2020 Volume 60 Issue 4 Pages 739-744
The effect of hydrogen sulfide (H2S) on the behavior of hydrogen entry into low alloy steel was investigated using electrochemical hydrogen permeation technique. In this study, the hydrogen entry side was galvanostatically charged to control the rate of hydrogen evolution reaction.
At pH of 3.0 in acetic buffer solution with 0.1 MPa H2S environment or that with deaerated environment, the potential, charging current density, and permeation current density were measured.
Hydrogen permeation current density had a linear relation to the square root of hydrogen charging current density, indicating that the hydrogen evolution reaction proceeds under Volmer-Tafel mechanism.
For analyzing the results of this study, the efficiency of hydrogen entry was calculated from the relationships among hydrogen charging current density, hydrogen permeation current density and hydrogen overpotential. It was found that the efficiency of hydrogen entry was drastically higher in H2S environment than that in the deaerated environment.
However, the coverage of hydrogen atoms adsorbed on hydrogen entry side did not change in H2S environment as compared with that in the deaerated environment.
All these results suggested that, although hydrogen coverage was not changed, hydrogen entry was accelerated in H2S environment.
