Electrochemical deprotonation of phosphate on stainless steel

Voltammetric experiments performed in phosphate buffer at constant pH 8.0 on platinum and stainless steel revealed clear reduction currents, which were correlated to the concentrations of phosphate. On the basis of the reactions proposed previously, a model was elaborated, assuming that both H2PO4 and HPO4 2 underwent cathodic deprotonation, and including the acid–base equilibriums. A kinetic model was derived by analogy with the equations generally used for hydrogen evolution. Numerical fitting of the experimental data confirmed that the phosphate species may act as an efficient catalyst of hydrogen evolution via electrochemical deprotonation. This reaction may introduce an unexpected reversible pathway of hydrogen formation in the mechanisms of anaerobic corrosion. The possible new insights offered by the electrochemical deprotonation of phosphate in microbially influenced corrosion was finally discussed.

[1]  A. Bergel,et al.  The role of hydrogenases in the anaerobic microbiologically influenced corrosion of steels. , 2002, Bioelectrochemistry.

[2]  S. Y. Qian,et al.  Kinetic rationalization of catalyst poison effects on cathodic H sorption into metals: relation of enhancement and inhibition to H coverage , 1998 .

[3]  F. Widdel,et al.  Corroding iron as a hydrogen source for sulphate reduction in growing cultures of sulphate-reducing bacteria , 1986, Applied Microbiology and Biotechnology.

[4]  R. Bryant,et al.  The effect of inorganic phosphate and hydrogenase on the corrosion of mild steel , 1993, Applied Microbiology and Biotechnology.

[5]  C. Spruit,et al.  Influence of Sulphate-reducing Bacteria on the Corrosion Potential of Iron , 1952, Nature.

[6]  Andrew G. Glen,et al.  APPL , 2001 .

[7]  R. Bryant,et al.  Localization of cytochromes in the outer membrane of Desulfovibrio vulgaris (Hildenborough) and their role in anaerobic biocorrosion. , 1995, Anaerobe.

[8]  T. Nakazato,et al.  On the assignment of the redox peaks observed in phosphate and phosphite solutions at a Pt electrode , 1990 .

[9]  R. C. Salvarezza,et al.  Passivity Breakdown of Mild Steel in Sea Water in the Presence of Sulfate Reducing Bacteria , 1980 .

[10]  Z. Stojek,et al.  Voltammetric reduction of polyprotic acids at the platinum microelectrode: dependence on supporting electrolyte , 1995 .

[11]  S. Y. Qian,et al.  Electrochemical sorption of H into Fe and mild-steel: kinetic conditions for enhancement or inhibition by adsorbed HS- , 1999 .

[12]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[13]  A. Lasia,et al.  Kinetics of hydrogen evolution on nickel electrodes , 1990 .

[14]  Shahed U. M. Khan,et al.  The effect of glucose on electroreduction of phosphate at a Pt electrode: An indirect method of glucose detection in KRPB solution , 1989 .

[15]  Y. Massiani,et al.  Microbiological battery induced by sulphate-reducing bacteria , 1988 .

[16]  A. Arvia,et al.  The electrochemical behaviour of mild steel in phosphate-borate-sulphide solutions , 1983 .

[17]  R. C. Weast.  CRC Handbook of Chemistry and Physics , 1973 .

[18]  A. Bergel,et al.  Electron transfer between hydrogenase and 316L stainless steel: identification of a hydrogenase-catalyzed cathodic reaction in anaerobic mic , 2004 .

[19]  A. Hubbard.  Study of the kinetics of electrochemical reactions by thin-layer voltammetry , 1969 .

[20]  S. Daniele,et al.  Voltammetry for Reduction of Hydrogen Ions from Mixtures of Mono- and Polyprotic Acids at Platinum Microelectrodes , 1998 .

[21]  V. Concialini,et al.  The use of phosphate to generate H-atoms at pH 5–8 as determined by photocurrents: electrochemical properties of H-atoms , 1990 .

[22]  R. Bryant,et al.  The role of hydrogenase in anaerobic biocorrosion. , 1990 .