethylstilbestrol by Electron Beam Irradiation 195
O
OH
·OH with diethylstilbestrol. Therefore, the degradation effi-
ciency of diethylstilbestrol is dependent on the initial pH values
of the solution.
OH
[8]
HO
HO
Analysis of organic products in the diethylstilbestrol
degradation process: When a new treatment process is being
concerned, not only for the removal of the target compound
but also for the products formed in the degradation process.
In our investigation, several organic acids produced by the
degradation of diethylstilbestrol were identified using ion
chromato-graphy. Fig. 7 shows the continuous accumulation
of short-chain organic acids in the degradation process of
diethylstilbestrol.
DES
[6]
OH
HOOC-COOH
[O]
(main)
CH3COOH
HCOOH
O
ring cleavage
[6]
[8]
HO
dimers and oligomers
polymerization
Fig. 8. Supposed degradation mechanisms of diethylstilbestrol
40
Oxalic acid
Formic acid
30
might undergo benzene ring cleavage to produce short-chain
organic acids identified using ion chromatography and might
cause polymerization to produce dimers and oligomers5.
Acetic acid
20
10
Conclusion
The investigation of diethylstilbestrol degradation induced
by electron beam irradiation demonstrated electron beam
irradiation was a promising method to reduce diethylstilbestrol.
The degradation rate in acetonitrile/water oxidation solution
was higher than in methanol/water reduction solution at a same
absorbed dose. This indicated that ·OH might play an important
role in degradation of diethylstilbestrol. The removal of
diethylstilbestrol followed pseudo-first-order kinetic in aceto-
nitrile/water solution and the kinetics rate constant decayed
exponentially with the increment of initial concentrations of
diethylstilbestrol. The degradation rate of diethylstilbestrol
decreased with increasing absorbed dose in acetonitrile/water
solution, which was illustrated by changes in specific reduction
efficiency and increased with decreasing initial concentration
at a constant absorbed dose. H2O2 could increase the decom-
position rates of diethylstilbestrol in acetonitrile/water solution
0.16
0.12
0.08
0.04
0.00
0
10
20
30
40
50
Dose (kGy)
Fig. 7. Concentrations of organic acids at different absorbed doses
Ion chromatography analysis (Fig. 7) shows that, the main
degradation product of diethylstilbestrol was acetic acid, which
was produced immediately after irradiation and increases with
increased absorbed dose. In addition, trace levels of formic
acid and oxalic acid were also detected at the same absorbed
dose. In the degradation process of diethylstilbestrol, the
concentration of acetic acid continuously increased up to 40.8
mg L-1 when 50 kGy was applied. In contrast, the concentra-
tion of formic acid increased slightly and maintained a steady
value of about 2.8 mg L-1 while the absorbed dose were ranged
from 15 to 50 kGy. Much more acetic acid was accumulated
than formic acid and oxalic acid in the degradation process of
diethylstilbestrol, which was probably due to acetic acid was
attacked poorly by ·OH. The results are in harmony with the
previous work5.
–
due to addition of H2O2 scavenging eaq and generate ·OH.
These characteristics also proved that ·OH played a crucial
role in decomposition of diethylstilbestrol. Different systems
saturated with O2 or N2 did not lead to an effectively increase
in the degradation of diethylstilbestrol. Degradation rate of
diethylstilbestrol increased in alkaline condition. Organic acid
such as acetic acid, formic acid and oxalic acid produced by
degradation of diethylstilbestrol were identified using ion
chromatography. By reviewing all the results, the diethylstil-
bestrol radiolysis may be caused by the mechanism that ·OH
attacked diethylstilbestrol molecules leading to the benzene
ring opening and formation of organic acids under electron
beam irradiation.
Supposed degradation mechanism of diethylstilbestrol:
Hydroxyl radical causes damage of the phenolic compounds
through electron transfer; hydrogen abstraction and ·OH
adduct7 and short-chain organic acids such as acetic acid,
formic acid and oxalic acid were generated in the diethyl-
stilbestrol degradation process. Considering all of the results
and discussions above and the literatures related to the oxida-
tion mechanisms of phenols27,28, the mechanism given below
has been proposed for the electron beam decomposition of
diethylstilbestrol (Fig. 8). The hydroxyl radicals produced by
the electron beam irradiation attacked the diethylstilbestrol
molecule in the 4-position. The oxidation of diethylstilbestrol
ACKNOWLEDGEMENTS
This work has been supported by National Natural Science
Foundation of China (No. 11025526, 40973073, 40830744,
11175112), National Key Technology R and D Program in
the 11th Five year Plan of China (No. 2009BAA24B04) and
Shanghai LeadingAcademic Discipline Project (No. S30109),
which were gratefully acknowledged.

196 Wang et al.
Asian J. Chem.
13. N.J. Drenzek, M.C. Nyman, N.L. Clesceri, R.C. Block and J.A. Stenken,
Chemosphere, 54, 387 (2004).
REFERENCES
14. C.L. Duarte, L.L. Geraldo, O. de Aquino, S.I. Borrely, I.M. Sato and
M.H.D.O. Sampa, Radiat. Phys. Chem., 71, 445 (2004).
15. J.B. Zhang, Z. Zheng, J.F. Luan, G.J. Yang, W.H. Song, Y. Zhong and
Z.C. Xie, J. Hazard. Mater., 142, 431 (2007).
1. W.J. Zhao, Z.F. Shi, F. Yuan, G.L. Li, Y.L. Sun, Y.Z. Zhang and Z.C.
Wang, Folia Histochem. Cytobiol., 48, 278 (2010).
2. E.J. O'Reilly, F. Mirzaei, M.R. Forman and A. Ascherio, Am. J.
Epidemiol., 171, 876 (2010).
16. B.G. Kwon, E. Kim and J.H. Lee, Chemosphere, 74, 1335 (2009).
17. S.J. Zhang, H.Q. Yu and L.X. Wu, Chemosphere, 57, 1181 (2004).
18. J.B. Zhang, Z. Zheng, T. Zhao, Y.F. Zhao, L.H. Wang, Y. Zhong and Y.
Xu, J. Hazard. Mater., 151, 465 (2008).
3. J.L. Zhao, G.G. Ying, L. Wang, J.F. Yang, X.B. Yang, L.H. Yang and X.
Li, Sci. Total Environ., 407, 962 (2009).
4. M. Sole, M.J.L. de Alda, M. Castillo, C. Porte, K. Ladegaard-Pedersen
and D. Barcelo, Environ. Sci. Technol., 34, 5076 (2000).
5. D. Zhou, F. Wu and N.S. Deng, Chemosphere, 57, 283 (2004).
6. N. Ben Abderrazik, A. Azmani, C. R'kiek, W.H. Song and K.E. O'Shea,
Catal. Today, 101, 369 (2005).
19. K.A. Mohamed, A.A. Basfar, H.A. Al-Kahtani and K.S. Al-Hamad,
Radiat. Phys. Chem., 78, 994 (2009).
20. M.H. Wu and B.R. Bao, Radiation Technology in Environmental Pro-
tection Applications, Chemical Industry Press. Publications, Beijing
(2002).
7. D.Y. Dou, Y.B. Liu, H.W. Zhao, L. Kong and S.D. Yao, J. Photochem.
Photobiol. A Chem., 171, 209 (2005).
21. J. Hu and J.L. Wang, Radiat. Phys. Chem., 76, 1489 (2007).
22. J. Xue and J.L. Wang, J. Environ. Sci. China., 20, 1153 (2008).
23. T.K. Lau, W. Chu and N. Graham, Chemosphere, 60, 1045 (2005).
24. M. Wang, R.Y. Yang, W.F. Wang, Z.Q. Shen, S.W. Bian and Z.Y. Zhu,
Radiat. Phys. Chem., 75, 286 (2006).
8. J.X. Zhou, M.H. Wu, G. Xu, J. Ma, L. Wang and N. Liu, Nucl. Sci.
Tech., 21, 334 (2010).
9. M.H. Wu, N. Liu, G. Xu, J. Ma, L. Tang, L. Wang and H.Y. Fu, Radiat.
Phys. Chem., 80, 420 (2011).
10. L. Tang, G. Xu, W.J. Wu, W.Y. Shi, N. Liu, Y.L. Bai and M.H. Wu, Nucl.
Sci. Tech., 21, 72 (2010).
25. E. Evgenidou, E. Bizani, C. Christophoridis and K. Fytianos, Chemosphere,
68, 1877 (2007).
11. Y.P. Chen, S.Y. Liu, H.Q. Yu, H. Yin and Q.R. Li, Chemosphere, 72,
532 (2008).
26. K.A. Halhouli, J. Photochem. Photobiol. A. Chem., 200, 421 (2008).
27. S.M. Khopde and K.I. Priyadarsini, Biophys. Chem., 88, 103 (2000).
28. S.Q. Yu, J. Hu and J.L. Wang, J. Hazard. Mater., 177, 1061 (2010).
12. F. Unob, A. Hagege, D. Lakkis and M. Leroy, Water Res., 37, 2113
(2003).