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Proyectos de Investigación
Jorge Ibáñez Cornejo
(JIC)
•
Procesos electroquímicos para:
•
Eficientar el uso de energía
•
Tratamiento de contaminantes
•
Electrogeneración de luz
PROCESOS SIMULTÁNEOS
• En electroquímica es frecuente que se use sólo
una de las dos reacciones de la celda para
producir una sustancia de interés.
• Por ello estamos trabajando en procesos en
donde se usa la electricidad en ambos
electrodos para llevar a cabo una reacción útil
Electrocoagulation
-
+
OHFe2+
OH-
Ibanez, J. G.; Singh, M. M.; Szafran, Z.; Pike, R. M. “Laboratory Experiments On Electrochemical Remediation Of The Environment.
Part 4. Color Removal of Simulated Wastewater by Electrocoagulation-Electroflotation”. J. Chem. Educ. 75 (8) 1040-1041 (1998).
Electrocoagulación asistida
por un campo magnético
Fuente de poder
VOLTAJE
-
+
Ánodo
(Fe)
Cátodo
+
-
Fe(OH)2
Fe(OH)3
Fe2+ [Ar]3d6 diamagnético
Fe3+ [Ar]3d5 paramagnético
Electrocoagulación asistida
por un campo magnético
Fe concentration, mg/L
Average Fe(II/III) production
as a function of the applied potential, in N 2
5
4
3
Avg. mg/L Fe2+
2
Avg. mg/L Fe3+
1
0
3
4.5
6
7.5
Voltage, volts
9
12
Producción y uso de Ag3+ para
oxidación de contaminantes
AgAg3+ + 3e3H2O + 3e-  3/2 H2 + 3OH-
Removal of insoluble MX(s)
by chelation and regeneration of M + L
CuCO3·Cu(OH)2 - surrogate pollutant
MX(s) + H2O
MX(s) + EDTA
Cu 2+
Cu2CO3(OH)2 (s)
CuO(s)
1.0
Fraction
0.8
0.6
0.4
0.2
0.0
0
2
4
6
8
10
12
14
pH
Ibanez, Jorge; Balderas-Hernández, Patricia; Garcia-Pintor, Elizabeth; Barba-Gonzalez, Sandy; Doria-Serrano, Maria;
Hernaiz-Arce, Lorena; Diaz-Perez, Armando; Lozano-Cusi, Ana. Laboratory Experim. on the Electrochem. Remediation of
Cu
pH = 3.5
H4 EDTA
ELECTROLUMINISCENCIA SIMULTÁNEA

ClO2  H2O  2e  
ClO  2OH
ClO  H2O  e  
Paired Electrochemical Processes
Biaani Sotomayor Martínez-Barranco, Daniel Zavala Araiza, Jorge G. Ibanez
Depto. Ing. y C. Químicas.
Mexican Microscale & Green Chemistry Center. U. Iberoamericana – México
Luminol (2,3-aminophthalohydrazide) can be
oxidized in basic conditions to yield a relatively longlived excited state from which it emits blue light. A
co reactant (H2O2) was used to increase light
emission.
Paired electrochemical processes:
- Avoid the need for a “sacrificial reaction”
- Reduce the generation of waste and the
consumption of energy
+
Both electrodic reactions can
be used for
ELECTROLUMINISCENCE (ECL)
FIRST EXAMPLE OF
SIMULTANEOUS ELECTROLUMINISCENCE
Study of individual
processses (i.e.,
conditions for ECL in
cathode and anode)
Characterization of
luminol and ClO- (LSV)
(Figures 1a – 1c)
Couple both processes
and attempt
simultaneous ECL
Obtain ECL separately
Cathodic ECL is more
sensitive; the cathodic
potenial is fixed at -200 mV
-1.05
Current ( m A)
Current ( m A)
300
250
200
-6.05
Reduction signal
at -450 mV
(should NOT occur
at the cathode)
0
-11.05
150
100
-16.05
50
0
0
200
400
600
800
1000
-21.05
-800
Potential (mV vs. Ag/AgCl)
-600
-500
-400
-300
-200
Potential (mV vs. Ag/AgCl)
-100
Reduction signal.
Starts at -200 mV
(should occur at
cathode).
-20
-30
-40
-50
-60
-1000
-700
* Figure 2 shows the cell
arrangement used for the
simultaneous process.
-10
Current (m A)
Oxidation signal
at 300 mV
(should occur at anode)
350
Blue ECL is produced in
both compartments
(constant in the anodic
side, intermittent in the
cathodic side).
-800
-600
-400
-200
0
200
400
0
Potential (mV vs. Ag/AgCl)
Figure 1 – (a) Anodic LSV for luminol in basic medium, (b) cathodic LSV for luminol in basic medium, (c) cathodic LSV for ClO2-.
Pt gauze
Reference electrode
(Ag / AgCl)
Reference electrode
(Ag/AgCl)
Pt flag
Catholyte:
1 M NaClO2 (5 mL)
Anolyte:
5.6 x 10-6 M luminol
solution made basic with
NaOH.
H2O2 was added as coreactant (30 μL of 10 %
*As electrochemical
reduction initiated, 2 mL of
luminol/H2O2 solution
(same as anolyte) was
added dropwise on top of
the Pt gauze.
H2O2 in 5 mL of test
solution)
Cationic Exchange membrane
Figure 2 – Experimental cell used for simultaneous ECL.
LITERATURE REFERENCES
1. Paddon, C.A.; Atobe, M.; Fuchigami, T.; He, P.; Watts, P.; Hasswel, S.J.; Pritchard,
G.J.; Bull, S.D.; Marken, F. Towards Paired and Coupled Electrode Reactions for Clean
Organic Microreactor Electrosyntheses, J. Appl Electrochem, 2005, 36, 617-634.
2. Rajeshwar, K.; Ibanez, J. G. Environmental Electrochemistry: Fundamentals and
Applications in Pollution Abatement. Academic Press, San Diego, 1997.
3. Gomez-Gonzalez, A.;. Ibanez, J. G.; Vasquez-Medrano, R. C.; Paramo-Garcia, U.;
Zavala-Araiza, D. Cathodic Production of ClO2 from NaClO3, J. Electrochem. Soc. 2009,
156 (7), E113-E117.
4. Mena-Brito, R.; Terrazas-Moreno, S.; Ibanez, J. G. Towards A Green Production Of
Chlorine Dioxide By Convergent Paired Electrosynthesis. (In press, Fresenius
Environmental Bulletin, Germany).
5. Liu, X.; Jiang, H.; Lei, J.; Ju, H. Anodic Electrochemiluminescence of CdTe Quantum
Dots and its Energy Transfer for Detection of Catechol Derivatives, Anal. Chem. 2007,
79, 8055 - 8060.
6. Bolton, E.; Richter, M.; Light Emission at Electrodes: An Electrochemiluminescence
Demonstration”, J. Chem. Ed., 2001, 78, 641 – 643.
7. Kumala, S.; Ala – Kleme, T.; Papkovsky, D.; Loikas, K. Cathodic Electrogenerated
Chemiluminescence of Luminol at Disposable Oxide – covered Aluminum Electrodes”,
Anal. Chem. 1998, 70, 1112 – 1118.
(7)
(8)
(9)
Luminol in NaOH + H2O2
The equilibrium between ClO2- and ClO- at a cathode
could allow for the use of this last species to provoke
the oxidation of the luminophore to produce an
excited state.
EXAMPLE: We developed a small–scale process
for the production of ClO2. (An environmentallyfriendly alternative to Cl2 for disinfection, water
treatment, pulp bleaching)
+ Reduction of ClO3-, oxidation of ClO2-
Cl2  2OH
LH  Cl2  AP2*
AP2*  AP2  hν
(6)
Gases: Indirect Oxidation, Outer-Cell Process
Electrochemical treatments of H2S
Lab experiment with H2S
Ibanez, J. G. “Laboratory Experiments On Electrochemical Remediation Of The Environment. Part 5. Indirect
H2S removal”. J. Chem. Educ. 2001 (6) 78, 778-779.
Oxidation of Sulfide Ions by Iodine
Iodine Regeneration by Electrolysis
Frost diagram of Cl species
11
10
9
8
7
-nE
6
pH 0
pH 14
5
4
3
2
1
0
-1
-2
-1
0
1
2
3
4
5
Oxidation number
6
7
8
Electrochemical Production
of Chlorine Dioxide
Paired production of ClO2
NaClO3, 1 M
NaClO2, 1 M
Identification
UV-Vis Spectrum of gaseous
chlorine dioxide
Ibanez, Jorge G.; Navarro-Monsivais, Carlos; Terrazas-Moreno, Sebastian; Mena-Brito, Rodrigo; Pedraza-Segura, Lorena; Mattson,
Bruce; Anderson, Michael P.; Fujita, Jiro; Hoette, Trisha. “Microscale Environmental Chemistry, Part 5. Production of ClO2, an
Environmentally-Friendly Oxidizer and Disinfectant”, Chem. Educator 2006, 11, 174-177.
Photocatalysis
eCB
VB
Ox 1
Red 1
Cu2+
Cu1+ or Cu
Red 1
Ox 1
Org
CO2
h+
Coupled oxidation and reduction
Cu(II) removal and organic oxidation
by photocatalysis
before
To power sourc e
UV lamp
quartz
tubes
TiO2 +
Cu(II) +
org
Ba(OH)2
Side view
Optional CO test
2
Top view
after
At/Ao
Cu (II) concentration change
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
60
70
t/min
Ibanez, Jorge G.; Mena-Brito, Rodrigo; Fregoso-Infante, Arturo. “Laboratory Experiments on the Electrochemical Remediation of the
Environment. Part 8. Microscale Photocatalysis”, J. Chem. Educ. 2005, 82, 1549-1551.