Research Article, Issue 4
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
------------------------
1. Introduction
One of the most important issues facing human
beings today and even endangering their health is
air pollution. Volatile organic compounds (VOCs)
are one of the most important pollutants, and
these compounds are listed as toxic [1, 2]. Global
warming, ozone depletion, photochemical smog,
and contributor of haze is the effect of this material
[3, 4]. The boiling point range of volatile organic
compounds is from 50 to 250 °C and because of
high vapor pressure creates a notable amount of the
molecules to evaporate and release in the air [5, 6].
Their health effects on humans are very important,
these compounds can irritate the respiratory system
and eyes, cause headaches and nausea, damage the
kidneys, liver, the central nervous system and even
in chronic exposure cause cancer [7-10]. Some of
the major industries producing volatile organic
compounds include petroleum refineries, chemical
industries, automotive industries, paint industry,
pharmaceuticals, cable and wire industries,
printing, aerospace, textile, etc. [1, 11]. BTEX
(Benzene, toluene, ethylbenzene, and xylene) are
the most common VOCs and usually used in the
Maling Gou
a,b
and Baharak Bahrami Yarahmadi
c,
*
a
State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu
610041, China
b
Department of Thoracic Oncology, Cancer Center, West China Hospital, Medical School, Sichuan University, Chengdu 610041, China
C,*
Occupational Health Engineering Department, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran
Removal of ethylbenzene from air by graphene quantum dots
and multi wall carbon nanotubes in present of UV radiation
*Corresponding Author: Baharak Bahrami Yarahmadi
Email: baharakb72@gmail.com
DOI: https://doi.org/10.24200/amecj.v2.i01.44
A R T I C L E I N F O:
Received 12 Sep 2019
Revised form 15 Nov 2019
Accepted 5 Dec 2019
Available online 28 Dec 2019
Keywords:
Graphene quantum dots,
Multi wall carbon nanotubes,
Ethylbenzene,
Air removal,
UV-radiation,
Solid gas removal
A B S T R A C T
Luminescent graphene quantum dots (GQDs) and multi wall carbon
nanotubes (MWCNTs) as photocatalytic sorbent based on was used for
removal of toxic ethylbenzene from air in present of UV-radiation. A novel
method based on solid gas removal (SGR) based on GQDs and MWCNTs
as an efficient adsorbent was used for ethylbenzene removal from air in
Robson quartz tubes (RGT). After synthesized and purified of GQDs and
MWCNTs, a system was designed for generation of ethylbenzene in air
with difference concentrations, and then the mixture was moved to quartz
tubes with UV radiation in optimized conditions. The ethylbenzene in
air was absorbed on the 25 mg of GQDs or MWCNTs, desorbed from
sorbent at 146
o
C and determined by GC-FID. The main parameters such
as, temperature, ethylbenzene concentration, amount of GQDs / MWCNTs
and flow rate were studied and optimized. The recovery of ethylbenzene
removal from air (more than 95%) and absorption capacity of adsorbent
(186.4 mg g
-1
) were achieved in present of UV radiation at room temperature
by GQDs. The flow rate and temperature were obtained at 300 mL min
-1
and less than 42
0
C, respectively. Based on results, the special surface area
and favorite porosity of GQDs caused to efficient removal of ethylbenzene
from air in present of UV as compared to other carbon compounds such as
MWCNTs, and graphene.
Removal of ethylbenzene from air Baharak Bahrami Yarahmadi et al
Analytical Methods in Environmental Chemistry Journal Vol 2 (2019) 59-70
60
Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)
petrochemical industry and as reagents for the
synthesis of multiple C-based products [11-13].
Among BTEX, ethylbenzene is mainly used in the
manufacture of styrene. The release of Ethylbenzene
into the air could be carcinogenic, cause secondary
aerosol and photochemical smog. Ethylbenzene is a
colorless liquid that smells like gasoline. The odor
threshold for ethylbenzene is 2.3 parts per million
(ppm). The chemical formula for ethylbenzene is
C
8
H
10
, and the molecular weight is 106.16 g mol
-1
.
The vapor pressure for ethylbenzene is 9.53
mm Hg at 25 °C, and its octanol/water partition
coefficient is 3.13. In petrochemical factories,
BTEX and mercury vapor released in air and can be
absorbed in humans via the inhalation and dermal
routes of exposure. So determination BTEX and
mercury in air, water and human matrixes is very
important [14-17]. Previous study reported the
carcinogenic effects of ethylbenzene in humans.
EPA has classified ethylbenzene as a Group D, not
classifiable as to human carcinogenicity. ACGIH
recommends a TLV-TWA of 100 ppm and STEL/C
of 125 ppm for ethylbenzene based on irritation
and central nervous system effects [18-20]. Acute
(short-term) exposure to ethylbenzene in humans
results in respiratory effects, such as throat irritation
and chest constriction, irritation of the eyes, and
neurological effects such as dizziness. Chronic
(long-term) exposure to ethylbenzene by inhalation
in humans has shown conflicting results regarding
its effects on the blood. Animal studies have
reported effects on the blood, liver, and kidneys from
chronic inhalation exposure to ethylbenzene [21-
23]. There are many successful techniques which
have been developed and applied to control the
VOCs emission, such as condensation, membrane,
absorption, adsorption, thermal combustion,
catalytic, photocatalytic oxidation, non-thermal
plasma, and biofiltration [24-27]. Photocatalytic
oxidation (PCO) as the most current generation
of air cleaning technology has a magnificent
potential to eliminate vaporous pollutants even at
low concentrations [28]. Exceptional features of
this method are operating at ambient temperature
without notable energy supply, environmentally
friendly final products (CO
2
and H
2
O), and
applicable for various pollutants [29]. PCO
implemented using photocatalyst, ultraviolet (UV)
light and oxygen to decay chemical pollutants[30].
Numerous researchers have reviewed the materials
for the removal of VOCs [27, 31]. Most sources
have been reviewed based on a particular kind
of material, such as TiO
2
[32], graphene-based
materials [33], zinc indium sulfide [34] and silica-
nanosphere-based materials, etc., or concentrating
on the catalytic oxidation processes in a specific
condition such as low-temperature, visible light,
or based on a review of the aspect of different
VOCs[35].
In this study, a novel analytical method based
on UV- GQDs or UV-MWCNTs was used for
ethylbenzene removal from air by SGR technology.
All of important parameter for photocatalytic
process were optimized and the results validated
by spiking standard concentration of ethylbenzene
to real samples. The mixture of ethylbenzene vapor
in air was generated and storage in polyethylene
bags and its concentration determined by GC-
MS before moved to quartz tubes. The removal
efficiencies were calculated in UV- GQDs, GQDs
and MWCNT
S
by SGR procedure.
2. Experimental
2.1. Gas Chromatography (GC-FID)
The gas chromatography with flame ionization
detector (GC-FID) based on air sample loop
injection was used for ethylbenzene determination
in gas phase (Agilent GC, 7890A, FID, Netherland).
Before injection to GC-FID, Slide the plunger
carrier down and tighten. An air sample introduced
into the carrier gas by sampling valves which was
used to sample gases or liquids. Air sampling
bags were used by valve and septum port (Tedlar,
Germany). GC with a split injector (200
o
C), flame
ionization detector (250°C), and a column with
methylsiloxane was used. The oven temperature
was adjusted from 25°C to 250°C which was held
for 15 min. The carrier gas of hydrogen with flow
rate of 1.2 mL min
-1
–1
were tuned. For batch system,
the vials (PTFE) with air-tight cap (parker) were
61
Removal of ethylbenzene from air Baharak Bahrami Yarahmadi et al
prepared. TGS 2180 (China) and Dräger 3500
(Lübeck, Germany) as gas detectors was used for
determination of H
2
O vapor and O
2
in air. The
ethylbenzene was evaporated and mixed with
purified air at 135
o
C in chamber.
2.2. Reagents
The ultra-pure chemicals were purchased from
Merck and Sigma Aldrich (Germany). The
Deionized Distilled water (DDW) was prepared
by (Millipore, CAS 7732-18-5). The standard
of ethylbenzene (C₆H₅C₂H₅) was generated
with ultra-pure air in chamber. The accuracy and
precision of the pilot was investigated by injecting
a concentration of ethylbenzene in chamber and
determination of ethylbenzene in air bags by
GC-MS before moved to RGT which was filled
with GQDs or MWCNTs. The high purity of
ethylbenzene was purchased from Merck (CAS
N: 100-41-4, EC N: 202-849-4, Germany) and the
calibration solutions of 0.1, 0.2, 0.5, 1.0, 1.5 and 2.0
% (v/v) were prepared. The GQDs and MWCNTs
were synthesized by RIPI.
2.3. Pilot of gas generation
By pilot design, the purified air was prepared
based on HEPA filter and activated carbon (HEPA-
AC) with electro air cleaner (EAC, Canada). The
HEPA-AC removed VOCs and the particles dust
from 200 to 300 nm. The pure air passed through
connection of PVC tubes and storage in 1-5 liter
of bulk bag. After adjusting of H
2
O, the mixture
moved to GQDs or MWCNTs in optimized flow
rate and temperature. All of lines and bags were
covered with heating jackets capable of controlling
the temperature up to 70 °C to prevent condensing.
2.4. Synthesis of LGQDs and MWCNTs
High-purity MWCNTs were synthesized by use of
camphor, an environment-friendly hydrocarbon as
a carbon source using chemical vapor deposition
(CVD) method on Co-Mo/MgO Nano-catalysts
[36]. We prepared GO from graphite adopting a
modified Hummers’ method [37, 38]. The GO
was used for synthesizing of GQDs by Dong et al.
Firstly, the amount of GO was refluxed with HNO3
(10 M) at 120
o
C for one day. When the reaction was
completed the color of solvent darkened. Then, the
suspension was centrifuged for 15 min after being
cooled at 25
o
C. The suspension was collected after
washing of product with DW and then centrifuged.
Secondly, the obtained GO was dispersed in 20
mL DW, heated hydrothermally in a Teflon-lined
stainless steel at 220
o
C for 10 hours and centrifuged
(3500) for 20 min (brown color). So, GQDs were
obtained in this procedure by green fluorescence
under 365 nm UV light irradiation [39].
2.5 Characteristics
After hydrothermal method for synthesis nano
Fig. 1b. TEM of MWCNTsFig. 1a. SEM of MWCNTs
62
Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)
materials, the SEM and TEM images of the
MWCNTs and GQDs were shown in Figure 1 (a,
b) and 2(a, b). The surface area and pore size of
GQDs and MWCNTs based on nitrogen adsorption
was evaluated by Brunauer-Emmett-Teller
(BET) method. The surface area and porosity of
the MWCNTs and GQDs, before and after heat
treatment were similar values. Raman spectra of
GQDs and MWCNTs show the G and D bands
that are characteristic for carbon structures. Raman
spectra show quality of nanostructure which was
deepened on I
G
/I
D
(Fig. 3). The pore size, length,
BET surface area and textural properties of GQDs
and MWCNTs were shown in Table 1 and 2.
2.6. Removal Procedure
The 25 mg of different GQDs and MWCNTs,
was used as sorbents for removal of ethylbenzene
from air in optimized conditions (flow rate 300
mL min
-1
, 42
O
C). The different concentration
of ethylbenzene in air (bulk bag) was passed
through the GQDs and MWCNTs sorbents. After
efficient adsorption in present of UV radiation, the
ethylbenzene concentration in air was determined
by GC-FID. Also, the removal efficiency calculated
after desorption of ethylbenzene from GQDs and
MWCNTs by thermal accessory at 150
O
C. For
sample blank, 1 mL of air in bulk bag was injected
Fig. 3. Raman spectroscopy of a) GQDs and b) MWCNTs
Fig. 2b. TEM of GQDsFig. 2a. SEM of GQDs
a b
63
Removal of ethylbenzene from air Baharak Bahrami Yarahmadi et al
to injector of GC-FID by Hamilton syringes and the
concentration of ethylbenzene was determined by
GC-FID and GC-MS (Agilent 7890A, USA). So,
SGR procedure based on GQDs can be efficiently
removed ethylbenzene from air.
2. Results and Discussion
3. 1. Optimizing of parameters
In optimized conditions, the adsorption capacity of
ethylbenzene in an air is the amount of adsorbate
ethylbenzene (mg) on GQDs sorbent (g). The
removal efficiency of GQDs is the ratio of removed
ethylbenzene to initial ethylbenzene concentration
in air. The removal efficiency and adsorption
capacity are depended on the important parameters
such as; kind of sorbent, size of nanoparticles,
temperature, flow rate, ethylbenzene concentration
and humidity which were optimized. The effect
of ethylbenzene concentration was investigated
by SGR method from 1.0 to 100 ppm. The results
showed us, high concentration of ethylbenzene,
based on the GQDs was saturated early graphene
dot sites. In optimized conditions, the ethylbenzene
concentration for 25 mg of GQDs and MWCNTs
was achieved, 4.66 ppm and 2.54 ppm, respectively
in 25
o
C (Fig. 4). So, the absorption capacity was
achieved 186.4 mg g
-1
and 102.4 mg g
-1
, respectively
(Fig. 5). For ethylbenzene removal from air, the
effects of humidity on removal efficiency of GQDs
and MWCNTs were studied between 10% - 70%.
Table 2. Pore size, length and BET surface area of GQDs and MWCNTs
Carbon Diameter (nm) Length (um) *I
G
/I
D
Surface Area (m
2
/gr)
MWCNT 4-20 8-14 0.77 375
GQDs
3-15 8-12 0.68 346
*(IG/ID): LG band originates from ordered, well-graphitized carbon, D band is the disorder-activated band
Table 1. Textural properties of GQDs and MWCNTs
Carbon S
BET
a
(m
2
/g) d
sp
b
(nm) d
lp
c
(nm) V
sp
d
(cm
3
/g)
V
lp
e
(cm
3
/g)
PA (A)
MWCNT 375 5.54 15.08 0.51
1.04
117.52
GQDs 343 4.65 14.17 0.53
0.89
101.18
a
BET specific surface area,
b
diameter of small pores,
c
diameter of large pores,
d
Volume of small
pores,
e
Volume of large pores, pore Diameter (PA)
Fig. 4. The effect of ethylbenzene concentration on air removal
64
Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)
The results showed, by increasing of humidity up to
10%, the removal efficiency wasn’t decreased. The
temperature has effected on adsorption capacity and
recovery of GQDs for ethylbenzene removal from
air. The effect of temperature was studied between
25─150
O
C. The results showed us, the absorption
efficiency of ethylbenzene by GQDs was achieved
under 420
o
C and desorption was obtained at
146
o
C (Fig. 6). In optimized flow rate value, the
maximum recovery was happened by GQDs by
SGR procedure. So, the effect of different flow
rates between 50 to 800 mL min
-1
was evaluated
based on GQDs for ethylbenzene removal from air.
The results showed, the recovery of removal was
decreased in more than 350 mL min
-1
. Therefore,
300 mL min
-1
was selected as optimum flow rate
(Fig. 7). The inside of quartz tubes was filled with
GQDs and MWCNTs as a sorbent for ethylbenzene
removal from air. Diameter and length of quartz
tubes and physical and chemical properties of
GQDs and MWCNTs is important factor for
adsorption efficiency of ethylbenzene which must
be optimized. Based on results, 0.3 cm of diameter
and 5 cm of length selected as optimum column for
Fig. 6. The effect of temperature on ethylbenzene removal from air by GQDs
Fig. 5. The effect of temperature on absorption capacity for ethylbenzene removal from air by GQDs
65
Removal of ethylbenzene from air Baharak Bahrami Yarahmadi et al
further study.
3.2. Analyzing and Validation
The GQDs was selected as a novel sorbent for
removal of ethylbenzene vapor from air in present
of UV radiation by SGR method. By procedure,
a mixture of 1─100 ppm of ethylbenzene in air
which was generated in chamber was validated
by GC-MS and then, passed through GQDs.
After absorption ethylbenzene on GQDs at room
temperature, the ethylbenzene desorbed from it
at 146
o
C and determined by GC-FID. Since, the
standard reference material (SRM) for ethylbenzene
in air aren’t available, the standard ethylbenzene
concentration was generated in a bag (5 Li) by
chamber and used for validation by spiking of real
samples (Table 3).
3.3. Discussion
Fei Yu et al. investigated the removal of TEX from
aqueous system by the functionalized magnetic
nanoparticle-carbon nanotubes composites that
were synthesized, characterized and applied.
The APCNTs-KOH composites exhibited high
adsorption capacity for TEX onto APCNTs-KOH
in a decrease order of ethylbenzene > m-xylene
> o-xylene > p-xylene > toluene (227.05,138.04,
63.34, 249.44, and 105.59 mg g
-1
), which was
higher than current study [40]. In another research,
Table 3. Validation of methodology with GC-FID/SGR for ethylbenzene removal from air by UV-GQDs (ppm)
* Bag GC-MS
Added Ethylbenzene
UV-GQDs
a
Recovery (%)
1.38 ± 0.08
------
1.34 ± 0.09 97.1
1.0
2.32 ± 0.12 98.0
5.58± 0.31
------
5.51± 0.32 98.7
5.0
10.38 ± 0.47 97.4
10.43 ± 0.44
------
10.07 ± 0.52 96.5
10.0
19.96 ± 0.93 98.9
20.65 ± 1.02
------
19.89 ± 1.13 96.3
20.0
40.11 ± 2.15 101.1
80.48 ± 3.88
------
78.65 ± 4.23 97.7
80.0
157.33 ± 7.86 98.4
a
Mean of three determinations ± confidence interval (P = 0.95, n = 5)
* (Air bag; 1-80 ppm in 5 Li bag,
300 mL min
-1
air flow rate, Peak Area, 25 mg, T=25
o
C)
Fig.7 . The effect of flow rate on ethylbenzene removal from air by GQDs
66
Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)
Natarajan et al. used the biofiltration method for
the removal of the ethylbenzene-xylene mixture
while the total inlet loading rate range was 25.408
g m
-3
per hour. The maximum removal capacities
attained for ethylbenzene and toluene were 85.63
and 63.2 g m
-3
per hour respectively, which was
lower than our proposed method. The elimination
capacities were evaluated at different loading rates
and found to vary in a linear pattern. Based on result
removal capacities was lower than this study [41].
Ye and Ariya used Fe
3
O
4
nanoparticles (NPs) at
different relative humidities (RH) as adsorption for
removal of gaseous benzene, toluene, ethylbenzene
and m-xylene (BTEX) and sulfur dioxide (SO
2
).
X-ray diffraction, Brunauer–Emmett–Teller, and
transmission electron microscopy were deployed
for nanoparticle surface characterization. Using
gas chromatography equipped with flame
ionization detection, Adsorption experiments of
BTEX on NPs were measured, which under dry
conditions indicated high removal efficiencies (up
to (95 ± 2)%), which are similar to our result [42].
Bina et al. used multi-walled, single-walled, and
hybrid carbon nanotubes (MWCNTs, SWCNTs,
and HCNTs) for removal of ethylbenzene (EB)
from aqueous solution. Ethylbenzene has a higher
adsorption tendency on CNTs so that more than
98% of it adsorbed in the first 14 min, which is
related to the low water solubility and the high
molecular weight. Isotherm’s study indicates
that the BET isotherm expression provides the
best fit for ethylbenzene sorption by SWCNTs
[43]. Kamaei et al. used nitrogen-doped
commercial TiO2 nano-catalysts for photocatalytic
decomposition of ethylbenzene in the air using a
packed-bed annular photoreactor. The removal
efficiency of ethylbenzene under UV irradiation
using N-doped catalyst was more than 90% for the
initial concentrations up to 0.586 gm
-3
(135 ppm)
at 1 min residence time Moreover the removal
efficiency under visible light radiation could be
obtained for the initial concentrations up to 0.1
gm
-3
(about 25 ppm) at 3 min residence time,
which is lower than this article[44]. Hadi et al. used
nano-magnetic particles (Fe
3
O
4
) as an adsorbent to
eliminate ethylbenzene from aqueous solutions.
The characterization of the adsorbent was
investigated by transmission electronic microscope
(TEM) and X-ray diffraction (XRD) pattern.
The results showed that the most amounts of
ethylbenzene adsorption and distribution ratio
in optimum condition were 49.9 mg g
-1
(which
was lower than our method) and, 261.9 Lg
-1
respectively. The results explained that the removal
rate of ethylbenzene was higher in batch (99.8
%) rather than continuous (97.4%) conditions
[8]. Ahmed et al. used nZVI for eliminating
benzene, toluene, ethylbenzene, and xylene
(BTEX) contaminants from aqueous solutions.
X-ray diffraction (XRD), UV spectrophotometry,
and scanning electron microscopy (SEM) were
used for nZVI characterization. The effects of
contact time, initial BTEX mixture concentration,
adsorbent dose, temperature, and pH on the amount
of BTEX absorbed were studied. The highest
removal efficiency of 97% for the BTEX mixture
was achieved at a stirring rate of 100 rpm, the
temperature of 60°C, and pH 7, which is higher
than our study. The minimum effective time for
efficient removal was 30 min, while the effective
dose for BTEX compounds removal was 0.22
gL
-1
[45]. Yan et al. used CuMgFe layered double
hydroxide (CuMgFe-LDH), for the degradation
of ethylbenzene. the degradation efficiency of
0.08 mmol L
-1
ethylbenzene was 93.7% under
the optimized conditions at 0.2 g L
−1
, CuMgFe-
LDH and 4.0 mmol L
−1
persulfate at pH 7.6,
which is lower than our result [46]. Azizi et al.
used the graphene oxide grafted with polymethyl
vinyl ketone and aniline (GO-MVK-ANI), for
the elimination of ethylbenzene. The synthesized
material was characterized via FTIR, SEM, energy-
dispersive X-ray spectroscopy and Brunauer–
Emmett–Teller analysis.
Based on the result with initial ethylbenzene
concentration of 20 mg g
-1
under the optimum
67
Removal of ethylbenzene from air Baharak Bahrami Yarahmadi et al
conditions (the contact time of 11 min, pH of 5.64
and adsorbent dose of 3.75 g L
-1
), ethylbenzene
could be adsorbed (73%), which is lower than
our result [47]. Samarghandi et al. investigated
Catalytic Ozonation Process (COP) to treat polluted
air streams containing ethylbenzene. Respectively
at 50 ppm of this pollutant, for single ozonation and
single modified pumice, the best removal efficiency
of ethylbenzene was 58–80%, while the maximum
removal efficiency of ethylbenzene was 90% for
COP (6 L min
-1
of flow rate of inlet air, 15 g of the
adsorbent, and 50 ppm of ethylbenzene), which is
lower than this study[48]. Also samarghandi et al.
used ozone and carbosieve in the catalytic removal
of ethylbenzene from the polluted airstream. GC –
FID was used for sampling and analysis. The results
of this study showed that the removal effectiveness
of a single ozonation process is averagely less
than 25%. Also, whit the concentration increase of
ethylbenzene the efficiency of absorbent decreased.
The increase ratio of the efficiency in the catalytic
ozonation process to the efficiency of carbosieve
adsorbent was averagely 45% which is lower than
the current study[49].
4. Conclusions
In this study, the GQDs and MWCNTs as nano
sorbents were used for ethylbenzene removal from
air in present of UV-radiation by SGR method.
According to experimental procedure, the simple,
reliable and sensitive method based on GQDs
was demonstrated in real samples. In optimized
conditions, the concentration of ethylbenzene,
air flow rate, amount of GQDs and MWCNTs,
temperature, and humidity were studied. The
results showed, the flow rate (300 ml L
-1
) can
more effected on capacity adsorption by GQDs
as physical adsorption. However, in optimized
conditions, the removal efficiency and adsorption
capacity of GQDs were obtained more than 95%
and 186.4 mg g
-1
, respectively as compared to
MWCNTs.
5. Acknowledgments
We are thankful to Kerman University of Medical
Sciences (KUMS) and Iranian Petroleum Industry
Health Research Institute (IPIHRI).
6. Reference
[1] R.K. Nath, M.F.M. Zain, M. Jamil, An environment-
friendly solution for indoor air purication by using
renewable photocatalysts in concrete: A review,
Renew. Sust. Energ. Rev., 62 (2016) 1184-1194.
[2] J. Yan, Y. Chen, W. Gao, Y. Chen, L. Qian, L. Han,
M. Chen, Catalysis of hydrogen peroxide with Cu
layered double hydrotalcite for the degradation of
ethylbenzene, Chem., 225 (2019) 157-165.
[3] M. Li, Z. Huang, F. Kang, Progress of volatile
organic compounds control technology, Chem. Ind.
Eng., 32 (2015) 2-9.
[4] H. Wang, Z. Xiang, L. Wang, S. Jing, S. Lou, S. Tao,
J. Liu, M. Yu, L. Li, L. Lin, Emissions of volatile
organic compounds (VOCs) from cooking and
their speciation: A case study for Shanghai with
implications for China, Sci. Total Environ., 621
(2018) 1300-1309.
[5] M. Feiz-Are, F. Ghorbani-Shahna, A. Bahrami, H.
Ebrahimi, A. Mahjub, Photocatalytic Removal of
Methylbenzene Vapors by MnO2/Al2O3/Fe2O3
Nano composite, Iran. J. Health Safe. Environ., 6
(2019) 1158-1166.
[6] S. Zhang, J. You, C. Kennes, Z. Cheng, J. Ye, D.
Chen, J. Chen, L. Wang, Current advances of
VOCs degradation by bioelectrochemical systems:
a review, Chem. Eng. J., 334 (2018) 2625-2637.
[7] A.N. Baghani, A. Sorooshian, M. Heydari, R.
Sheikhi, S. Golbaz, Q. Ashournejad, M. Kermani,
F. Golkhorshidi, A. Barkhordari, A.J. Jafari, A case
study of BTEX characteristics and health effects by
major point sources of pollution during winter in
Iran, Environ. pollut., 247 (2019) 607-617.
[8] M. Hadei, M. Aalipour, N. Mengli Zadeh, H.
Pourzamani, Ethylbenzene removal from aqueous
solutions by nano magnetic particles, Arch. Hyg.
Sci., 5 (2016) 22-32.
68
Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)
[9] A. Masih, A.S. Lall, A. Taneja, R. Singhvi, Exposure
levels and health risk assessment of ambient BTX
at urban and rural environments of a terai region of
northern India, Environ. Pollut., 242 (2018) 1678-
1683.
[10] L. Wang, C. Yang, Y. Cheng, J. Huang, H. Yang,
G. Zeng, L. Lu, S. He, Enhanced removal of
ethylbenzene from gas streams in biotrickling
lters by Tween-20 and Zn (II), J. Environ. Sci., 26
(2014) 2500-2507.
[11] A. Carvajal, I. Akmirza, D. Navia, R. Pérez, R.
Muñoz, R. Lebrero, Anoxic denitrication of
BTEX: Biodegradation kinetics and pollutant
interactions, J. environ. manage., 214 (2018) 125-
136.
[12] M.H. El-Naas, J.A. Acio, A.E. El Telib, Aerobic
biodegradation of BTEX: progresses and prospects,
J. Environ. Chem. Eng., 2 (2014) 1104-1122.
[13] R. Moolla, C.J. Curtis, J. Knight, Assessment of
occupational exposure to BTEX compounds at a bus
diesel-refueling bay: A case study in Johannesburg,
South Africa, Sci. Environ., 537 (2015) 51-57.
[14] H.Z. Mousavi, A. Asghari, H. Shirkhanloo,
Determination of Hg in water and wastewater
samples by CV-AAS following on-line
preconcentration with silver trap, J. Anal. Chem.,
65 (2010) 935-939.
[15] H. Shirkhanloo, A. Khaligh, H.Z. Mousavi, M.M.
Eskandari, A.A. Miran-Beigi, Ultra-trace arsenic
and mercury speciation and determination in
blood samples by ionic liquid-based dispersive
liquid-liquid microextraction combined with ow
injection-hydride generation/cold vapor atomic
absorption spectroscopy, Chem. Paper., 69 (2015)
779-790.
[16] H. Shirkhanloo, M. Osanloo, M. Ghazaghi, H.
Hassani, Validation of a new and cost-effective
method for mercury vapor removal based on silver
nanoparticles coating on micro glassy balls, Atmos.
Pollut. Res., 8 (2017) 359-365.
[17] L. Zhao, X. Qin, X. Hou, Y. Li, K. Zhang, W. Gong,
J. Nie, T. Wang, Research on determination of
BTEX in human whole blood using purge and trap-
gas chromatography-mass spectrometry combined
with isotope internal standard, Microchem. J., 145
(2019) 308-312.
[18] Ethylbenzene, International Agency for Research
on Cancer (IARC), 77 (2000) 227-266.
[19] Threshold limit values for chemical substances and
physical agents and biological exposure indices, in,
American Conference of Governmental Industrial
Hygienists(ACGIH), 1995.
[20] S. Wilbur, S. Bosch, Interaction prole for: benzene,
toluene, ethylbenzene, and xylenes (BTEX),
Agency for Toxic Substances & Disease Registry
(ATSDR), 2004.
[21] M. Delikhoon, M. Fazlzadeh, A. Sorooshian,
A.N. Baghani, M. Golaki, Q. Ashournejad, A.
Barkhordari, Characteristics and health effects of
formaldehyde and acetaldehyde in an urban area in
Iran, Environ. pollut., 242 (2018) 938-951.
[22] F. Golkhorshidi, A. Sorooshian, A.J. Jafari,
A.N. Baghani, M. Kermani, R.R. Kalantary, Q.
Ashournejad, M. Delikhoon, On the nature and
health impacts of BTEX in a populated middle
eastern city: Tehran, Iran, Atmos. Pollut. Res., 10
(2019) 921-930.
[23] S. Hazrati, R. Rostami, M. Fazlzadeh, F. Pourfarzi,
Benzene, toluene, ethylbenzene and xylene
concentrations in atmospheric ambient air of
gasoline and CNG refueling stations, Air Qual.
Atmos. Health, 9 (2016) 403-409.
[24] M. Bahri, F. Haghighat, Plasma-based indoor air
cleaning technologies: the state of the art-Review,
Clean Soil Air Water, 42 (2014) 1667-1680.
[25] M. Sansotera, S.G.M. Kheyli, A. Baggioli,
C.L. Bianchi, M.P. Pedeferri, M.V. Diamanti,
W. Navarrini, Absorption and photocatalytic
degradation of VOCs by peruorinated ionomeric
coating with TiO2 nanopowders for air purication,
Chem. Eng. J., 361 (2019) 885-896.
[26] K.W. Shah, W. Li, A Review on Catalytic
Nanomaterials for Volatile Organic Compounds
VOC Removal and Their Applications for Healthy
Buildings, Nanomaterials., 9 (2019) 910.
[27] C. Yang, G. Miao, Y. Pi, Q. Xia, J. Wu, Z. Li, J.
69
Removal of ethylbenzene from air Baharak Bahrami Yarahmadi et al
Xiao, Abatement of various types of VOCs by
adsorption/catalytic oxidation: A review, Chem.
Eng. J., 370 (2019) 1128-1153.
[28] L. Zhong, F. Haghighat, Photocatalytic air
cleaners and materials technologies–Abilities and
limitations, Buid. Environ., 91 (2015) 191-203.
[29] M. Malayeri, F. Haghighat, C.-S. Lee, Modeling
of volatile organic compounds degradation by
photocatalytic oxidation reactor in indoor air: A
review, Buid. Environ., 154 (2019) 309-323.
[30] A.H. Mamaghani, F. Haghighat, C.-S. Lee,
Photocatalytic oxidation technology for indoor
environment air purication: the state-of-the-art,
App. Catal. B: Environ., 203 (2017) 247-269.
[31] M. Hussain, P. Akhter, J. Iqbal, Z. Ali, W. Yang, N.
Shehzad, K. Majeed, R. Sheikh, N. Russo, VOCs
photocatalytic abatement using nanostructured
titania-silica catalysts, J. Environ. Chem. Eng., 5
(2017) 3100-3107.
[32] C.H.A. Tsang, K. Li, Y. Zeng, W. Zhao, T. Zhang,
Y. Zhan, R. Xie, D.Y. Leung, H. Huang, Titanium
oxide based photocatalytic materials development
and their role of in the air pollutants degradation:
Overview and forecast, Environ. int., 125 (2019)
200-228.
[33] M. Hu, Z. Yao, X. Wang, Graphene-based
nanomaterials for catalysis, Ind. Eng. Chem. Res.,
56 (2017) 3477-3502.
[34] Y. Pan, X. Yuan, L. Jiang, H. Yu, J. Zhang, H. Wang,
R. Guan, G. Zeng, Recent advances in synthesis,
modication and photocatalytic applications of
micro/nano-structured zinc indium sulde, Chem.
Eng. J., 354 (2018) 407-431.
[35] A. Truppi, F. Petronella, T. Placido, M. Striccoli,
A. Agostiano, M.L. Curri, R. Comparelli, Visible-
light-active TiO2-based hybrid nanocatalysts for
environmental applications, Catal., 7 (2017) 100.
[36] A. Rashidi, M. Akbarnejad, A. Khodadadi, Y.
Mortazavi, A. Ahmadpourd, Single-wall carbon
nanotubes synthesized using organic additives to
Co–Mo catalysts supported on nanoporous MgO,
Nanotech., 18 (2007) 315605.
[37] Y. Xu, H. Bai, G. Lu, C. Li, G. Shi, Flexible
graphene lms via the ltration of water-soluble
noncovalent functionalized graphene sheets, J. Am.
Chem. Soc., 130 (2008) 5856-5857.
[38] N.I. Kovtyukhova, P.J. Ollivier, B.R. Martin,
T.E. Mallouk, S.A. Chizhik, E.V. Buzaneva, A.D.
Gorchinskiy, Layer-by-layer assembly of ultrathin
composite lms from micron-sized graphite oxide
sheets and polycations, Chem. mater., 11 (1999)
771-778.
[39] Y. Dong, H. Pang, S. Ren, C. Chen, Y. Chi, T. Yu,
Etching single-wall carbon nanotubes into green
and yellow single-layer graphene quantum dots,
Carbon, 64 (2013) 245-251.
[40] F. Yu, J. Ma, J. Wang, M. Zhang, J. Zheng, Magnetic
iron oxide nanoparticles functionalized multi-
walled carbon nanotubes for toluene, ethylbenzene
and xylene removal from aqueous solution,
Chemosphere, 146 (2016) 162-172.
[41] R. Natarajan, J. Al-Sinani, S. Viswanthan, R.
Manivasagan, Biodegradation of ethyl benzene and
xylene contaminated air in an up ow mixed culture
biolter, Int. biodet. biodeg., 119 (2017): 309-315.
[42] Z.Y. Connie, P.A. Ariya, Co-adsorption of gaseous
benzene, toluene, ethylbenzene, m-xylene (BTEX)
and SO2 on recyclable Fe3O4 nanoparticles at
0–101% relative humidities, J. Environ. Sci., 31
(2015) 164-174.
[43] B. Bina, H. Pourzamani, A. Rashidi, M.M. Amin,
Ethylbenzene removal by carbon nanotubes from
aqueous solution, J. environ. pub. health, 2012
(2012).
[44] M. Kamaei, H. Rashedi, S.M.M. Dastgheib, S.
Tasharro, Comparing photocatalytic degradation
of gaseous ethylbenzene using N-doped and pure
TiO2 nano-catalysts coated on glass beads under
both UV and visible light irradiation, Catal., 8
(2018) 466.
[45] A.S. Mahmoud, M.K. Mostafa, S.A. Abdel-Gawad,
Articial intelligence for the removal of benzene,
toluene, ethyl benzene and xylene (BTEX) from
aqueous solutions using iron nanoparticles, Water
Suply., 18 (2018) 1650-1663.
[46] J. Yan, Y. Chen, L. Qian, W. Gao, D. Ouyang,
70
Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)
M. Chen., Heterogeneously catalyzed persulfate
with a CuMgFe layered double hydroxide for the
degradation of ethylbenzene. J. hazard. mater., 338
(2017) 372-380.
[47] A. Azizi, A. Torabian, E. Moniri, A.H. Hassani,
H. Ahmad Panahi, Investigating the removal
of ethylbenzene from aqueous solutions using
modied graphene oxide: application of response
surface methodology, Int. J. Environ. Sci. Tec., 15
(2018) 2669-2678.
[48] M.R. Samarghandi, Z. Daraee, G. Shekher, G.
Asgari, A. Reza Rahmani, A. Poormohammadi.,
Catalytic ozonation of ethyl benzene using modied
pumice with magnesium nitrate from polluted air.
Int. J. Environ. Stutdies, 74 (2017), 486-499.
[49] M.R. Samarghandi, G. Asgari, F. Ghorbani, S.A.
Babaee., The study of effect the combined use
of ozone and carbosieve in the catalytic removal
of ethylbenzene from the polluted airstream, J.
Neyshabur UN. Medical. Sci., 5 (2017) 86-98.
