Synergistic inhibition of Mikania micrantha extract with iodide ion on the corrosion of cold rolled steel in trichloroacetic acid medium

The corrosion inhibition behavior of Mikania micrantha extract (MME) and iodide ion in a synergistic system consisting of 0.10 M trichloroacetic acid (Cl₃CCOOH, TCA) on cold rolled steel (CRS) materials and its mechanism was fully investigated by weightlessness, electrochemical, and surface analysis measurements. The results show that MME/I⁻ performs higher inhibition than either MME or I⁻ with a peak inhibition efficiency of 96.3 %. The adsorption of MME, I⁻ and MME/I⁻ on CRS follow with Langmuir isotherm. MME/I⁻ retards both anodic and cathodic reactions. With the MME/I⁻ complex inhibitor, the capacitance arc radius reaches a maximum. The results of scanning electron microscopy (SEM), atomic force microscopy (AFM), and confocal laser scanning microscopy (CLSM) showed that there were obvious adsorbent films on the surface of the suppressed CRS. Compositional analysis of surface adsorbates on CRS by X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS) revealed that the main components of the adsorption film on the surface of CRS contained a large number of polar compounds, notably the formation of chemical bonds by iron atoms.