Cinnamon (Cinnamomum burmanni Nees and T. Nees) leaves extract as green corrosion inhibitor for mild steel in HCl solution

• R. Rohil, Y. Stiadi and E. Emriadi

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Andalas University, Padang, 25163, Indonesia

Abstract: This research focuses on the use of cinnamon leaf extract (CLE) as an eco-friendly corrosion inhibitor for mild steel in hydrochloric acid (HCl) solution. Based on weight loss tests, an inhibition efficiency of up to 93% was obtained at a concentration of 10 g/L. Potentiodynamic polarization (PDP) results showed that the extract acted as a mixed-type inhibitor by slowing down both anodic and cathodic reactions. Functional groups in the extract that bonded to the steel surface and helped form a protective layer were detected through FTIR analysis. Scanning Electron Microscope (SEM) images confirmed that corrosion damage was significantly reduced on the protected surface. Adsorption behaviour was found to follow the Langmuir isotherm model, suggesting that the process occurred spontaneously and involved both physical and chemical adsorption. Contact angle measurements also showed that the surface treated with the extract had a higher contact angle compared to the untreated one. This means that inhibitor molecules were adsorbed onto the metal surface, replacing water molecules and forming a more hydrophobic protective film. All surface characterization results support that this protective film plays an important role in minimizing the corrosion rate.

Keywords: cinnamon leaf extract (CLE), corrosion inhibitor, mild steel, weight loss

Int. J. Corros. Scale Inhib., 2025, 14, no. 4, 1798-1812
doi: 10.17675/2305-6894-2025-14-4-4

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