Skip to main content
SpringerLink
Log in

The role of mass transfer in the electrolytic reduction of hexavalent chromium at gas evolving rotating cylinder electrodes

  • Papers
  • Published:
Journal of Applied Electrochemistry Aims and scope Submit manuscript

Abstract

The rate of electrolytic reduction of hexavalent chromium from acidic solution at a hydrogen-evolving rotating cylinder lead cathode was studied under conditions of different current densities, Cr6+ concentrations and rotation speeds. The rate of the reaction was found to follow a first order rate equation. The specific reaction rate constant was found to increase with increasing rotation speed until a limiting value was reached with further increase in rotation speed. Mechanistic study of the reaction has shown that at relatively low rotation speeds the reduction of Cr6+ is partially diffusion controlled, at higher speeds the reaction becomes chemically controlled. The limiting specific reaction rate constant was related to the operating current density by the equationK=0.044i 1.385. The current efficiency of Cr6+-reduction was measured as a function of current density, initial Cr6+ concentration and rotation speed. Possible practical applications are discussed.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

Abbreviations

A :

electrode area (cm2)

a, b :

constants in Equations 5 and 13, respectively

C :

bulk concentration of Cr6+ at timet(M)

C o :

initial concentration of Cr6+ (M)

C i :

interfacial concentration of Cr6+ (M)

d :

cylinder diameter (cm)

D :

diffusivity of Cr6+ (cm2 s−1)

e o :

standard electrode potential (V)

F :

Faraday's constant (96 487 C)

\(I_{H_2 } \) :

current consumed in hydrogen discharge (A)

i :

current density (A cm−2)

I :

cell current (A)

K l :

mass transfer coefficient (cm s−1)

K r :

mass transfer coefficient due to cylinder rotation (cm s−1)

K o :

natural convection mass transfer coefficient (cm s−1)

K g :

mass transfer coefficient due to hydrogen stirring (cm s−1)

K 2 :

specific reaction rate constant (cm s−1)

K :

overall rate constant (cm s−1)

m :

theoretical amount of Cr6+ reduced during electrolysis (g)

P :

gas pressure (atm)

R :

gas constant (atm cm3 mol−1 K−1)

T :

temperature (K)

t :

time (s)

V :

linear speed of the rotating cylinder (cm s−1)

\(V_{H_2 } \) :

hydrogen discharge rate (cm3 cm−2 s−1)

V s :

solution volume (cm3)

z :

electrochemical equivalent (g C−1)

Z :

number of electrons involved in the reaction

Re :

Reynolds number (Vd/v)

Sh :

Sherwood number (K r d/D)

Sc :

Schmidt number (v/D)

ω:

rotation speed (r.p.m.)

⋎:

kinematic viscosity (cm2 s−1)

References

  1. H. F. Lund, ‘Industrial Pollution Control Handbook’, McGraw-Hill, New York (1971).

    Google Scholar 

  2. I. C. Agarwal, A. M. Rochon, H. D. Gesser and A. P. Sparling,Water Res. 18, (1984) 227.

    Google Scholar 

  3. D. Golub and Y. Oren,J. Appl. Electrochem. 19 (1989) 311.

    Google Scholar 

  4. A. F. Diaz and D. Schermer,J. Electrochem. Soc. 132 (1985) 2572.

    Google Scholar 

  5. J. S. Lee and T. Sekine,Denki Kagaku 44 (1976) 176.

    Google Scholar 

  6. A. I. Vogel, ‘Quantitative Inorganic Analysis’, 2nd edn, Longmans, 4 Green and Co., London (1958).

    Google Scholar 

  7. R. R. Lloyed, W. T. Rawles and R. G. Feeney,Trans. Electrochem. Soc. 89 (1946) 443.

    Google Scholar 

  8. W. H. Wade and L. F. Yntema,74 (1938) 461.

    Google Scholar 

  9. G. Isserlis,in ‘Industrial Electrochemical Processes’ (edited by A. T. Kuhn) Elsevier, New York (1971).

    Google Scholar 

  10. F. C. Walsh and D. R. Gabe,Trans. I Chem E 68 (1990) 107.

    Google Scholar 

  11. F. S. Holland,Chemistry and Industry (July 1978) 453.

  12. M. M. Nassar, O. A. Fadali and G. H. Sedahmed,Pulp & Paper Canada 84 (1983) T275.

    Google Scholar 

  13. M. M. Nassar, O. A. Fadali and G. H. Sedahmed,Z. Metallkunde 80 (1988) 60.

    Google Scholar 

  14. J. W. Mellor, ‘A Comprehensive Treatise on Inorganic and Theoretical Chemistry’, Longmans Green and Co, London (1951).

    Google Scholar 

  15. T. Moeller, ‘Inorganic Chemistry’, Wiley, New York (1952).

    Google Scholar 

  16. A. T. Kuhn and R. Clarke,J. Appl. Chem. and Biotechnol. 26 (1976) 407.

    Google Scholar 

  17. A. Findlay and J. A. Kitchener, ‘Practical Physical Chemistry’, 8th edn, Longmans, London (1965).

    Google Scholar 

  18. M. Eisenberg, C. W. Tobias and C. R. Wilke,J. Electrochem. Soc. 103 (1953) 413.

    Google Scholar 

  19. H. Vogt,Electrochim Acta 23 (1978) 203.

    Google Scholar 

  20. D. Landolt, R. Acosta, R. H. Muller and C. W. Tobias,J. Electrochem. Soc. 117 (1970) 839.

    Google Scholar 

  21. H. Vogt,Electrochim. Acta 32 (1987) 633.

    Google Scholar 

  22. J. A. Leistra and P. J. Sides,32 (1987) 1489.

    Google Scholar 

  23. M. G. Fouad and G. H. Sedahmed,19 (1974) 861.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Chemical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, Egypt

    A. Radwan, A. El-Kiar, H. A. Farag & G. H. Sedahmed

Authors
  1. A. Radwan
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. A. El-Kiar
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. H. A. Farag
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. G. H. Sedahmed
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Radwan, A., El-Kiar, A., Farag, H.A. et al. The role of mass transfer in the electrolytic reduction of hexavalent chromium at gas evolving rotating cylinder electrodes. J Appl Electrochem 22, 1161–1166 (1992). https://doi.org/10.1007/BF01297418

Download citation

  • Received:

  • Revised:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF01297418

Keywords

Search

Navigation