Corrosion Behavior of Mild Steel in Presence of Two Non-Toxic Organic Inhibitor Compounds in Acidic Media
Authors: Díaz Cárdenas María Yesenia , Uruchurtu Jorge , Valladares María Guadalupe , Lagunas Selene , Menchaca Carmina 
Published: February 2020

Mild steel is used by industries due to their properties and low cost. Pipes, machinery, civil structures, and other devices are made from mild steel, and are used in diverse environments. However, corrosion is an electrochemical deteriorative process, that affects metallic materials. This degrading mechanism can be minimized by some corrosion prevention measures such as inhibitors. In fact, several researches have demonstrated that organic compounds reduce corrosion rates. However, several of these compounds had caused negative effects in the environment. Hence in the development of novel corrosion inhibitors has considered in their design non-toxic compounds. In fact, recent researches had been studied natural and synthetized inhibitors. Some of them have been obtained from natural products, which have showed to be a good alternative. Even more, others have been studied synthetized organic non-toxic compounds with good results.

The principal focus of this project was to find out alternatives to avoid environmental damages in preventing corrosion. We studied the metal behavior of mild steel in the presence of two organic compounds (a natural product and one synthesized) considered non-toxic, by electrochemical techniques such as polarization curves, and Electrochemical Impedance Spectroscopy in acidic media (H2SO4 0.5 M) at different concentrations (20, 50, 100 and 300 ppm) at room temperature. Even more, we studied the electrochemical behavior for the passive film formed in the presence of both inhibitors by EN noise tests in potentiostatic regime during 24 hours. The potential applied was +600 mV for the natural inhibitor, and +500 for the synthetized inhibitor.

The preliminary evaluation of mild steel in the presence of two different organic compounds, showed that in the case of the polarization curves the best efficiency (75%) for the synthetized inhibitor. However, up to +500 mV both inhibitors showed passive conditions. The frequency and amplitude of transients were analyzed by Power Spectral Density plots, and noise analysis in current under potenctiostatic regime reveals the presence of a passive film over the metal surface, which reduces the corrosion rate. The behavior during the formation depends on the concentration of the inhibitor, the stability of the film formed and the potential applied. Mild steel is used by industries due to their properties and low cost. Pipes, machinery, civil structures, and other devices are made from mild steel, and are used in diverse environments. However, corrosion is an electrochemical deteriorative process, that affects metallic materials. This degrading mechanism can be minimized by some corrosion prevention measures such as inhibitors. In fact, several researches have demonstrated that organic compounds reduce corrosion rates. However, several of these compounds had caused negative effects in the environment. Hence in the development of novel corrosion inhibitors has considered in their design non-toxic compounds. In fact, recent researches had been studied natural and synthetized inhibitors. Some of them have been obtained from natural products, which have showed to be a good alternative. Even more, others have been studied synthetized organic non-toxic compounds with good results.

The principal focus of this project was to find out alternatives to avoid environmental damages in preventing corrosion. We studied the metal behavior of mild steel in the presence of two organic compounds (a natural product and one synthesized) considered non-toxic, by electrochemical techniques such as polarization curves, and Electrochemical Impedance Spectroscopy in acidic media (H2SO4 0.5 M) at different concentrations (20, 50, 100 and 300 ppm) at room temperature. Even more, we studied the electrochemical behavior for the passive film formed in the presence of both inhibitors by EN noise tests in potentiostatic regime during 24 hours. The potential applied was +600 mV for the natural inhibitor, and +500 for the synthetized inhibitor.

The preliminary evaluation of mild steel in the presence of two different organic compounds, showed that in the case of the polarization curves the best efficiency (75%) for the synthetized inhibitor. However, up to +500 mV both inhibitors showed passive conditions. The frequency and amplitude of transients were analyzed by Power Spectral Density plots, and noise analysis in current under potenctiostatic regime reveals the presence of a passive film over the metal surface, which reduces the corrosion rate. The behavior during the formation depends on the concentration of the inhibitor, the stability of the film formed and the potential applied.