Hydrogen Permeation of Carbon Steel in Weak Alkaline Solution Containing Hydrogen Sulfide and Cyanide Ion

The hydrogen permeation behavior of carbon steel (CS) was investigated electrochemically in weak alkaline solutions containing hydrogen sulfide (H₂S) with various cyanide ion (CN^–) concentrations under open-circuit conditions. Anodic and cathodic polarization behaviors of CS also were investigated under the same environmental conditions. Little hydrogen content (C₀) was detected in alkaline solutions without CN^–. However, when a small amount of CN^– was added in the alkaline solution, a rapid increase in C₀ was observed after the induction time, which corresponded to a rapid decrease in rest potential. Surface abrasion also produced a similar increase in C₀ in the presence of CN^–. Results were explained in terms of formation and destruction of iron sulfide (FeS), soluble species of H₂S, and iron dissolution.