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Journal of Applied Electrochemistry

, Volume 39, Issue 1, pp 71–81 | Cite as

Effects of electrolyte parameters on the iron/steel cathode potential in the chlorate process

  • Linda NylénEmail author
  • Ann Cornell
Original Paper

Abstract

This study focuses on how different electrolyte parameters of the chlorate process affect the cathode potential for hydrogen evolution on iron in a wide current-density range. The varied parameters were pH, temperature, mass transport conditions and the ionic concentrations of chloride, chlorate, chromate and hypochlorite. At lower current densities, where cathodic protection of the electrode material is important, the pH buffering capacity of the electrolyte influenced the potential to a large extent. It could be concluded that none of the electrolyte parameters had any major effects (<50 mV) on the chlorate-cathode potential at industrially relevant current densities (around 3 kA m−2). Certainly, there is more voltage to gain from changing the cathode material than from modifying the electrolyte composition. This is exemplified by experiments on steel corroded from operation in a chlorate plant, which exhibits significantly higher activity for hydrogen evolution than polished steel or iron.

Keywords

Chlorate cathode Chlorate process Hydrogen evolution Iron Steel 

List of symbols

ci

Concentration of species i (mol m−3)

Di

Diffusion coefficient of species i (m2 s−1)

E

Cathode potential vs reference electrode (Ag/AgCl) (V)

F

Faraday constant (As mol−1)

jk

Current density for reaction k (A m−2)

\( k^{\prime}_{2} \)

Coefficient in the Tafel expression of Eq. 2, which is given in Eq. 15 (mol m−2 s−1)

k14

Coefficient in the Tafel expression of Eq. 14, which is given in equation 16 (m s−1)

Ni

Molar flux of species i (mol m−2 s−1)

R

Universal gas constant (J mol−1 K−1)

Ri

Homogeneous production rate of species i (mol m−3 s−1)

T

Temperature (K)

uz

Convective velocity perpendicular to the electrode surface, i.e. in the direction of the z-axis (m s−1)

z

Axial coordinate (m)

α

Transfer coefficient

δD

Diffusion layer (m)

δR

Reaction layer (m)

Notes

Acknowledgements

This work was financed by the Swedish Energy Agency, Eka Chemicals AB and Permascand AB.

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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Applied Electrochemistry, School of Chemical Science and EngineeringRoyal Institute of Technology (KTH)StockholmSweden

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