Journal of Applied Electrochemistry

, Volume 21, Issue 10, pp 915–921 | Cite as

Coupling between electrolysis and liquid-liquid extraction in an undivided electrochemical reactor: applied to the oxidation of Ce3+ to Ce4+ in an emulsion Part I. Experimental

  • D. Horbez
  • A. Storck
Papers

Abstract

The effect ofin situ simultaneous extraction of tetravalent cerium by an organic phase (di-2 ethylhexylphosphoric acid in kerosene) on the performance of an undivided batch electrochemical reactor using the Ce3+/Ce4+ system was investigated. The influence of the most important parameters (initial concentration of Ce3+, composition and volume percentage of the organic phase) were studied experimentally under potentiostatic control of the anode potential. A conversion factor of Ce3+ and extraction factor larger than 90% are obtained for the best operating conditions, but the presence of the organic phase and the necessity of avoiding oxygen gas evolution considerably reduce the operating anodic current densities. The transient cell behaviour and the final “equilibrium” state conditions are found to be in very good qualitative agreement with the conclusions of a preliminary study of the electrochemical kinetics of the Ce3+/Ce4+ system and extraction mechanisms of Ce4+ by the organic phase.

Nomenclature

Ae

electrode area (m2)

C

concentration (M)

CF

conversion factor of Ce3+

D

molecular diffusion coefficient (m2 s−1)

E

electrode potential (V)

E00

standard potential of the Ce3+/Ce4+ redox system (V)

EF

extraction factor

F

Faraday constant (96485 A s mol−1)

i

current density (A m−2)

I

current (A)

i0

exchange current density (A m−2)

k00

standard electrochemical rate constant of the Ce3+/Ce4+ system (m s−1)

kd

mass transfer coefficient (measured by electrochemical reduction of Ce4+ except Fig. 5) (m s−1)

KM

equilibrium constant of the extraction mechanism (mol2l−6)

m

partition coefficient of tetravalent cerium

R

perfect gas constant (J mol−1 K−1)

t

time (s)

T

temperature (K)

V

reactor volume (l)

Greek symbols

α

anodic charge transfer coefficient

β

cathodic charge transfer coefficient

ε

volumic organic phase ratio in the dispersion

η

overall current efficiency or overpotential (-or V)

ve

number of electrons involved in the electrochemical process (=1)

Subscripts

a

anodic

c

cathodic

3

trivalent cerium

4

tetravalent cerium

0

at timet=0

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Copyright information

© Chapman & Hall 1991

Authors and Affiliations

  • D. Horbez
    • 1
  • A. Storck
    • 2
  1. 1.Rhône-Poulenc—Centre de Recherches d'AubervilliersAubervilliers, CedexFrance
  2. 2.Laboratoire des Sciences du Génie ChimiqueCNRS-ENSICNancy, CedexFrance

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