Degradation of a veterinary pharmaceutical product in water by electro-oxidation using a BDD anode

Article abstract of DOI:10.4067/S0717-97072014000200024

The electrochemical oxidation (EO) treatment in water of Fantetra, a veterinary drug widely used in Chile, and its components: oxytetracycline hydrochloride, phtalylsulfathiazole and diphenhydramine, has been carried out at constant current using a BDD/Stainless steel system. First, solutions of each drug were electrolyzed following the decay of the absorbance of each compound and total organic carbon abatement. The mineralization of the Fantetra commercial formulation was also studied. An analysis of the degradation by-products was made by high performance liquid chromatography. Thus, during the degradation of each pharmaceutical by the electrochemical oxidation process, aliphatic carboxylic acids were detected prior to their complete mineralization to CO₂ and nitrogen ions, while NO₃^- and NH₄⁺ remain in the treated solution. This is an essential preliminary step towards the applicability of the EO processes for the treatment of wastewater containing pharmaceutical compounds.

Full text of DOI:10.4067/S0717-97072014000200024

J. Chil. Chem. Soc., 59, Nº 2 (2014)
DEGRADATION OF A VETERINARY PHARMACEUTICAL PRODUCT IN WATER BY ELECTRO-OXIDATION
USING A BDD ANODE
C. ESPINOZA, N. CONTRERAS, C. BERRÍOS, R. SALAZAR*
Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Casilla 40, Correo 33, Santiago, Chile
Paper submitted to be published in The Journal of The Chilean Chemical Society
In honor of professor L J. Núñez-Vergara
ABSTRACT
The electrochemical oxidation (EO) treatment in water of Fantetra, a veterinary drug widely used in Chile, and its components: oxytetracycline hydrochloride,
phtalylsulfathiazole and diphenhydramine, has been carried out at constant current using a BDD/Stainless steel system. First, solutions of each drug were electrolyzed
following the decay of the absorbance of each compound and total organic carbon abatement. The mineralization of the Fantetra commercial formulation was also
studied. An analysis of the degradation by-products was made by high performance liquid chromatography. Thus, during the degradation of each pharmaceutical
-
by the electrochemical oxidation process, aliphatic carboxylic acids were detected prior to their complete mineralization to CO and nitrogen ions, while NO and
2
3
+
NH4 remain in the treated solution.
This is an essential preliminary step towards the applicability of the EO processes for the treatment of wastewater containing pharmaceutical compounds.
Keywords: Oxytetracycline; phthalylsulfathiazole; diphenhydramine; boron-doped diamond electrode; mineralization.
1
. INTRODUCTION
doped diamond (BDD) thin film in EO provides total mineralization with high
21
current efficiency for different organics in real wastewater. The BDD anode
is the best non-active electrode because it does not provide any catalytically
active site for the adsorption of reactants and/or products in aqueous media,
and for this reason it has been proposed as the preferable anode for treating
The wide range of products of the pharmaceutical industry has attracted
attention in recent years due to their adverse effects on natural organisms and
possible effects on human beings, and they are classified as pollutants when
1
22
found in high concentrations in water and soil. Different types of persistent
organics by EO. Moreover, the BDD electrode has several properties such as
organic pollutants (POPs) are introduced in the environment daily, coming
from a variety of sources such as effluent treatment plants and others. In the
an extremely wide potential window in aqueous and non-aqueous electrolytes,
an inert surface with low adsorption properties, remarkable corrosion stability
2
2
3
case of pharmaceuticals the main sources are wastewater treatment plants in the
even in strongly acidic media, and extremely high O evolution overvoltage.
2
3
pharmaceutical industry, hospitals, and farming.
Fantetra is a drug widely used in Chile as intrauterine tablets, serving
24
Recent studies confirm the presence of pharmaceutical products in
for placenta retention in large animals such as cattle, pigs and sheep. The
active compounds in the Fantetra capsules are oxytetracycline hydrochloride,
phtalylsulfathiazole, and diphenhydramine hydrochloride. Oxytetracycline is
a common antibiotic, one of ten antimicrobials licensed as growth promoters
for livestock in the United States. In general, tetracyclines are the second most
important group of antibiotics, both in terms of global production and use.
Phthalylsulfathiazole is part of the family of sulfonamides and is medically
listed as antidiarrheal or intestinal anti-infective, besides being the second most
4
groundwater, surface water, and even drinking water. For this reason, the need
to find satisfactory water treatment methods became a priority for the reduction
or elimination of drugs, which are defined as POPs) because their presence
5
,6
causes bacterial resistance.
In this sense, electrochemical advanced oxidation processes (EAOPs),
together with traditional oxidation methods, represent a potential way to
achieve greater efficiency in the decontamination of wastewater containing
7
,8
25
organic pollutants like pharmaceuticals. The most popular EAOPs used
for improving wastewater containing organic pollutants are electrochemical
most used veterinary antibiotic in Europe. Diphenhydramine hydrochloride,
whose function is to act as an antihistamine, sedative and hypnotic, is used
9
,10
11,12
13
26
oxidation (EO) , electro-Fenton (EF) , electro catalysis (EC), and
in the treatment of allergies, rhinitis, allergic conjunctivitis, and urticaria.
1
4,15,16
photoassisted systems like photoelectron-Fenton (PEF)
and photoelectron
The particular persistence of these pharmaceuticals in natural waters is mainly
related to their low biodegradability, and they have also shown high toxicity
13
catalysis (PEC) . Of the EAOPs, EO is actually the most widely used method
because it allows the treatment of highly toxic waste, converting completely
6
with mutagenic and carcinogenic effects.
1
7-1819
the pollutants present in it into carbon dioxide
. The EO process occurs
For these reasons, there is great interest in the use of diverse methods
with enough capability to mineralize persistent drugs in aqueous media to
avoid their dangerous accumulation in the aquatic environment. Studies on
the elimination of oxytetracycline hydrochloride, phtalylsulfathiazole, and
by direct reaction of pollutants present in the wastewater with physisorbed
·
hydroxyl radicals ( OH) electrogenerated from water discharge at the anode
surface (M):
diphenhydramine hydrochloride using different methods have been published
·
+
-
27-282930
M + H O → M( OH) + H + e
(1)
in recent years.
However, there are no studies about the removal of these
2
three drugs simultaneously or from a commercial drug.
·
The physisorbed hydroxyl radicals M( OH) react with the pollutants to
The aim of this work was to study the electrooxidation of Fantetra at
constant current density using a BDD/Steel system. Electrooxidation of each
active ingredient was studied independently, and then the degradation of the
drug in a mixture prepared in the laboratory and directly from the commercial
formulation was also investigated. The abatement of total organic carbon in
solutions of each compound and the intermediary compounds formed during
the abatement process were identified and quantified.
give fully oxidized reaction products such as CO according to the reaction
2
·
-
+
aM( OH) + R + ye
→ aM + mCO + nH O + xH
(2)
2
2
where R is an organic compound with m carbon atoms. Thus, organic
pollutants are completely mineralized to CO , water and inorganic salts. For
2
this reason, the EO method is called “electrochemical combustion”. The
hydroxyl radical has a high standard potential (E = 2.80 V vs. SHE), ensuring
0
2. EXPERIMENTAL
its fast reaction with most organics, producing dehydrogenated or hydroxylated
derivatives up to conversion into CO2.
2.1. Chemicals
Oxytetracycline
Both the electrochemical generation and chemical reactivity of
hydrochloride
((4S,4aR,5S,5aR,6S,12aS)-4-
·
20
heterogeneous M( OH) are dependent on the nature of the electrode material.
(dimethylamino)-3,5,6,10,11,12a-hexahydroxy-6-methyl-1,12-dioxo-
1,4,4a,5,5a,6,12,12a-octahydrotetracene-2-carboxamide hydrochloride, OTC),
95% purity ( Sigma-Aldrich) was used as received. Phthalylsulfathiazole
Thus, a non-active anode is required for the oxygen evolution reaction, because
·
this kind of electrode interacts very weakly with OH. The use of a boron
2
507

J. Chil. Chem. Soc., 59, Nº 2 (2014)
2
-(((4-[(1,3-thiazol-2-ylamino) sulfonyl) phenyl) amino) carbonyl] benzoic
2.2. Electrochemical system
acid, PhSTZ 99%, and diphenhydramine, 2-diphenyl methoxy)-N,N-
dimethylamine hydrochloride, DPH 99%, were supplied by Dispert S.A and
were used as received. The chemical structure and some characteristics of the
antibiotics studied are shown in Table 1. Fumaric, maleic, oxalic and oxamic
acids were analytical grade (Sigma-Aldrich). Solutions of anhydrous sodium
sulfate (analytical grade, Merck) prepared with distilled water previously
deionized and with its pH adjusted with 1.0 M analytical grade sulfuric acid or
sodium hydroxide (both Merck) were used as supporting electrolyte. Organic
solvents and other chemicals used in the analysis procedure were either HPLC
or analytical grade from Merck or Sigma-Aldrich.
Volumes of 0.1 L of each pharmaceutical solution were introduced into
a single compartment electrolytic cell with constant stirring at 25 ºC. A BDD
thin film (on Si) electrode from Adamant Technologies was used as anode and
2
an AISI 304 stainless steel plate as cathode, both 5 cm geometric area, with
-1
1.0 cm of interelectrode gap. Solutions of each drug containing 100 mg L of
total organic carbon were prepared in 0.1 M Na SO to provide enough ionic
2
4
-2
strength at pH 7.0 were treated by EO at a current density (j) of 50 mA cm ,
resulting in average cell voltages of 13.0 (±0.3) V.
Table 1. Chemical structure and characteristics of the degraded pharmaceuticals.
2
.3. Apparatus and analytical procedures
taken according to the mineralization reactions as 104 for OTC (reaction 4), 98
for PhSTZ (reaction 5) and 92 for DPH (reaction 6), considering the complete
Galvanostatic electrolyses were performed with an MCP model M10-
QD305 power supply which also displayed the cell voltage. The pH was
measured with a HANA Instrument pH-meter Model HI8424. During the
electrolysis, samples were withdrawn at regular time intervals from the solution
kept in the cell and then refrigerated until performing the analytical procedures.
The degree of mineralization was monitored from total organic carbon (TOC)
determined with a Vario TOC Select (Elementar) analyzer. Reproducible TOC
values with an accuracy of ±1% were always found injecting 500 µL aliquots
in the analyzer. From these data, the mineralization current efficiency (MCE)
–
–
mineralization to CO , SO and NO3 ions from the following reactions:
2
4
+
–
C H N O + 41 H O → 22 CO + 106 H + 2 NO + 104e
(4)
2
2
24
2
9
2
2
3
+
–
–
C H N O S + 46 H O → 17 CO + 105H + 3 NO + 2SO4 + 98e (5)
C H NO + 36 H O → 17 CO + 93 H + NO + 92e
1
7
13
3
5
2
2
2
3
+
–
(6)
1
7
21
2
2
3
The aliphatic carboxylic acids obtained as intermediary products were
identified and quantified by ion-exclusion chromatography using a Waters
625 Chromatograph with diode array detector 2966, fitted with a Bio-Rad
Aminex HPX 87H, 30 cm x 7.8 mm (i.d.), column at 35 ºC, at · = 210 nm.
3
1,32
for each treated solution was then calculated from Eq. (3):
-1
The mobile phase was 4 mM H SO at 0.6 mL min . The corresponding
2
4
(3)
calibration curves were constructed using pure acid samples. Absorption
peaks with retention times (t ) of 7.1 min for oxalic, 8.8 min for maleic, 10.1
R
min for oxamic, 15.0 min for fumaric, and 15.7 min for acetic acids were
obtained in the corresponding chromatograms. Released inorganic ions were
quantified by ionic chromatography by injecting 50 µL aliquots in a Waters
600 chromatograph equipped with a 600 controller pump and a Waters 431
where n is the number of electrons consumed in the mineralization of
-1
the respective pharmaceutical, F is Faraday’s constant (96487 C mol ), V is
s
-1
the solution volume (L), D(TOC)exp is the experimental TOC decay (mg L )
evaluated as the difference between the initial value and that analyzed at time
–
-
conductivity detector. The NO3 and Cl concentrations in the electrolyzed
solutions were determined using an IC-Pak AHR, 75 mm × 4.6 mm (i.d.), anion
7
-1
-1
t, 4.32· 10 is a conversion factor (3600 s h · 12000 mg of C mol ), I is the
applied current (A), t is the electrolysis time (hours), and m corresponds to
the number of carbon atoms present in the pharmaceutical molecules, which
are 22, 17 and 17 for OTC, PhSTZ and DPH, respectively. The n-values were
-1
column at 35 ºC and a mobile phase of borate/gluconate at 1.0 mL min . The
+
NH4 formation was determined with an IC-Pak C M/D, 150 mm × 3.9 mm
-1
(
i.d.) cation column at 25 ºC and 0.1 mM EDTA/3.0 mM HNO at 1.0 mL min
3
as mobile phase.
2
508

J. Chil. Chem. Soc., 59, Nº 2 (2014)
2
.4. Simultaneous degradation of pharmaceuticals.
Fantetra tablet weights of 4.10 ± 0.11 g containing 0.50 g of OTC, 2.00 g
of PhSTZ and 0.02 g of DPH were usede. Solutions of Fantetra were prepared
-1
dissolving 100 mg L of tablet in 0.1 L of 0.1 M Na SO at pH 7.0. The
2
4
composition of the solution was 12.4 mg of OTC, 49.5 mg of PhSTZ and 1.2 mg
of DPH. Electrolysis were performed in the same system as was used for each
separate drug. Moreover, a synthetic solution was prepared and electrolyzed
adding the same quantities of each component in 0.1 L of electrolytic solution.
The solution prepared in the laboratory will be called “Fantetra synthetic
solution (FSS)”, while the solution prepared from the commercial formulation
will be called “commercial Fantetra solution (CFS)”.
3
. RESULTS AND DISCUSSION
3
.1 Degradation and mineralization of each pharmaceutical separately.
The degradation and mineralization of OTC, PhSTZ and DPH was
studied independently by electrochemical oxidation using a BDD/Steel
-1
plate system. Thus, solutions with 100 mg L of each pharmaceutical were
-2
electrolyzed at initial pH 7.0 with a current densisty of 50 mA cm during 3
hours. OTC shows a spectrum with two maxima at 277 and 360 nm, which
decay with electrolysis time as shown in Fig. 1a. At the end of the electrolysis
the solution turne a slight pale yellow and the appearance of new bands were
not detected under our experimental conditions. A similar trend was found
-1
for the degradation of 100 mg L of PhSTZ (Fig. 1b), which has a maximum
at 252 nm and decays by 60% after 3 hours of electrolysis. It is known that
during the reaction of organic compounds with hydroxyl radicals, organic
intermediates are generated, and they can absorb at the same wavelengths as
the corresponding initial compounds. Chromatographic analysis showed that
the chromatographic peak corresponding to PhSTZ disappeared completely
after 60 min of electrolysis (inset in Figure 1b) and the formation of new peaks
corresponding to oxidation products was observed. A different trend was seen
in the case of DPH elimination. As can be seen in Fig. 1c, the initial spectrum
presents a maximum at 260 nm which disappears completely after 10 min of
electrolysis, and the absorption spectrum shows an increase in the absorbance
at the same wavelength as the original compound. It is important to note that
the spectrum generated does not match the original, showing that in a short
time the compound has been completely degraded. Figure 2a summarizes the
above for the decay of the maximum absorbance of each compound. Thus, the
decrease of the maximum absorbance for OTC reaches 95% after 150 minutes
of electrolysis. For PhSTZ the absorbance at 252 nm decreased by about 60%
after 3 hours of electrolysis. Something different is seen for DPH, since as
noted, it showed a variation in the spectrum after 10 min of electrolysis with
an increase in signal intensity at the same wavelength of the initial DPH. Thi
new spectrum produced with greater intensity after 10 min of electrolysis,
subsequently decays during the electrolysis. One possible explanation for this
could be that the products or intermediates generated by the reaction between
DPH and the hydroxyl radicals, having molar absorption coefficient greater
than DPH, give rise to greater absorbance in the area of the main band, so it is
possible to presume that the DPH is degraded in the first minutes of electrolysis.
l/nm
-
1
Figure 1. Spectra decay during the electrooxidation of 0.1 L of 100 mg L
of (a) OTC, (b) PhSTZ and (c) DPH solutions in 0.1 M Na SO at 35 ºC and pH
7.0 using the BDD/stainless steel system. Applied current density: 50 mA cm
Inset in (b): chromatographic peak decay of PhSTZ during the electrolysis.
2
4
-
2
.
The decay of the absorbance shows that pharmaceuticals are degraded
independently by electrogenerated hydroxyl radicals. Thus, the abatement of
total organic carbon (TOC) allows us to check if they are completely mineralized
Spectra were obtained every 20 min.
Differences between absorbance and TOC decay of each compound were
found, probably related to the different molecular structure of pharmaceuticals.
Moreover, each pharmaceutical is eliminated before total organic carbon,
showing the formation of organic intermediates from each compound, which
are also rapidly destroyed by hydroxyl radicals, reaching a total decay of organic
compounds to achieve complete mineralization, i.e., complete transformation
into CO and H O. In this work, the main intermediaries detected during EO
to CO . In Fig. 2b, the decay of TOC is shown during electrolysis for each
2
compound. In the same way of the decay of the maximum absorbance of the
compounds, the TOC decreases with electrolysis time, confirming conversion
to CO . A complete mineralization of DPH (> 95%) was seen toward the end
2
of the electrolysis, while 70% was obtained for PhSTZ mineralization and
6
5% for OTC. In the latter case it could be projected that at longer electrolysis
2
2
time complete mineralization of the solution may be reached. However, during
the electrolysis of PhSTZ and OTC, the starting compound was completely
removed from the solution, therefore the TOC remaining in the solutions would
correspond to the presence of organic intermediate or reaction products formed
by attack of the hydroxyl radicals generated on the anode surface. Figure 2c
shows the values of current efficiency for the mineralization process for each
drug according to Eq. (3). The values obtained are close to 20%, which is in
agreement with results reported by other authors when POPs are electrolyzed
where carboxylic acids and inorganic ions.
3.2. Organic intermediates detected during EO of Fantetra components.
It is known that during the degradation of aromatic compounds, formation
of short-linear carboxylic acids takes place, and then they are transformed into
3
3
oxalic acid as ultimate product before the complete mineralization to CO2.
The carboxylic acids formed during the oxidation of the pharmaceutical
studied were determined by liquid ion-exclusion chromatography. To identify
each carboxylic acid seen in the chromatogram, samples of the most probable
pure carboxylic acid and their mixtures were used as standards under the same
experimental conditions. Thus, during the EO of OTC, oxalic, maleic, oxamic,
fumaric and acetic acids were identified. Probably, fumaric and maleic acids
come from the oxidation of the aryl moiety of the aromatics. The oxidation of
these acids may generate acetic acid, while oxamic acid may be formed from
1
0
using a system similar to that used in this work.
On the other hand, the changes in the pH of the solutions at the end
of electrolysis were to 7.26 ± 0.11 for an initial pH = 7.0. This result is an
important finding in view of the future scaling-up of this technology in the
treatment of water containing pharmaceuticals, because self-adjustment of pH
simplifies the treatment and makes it more cost-affordable.
2
509

J. Chil. Chem. Soc., 59, Nº 2 (2014)
·
the attack of OH on amine or amide groups. In the case of PhSTZ oxalic,
On the basis of the findings discussed above, the total mineralization of
·
maleic and oxamic acid were found. And for DPH formic, oxalic and oxamic
acids were found. In all cases, at the end of the electrolysis, as expected, oxalic
and oxamic acids are the last carboxylic acids that are directly transformed
OTC, PhSTZ and DPH by EO is due to attack of OH that may be involved
·
in the formation of aromatic intermediates which react with OH to produce a
–
+
mixture of carboxylic acids together with NO3 and NH4 ions. The carboxylic
acids continue reacting until they turn into oxalic acid, and subsequently into
CO plus H O, while the initial pharmaceutical molecule, either OTC, PhSTZ
32
into CO2.
2
2
or DPH, becomes completely mineralized according to equations (4-6).
3
.3. Degradation of Fantetra from a prepared solution and from commercial
formulation.
Finally, the method of electro-oxidation was applied for the simultaneous
degradation of the three drugs in the Fantetra commercial tablet. Fig. 3a shows
the spectra for each drug. As can be seen, only the absorbance of PhSTZ and
OTC are well defined to be analyzed at the wavelengths mentioned in the
previous sections. The case of DPH is different, because it has a band that is
within the overall spectrum, but with a much lower absorbance than that of the
other two compounds present in the formulation, and therefore it cannot be
evaluated spectrophotometrically in the mixture.
Solutions of 100 ppm of the pharmaceutical formulation of Fantetra were
degraded in water under the same experimental conditions at which each drug
was degraded independently. Furthermore, solutions containing the three
compounds in the same proportions as present in the commercial pharmaceutical
formulation of Fantetra were prepared and degraded as mentioned before. The
spectra corresponding to the degradation of both solutions for 3 h of electrolysis
are shown in Figures 3b and 3c, respectively.
Figure 2. (a) Normalized absorbance at maximum wavelength; (b) TOC
abatement; and (c) variation of mineralization current efficiency calculated
-1
from Eq. (3) vs. time for the electrooxidation of 0.1 L of 100 mg L of (¢)
PhSTZ, (▲) OTC and (●) DPH. Experimental conditions: 0.1 M Na SO at
2
4
-2
3
5 ºC and pH 7.0, applying 50 mA cm using the BDD/stainless steel system.
Data are the average of three independent experiments.
The determination of nitrogen requires the presence of inorganic cations
+
-
or anions. It is very common to detect nitrogen compounds as NH and NO3
4
3
4
ions in the mineralization of N-derivatives. The presence of these ions was
followed by liquid ionic chromatography. The results indicate the presence
of NO3- and NH . At the end of the electrolysis, NO concentrations of 3.5
+
4
-
3
ppm for OTC, 1.2 ppm for PhST and 0.8 ppm for DPH were detected. The
+
concentration of NH at the end of electrolysis for the three compounds was
4
+
lower than 0.5 ppm. Probably, the low NH4 concentration detected at the end
of the electrolysis of the pharmaceutical are due to the fact that the pH of the
–
+
solution is slightly basic (7.26 ± 0.11). Final concentrations of NO3 and NH4
l/nm
ions detected at the end of the electrolysis correspond to 12.1% of initial N for
OTC, 10.6 % for PhST and 6.4% for DPH. Since the corresponding remaining
oxamic acid only contains 1.0% of the initial N, it can be inferred that a large
fraction of the N of the initial molecules (ca. 3%) is lost as volatile species,
mainly as N and/or a NO .
-1
Figure 3. (a) Spectra of 100 mg L of each component of Fantetra; (b)
-1
spectra decay during the electrooxidation of 0.1 L of 100 mg L of FSS; and (c)
CFS solutions in 0.1 M Na SO at 35 ºC and pH 7.0 using the BDD/stainless
steel system. Applied current density: 50 mA cm .
2
4
-2
2
x
2
510

J. Chil. Chem. Soc., 59, Nº 2 (2014)
It was found that for both mixtures, FSS (Fig. 3b) and CFS (Fig. 3c),
bands corresponding to both OTC and PhSTZ decay during electrolysis. These
results allow us to conclude that the method is applicable to the removal of
both drugs from waters containing them, under the experimental conditions
employed. In both cases it is seen that the band at 360 nm corresponding to
OTC decays completely after the first 10 minutes of electrolysis. The bands
in the range of 250-300 nm associated with OTC and PhSTZ decay gradually
during electrolysis, reaching a value close to zero at the end of the process. The
difference between the FSS and CFS solutions is the presence of excipients in
CFS (Table 2). As can be seen in Figs. 3 a and b, commercial tablets do not
show a significant difference when analyzing the decay of the absorbance of
each component of the mixture. In both cases, complete elimination of TOC is
achieved after 3 hours of electrolysis (Table 2).
5
6
7
D.I. Andersson, D. Hughes. Drug Resistance Updates 15, 162, (2012).
M. Klavarioti, D. Mantzavinos, D. Kassinos. Environ. Int. 35, 402, (2009).
C.A. Martínez-Huitle, E. Brillas. Appl Catalysis B: Environ 87, 105,
(2009).
Ch. Comninellis, G. Chen. Electrochemistry for the Environment. 1st ed.
New York. Springer, 2009, pp.1-23.
8
9
M. Panizza, A. Kapalka, Ch. Comninellis. Electrochim. Acta 53, 2289,
(2008).
10 J. Urzúa, C. González-Vargas, F. Sepúlveda, M.S. Ureta-Zañartu, R.
Salazar. Chemosphere 93, 2774, (2013).
11 R. Salazar, M.S. Ureta-Zañartu. Water Air Soil Pollut. 223, 4199, (2012).
12 M. Panizza, G. Cerisola. Water Res. 43, 339, (2009).
13 P.A. Carneiro, M.E. Osugi, J.J. Sene, M.A. Anderson, M. Valnice, B.
Zanoni. Electrochim. Acta 49, 3807, (2004).
14 R. Salazar, M.S Ureta, J. Chil. Chem. Soc. 57, 999, (2012).
15 S. Garcia-Segura, R. Salazar, E. Brillas. Electrochim. Acta 113, 609,
(2013).
-1
Table 2. Composition of 100 mg L of FSS and CFS and total organic
carbon before and after the electro-oxidation treatment. Experimental
-2
conditions: 0.1 M Na SO at 35 ºC and pH 7.0 applying 50 mA cm using
2
4
the BDD/stainless steel system. Data are the average of three independent
experiments.
16 R. Salazar, E. Brillas, I. Sirés. Appl. Catalysis B: Environ. 115– 116, 107,
(2012).
1
7
Jong Young Choia, You-Jin Leea, Jina Shina, Ji-Won Yanga. J. Hazard.
Mat. 179, 762, (2010).
-1
-1
Composition (mg L )
TOC (mg L )
Solution PhSTZ DPH OTC Excipients
Initial
36.0
Final
2.8
18 C.I. Brinzila, M.J. Pacheco, L. Ciríaco, R.C. Ciobanu, A. Lopes. Chem.
Eng. J. 209, 54, (2012).
CFS
FSS
49.5
49.2
1.2
1.3
12.4
12.2
0.037
-
1
9
E. Tsantaki, T. Velegraki, A. Katsaounis, D. Mantzavinos. J. Hazard. Mat.
07–208, 91, (2012)..
2
24.0
2.7
2
2
2
0
1
2
M. Panizza, G. Cerisola. Electrochim. Acta 48, 3491, (2003).
M. Panizza, G. Cerisola. Electrochim. Acta 51, 191, (2005).
E. Guinea, F. Centellas, E. Brillas, P. Cañizares, C. Sáez, M.A. Rodrigo.
Appl Catalysis B: Environ 89, 645, (2009).
4
. CONCLUSIONS
OTC, PhSTZ and DPH could be degraded by EO with the generation
of hydroxyl radicals on the anode surface, reaching >70% of mineralization
for each compound separately. On the other hand, complete degradation and
mineralization is obtained for solution containing 100 mg L-1 of Fantetra
in solutions prepared from each drug or from the commercial formulation.
Finally, the mineralization process of Fantetra components by EO generates
organic intermediates as carboxylic acids (oxalic, oxamic, maleic, acetic),
ammonia and nitrate ions before their complete transformation into CO2.
2
2
2
2
2
2
2
3
4
5
6
7
8
9
C.A. Martinez-Huitle, E. Vieira dos Santos, D. Medeiros de Araujo, M.
Panizza. J. Electroanal. Chem. 674, 103, (2012).
Ministerio de agricultura de Chile. Medicamentos veterinarios autorizados
por el Servicio Agrónomo y ganadero, SAG
X.Liang, Z.Wang, C. Wang, K. Wen, T. Mi, J. Zhang, S. Zhang. Anal.
Biochem. 438, 110, (2013).
S.M. Miller, K.L. Cumpston. Encyclopedia of Toxicology (Third Edition),
2
014, pp 195-197.
K. Li, A. Yediler, M.Yang, S. Schulte-Hostede, M. Hung Wong.
Chemosphere 72, 473, (2008).
ACKNOWLEDGMENTS
L. M. Pastrana-Martínez, J.L. Faria, J.M. Doña-Rodríguez, C. Fernández-
Rodríguez, A. Silva. Appl Catalysis B: Environ 113– 114, 221, (2012).
M. Velázquez, I. P. Santander, D.R. Contreras, J. Yáñez, C. Zaror, R.A.
Salazar, M. Pérez-Moya, H.D. Mansilla. Journal of Environmental Science
and Health, Part A 49, 661, (2014).
Financial support of FONDECYT under Project 1130391 and DICYT-
USACH is gratefully acknowledged.
REFERENCES
3
3
3
0
1
2
S. Morales-Torres, L.M. Pastrana-Martínez, J.L. Figueiredo, J.L. Faria, A.
Silva. Appl. Surf. Sci. 275, 361, (2013).
R. Salazar, S. Garcia-Segura, M.S. Ureta-Zañartu, E. Brillas. Electrochim.
Acta 56, 6371, (2011).
M. Skoumal, C. Arias, P. L. Cabot, F. Centellas, J.A. Garrido, R. M.
Rodrıguez, E. Brillas
1
2
J. Rivera-Utrilla, M. Sánchez-Polo, M.A. Ferro-García, G. Prados-Joya, R.
Ocampo-Pérez. Chemosphere 93, 1268, (2013).
I. Arslan-Alaton, T. Olmez-Hanci. New and Future Developments in
Catalysis. Catalysis for Remediation and Environmental Concerns.
Chapter 12 – Sources of Environmental Pollution: Persistent Organic
Pollutants. Elsevier, 2013, pp 303–398.
G. Mascolo, L. Balest, D. Cassano, G. Laera, A. Lopez, A. Pollice, C.
Salerno. Bioresource Technol 101, 2585, (2010).
O.A. Jones, J.N. Lester, N. Voulvoulis, Trends in Biotechnol 23, 163,
Chemosphere 71, 1718, (2008).
3
3
3
4
3
4
S. Garcia-Segura, E. Brillas. Water Res. 45, 2975, (2011).
M. Hamza, R. Abdelhedi, E. Brillas, I. Sires. J. Electroanal. Chem. 627,
4
1, (2009).
(2005).
2
511