Comparative study of Hibiscus rosa-sinensis and Azadirachta indica leaf extracts as efficient green corrosion inhibitors for mild steel in 1M HCl

Malays. J. Anal. Sci. Volume 30 Number 1 (2026): 1670

Research Article

Comparative study of Hibiscus rosa-sinensis and Azadirachta indica leaf extracts as efficient green corrosion inhibitors for mild steel in 1M HCl

Mohd Lias Kamal^1*, Farah Hanis Hamid¹, Shahrizal Hasan¹ and Khairil Anuar Jantan^2*

¹Faculty of Applied Sciences, Universiti Teknologi MARA, Perlis Branch, 02600, Arau, Perlis, Malaysia

²School of Chemistry and Environment, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

^*Corresponding author: e-mail: mohdlias@uitm.edu.my and khairil0323@uitm.edu.my

Received: 3 September 2025; Revised: 12 December 2025; Accepted: 5 January 2026; Published: 28 February 2026

Abstract

This study established Hibiscus rosa-sinensis (HRS) leaf extract as a highly superior green corrosion inhibitor for mild steel in 1 M HCl, directly outperforming Azadirachta indica (Neem). Through a multi-methodological approach, the study demonstrated that both ethanolic extracts served as effective mixed-type inhibitors, with efficiency scaling with concentration. At an optimal concentration of 400 ppm, HRS achieved exceptional inhibition efficiencies of 92%—96%, significantly surpassing the 87%—91% range shown by Neema cross electrochemical and gravimetric evaluations. FTIR-ATR analysis confirmed the presence of rich concentrations of flavonoids and polyphenolics in both extracts, with the superior performance of HRS attributed to its enhanced adsorption capability and the formation of a more robust protective film, a mechanism unequivocally validated by SEM surface analysis. These findings not only provided a definitive comparative assessment, but also positioned HRS leaf extract as an outstanding, eco-friendly alternative for industrial corrosion mitigation in acidic environments.

Keywords: corrosion inhibitor, mild steel, hydrochloric acid, Hibiscus rosa-sinensis, Azadirachta indica

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