Inhibition effect of ethanol in naproxen degradation by catalytic ozonation with NiO

Article abstract of DOI:10.1039/c9ra02133g

This work evaluated the inhibition effect of low molecular weight alcohol (ethanol) on naproxen (NAP) degradation by conventional and catalytic ozonation. The reaction system considered the ethanol as complementary organic matter in water. The conventional ozonation and in the presence of nickel oxide (O₃-NiO) achieved 98% NAP degradation during the first 15 min of reaction despite the presence of ethanol. However, NAP degradation presented a delaying effect during the first minutes of treatment with this alcohol. The latter phenomenon indicates that ethanol concentration played a meaningful role in ozonation effectiveness in comparison with the presence of NiO catalyst. The presence of NiO did not generate differences in the byproducts in comparison with conventional ozonation. The intermediates were detected using the Electrospray Ionization Mass Spectrometry technique and have only one aromatic ring in their chemical structure. In samples without ethanol, these byproducts appeared only in the first 5 min of reaction. The TOC study demonstrated the increment of 25% in the mineralization degree with the presence of NiO due to the formation of ·OH species.

Full text of DOI:10.1039/c9ra02133g

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PAPER
Inhibition effect of ethanol in naproxen
degradation by catalytic ozonation with NiO†
Cite this: RSC Adv., 2019, 9, 14822
b
Claudia Marissa Aguilar,a Isaac Chairez,a Julia Liliana Rodrıguez,
*
´
c
Hugo Tiznado,
Ricardo Santillan,d Daniel Arrietae and Tatiana Poznyakb
´
This work evaluated the inhibition effect of low molecular weight alcohol (ethanol) on naproxen (NAP)
degradation by conventional and catalytic ozonation. The reaction system considered the ethanol as
complementary organic matter in water. The conventional ozonation and in the presence of nickel oxide
(O3–NiO) achieved 98% NAP degradation during the first 15 min of reaction despite the presence of
ethanol. However, NAP degradation presented a delaying effect during the first minutes of treatment with
this alcohol. The latter phenomenon indicates that ethanol concentration played a meaningful role in
ozonation effectiveness in comparison with the presence of NiO catalyst. The presence of NiO did not
generate differences in the byproducts in comparison with conventional ozonation. The intermediates
were detected using the Electrospray Ionization Mass Spectrometry technique and have only one aromatic
ring in their chemical structure. In samples without ethanol, these byproducts appeared only in the first
5 min of reaction. The TOC study demonstrated the increment of 25% in the mineralization degree with
the presence of NiO due to the formation of $OH species.
Received 20th March 2019
Accepted 7th May 2019
DOI: 10.1039/c9ra02133g
rsc.li/rsc-advances
depend on the size of the hospital, the average number of
patients, and the number of medical specialties, among others.
1. Introduction
Usually, disinfectants, detergents, biological liquids, toxic or
hazardous chemicals, pharmaceutical residues, xer solutions
from photographic lm and/or infections agents can be also
found in these effluents. Hospital wastewater is discharged into
the municipal sewer network. Due to the aforementioned
characteristics, the hospital wastewater should not be treated as
domestic discharge. Instead, these residuals must be consid-
ered as industrial wastewater.
The inappropriate disposal of pharmaceutical industry
wastewater also contributes to this environmental problem.
Because their wastewaters contain drugs with different chem-
ical nature.4 Hence, the possible treatment of such kind of
wastewaters is more complicated due to the diversity of
compounds. The inadequate treatment of effluents containing
several medicaments may have relevant health consequences
for plants, animals, and the human beings.5
A wide variety of anti-inammatory drugs are consumed in
human and veterinary medicine around the world. These drugs
are metabolized incompletely, being eliminated from the
bodies of human patients in fecal and urine excretions which
end up in the sewer system.1 The irrational consumption of
such pharmaceutical products has contributed to the environ-
mental problems because these compounds can be toxic and
recalcitrant to conventional wastewater treatments. Further-
more, pharmaceutical products may be able to change the
reproduction cycles in aquatic species.2 The presence of these
kinds of compounds is a potential danger to water bodies.3
Hospitals are a continuous and uncontrolled source of
medicaments (anesthetics, analgesic, anti-inammatories, etc.)
in sewer effluents. According to Carraro et al.1 hospital effluents
a
´
´
Departamento de Bioprocesos, UPIBI-Instituto Politecnico Nacional, Ticoman, 07340
Gibson et al.6 reported that agricultural soil irrigated with
wastewater in the Tula Valley (Mexico) introduced various
pollutants into the terrestrial environment (including pharma-
ceuticals and personal care products). The bioremediation
technologies applied to eliminate pharmaceutical compounds
have not been successful.7,8
Mexico, Mexico
b
´
´
Lab. Ing. Quımica Ambiental, ESIQIE-Instituto Politecnico Nacional, Zacatenco,
07738 Mexico, Mexico. E-mail: ozliliana@yahoo.com.mx; Tel: +52-55-57296000 ext.
54252
cUniversidad Nacional Autonoma de Mexico, Centro de Nanociencias
y
´
´
Nanotecnologıa, Km. 107 Carretera Tijuana a Ensenada, 22860 Ensenada, Baja
California, Mexico
On the other hand, the advanced oxidation processes
produced reactive species which attack different pollutants
present in water.9 The common characteristic of these kinds of
processes is the production of hydroxyl radicals ($OH, 2.80 eV)
which have low reaction selectivity with organic compounds.
d
´
´
Lab. de polımeros, ESIQIE-Instituto Politecnico Nacional, Zacatenco, 07738 Mexico,
Mexico
e
´
´
Centro de Nanociencias y Micro y Nanotecnologıas CNMN-Instituto Politecnico
Nacional, Zacatenco, 07738 Mexico, Mexico
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c9ra02133g
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The combination of the catalyst with ozone is one of the most
successful methods to produce $OH10,11 because to reduce the
drawbacks of conventional ozonation for instance, the forma-
tion of toxic bromate12 and the accumulation of intermediates
of low reaction constant with ozone. The presence of the catalyst
can accelerate the decomposition and mineralization of
pollutants in water.13–15
Several catalysts have been evaluated in catalytic ozonation
(TiO2, SiO2, CeO2, etc.). Among them, NiO has shown a superior
mineralization capacity over TiO2 in the elimination of the
herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). In this case,
NiO improved the TOC removal in around 30% in comparison
to conventional ozonation (O3-conv) and other catalysts (TiO2,
SiO2, Al2O3).16 The degradation of benzoic and phthalic acids in
aqueous solution by ozonation with NiO conrmed the activity
catalyst yielding the 98% of TOC removal (52% more than O3-
conv). In these works, the authors attributed the effect of NiO at
three mechanisms: (1) $OH generation, (2) direct reaction with
ozone and (3) complex formation in the surface of NiO.17 The
published results demonstrated that NiO is an effective catalyst
for the ozonation process.
Catalytic ozonation has been evaluated as a promising
technology that may degrade pharmaceutical products.18
Nowadays, the number of studies discussing the pharmaceuti-
cals degradation is growing. However, only a few of them have
studied the effect of the water matrix. The composition of the
water matrix is an important parameter that must be consid-
ered in the contaminants elimination. For example, in hospitals
and pharmaceutical industry effluents, ethanol is one of the
components in wastewater. Chen et al.19 characterized a water
effluent coming out from the main residual stream (a mixture of
solvents and cleaning products) of the Pharmacy Company
Manufacturing Co., a bigger amount of ethanol was detected in
such residuals. To the authors' knowledge, there is a lack of
information about the ethanol effect on the elimination of
diverse pharmaceutical compounds.
2. Experimental conditions
2.1 Materials and reagents
All the reagents were analytic grade. The catalyst was commercial
nickel(II) oxide nanoparticles with diameters of less than 50 nm
(Sigma-Aldrich, 99%). The NAP solution was 20 mg Lꢀ1 (Sigma-
Aldrich, 99.8%) in 0 : 100, 10 : 90, 30 : 70 and 50 : 50 v/v ethanol/
distillate water mixture (Chemical Meyer, 99.5%). The prepara-
tion of the model solutions included a vigorously stirring process
applied during 5 h for the ethanol/water mixtures and 48 h for the
solutions without ethanol. The experimental temperature was 22.0
ꢁ 2.0 ꢂC. The initial pH of the model solution was 5.0 ꢁ 0.5, and it
was not controlled during the ozonation.
2.2 Ozonation procedure
The experiments were carried out in a semi-batch type reactor
(0.5 L). The ceramic diffuser was installed at the bottom of the
selected Pyrex glass reactor. An ozone–oxygen mixture bubbled
through a ceramic porous lter induced the agitation in the
reactor. The HTU500 G ozone generator (corona discharge type)
from AZCO Industries Limited – Canada produced the ozone.
An ultra-dried oxygen stream was fed into the ozone generator.
This ozone/oxygen stream entered in the semi-batch reactor
with the ow of 0.5 L minꢀ1. The ozone concentration was 5.5 ꢁ
0.5 mg Lꢀ1. The BMT 946BT ozone analyzer measured the ozone
concentration in the gaseous phase (BMT Messtechnik, Berlin).
The NiO concentration was constant in all the catalytic ozona-
tion experiments (100 mg Lꢀ1).ꢂIn the slurry mode, the NiO was
previously dried for 1 h at 100 C.
2.3 Adsorption studies
The adsorption experiments considered the mechanic agitation
of the sample during 60 min with 100 mg Lꢀ1 NiO for all the
ethanol/water mixtures (0 : 100, 10 : 90, 30 : 70 and 50 : 50 v/v).
The pH and temperature were kept constant along the adsorp-
tion study.
Among pharmaceutical compounds, anti-inammatory
drugs are detected in the effluents of the municipal waste-
water treatment plants.7 NAP is
a non-steroidal anti-
2.4 Analytical procedure for NAP degradation and
byproducts identication
inammatory drug. This medicament is usually prescribed in
the treatment of rheumatoid arthritis and inammation of
diverse articulations and muscles. Moreover, this anti- The PerkinElmer Flexar device (with DAD detector) was used by
inammatory can be purchased without a prescription. This the HPLC analysis. The HPLC conditions for the NAP analysis
is the main reason to justify its common presence in municipal were: (a) Platinum C18 column (250 ꢃ 4.6 mm, 5 mm), (b) the
wastewaters.
mobile phase was acetonitrile/water 50 : 50 adjusted to pH 2.5
The degradation of NAP is ineffective by the biological with H3PO4, (c) UV-lamp wavelength of 240 nm and (d) the ow
treatments.8 Researches on wastewater treatments such as was 0.3 mL minꢀ1
.
photolysis,20 the photocatalytic process21,22 and catalytic ozon-
The analysis conditions for byproducts (organic acids) were:
ation,23 some of these works did not consider the effect of the (a) prevail organic acid column (150 mm ꢃ 4.6 mm, 5 mm), (b)
water matrix.
the mobile phase was KH2PO4 buffer at 25 mM adjusted to pH
The aim of this work is to evaluate O3–NiO in NAP degradation 2.3 with H3PO4, (c) UV-lamp wavelength of 210 nm, and (d) ow
when it is dissolved in ethanol/water mixture (0 : 100, 10 : 90, of 1 mL minꢀ1. The samples were previously ltered with 0.2 mm
30 : 70 and 50 : 50 v/v). Besides, the inuence of NiO in the acrodisc syringe lter. This study reports only the mean of
ozonation effectiveness. The study also analyzed the inhibitor triplicate concentration for each sample.
effect of ethanol over the NAP decomposition efficiency by O3–
The Electrospray Ionization Mass Spectrometry (ESI-MS)
NiO. Details reaction pathways towards catalytic ozonation of technique was used to identify the NAP byproducts from O3–
NAP elimination has been further proposed and discussed.
NiO and O3-conv treatments with and without ethanol. The
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spectra were acquired in the negative ion scan mode using package processes the raw data. Furthermore, NiO commercial
a Bruker MICROTOF-Q II 10392. The analysis was carried out by were characterized by other techniques, Fig. S1 and S2.†
direct injection in the ESI-TOF-MS system. The studied m/z
range was 50 to 3000 (n ¼ 2). The analysis conditions were: (a) 8
2.7 Kinetic analysis
mL minꢀ1 of constant volumetric ow rate which was achieved
The kinetics study of NAP ozonation is complex because there
are several oxidant species that cannot be measured on line.
Then, any feasible mathematical model of such a reaction must
consider a large number of intermediaries. In this study,
a different kinetics analysis served to compare the catalyst and
the ethanol concentration effect. It is usual to consider the
pseudo-monomolecular reaction to characterize the kinetics of
oxidative reactions if the radical's species are not available. The
NAP ozonation is characterized by the rst order kinetic reac-
with 100 mL of sample using a Cole Parmer syringe pump
(74900-00-05), (b) the capillary temperature was 180 C, (c) the
ꢂ
ionization voltage was 2700 V and (d) the nitrogen spray gas ow
rate was 4 L minꢀ1 (0.4 bar). The analysis carried out for 1 min
with scan and interscan times of 10 s and 0.1 s, respectively. The
m/z ions (detected in the tandem analysis of ESI-MS) were
evaluated by the ESI-MS-MS technique with the same analysis
conditions with appropriate set mass. The fragments were
analyzed by a Bruker Compass Data Analysis 4.0 (Bruker Dal-
tonics). The widely accepted accuracy threshold for conrma-
tion of elemental compositions was established at 5 ppm.
tion with the reaction rate constant kNAP
.
The proposed model considers the formation and decom-
position of byproducts. The mathematical form used to char-
acterize this dynamic is:
2.5 Chemical oxygen demand (COD) and total organic carbon
(TOC)
dcjðtÞ
¼ kjacNAPðtÞ ꢀ kjdcjðtÞ þ djðtÞ cjð0Þ ¼ DB0
(1)
dt
The COD analysis was made only in the samples without
ethanol with 5 and 60 min of ozonation time by chemical
digestion according to method 410.4 (USEPA). The standard
COD analysis kit applies the ready-to-use vials. The low range
Hanna (HI94754A) reagent vials were used to digest the
samples. The samples were ltered with a 0.2 mm pore lter
previous digestion for 2 h at 150 ꢂC. Aer digestion, the samples
were measured in the equipment UV-Vis spectroscopy Perki-
nElmer Lambda 25 at 600 nm.
On the other hand, the TOC analysis was determined by
direct injection in the Torch IQOQ equipment (Teledyne Tek-
mar). The solutions were previously ltered by 0.2 mm
membrane. The TOC study only evaluated the samples without
ethanol. These experiments used tert-butanol (TBA) as $OH
scavenger with a 200 mg Lꢀ1. The TOC technique measured the
amount of organic carbon in the sample. In consequence, the
TBA presence modies the measured TOC. A reference experi-
ment with TBA only dened the offsetting of additional organic
matter in the system. Furthermore, this method determines the
effect of $OH on the ozonation efficiency (measured as miner-
alization), due to the scavenging of all available formed $OH.
In eqn (1), the parameter kja is the reaction rate constant
(RRC) for the accumulation of the byproduct cj generated by
the NAP elimination [sꢀ1]. The parameter kdj is the RRC that
characterizes the byproduct decomposition [sꢀ1]. The model
can be modied if the nal compounds are studied by
choosing the value of the constant kdj as zero. The term dj
represents the effect of the reactions that may contribute to the
byproducts dynamics (i.e. the OH radical's reaction with cj and
some others). A more complex representation of the byprod-
ucts dynamics is obtained considering the interaction between
the intermediary and nal accumulated products (oxalic acid
for example). The differential equation that represents these
dynamics is the following:
dckðtÞ
¼ kja;kcjðtÞ ꢀ kjd;kckðtÞ þ djðtÞ ckð0Þ ¼ ck;0
(2)
dt
where kaj,k is the pseudo-monomolecular RRC characterizing the
ꢀ
accumulation process of the nal compounds k, ck is the accu-
mulated byproduct concentration (no evidence of its decomposition
is gotten during the ozonation period) produced by the decompo-
sition of cj and kdj,k is the decomposition RRC of this byproduct. In
2.6 Analysis of NiO by XPS
ꢀ
ꢀ characterizes all the reactions that affect the c
this case, the term dj
k
The X-ray photoelectron spectroscopy (XPS) system (SPECS
model) determined the photoelectron core-level spectra of
ozonation samples. The XPS system has the Al Ka X-ray
monochromatic source (1487 eV). The constant reference
pressure was 6 ꢃ 10ꢀ10 mTorr. A double-sided carbon tape
supported the powder samples. The 400 mm spot size (50 eV
analyzer pass energy) generated the high-resolution scans.
The internal reference for charge correction was C 1s (284.6
eV). The t parameters for the raw data were similar to the ones
proposed by Payne et al., 2009. All the tting procedures
considered the application of Gaussian–Lorentzian (70–30%)
curve shapes and Shirley-type background. Considering that NiO
was the main analyzed component, the parameters suggested in
Biesinger et al. (2009) were selected. The CasaXPS 2.3.16 soware
dynamics, such as the ones considered for eqn (2). The rst-order
reaction dynamics in (1, 2) have linear parameters.
The parametric identication solution used in this study
(estimate the values of kNAP, kaj , kjd, kja,k and kjd,k) uses a robust
exact differentiator based on the super-twisting algorithm or
STA for short:24
d
^
caðtÞ ¼ daðtÞ
dt
pffiffiffiffiffiffi
^
^
^
daðtÞ ¼ cbðtÞ ꢀ ra jcaðtÞ ꢀ caðtÞj signðcaðtÞ ꢀ caðtÞÞ
d
c^bðtÞ ¼ ꢀrb signðc^aðtÞ ꢀ caðtÞÞ
(3)
dt
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ˆ
where ca is the estimation for the concentration of ca. Notice
here that ca may represent each of the compounds considered
in the model of the catalytic ozonation (NAP and byproducts),
ˆ
cb is an auxiliary variable needed to execute the differentiator, da
is the estimation of the time derivative of ca which is used
further to calculate the uncertain RRCs. The constants ra and rb
are positive and should be selected according to the theoretical
result presented by Moreno and Osorio.25 For instance, in the
case of the model proposed in (4), it can be represented as:
a
d
ꢀ(t)
(4)
yk(t) ¼ kj,kcj(t) ꢀ kj,kcꢀk(t) + dj
dckðtÞ
where ykðtÞ ¼
.
dt
ꢀ
If the STA is applied considering that ca ¼ ck. Therefore, aer
a nite time T, da(t) ¼ yk(t) for all t $ T. The estimation of kaj,k and
kdj,k can be solved by the least mean squares method considering
the sampling process of the experimental data.
Fig. 1 NAP adsorption study on NiO in presence of diverse ethanol/
water ratios.
The model in (5) is (conspiring the sample data at specic
time t ¼ ts):
ratio. It was found that the adsorption contribution in NAP
removal is less than 7.5% of the NAP concentration.
yjðtsÞ ¼ qT 4ðtsÞ þ djðtsÞ
h
i
qT ¼ kja;kkjd;k
(5)
Â
Ã
4T ðtsÞ ¼ cjðtsÞ ꢀ csðtÞ
3.2 Ozonation of NAP in water with and without NiO
This section reports the inuence of different ethanol/water
ratios on the NAP elimination with or without NiO (Fig. 2).
Both, O3-conv and O3–NiO removed 98% of initial NAP
concentration aer 15 min of treatment independently of
ethanol/water ratios (Fig. 2). The latter results demonstrated the
effectiveness of O3-conv to removed NAP.
The reported NAP and other drugs concentrations are
underneath other components concentrations in waste-
water.29,30 These uneven distributions (pharmaceutical/organic
compounds in the wastewater) difficult pharmaceutical
compounds degradation. In the case of drugs, they are dissolved
in complex mixtures of organic compounds. Pharmaceutical
products from hospitals, manufacturing industry, among
The solution of the parametric modelling strategy is:
S
S
X
X
À
Áꢀ1
À
Á
q* ¼
4T ðtsÞ4ðtsÞ
4ðtsÞyjðtsÞ
(6)
S¼1
S¼1
where S is the number of samples taken during ozonation. The
similar procedure can be used to estimate the remainder RRC
for cNAP and cj.
3. Results and discussion
3.1 Adsorption of NAP on NiO
Prior to the ozonation treatments, NAP adsorption experiments others release pharmaceuticals into the water. These effluents
on NiO showed the pollutant removal from the solution by mass feature is the ethanol content because this organic compound is
transfer of the contaminant to the catalyst. The results from widely used as a raw material and disinfectant agent.31 There-
these experiments aer 60 min of NAP contact with NiO are fore, we use ethanol as an articial organic matter. High
shown in Fig. 1. At the pH 5.0 ꢁ 0.5, the maximum adsorption of proportions of ethanol in the solution allows studying the effect
NAP aer 60 min with 50% of ethanol was 7.4% while without of organic matter on the degradation of recalcitrant molecules
ethanol was of 4.5%. At the pH of 5.0, the NiO surface is posi- at trace levels. So far, few studies have analyzed the effect of
tively charged due to the formation of NiO–OH specie.
interfering compounds on the ozonation kinetics and on the
On the other hand, NiO zero potential is at pH 10.8 which is target compound decomposition efficiency. Here, the organic
bigger than the experimental pH.26 In our adsorption experi- matter inuence was evaluated with the mixtures ethanol/water
ments, the charge in the NiO surface might promote an elec- (0 : 100, 10 : 90, 30 : 70, 50 : 50 v/v).
trostatic interaction with the deprotonated molecules of NAP.
Fig. 2a depicts the variation of NAP concentrations as
The NAP deprotonation was incomplete as a consequence of the a function of the ethanol/water ratio in O3 treatment. Higher
NAP pKa of 4.16.27 Therefore, charge differences (positive for the ethanol concentrations (50% v/v) delayed NAP elimination to
NiO and slightly negative for the NAP) may explain the low 60% aer 3 min of treatment. In the experiments without
adsorption obtained in this study. On the other hand, Pacheco ethanol, the NAP elimination by O3 was 97.3% at the same time
28
´
and Martınez reported that the solubility of NAP is governed of reaction. According to the results shown in Fig. 2, NAP
by the solvation of the pharmaceutical with 30% of ethanol in degradation was slower if the ethanol proportion was larger,
the solution. Based on these results, NAP removal by adsorption independently of the catalyst presence. Despite ethanol nature
has not a signicant difference regarding the ethanol/water as a radical scavenger32 and its high concentrations (10, 30 and
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Fig. 2 NAP concentration profiles with 0, 10, 30 and 50% v of ethanol. (a) Conventional and (b) catalytic ozonation with NiO.
50% v), the NAP degradation was above 98% aer 15 min of NiO) have limited contribution efficiency of the model
treatment.
compound elimination. However, the radicals might be
The interference effect of ethanol in naphthalene elimina- involved in NAP byproducts degradation.
tion was reported by Aguilar et al.33 In the case of naphthalene,
3.3.1 Byproduct identied by ESI-MS-MS. All the NAP
the presence of 30% v/v of ethanol aer 60 min of O3-conv treated samples were evaluated by ESI-MS-MS. The analysis
degraded 99%, however, 50% v/v of ethanol reached only 66% of strategy considered samples with and without ethanol obtained
degradation. On the other hand, Ghauch et al.32 studied the at 5 and 60 min of O3-conv (the rst time was selected for the
interference of ethanol (as a $OH scavenger) on the NAP fastest NAP elimination without ethanol and the later time
degradation treated by thermally active persulfate. The persul- corresponding to the end of the reaction). In all samples, the
fate treatment reported 32% of NAP elimination with ethanol NAP ion (229.09 m/z) was not detected. However, ten ion signals
compared to 82% without ethanol aer 60 min. Therefore, appeared in ESI-MS analysis in negative mode.
ethanol presence affects contaminants degradation efficiency as
The absence of the NAP ion and the detection of some other
a result of ethanol scavenger activity attributed to its reaction ions demonstrated that NAP molecule has been transformed into
with $OH (k ¼ 1.9 ꢃ 109 Mꢀ1 sꢀ1).34
its byproducts without reaching complete mineralization in all
The catalytic effect of NiO in the NAP degradation appears in treatments. In the absence of ethanol, the ESI-MS technique
the Fig. 2b. Both O3-conv and O3–NiO degraded NAP with identied the signals corresponding to four specic ions that
a similar degradation rate despite the ethanol concentration. appeared in both treatments with and without the catalyst:
The latter indicates that direct ozonation mechanism governs 133.06, 149.06, 177.06, and 237.11 m/z. Furthermore, the ion with
NAP degradation.
221.04 m/z was only detected in O3-conv. In the case of the O3–
NiO, it was the 217.08 m/z. All these ions corresponded to the
In summary, the presence of ethanol showed two effects:
(a) The presence of ethanol inhibited the NAP elimination, byproducts formed along the rst 5 min of NAP degradation.
which increased if high (30 and 50%) proportions of alcohol are
in the ozonation system.
The ESI-MS technique did not detect any byproduct in the
samples taken at 60 min without ethanol. If ethanol was in the
(b) The presence of catalyst did not change the NAP reaction, the analysis of ESI-MS aer 60 min of treatment detected
concentration proles in comparison with conventional ozon- similar peaks observed in samples without alcohol at 5 min
ation. Recall that if the reaction rate of organic compound with (133.06, 149.05, 159.05, 177.05, 193.05, 205.09, 217.08, 221.04,
ozone did not change under the presence of catalyst, it is 237.11 and 249.11 m/z). The latter indicates that the same reaction
feasible that ozone reacts intensively with the contaminants pathway might regulate the O3-conv and O3–NiO systems.
(direct reaction mechanism). By this reason, there was not an
Table 1 shows the ions detected by the ESI-MS-MS during the
evident effect of catalyst on the NAP ozonation. However, the NAP degradation (Fig. S3 and S4†). Compound with 217.08 m/z is
reaction of ozone and catalyst produces $OH which promote the attributed to 1-(6-methoxynaphthalen-2-yl)ethylhydroperoxide.
byproducts elimination. Diverse publications demonstrated the This compound appears as an intermediary of NAP degradation
effect of catalyst in combination with ozone on the by photocatalytic21,37,38 and photolysis systems.20 The 217.08 m/z
intermediate.17,35,36
byproduct is generated by the loss of –COOꢀ from the propionic
ꢀ
acid substituent with a subsequent attack by O2 c.21,37 The
compounds 237.11, 221.11, 205.09, 177.06 and 149.06 m/z sug-
gested molecules with a single aromatic ring. The presence of
these ions demonstrated the oxidation capacity of O3-based
treatments for breaking down one of the aromatic rings of NAP.
These single aromatic ring structures have not been reported
before by any other oxidation processes.
3.3 Identication of byproducts obtained during NAP
ozonation
In all the degradation experiments (Fig. 2), O3–NiO decomposes
the initial contaminant equally faster than O3-conv. This may
indicate that radicals (including $OH which are provided by O3–
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Table 1 Ions m/z detected in ESI-MS-MS analysis (negative mode) in samples of NAP degradationa
Error
Abundance
Compound
Structure
Formula [M–H]ꢀ (ppm) mSigma (%)
2-(3-(Hydroxymethyl)-4-(2-methoxyethyl)phenyl)propanoic
acid
1
C13H18O4 237.1125
3.1 2.9
3.6
2.5
2 2-(4-(2-Mmethoxyethyl)-3-methylphenyl)propanoic acid
3 1-(6-Methoxynaphthalene-2-yl)ethylhydroperoxide
C13H18O4 221.1153 15.9 1.2
C13H14O3 217.0852
8.2 9.4
1.6
4 2-(4-(2-Hydroxyvinyl)phenyl)acetic acid
5 2-(4-(2-Hydroxyvinyl)phenyl)acetic acid
C12H14O3 205.0833 ꢀ18.0 9.8
2.0
3.2
C10H10O3 177.0554
1.7 12.4
6 2-(p-Tolyl)acetic acid
C9H10O2 149.0592 ꢀ10.8 8.5
1.8
a
Error [ppm]: absolute value of the deviation between measured mass and theoretical mass of the selected peak in [ppm]. mSigma: combined value
for the standard deviation of the masses and intensities for all peaks, given in [milliSigma].
It is known that short chain organic acids are the main
products of conventional ozonation treatments. These acids
accumulated due to their low constants reaction rates with
ozone.39 In this study, the oxalic acid was the main product in all
the studies systems (Fig. 3b). The proles of oxalic acid
concentration had an accumulative tendency in the presence of
ethanol. In the higher ethanol concentration (50% v/v), the
oxalic acid duplicates its presence in comparison with treat-
ments with 30% v/v of ethanol aer 60 min. The experiments
with 10% v/v of ethanol produced 20 mg Lꢀ1 of oxalic acid,
which is about the half of the obtained with 30% v/v of ethanol.
The proportional increments of oxalic acid with respect to
ethanol concentrations indicate that ethanol degradation
contributed to this organic acid accumulation. In absence of
ethanol, the oxalic acid contribution was from the byproducts
generated from the NAP degradation. Several studies suggest
that the oxalic acid is the product of the attack to NAP0 pro-
pionic acid. Jallouli et al.4 proposed that the oxalic acid
formation is due to the breakout of the 3-carbon fragment in the
NAP molecule which transforms the carboxylic link into malic
acid (4-atom carbon acid). In consequence, the decomposition
of malic acid leads to the formation of oxalic acid.
3.3.2 Final product identied by HPLC. In both O3-conv
and O3–NiO, the non-identied compound (with a retention time
(RT) of 12.9 min HPLC) showed the effect of ethanol (Fig. 3a). In
the presence of 50% v/v of ethanol, the higher intensity of the
non-identied compound appeared around 10 min. However, in
the ethanol concentration of 30% v/v, the time for the higher
intensity value changed to 5 min. In absence of ethanol, the
greater accumulation of this compound occurred aer 3 min of
reaction. It was concluded that larger ethanol concentrations
increase the time when the maximum byproduct accumulation
happens. The byproduct elimination is also inuenced by the
ethanol concentration. In reactions with higher ethanol
concentrations (30 and 50% v/v), complete elimination of this
byproduct was not observed even aer 60 min of treatment. The
samples collected at 60 min of O3-conv and O3–NiO treatments
achieved around 50, 70 and 95% elimination for this byproduct
with 50, 30 and 10% v/v of ethanol, respectively. When the
solution did not contain the ethanol, the complete removal of
this byproduct was achieved aer 10 min of ozonation (six times
lower than the time obtained with 10% v/v of ethanol). The
observed inhibitory effect was a consequence of the reaction
between ozone and ethanol. The presence of NiO did not modify
the byproduct prole in comparison with O3-conv. This fact was
conrmed independently of the ethanol concentration.
The O3–NiO treatment produced higher concentrations of
oxalic acid than the O3-conv. The most important difference
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Fig. 3 Dynamics of (a) non-identified compound (12.9 min of RT) and (b) oxalic acid a different ethanol/water ratio by conventional and catalytic
ozonation. Inset: oxalic acid concentration without ethanol in the first five min of reaction.
between oxalic acid concentration in O3-conv and O3–NiO
The TOC analysis, for NAP degradation without ethanol,
treatments appeared in mixtures with 30 and 50% v/v of ethanol showed a 12.3% of TOC removal in O3-conv at 60 min (Fig. 5b).
in the rst minutes of reaction (Fig. 3b). The treatments without The percentage removal increased with the use of NiO (34.1%).
ethanol produced the maximum oxalic acid concentrations. In These results proved the effectiveness of the catalyst in the NAP
the case of the O3–NiO treatments, oxalic acid was approxi- and its intermediaries' elimination. The increment of the
mately 10.8 mg Lꢀ1, meanwhile, O3-conv generated 3.6 mg Lꢀ1 ozonation time up to 120 min forced the mineralization incre-
both in the 3 min of reaction (inset in Fig. 3b). The difference in ment by the effect of the catalyst. The use of NiO increased the
the oxalic acid concentration was attributed to the presence of TOC removal from 23.5% by O3-conv to 48.1% at 120 min.
NiO. The dissimilarities of organic acids production as a func- According to Zhang et al.41 the NiO in ozonation induces $OH
tion of the catalysts in advanced oxidations processes was also production. The $OH production obtained from NiO is justied
reported by Fuentes et al.40 in the terephthalic acid degradation by the interaction of the actives sites on the catalyst with ozone
by the photocatalytic ozonation with VxOy/TiO2.
as Ni(OH)2–O–H which is produced by the interaction with the
Considering the byproducts identication (HPLC and ESI- adsorbed water. The $OH generated by the catalyst contributed
MS-MS) and TOC analysis, the NAP degradation pathway was to the decomposition of NAP, its intermediaries, and the accu-
proposed (Fig. 4). The ESI-MS-MS ions analysis (Table 1) leads to mulated products. This contribution depends on the $OH
propose some byproducts having only one aromatic ring. The concentration obtained in presence of the catalyst during the
NAP ring-cleavage corresponds to the rst general stage in the ozonation. One common manner to evaluate the $OH contri-
identied degradation pathway. Such NAP degradation pathway bution is adding a strong radical scavenger.32,42 The presence of
has not been described by any other authors. On the other $OH in catalytic ozonation was demonstrated by the use of TBA
hand, the ion 218.08 m/z (detected by ESI-MS-MS analysis) has as a scavenger.
been previously reported.37,38 The similarity of molecular
Fig. 5b shows the TOC analysis of NAP catalytic ozonation
weights between NAP and this byproduct justied the modi- (60 min of reaction) in samples without ethanol and in presence
cation of the carboxylic acid substituent. In this degradation of TBA (200 mg Lꢀ1). The TOC removal was 19% at the end of
way, no changes in the aromatic ring can be assumed. This the ozonation. This removal was 6.64% higher than the
byproduct was introduced as part of a secondary pathway in the conventional treatment and 15% smaller than the TOC removed
degradation process of NAP. In both treatments (O3-conv and for the catalytic system. The TOC reduction in samples with TBA
O3–NiO) the oxalic and formic acid detection demonstrated the demonstrates the $OH generation by NiO. This production
breakdown of the NAP molecule. The TOC study conrmed contributed to the NAP degradation as well as the byproducts
partial mineralization in the system (Section 3.4).
mainly.
On the other hand, Pocostales et al.43 reported a manner to
know the average oxidation stated of the carbon atoms (AOSC)
from the results of TOC and COD. The AOSC value satises the
expression (7).
3.4 Chemical oxygen demand and total organic carbon
removals
Fig. 5a shows the COD analysis of NAP samples without ethanol
in the O3-conv and O3–NiO. The addition of the NiO diminished
the COD at 84% in comparison with the 27% obtained with O3-
conv. These results conrmed that NiO contributed to elimi-
nating the NAP through radical species generation. The samples
collected at 60 min without ethanol did not present signicant
COD differences with the results of samples at 5 min due to
recalcitrant byproducts in the reaction.
COD
AOSC ¼ 4 ꢀ 1:5
(7)
TOC
The lower AOSC values determine the lower oxidation state
of organic matter present in the solution. The AOSC results are
in the interval of +4 to ꢀ4 (examples of carbon dioxide and
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Fig. 4 Reaction pathway proposed for the degradation of NAP in samples with ethanol by conventional and catalytic ozonation.
methane AOSC values, respectively).43 Fig. 5c presents the AOSC like the values of initial samples, while the reaction in presence
from the samples of O3-conv and O3–NiO at 60 min of treat- of NiO increased this parameter to 3.68. These results demon-
ment. The single ozonation had AOSC values of 2.86, which are strated that the initial compound was removed by O3-conv. On
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Fig. 5 (a) COD concentration, (b) TOC analysis ([NAP + TBA]0 ¼ 319.84 mg C Lꢀ1, [NAP + TBA]t¼60 min ¼ 259.22 mg C Lꢀ1) and (c) AOSC results (at
60 min) of the degradation of NAP in samples without ethanol by conventional and catalytic ozonation.
the other hand, the refractory compounds produced by ozone to O2ꢀ in NiO, alongside with the known peak for oxygen in
were eliminated by the catalyst action ($OH or/and surface defective sites of nickel oxide, NiOdef, at 530.9 eV.44 A further
oxidation reactions).
peak at 531.0 eV for oxygen in Ni(OH)2 was included. The
intensity ratio of NiO and NiOdef to Ni(OH)2, was intentionally
xed to the same value seen for the same species in the Ni 2p
region; in this case is 2 with a good tting (Fig. 6b). This result
mutually supports each other. In the C 1s region are the carbon
associated specie incorporated in the O 1s ttings (Fig. 6c).
Aer 60 min reaction time, Fig. 6d–f, the overall nickel to
carbon intensity ratio is very close to that aer 30 min. Also, the
intensity ratio NiO/Ni(OH)2 is now 3.3 in the Ni 2p3/2 region, as
well as in the corresponding O 1s region. In the C 1s, there is the
distribution of carbon-associated species similar to the one
observed aer 30 min. Next, the reaction medium was enriched
in ethanol up to a 50 : 50 v/v mixture ratio with water. Aer
30 min reaction time, Fig. 6g and h, the intensity ratio NiO/
Ni(OH)2 reached the lowest value at 1.6. In the 60 min of
treatment, it increased up to 2.3 Fig. 6j and k.
3.5 XPS analysis
To investigate the effect of the reaction medium, 30 : 70 and
50 : 50 ethanol/water mixtures were selected because of their
interference effect in the elimination of NAP's intermediaries.
First, the ozonation was carried out in a water rich mixture of
30 : 70 volume ratio. Aer 30 min, a catalyst sample was
analyzed as showed in Fig. 6a–c.
Spectrum (a) shows the entire Ni 2p region. The main
structure, 2p3/2, was tted according to the model proposed by
Biesigner et al.44 For sake of clarity, satellite peaks are the
dashed line style while the main photoelectron peaks have
continuous line style. The most intense peak shows up at
553.6 eV correspond to Ni2+ in NiO. The second peak at 855.7 eV
(and satellite) was necessary to t correctly the raw data, it
correlates very close to the binding energy for nickel hydroxide,
Ni(OH)2.45 The intensity ratio of NiO/Ni(OH)2 is 2.0.
The distribution of carbon species was scarcely inuenced by
the reaction time, as seen aer 60 min in Fig. 6l. Similarly, the
richer ethanol medium did not inuence carbon species.
However, the overall nickel to carbon intensity ratio is the
The O 1s region is tted with peaks for oxygen species
associated with carbon. The main peak at 529.1 eV corresponds
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Fig. 6 High resolution XPS spectra for catalyst samples recovered from ozonation reactions of NAP. The first reaction was carried out in a 30 : 70
mixture volume ratio: (a–c) 30 and (d–f) 60 min reaction time. For the second reaction a 50 : 50 mixture was used: (g–i) 30 and (j–l) 60 min
reaction time.
highest at 30; compared to a ratio of 15 for 30 min reaction time.
It was observed that the added ethanol helped to keep the nickel (1) and (2) was suitable to compare the relative efficiency of each
catalyst surface from carbonaceous accumulation. ozonation system (including the effect of ethanol) considered in
The mathematical structure of the reactions proposed in eqn
XPS results show that ethanol presence did not change the this study. The rst result of the kinetic analysis was the decom-
chemical environment on catalyst when the NAP elimination position dynamics of NAP. It was determined (constant kinetic
took place. A preliminary study demonstrated that the naph- reaction decreased 87.5%) by the presence of 10% v/v ethanol
thalene ozonation with ethanol as cosolvent generated Ni- while the catalyst showed a less important effect on the ozonation
carbonaceous on the catalyst (conrmed by XPS). In conse- reaction rate. In the ethanol concentration of 50% v/v, the NAP
quence, the initial compound is a key factor to explain the decomposition reaction rate was the smallest (considering the
catalyst (NiO) surface modications during the ozonation.
ethanol concentration as the comparison variable) despite the
presence of the catalysts. The reduction of ethanol concentration
to 30% v/v increased the constant kinetic reaction 8 times for the
O3–NiO and 16 times for the O3-conv. This difference is a conse-
quence of the $OH scavenger nature of ethanol which affects the
catalytic process, (Fig. S5 and S6†). However, the reaction rates
were similar (0.0851 and 0.0845 sꢀ1) despite the presence of the
catalytic. The similarity of reaction rates between the O3-conv and
O3–NiO keep if the ethanol concentration decreased to 10% and
the 0%. These results conrmed that the kinetic rate constants
depend on ethanol concentration.
3.6 Kinetic study of NAP decomposition and byproducts
dynamics
The solution of the method proposed in (5) yields to charac-
terize the decomposition of NAP. The same method was also
used to describe the decomposition and accumulation of
byproducts formed through out ozonation. Table 2 incorporates
a summary of all RRC and correlation coefficients. The higher
values of all the correlation factors prove that the simplied
model proposed in this study can be used to characterize the
kinetic reactions.
The kinetic rate constants of the non-identied compound
(RT ¼ 12.9 min) was also determinate for all the studied
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Table 2 Reaction rate constants and statistical analysis determined for the conventional and catalytic ozonation processes under different
ethanol concentrationsa
Byproduct compound (12.9 min of
RT) kIC (sꢀ1
)
Ethanol (% v)
Treatment
Naproxen kNAP (sꢀ1
)
Oxalic acid kOA (sꢀ1
)
Accumulation
Degradation
0
O3 conv
O3–NiO
O3 conv
O3–NiO
O3 conv
O3–NiO
O3 conv
O3–NiO
0.144 (0.986)
0.167 (0.952)
0.126 (0.979)
0.143 (0.926)
0.085 (0.936)
0.085 (0.925)
0.005 (0.956)
0.010 (0.977)
0.025 (0.933)
0.013 (0.946)
1.251 (0.966)
1.569 (0.915)
4.414 (0.956)
4.907 (0.932)
7.696 (0.966)
6.166 (0.923)
0.990 (0.914)
0.976 (0.966)
0.895 (0.975)
0.886 (0.974)
0.770 (0.984)
0.813 (0.921)
0.976 (0.924)
0.305 (0.890)
0.091 (0.946)
0.086 (0.937)
0.060 (0.966)
0.053 (0.957)
0.025 (0.967)
0.022 (0.896)
0.015 (0.934)
0.014 (0.915)
10
30
50
a
The correlation data are presented in parentheses.
systems. The increment of the non-identied compound RRC
has the same tendency that NAP decomposition. The accumu-
lation kinetics rate constant of the non-identied compound in
presence of the catalyst showed a variation of 320% between the
reaction rate with 50% v and without ethanol.
4. Conclusions
The nal remarks of this study are:
ꢄ The NAP degradation by O3-conv and O3–NiO in solutions
with (10, 30 and 50% v/v) and without ethanol was reached aer
15 min of treatment. The increment of ethanol concentration
(used to emulated organic matter) reduced the reaction rate of
NAP elimination, only during the initial period (5 min) of the
reaction. This fact serves as an indirect conrmation of the
inhibitory effect by ethanol in the catalytic ozonation of NAP.
ꢄ The byproducts analysis (ESI-MS-MS) suggested the NAP
degradation by two pathways. The rst pathway considers the
attacking and breaking of the aromatic ring in the NAP
(byproducts not described by other authors). The second
manner suggested changes in the propionic acid substituent
without breaking the aromatic structure. Without ethanol, the
detected byproducts appeared only in the rst 5 min of reaction.
All these results conrmed that ethanol in the samples inter-
fered on the degradation of the byproducts formed aer 60 min
of ozonation. The byproducts remained in the solution aer
this reaction time.
ꢄ The NiO effect was scarcely observed in the NAP degrada-
tion proles. However, the oxalic acid had a different behavior
depending on the ozonation system (conventional or catalytic).
In samples without ethanol, the NiO presence increased 25%
the mineralization degree in comparison with conventional
ozonation (2 h of reaction).
ꢄ The AOSC analysis conrmed the higher oxidation of
organic matter with the catalyst. The TBA study conrmed the
production of $OH by the NiO in the treatment, promoting an
indirect mechanism of the reaction.
The higher concentration of ethanol in the ozonation
showed the slower reaction rates to decompose the NAP and its
intermediary. This reaction condition yields to the larger rate to
accumulate oxalic acid. When the O3-conv was evaluated, the
accumulation kinetic rate constants of oxalic acid was 0.025 sꢀ1
without ethanol. In the case of the ethanol concentration of
50% v/v, kinetic rate constants increased around 308% (k ¼
7.696 sꢀ1). The O3–NiO produced the increment in kinetic rate
constants from 0.013 to 6.166 sꢀ1 under the ethanol proportions
of 0 and 50% v/v, respectively. The signicant differences in
accumulation rate constants for oxalic acid with respect to the
decomposition rates for the non-identied compound demon-
strated that ethanol was also transformed to oxalic acid by the
ozonation, independently of the catalyst presence.
Taking into consideration the results obtained for NAP
removal as well as the non-identied compound and oxalic acid
production, ethanol strongly affects the ozonation efficiency.
This condition is more evident at the higher accumulation of
recalcitrant short chain organic acids. The removal of oxalic
acid was not detected in the ozonation reactions considered in
this study. This condition is rarely achieved in chemical
oxidation processes based on the application of conventional
ozone. The kinetic study was supported by the narrow correla-
tion factors obtained for all the reaction rate constants calcu-
lated by the method proposed in this study. All these values
were 0.90 or above.
In summary, the contribution of this researching study is the
conrmation of the full degradation of a NAP by O3-conv and
O3–NiO in presence of different concentrations of ethanol. This
strategy offers an alternative manner of using ethanol as an
articial organic matter. The effect of ethanol was characterized
as a retardant of the NAP and byproducts elimination. Never-
theless, the O3–NiO increased the mineralization degree and
oxidation state of byproducts obtained from the NAP oxidation.
These byproducts were analyzed by the ESI-MS-MS.
Conflicts of interest
There are no conicts to declare.
Acknowledgements
The author thanks the Eng. David Dominguez for the XPS
support, Denisse Fabiola Gonzalez Ramırez, Iveete Cecilia
´
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Guzman Rodrıguez and the institutions UNAM PAPIIT 23 R. Rosal, A. Rodrıguez, M. S. Gonzalo and E. Garcıa-Calvo,
´
´
1N105114, 1N107715 and Instituto Politecnico Nacional-Mexico
Appl. Catal., B, 2008, 84, 48–57.
(Project: SIP 20180459, SIP 20195237, SIP 20195998) for the 24 E. Cruz-Zavala, J. A. Moreno and L. M. Fridman, IFAC
economic support.
Proceedings Volumes, 2011, 44, 3039–3044.
25 J. A. Moreno and M. Osorio, 2008.
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26 N. Hernandez, R. Moreno, A. J. Sanchez-Herencia and
Reference
J. L. G. Fierro, J. Phys. Chem. B, 2005, 109, 4470–4474.
1 E. Carraro, S. Bonetta, C. Bertino, E. Lorenzi and G. Gilli, J.
Environ. Manage., 2016, 168, 185–199.
´
´
´
ˇ
27 S. Babic, A. J. M. Horvat, D. Mutavdzic Pavlovic and
ˇ
M. Kastelan-Macan, TrAC, Trends Anal. Chem., 2007, 26,
2 J. C. Park, J. Han, M. C. Lee, J. S. Seo and J. S. Lee, Aquat.
Toxicol., 2017, 189, 16–24.
1043–1061.
´
28 D. P. Pacheco and F. Martınez, Phys. Chem. Liq., 2007, 45,
3 K. Grabicova, R. Grabic, G. Fedorova, J. Fick, D. Cerveny,
J. Kolarova, J. Turek, V. Zlabek and T. Randak, Water Res.,
2017, 124, 654–662.
581–595.
´
´
29 C. Gadipelly, A. Perez-Gonzalez, G. D. Yadav, I. Ortiz,
´˜
R. Ibanez, V. K. Rathod and K. V. Marathe, Ind. Eng. Chem.
4 N. Jallouli, K. Elghniji, O. Hentati, A. R. Ribeiro, A. M. T. Silva
and M. Ksibi, J. Hazard. Mater., 2016, 304, 329–336.
5 D. Muir, D. Simmons, X. Wang, T. Peart, M. Villella, J. Miller
and J. Sherry, Sci. Rep., 2017, 7, 16999.
Res., 2014, 53, 11571–11592.
30 A. Grossberger, Y. Hadar, T. Borch and B. Chefetz, Environ.
Pollut., 2014, 185, 168–177.
31 S. Sajedi-Amin, M. Barzegar-Jalali, A. Fathi-Azarbayjani,
6 R. Gibson, J. C. Duran-Alvarez, K. L. Estrada, A. Chavez and
B. Jimenez Cisneros, Chemosphere, 2010, 81, 1437–1445.
7 M. Gavrilescu, K. Demnerova, J. Aamand, S. Agathos and
F. Fava, New Biotechnol., 2015, 32, 147–156.
8 J. B. Quintana, S. Weiss and T. Reemtsma, Water Res., 2005,
39, 2654–2664.
9 R. Andreozzi, V. Caprio, A. Insola and R. Marotta, Catal.
Today, 1999, 53, 51–59.
10 B. Xu, F. Qi, J. Zhang, H. Li, D. Sun, D. Robert and Z. Chen,
Chem. Eng. J., 2016, 284, 942–952.
´
A. Kebriaeezadeh, F. Martınez and A. Jouyban, J. Mol. Liq.,
2017, 232, 152–158.
32 A. Ghauch, A. M. Tuqan and N. Kibbi, Chem. Eng. J., 2015,
279, 861–873.
33 C. M. Aguilar, J. L. Rodriguez, I. Chairez, H. Tiznado and
T. Poznyak, Environ. Sci. Pollut. Res. Int., 2017, 24, 25550–
25560.
34 G. V. Buxton, C. L. Greenstock, W. P. Helman and A. B. Ross,
J. Phys. Chem. Ref. Data, 1988, 17, 513–886.
35 J. L. Rodriguez, M. A. Valenzuela, T. Poznyak, L. Lartundo
and I. Chairez, J. Hazard. Mater., 2013, 262, 472–481.
36 B. Xu and F. Qi, Clean: Soil, Air, Water, 2016, 44, 1099–1105.
11 Z. Song, Y. Zhang, C. Liu, B. Xu, F. Qi, D. Yuan and S. Pu,
Chem. Eng. J., 2019, 357, 655–666.
12 Y. Zhang, Y. Xia, Q. Li, F. Qi, B. Xu and Z. Chen, Sep. Purif.
Technol., 2018, 197, 261–270.
13 J. Nawrocki and B. Kasprzyk-Hordern, Appl. Catal., B, 2010,
99, 27–42.
14 S. Esplugas, D. M. Bila, L. G. T. Krause and M. Dezotti, J.
Hazard. Mater., 2007, 149, 631–642.
´
37 N. Jallouli, L. M. Pastrana-Martınez, A. R. Ribeiro,
N. F. F. Moreira, J. L. Faria, O. Hentati, A. M. T. Silva and
M. Ksibi, Chem. Eng. J., 2018, 334, 976–984.
38 F. Wang, Y. Wang, Y. Feng, Y. Zeng, Z. Xie, Q. Zhang, Y. Su,
P. Chen, Y. Liu, K. Yao, W. Lv and G. Liu, Appl. Catal., B,
2018, 221, 510–520.
15 B. Xu, F. Qi, D. Sun, Z. Chen and D. Robert, Chemosphere,
2016, 146, 22–31.
39 J. Feng, X. M. Zhang, J. S. Fu and H. L. Chen, Catal. Commun.,
2018, 110, 28–32.
´
16 J. L. Rodrıguez, M. A. Valenzuela, T. Poznyak, L. Lartundo
40 I. Fuentes, J. L. Rodriguez, T. Poznyak and I. Chairez,
Environ. Sci. Pollut. Res. Int., 2014, 21, 12241–12248.
41 X. Zhang, X. Li and W. Qin, Chem. Phys. Lett., 2009, 479, 310–
315.
42 S. Nasseri, A. H. Mahvi, M. Seyedsalehi, K. Yaghmaeian,
R. Nabizadeh, M. Alimohammadi and G. H. Safari, J. Mol.
and I. Chairez, J. Hazard. Mater., 2013, 262, 472–481.
17 D. Magallanes, J. L. Rodriguez, T. Poznyak, M. A. Valenzuela,
L. Lartundo and I. Chairez, New J. Chem., 2015, 39, 7839–
7848.
´
18 B. Kasprzyk-Hordern, M. Ziołek and J. Nawrocki, Appl. Catal.,
B, 2003, 46, 639–669.
Liq., 2017, 241, 704–714.
´
19 Z. Chen, N. Ren, A. Wang, Z.-P. Zhang and Y. Shi, Water Res.,
2008, 42, 3385–3392.
´
43 P. Pocostales, P. Alvarez and F. J. Beltran, Chem. Eng. J., 2011,
168, 1289–1295.
´
´
20 E. Arany, R. K. Szabo, L. Apati, T. Alapi, I. Ilisz, P. Mazellier,
A. Dombi and K. Gajda-Schrantz, J. Hazard. Mater., 2013,
262, 151–157.
44 M. C. Biesinger, B. P. Payne, L. W. M. Lau, A. Gerson and
R. S. C. Smart, Surf. Interface Anal., 2009, 41, 324–332.
45 B. P. Payne, M. C. Biesinger and N. S. McIntyre, J. Electron
Spectrosc. Relat. Phenom., 2009, 175, 55–65.
¨
21 D. Kanakaraju, C. A. Motti, B. D. Glass and M. Oelgemoller,
Chemosphere, 2015, 139, 579–588.
´
´
22 F. Mendez-Arriaga, S. Esplugas and J. Gimenez, Water Res.,
2008, 42, 585–594.
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