Abstract
In this work, economy novel hydrazine-derived coumarin 4-(6-methylcoumarin)acetohydrazide (MCA) were synthesized, characterized, and tested as an inhibitor for the corrosion of a surface of mild steel in an acidic environment through weight loss and Scanning electron microscopy (SEM) techniques. Results showed that the synthesized inhibitor can inhibit the corrosion of mild steel surface in a 1 M hydrochloric acid environment. The corrosion inhibition efficiency of MCA increases with increasing MCA concentration and decreases with increasing temperature. SEM analysis showed the formation of a film as a protective layer from MCA molecules on the surface of mild steel. Adsorption of the MCA molecules on the mild steel surface in the presence of hydrochloric acid environment was obeyed Langmuir isotherm. The density functional theory (DFT) calculations were used to study the relationship between molecular structure and inhibition efficiency and they found in good agreement.
Highlights
One of the significant alloys used in many industrial processes is mild steel due to its superior mechanical characteristics and cost-effectiveness
Coumarins act as corrosion inhibitors due to the presence of aromatic systems and heteroatoms, which adsorb onto the mild steel surface via ion-pairs of electrons on heteroatom
The conducted experiments at higher concentrations of inhibitor (˃ 0.5 mM) imply that there was no significant increase in the inhibition efficiency and we found that the inhibitor at the concentration of 0.5 mm was found to be the optimal inhibition concentration
Summary
One of the significant alloys used in many industrial processes is mild steel due to its superior mechanical characteristics and cost-effectiveness. Coumarins act as corrosion inhibitors due to the presence of aromatic systems and heteroatoms, which adsorb onto the mild steel surface via ion-pairs of electrons on heteroatom. This induces superior adsorption of the inhibitor molecules and excellent inhibition efficiency in addition to decreases the corrosion rate [10,11,12,13]. Physisorption and/or chemisorption are the techniques that inhibitors adsorb onto a surface of mild steel and form a film as a protective barrier from acidic solutions [14].
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