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Journal of Applied Electrochemistry

, Volume 41, Issue 5, pp 609–616 | Cite as

Modelling of three-dimensional bipolar electrodes with irreversible reactions

  • O. González Pérez
  • J. M. BisangEmail author
Original Paper

Abstract

The behaviour of an electrochemical reactor with three-dimensional bipolar electrodes for irreversible reactions is analysed. Copper deposition at the cathodic side and oxygen evolution at the anodic one were adopted as test reactions at the bipolar electrode, from an electrolyte solution with a copper concentration lower than 1000 mg dm−3, pH 2 and 1 M Na2SO4 as supporting electrolyte. A mathematical model considering the leakage current is proposed, which can represent the tendency observed in the experimental data related to cathodic thickness and potential at both ends of the bipolar electrode. High values of leakage current were determined, which restricts the faradaic processes to small thicknesses at both ends of the bipolar electrode. Likewise, the performance of the bipolar electrochemical reactor for the treatment of effluents is experimentally and theoretically examined. In this case, the conversion for copper removal was 90.1% after 480 min of operation with one bipolar electrode and 94.8% after 300 min of operation with two bipolar electrodes at a total current of 3 A.

Keywords

Bipolar electrodes Current distribution Electrochemical reactors Leakage current Three-dimensional electrodes 

List of symbols

As

Surface area per unit electrode volume (m−1)

C

Concentration (mol m−3, mg dm−3)

CE

Current efficiency (%)

E

Electrode potential (V)

E0

Reversible electrode potential (V)

\( E_{ 0}^{ 0} \)

Reversible electrode potential under standard conditions (V)

F

Faraday constant (C mol−1)

H

Electrode length (m)

i

Current density (A m−2)

ib,F

Faradaic macrokinetic current density defined by Eq. 9 (A m−2)

I

Total current (A)

I*

Leakage current (A)

j

Reaction rate (A m−2)

j0

Exchange current density (A m−2)

jL

Limiting current density (A m−2)

km

Mass-transfer coefficient (m s−1)

L

Thickness of the bipolar electrode (m)

Q

Volumetric flow rate (m3 s−1)

RT/F

Constant (0.0261 V at 30 °C) (V)

S

Membrane area (m2)

t

Time (s or min)

U

Cell voltage (V)

VM

Reservoir volume (m3)

VR

Reactor volume (m3)

W

Electrode width (m)

x

Axial coordinate (m)

y

Axial coordinate (m)

z

Axial coordinate (m)

Greek characters

α

Charge-transfer coefficient

β

Charge-transfer coefficient

ΔL

Thickness of the inert region of the bipolar electrode (m)

ε

Void fraction

νe

Charge number of the electrode reaction

ρ

Effective resistivity (Ω m)

ρ°

Electrolyte resistivity (Ω m)

ψ

By-passed fraction of the total current = I*/I

τM

Reservoir residence time = V M/Q (s)

τR

Reactor residence time = εV R/Q (s)

Subscripts

a

Anodic

c

Cathodic

exp

Experimental

F

Faradaic

i

Reactor inlet

m

Metal phase

mean

Mean value

o

Reactor outlet

s

Solution phase

SCE

Saturated Calomel Electrode

th

Theoretical

Notes

Acknowledgments

This work was supported by the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional del Litoral (UNL) of Argentina.

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Programa de Electroquímica Aplicada e Ingeniería Electroquímica (PRELINE), Facultad de Ingeniería QuímicaUniversidad Nacional del LitoralSanta FeArgentina

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