procesos electroquímicos para: eficientar el uso de energía tratamiento de contaminantes

• Procesos electroquímicos para:

• Eficientar el uso de energía

• Tratamiento de contaminantes

• Electrogeneración de luz

Proyectos de

Investigación Jorge Ibáñez Cornejo

(JIC)

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

-+

Fe2+

OH-

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

Fe2+ [Ar]3d6 diamagnético

Fe3+ [Ar]3d5 paramagnético

+-

VOLTAJ EFuente de poder

Ánodo(Fe)

Cátodo

+-

-

Fe(OH)2

Fe(OH)3

Electrocoagulación asistida por un campo magnético

Average Fe(II/III) production as a function of the applied potential, in N2

0

1

2

3

4

5

3 4.5 6 7.5 9 12

Voltage, volts

Fe

co

nc

en

tra

tio

n, m

g/L

Avg. mg/L Fe2+

Avg. mg/L Fe3+

Producción y uso de Ag3+ para oxidación de contaminantes

AgAg3+ + 3e-

3H2O + 3e- 3/2 H2 + 3OH-

Removal of insoluble MX(s) by chelation and regeneration of M

+ L

MX(s) + H2O MX(s) + EDTA

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10 12 14

Fra

ctio

n

pH

Cu Cu CO (OH) (s) CuO(s)2+22 3

CuCO3·Cu(OH)2 - surrogate pollutant

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 the Environ. Part 9. Microscale Recovery of a Soil Metal Pollutant and its Extractant. J. Chem. Educ. (Web): May 20, 2011.

H4 EDTA

Cu

pH = 3.5

Paired Electrochemical Processes

Paired electrochemical processes:- Avoid the need for a “sacrificial reaction”- Reduce the generation of waste and theconsumption of energy

EXAMPLE: We developed a small–scale processfor the production of ClO2. (An environmentally-friendly alternative to Cl2 for disinfection, watertreatment, pulp bleaching)+ Reduction of ClO3

-, oxidation of ClO2-

Both electrodic reactions can be used for

ELECTROLUMINISCENCE (ECL)

Luminol (2,3-aminophthalohydrazide) can be oxidized in basic conditions to yield a relatively long-lived excited state from which it emits blue light. A co reactant (H2O2) was used to increase light emission.

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.

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.

+

FIRST EXAMPLE OF SIMULTANEOUS ELECTROLUMINISCENCE

Study of individual processses (i.e.,

conditions for ECL in cathode and anode)

Study of individual processses (i.e.,

conditions for ECL in cathode and anode)

Characterization ofluminol and ClO- (LSV)

(Figures 1a – 1c)

Characterization ofluminol and ClO- (LSV)

(Figures 1a – 1c)Obtain ECL separatelyObtain ECL separately

Couple both processesand attempt

simultaneous ECL

Couple both processesand attempt

simultaneous ECL

Cathodic ECL is more sensitive; the cathodic

potenial is fixed at -200 mV

Cathodic ECL is more sensitive; the cathodic

potenial is fixed at -200 mV

Blue ECL is produced in both compartments (constant in the anodic side, intermittent in the cathodic side).

* Figure 2 shows the cell arrangement used for the simultaneous process.

Blue ECL is produced in both compartments (constant in the anodic side, intermittent in the cathodic side).

* Figure 2 shows the cell arrangement used for the simultaneous process.

0

50

100

150

200

250

300

350

0 200 400 600 800 1000

Potential (mV vs. Ag/AgCl)

Curre

nt (

mA)

-21.05

-16.05

-11.05

-6.05

-1.05

-800 -700 -600 -500 -400 -300 -200 -100 0


Cur

rent

(m

A)

-60

-50

-40

-30

-20

-10

0

-1000 -800 -600 -400 -200 0 200 400


Curre

nt (m

A)

Figure 1 – (a) Anodic LSV for luminol in basic medium, (b) cathodic LSV for luminol in basic medium, (c) cathodic LSV for ClO2-.

0

50

100

150

200

250

300

350

0 200 400 600 800 1000


Curre

nt (

mA)

-21.05

-16.05

-11.05

-6.05

-1.05

-800 -700 -600 -500 -400 -300 -200 -100 0


Cur

rent

(m

A)

-60

-50

-40

-30

-20

-10

0

-1000 -800 -600 -400 -200 0 200 400


Curre

nt (m

A)


0

50

100

150

200

250

300

350

0 200 400 600 800 1000


Curre

nt (

mA)

-21.05

-16.05

-11.05

-6.05

-1.05

-800 -700 -600 -500 -400 -300 -200 -100 0


Cur

rent

(m

A)

-60

-50

-40

-30

-20

-10

0

-1000 -800 -600 -400 -200 0 200 400


Curre

nt (m

A)


Oxidation signalat 300 mV

(should occur at anode)

Oxidation signalat 300 mV

(should occur at anode)

Reduction signalat -450 mV

(should NOT occurat the cathode)

Reduction signalat -450 mV

(should NOT occurat the cathode)

Reduction signal.Starts at -200 mV(should occur at

cathode).

Reduction signal.Starts at -200 mV(should occur at

cathode).

Reference electrode(Ag / AgCl)

Pt gauze

Reference electrode(Ag/AgCl)

Pt flag

Cationic Exchange membrane

Catholyte:1 M NaClO2 (5 mL)*As electrochemicalreduction initiated, 2 mL ofluminol/H2O2 solution(same as anolyte) wasadded dropwise on top ofthe Pt gauze.

Anolyte:5.6 x 10-6 M luminolsolution made basic withNaOH.H2O2 was added as co-reactant (30 μL of 10 % H2O2 in 5 mL of testsolution)

Figure 2 – Experimental cell used for simultaneous ECL.


Pt gauze


Pt flag





Pt gauze


Pt flag




Pt gauze


Pt flag


Pt gauze


Pt flag




Figure 2 – Experimental cell used for simultaneous ECL.

Biaani Sotomayor Martínez-Barranco, Daniel Zavala Araiza, Jorge G. Ibanez Depto. Ing. y C. Químicas.

Mexican Microscale & Green Chemistry Center. U. Iberoamericana – México

LITERATURE REFERENCES1. 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, FreseniusEnvironmental 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 ElectrochemiluminescenceDemonstration”, J. Chem. Ed., 2001, 78, 641 – 643.7. Kumala, S.; Ala – Kleme, T.; Papkovsky, D.; Loikas, K. Cathodic ElectrogeneratedChemiluminescence of Luminol at Disposable Oxide – covered Aluminum Electrodes”, Anal. Chem. 1998, 70, 1112 – 1118.

2OHClO

2eO2H2ClO (6)

2OH2Cl

eO2HClO (7)

*2AP2ClLH (8)

hν2AP*2AP (9)

ELECTROLUMINISCENCIA SIMULTÁNEAL

uminol in N

aOH

+ H

2 O2

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

-2

-1

0

1

2

3

4

5

6

7

8

9

10

11

-1 0 1 2 3 4 5 6 7 8

Oxidation number

-nE pH 0

pH 14

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

Cu2+ Cu1+ or CuCB

VB

e-

h+

Ox 1 Red 1

Red 1 Ox 1 Org CO2

Coupled oxidation and reduction

Cu(II) removal and organic oxidation by photocatalysis

To p vie w

Sid e vie w

O p tio na l C O te st2

UV la m p

To p o we r so urc e

Ba(OH)2

quartz tubes

TiO2 + Cu(II) + org

before

after

Cu (II) concentration change

00.10.20.30.40.50.60.70.80.9

1

0 10 20 30 40 50 60 70

t/min

At/

Ao

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.

procesos electroquímicos para: eficientar el uso de energía tratamiento de contaminantes

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