ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Unravelling mild steel protection in acidic solution via electrochemical behaviour and molecular descriptions of Phanera vahlii leaf extract

Gaurav Thakur, Akhil Saxena, and Jasdeep Kaur

Department of Chemistry, Chandigarh University, Ludhiana-Chandigarh National Highway, Mohali, India

E-mail: akhil.uis@cumail.in

Received: 5 February 2026  Accepted: 30 April 2026

Abstract:

The strength, longevity, and safety of metal buildings exposed to harsh acidic conditions like HCl and H₂SO₄ are all greatly impacted by corrosion. With potential uses in acid pickling and industrial cleaning procedures, Phanera vahlii extract was examined in this work as a green corrosion inhibitor for mild steel in 0.5 M H₂SO₄. Gravimetric tests, UV–visible spectroscopy, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and quantum chemical computations were used to assess the inhibitory performance. The findings showed that at 4000 mg L⁻¹, the greatest inhibitory efficiency was 96.47%. The development of a protective adsorbed layer was indicated by the EIS analysis, which revealed a considerable increase in charge transfer resistance with increasing inhibitor concentration. The extract functions as a mixed-type (bifunctional) inhibitor, according to PDP data. Surface protection in the presence of the inhibitor was further corroborated by SEM observations. Phytoconstituents like Quercetin-3-O-rhamnoside and Davinvolunol B, which have heteroatoms and π-electron systems that promote adsorption onto the metal surface, are thought to be responsible for the anticorrosion activity. All things considered, Phanera vahlii extract inhibits corrosion in acidic medium in an effective and eco-friendly manner. To provide qualitative molecular insights into adsorption behaviour, theoretical calculations were carried out utilizing representative phytochemicals reported in the literature.

Graphical abstract

Keywords: Phanera vahlii extract; Steel corrosion; Green corrosion inhibitor; Potentiodynamic polarization measurement; Scanning Electron Microscopy

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04992-2

Chemical Papers 80 (9) 10063–10082 (2026)