Green Corrosion Inhibitor of the Matricaria Chamomilla Oil to Protect Steel in the Acidic H2S-Containing Solution

We aim to examine inhibiting behavior and adsorption of Matricaria Chamomilla Oil on the surface of carbon steel and evaluate the corrosion performance in the acidic H2S-containing solution at room temperature. Electrochemical impedance spectroscopy (EIS) and Tafel polarization tests are used to study the electrochemical behavior of the substrate. We also use scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) to study the steel surface after applying the inhibitor. The obtained results revealed that the inhibitor efficiency increases with inhibitor concentration up to 96% for 4.5 g/L. Corrosion inhibition of the Matricaria Chamomilla Oil can be ascribed to the adsorption the extract molecules on the carbon steel surface which can be discussed in the view of Langmuir adsorption isotherm. Quantum chemical parameters such as eLUMO, eHOMO and energy gap (Δe = eLUMO – eHOMO) for the main constituents of Matricaria Chamomilla Oil are calculated.