Abstract
In the present study, the corrosion inhibition effect of Spilanthes acmella aqueous leaves extract (SA-LE) on mild steel was investigated in 1.0 M HCl solution at different temperature using weight loss, Tafel polarization, linear polarization resistance (LPR), and electrochemical impedance (EIS) measurements. Adsorption of inhibitor on the surface of the mild steel obeyed both Langmuir and Temkin adsorption isotherms. The thermodynamic and kinetic parameters were also calculated to determine the mechanism of corrosion inhibition. The inhibition efficiency was found to increase with an increase in the inhibitor concentration i.e., Spilanthes acmella aqueous leaves extract, however, the inhibition efficiency decreased with an increase in the temperature. The phytochemical constituents with functional groups including electronegative hetero atoms such as N, O, and S in the extract adsorbed on the metal surface are found responsible for the effective performance of the inhibitor, which was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet–visible spectroscopic (UV-Vis) studies. Protective film formation against corrosion was confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle studies. The result shows that the leaves extract acts as corrosion inhibitor and is able to promote surface protection by blocking active sites on the metal.
Highlights
Corrosion is typically defined as the chemical or electrochemical reaction between a material and its environment, which usually includes a metal or alloy
The Bode plots revealed that the adsorption of the inhibitor on mild steel surface occurs in a single process
Weight loss measurements of mild steel coupons in the presence and absence of Spilanthes acmella aqueous leaves extract (SA-LE) in 1.0 M HCl medium suggest that the percentage of inhibition efficiency increases progressively with increasing inhibitor concentrations
Summary
Corrosion is typically defined as the chemical or electrochemical reaction between a material and its environment, which usually includes a metal or alloy. This process usually leads to the deterioration of the material and its properties. Corrosion of metals results in the deterioration of the surface of metallic structure or metal alloy in the course of their chemical, electrochemical, or biochemical interaction with the surrounding. It is an undesirable process resulting from the unwanted attack on the surface of metals or metal alloys by their environment [1]. These inhibitors delay the process of corrosion by various mechanisms
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