Corrosion inhibition of mild steel in acidic media using newly synthesized heterocyclic organic molecules

Hydrogen evolution reaction (HER) (cathodic reaction) of mild steel immersed in H2SO4 acid was investigated. Electrochemical corrosion behavior and hydrogen evolution reaction of mild steel has been investigated using different electrochemical techniques. Steel was polarized vs. saturated calomel electrode (SCE) in naturally aerated 1.0 M H2SO4 aqueous solution containing four organic inhibitors (newly synthesized heterocyclic compounds) of different concentrations. The observed different influence of corrosion inhibitors on the hydrogen evolution reaction was associated with the different chemical composition and structure. Polarization results showed that corrosion current density, icorr, and hydrogen evolution decreases with increasing concentration of inhibitors in 1.0 M H2SO4, indicating a decrease in the corrosion rate. Electrochemical impedance spectroscopy (EIS) measurements confirmed this behavior. An increase of temperature leads to increase in the corrosion or hydrogen evolution rate and a decrease of the total resistance value, RT. The obtained results were confirmed by surface examination.