Effect of the inhibitor structure on the corrosion and hydrogen permeation of iron

To investigate the relationship between the 3D molecular structure of two non‐planar amines (tribenzylamine – TBA, and N,N‐dibenzylaniline – DBA) and their corrosion and hydrogen permeation inhibition efficiencies for iron in H₂SO₄ solution.

Potentiodynamic polarization and bipolar hydrogen permeation techniques were used to evaluate the inhibition efficiencies of the investigated amines, which were selected according to their structural differences, which were limited to only one substituent. As a result, a simplified 3D model was used to correlate the molecular structures with the experimental results.

Both amines are good cathodic corrosion inhibitors; however, the DBA displays low hydrogen permeation inhibition efficiency, in contrast to the TBA. These efficiencies can be ascribed to the sole structural difference between the compounds, which determines their spatial geometry in the adsorbed states.

It may be difficult to find non‐planar organic inhibitors for iron in acidic solutions with the desired structural differences and a suitable solubility for further investigations.

The proposed approach allows a systematic analysis and an unambiguous correlation between the molecular structure and the protectiveness of prospective organic inhibitors.