Combined experimental and computational evaluation of Asplenium nidus leaf extract as a green corrosion inhibitor for mild steel in hydrochloric acid medium

• Y. Stiadi¹, M.A. Shadiq¹, Emriadi¹, Rahmayeni² and T.P. Wendari¹

¹ Electrochemistry and Energy Laboratory, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Andalas, Kampus Limau Manis, Padang 25163, Indonesia
² Materials Chemistry Laboratory, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Andalas, Kampus Limau Manis, Padang 25163, Indonesia

Abstract: Indonesia, one of the world’s megadiverse countries, hosts extraordinary biological resources that remain largely underexplored. Among these, tropical ferns show promise as precursors for environmentally benign corrosion inhibitors. The increasing demand for green inhibitors arises from the toxicity and environmental concerns associated with many synthetic alternatives. In this study, the methanolic extract of Asplenium nidus leaves was systematically investigated as a sustainable corrosion inhibitor for mild steel in 1 M HCl, using a combination of experimental and computational approaches. Phytochemical screening and LC–MS/MS analysis revealed the presence of abundant flavonoids, phenolics, alkaloids, and triterpenoids, with tenivastatin identified as the major component (31.33%). Weight-loss measurements showed a pronounced decrease in corrosion rate with increasing inhibitor concentration and temperature, while potentiodynamic polarization confirmed mixed-type inhibition with significant suppression of both anodic and cathodic reactions. At 4 g/L and 60℃, the extract achieved a maximum inhibition efficiency of 90.9%. Electrochemical impedance spectroscopy further indicated a substantial increase in charge-transfer resistance, accompanied by a reduction in double-layer capacitance. Spectroscopic and surface analyses (FTIR, UV–Vis, AFM, and contact-angle measurements) supported the formation of a compact organic protective film on the steel surface. DFT calculations (B3LYP/6-31G) demonstrated strong adsorption tendencies of tenivastatin through electron donation from carbonyl, hydroxyl, and aromatic groups, promoting Fe–ligand complex formation. Adsorption followed the Langmuir isotherm, with negative ΔG⁰_ads indicating spontaneous mixed physisorption–chemisorption. Overall, the integrated findings establish Asplenium nidus extract as an efficient and sustainable corrosion inhibitor for acidic environments.

Keywords: Asplenium nidus, corrosion inhibition, weight loss analysis, potentiodynamic polarization, Langmuir adsorption isotherm

Int. J. Corros. Scale Inhib., 2026, 15, no. 2, 220-252
doi: 10.17675/2305-6894-2026-15-2-14

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