Corrosion inhibition of mild steel using Momordica dioica extract in acidic medium
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Date
2024
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Faculty of Science, University of Kelaniya Sri Lanka
Abstract
Corrosion is a natural phenomenon where refined metals transform into more stable substances like metal oxides, sulfides, or hydroxides, resulting in the metal's degradation. Metals higher in the reactivity series, like iron and zinc, are more prone to corrosion, indicating that corrosion involves the oxidation of metals. When an electron acceptor or depolarizer is present, corrosion occurs as an electrochemical process, with oxidation and reduction reactions occurring at different sites on the metal surface. For example, iron corrodes to form a visible reddish-brown layer of iron oxide. Oxygen and moisture are key factors that facilitate corrosion. This degradation can compromise the desired properties of the metal, highlighting the importance of preventive measures to preserve these properties. Mild steel, a type of low-carbon steel, is widely used in various industries. However, its main disadvantage is its vulnerability to corrosion. To improve the corrosion resistance of mild steel, several methods can be utilized, with the addition of inhibitors being the most straightforward and effective. Inhibitors are categorized into three types: cathodic, anodic, and adsorption inhibitors, with natural inhibitors or plant extracts falling into the adsorption category. This study employed electrochemical techniques to examine the effect of methanol plant extract from Momordica dioica on the corrosion inhibition of mild steel. The corrosion inhibition properties of the plant extract were assessed using cyclic voltammetry, which measures the current in an electrochemical cell under a constant potential. An acidic corrosive medium was prepared using a 1 M HCl solution, with the concentration of the plant extract inhibitor in this medium varying from 2% to 8% v/v. This range was chosen based on prior studies that indicated optimal inhibition effects within this concentration. To achieve the same current flow through the inhibitor solutions as compared to control solutions, the applied potential difference had to be increased, indicating resistance to current flow in the inhibitor solutions. The components in the inhibitor solution adsorb onto the surface of the mild steel specimens, forming a protective layer between the mild steel and the corrosive medium. The study confirmed that concentrations within this range provided a significant increase in corrosion resistance, as evidenced by the higher required potential values to maintain the same current flow in inhibitor solutions compared to blank solutions. This suggests that Momordica dioica extract effectively inhibits mild steel corrosion in acidic environments.
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Keywords
Corrosion Inhibition, Cyclic Voltammetry, HCl Acid, Momordica dioica, Mild Steel
Citation
Pradeepani E. P. M.; Jayawardena S. (2024), Corrosion inhibition of mild steel using Momordica dioica extract in acidic medium, Proceedings of the International Conference on Applied and Pure Sciences (ICAPS 2024-Kelaniya) Volume 4, Faculty of Science, University of Kelaniya Sri Lanka. Page 214