Investigation of indole-3-carboxylic acid as steel inhibitor in 0.1 M H2SO4 solution

Corrosion inhibition of indole-3-carboxylic acid (ICA) on mild steel in 0.1 M H2SO4 solution has been studied through weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) experiments. Plots from polarization and EIS techniques show ICA acts as a mixed type inhibitor and its high inhibition effectiveness is assumed to occur via the adsorption of the inhibitor molecules on steel surface. It is then found that this adsorption behavior obeys the Langmuir adsorption isotherm. Theoretical techniques incorporating molecular mechanics and molecular dynamics were used to simulate the adsorption of ICA molecule on Fe(1 1 0) surface.