Corrosion Inhibition Mechanism and Stability of Quinic Acid as a Green Corrosion Inhibitor on Mild Steel

Although corrosion prevention methods have been studied for many years, they still maintain their relevance and popularity. Today's metal protection methods are desired to be cheap, easy to use, permanent, and effective, as well as environmentally friendly. Organic-based inhibitors are preferred due to their effectiveness and environmental benefits. Among these, organic acids, such as quinic acid, are particularly valued for their corrosion inhibition properties. Quinic acid, an organic acid found in various plants, serves as an effective corrosion inhibitor for mild steel in 0.5 M HCl solutions. This study evaluates its corrosion inhibition efficiency and stability under different storage conditions. Electrochemical techniques, including electrochemical impedance spectroscopy and polarization curve analysis, are employed to assess the inhibition performance. Surface characterization is conducted using scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements. Additionally, density functional theory analysis is performed to elucidate the molecular interactions of quinic acid. Experimental results demonstrate that quinic acid, at a concentration of 80 ppm in 0.5 M HCl, achieves a corrosion inhibition efficiency of 92% and maintains stability for up to 144 h. Environmentally friendly quinic acid has a high potential for use as inhibitors of mild steel corrosion.