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

Eco-friendly corrosion inhibition of C1020 carbon steel in 1 M HCl by Cytisus villosus leaf extract: combined electrochemical, surface, and molecular-level insights

Malika Khelfaoui, Amina Benaissa, Daoiya Zouied, Noura Naili, Youghourta Belhocine, Radja Nada Boucetta, Faiza Chekkal, Mounira Rouainia, and Bachir Zouchoune

Laboratory LGCES, Faculty of Technology, 20 August 1955 University, Skikda, Algeria

E-mail: m.khelfaoui@univ-skikda.dz

Received: 20 November 2025  Accepted: 6 February 2026

Abstract:

The corrosion of carbon steel in acidic environments, with its associated economic and material costs, presents significant challenges across industries. This study introduces an aqueous extract from Cytisus villosus leaves (CVL) as a renewable, eco-friendly corrosion inhibitor for C1020 carbon steel in 1 M HCl. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), and theoretical modeling were employed to characterize the electrochemical behavior and surface morphology. EIS results show that a 1000 ppm concentration of CVL extract significantly reduces corrosion, achieving an inhibition efficiency of 98.43% after 30 min of immersion. Polarization measurements indicate that CVL predominantly acts through an anodic inhibition mechanism, altering metal dissolution kinetics. Adsorption studies suggest that CVL components adhere to the steel surface via physisorption, following the Langmuir adsorption isotherm, forming a stable protective barrier. SEM analysis confirms the formation of a compact, adherent, and homogeneous protective film, enhancing resistance to acid attack. Computational simulations using density functional theory and molecular dynamics support the experimental findings, illustrating the electron donation and acceptance properties of CVL components and their adsorption on the steel surface. Overall, the results of this study demonstrate that CVL extract is an effective and environmentally friendly corrosion inhibitor for C1020 carbon steel. The extract shows significant inhibition efficiency in acidic media, indicating its potential as a sustainable option for mitigating corrosion, particularly in hydrochloric acid pickling processes. Further research is necessary to evaluate its stability, durability, and long-term performance under practical industrial conditions, which are critical factors for validating its feasibility for industrial applications.

Keywords: C1020 Carbon steel; Cytisus villosus; Corrosion inhibitor; EIS; Inhibition efficiency; Adsorption mechanism; Computational simulation

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04726-4

Chemical Papers 80 (5) 5517–5539 (2026)