Effect of hydrodynamic conditions on the inhibition performance of l-methionine as a “green” inhibitor

Influence of hydrodynamic conditions on the behavior of l-methionine (l-MTI) as a green organic inhibitor was studied using mild steel rotating disc electrode. Electrochemical impedance spectroscopy (EIS) and polarization measurements were carried out in the absence and presence of inhibitor in 1 M H2SO4 solution under static conditions and at different rotation speeds; the inhibitor concentration was 5 × 10−3 M in all tests. The open circuit potentials (OCP) were measured versus time in all studied rotation speeds; it was found that the OCP shifted toward more positive potentials as the rotation speed increased. It was also found that the inhibition efficiencies for still electrode and low speed rotations did not have noticeable changes, but in much higher rotation speeds, increased efficiencies were observed. This behavior could be attributed to the enhanced mass transport of inhibitor molecules from bulk to the metal surface in high rotation rates.