Synergistic experimental and theoretical investigation of 3 benzylsulfanyl-4H-(1,2,4)triazole as an efficient corrosion inhibitor for mild steel in hydrochloric acid

• F. Zulkifli¹, S.A. Yousif², A.A. Al-Amiery³, W. Daoudi⁴, M.S.M. Ghazali¹, E. Berdimurodov^5,6,7, B. Hammouti⁸, A. Pradityana⁹, W.B. Wan Nik^1,9, B.M. Praveen¹⁰, J. Haque¹¹ and A. Thakur¹²

¹ Faculty of Ocean Engineering Technology, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
² College of Pharmacy, Al-Ayen Iraqi University, AUIQ, An Nasiriyah, P.O. Box: 64004, Thi Qar, Iraq
³ Energy and Renewable Energies Technology Center, University of Technology, Baghdad, P.O. Box: 10001, Iraq
⁴ Laboratory of Education, Sciences and Techniques, Higher School of Education and Training of Berrechid, Hassan First University, Morocco
⁵ Faculty of Chemistry, National University of Uzbekistan, Tashkent, 100034, Uzbekistan
⁶ University of Tashkent for Applied Sciences, Str. Gavhar 1, Tashkent, 100149, Uzbekistan
⁷ School of Medicine, Central Asian University, Tashkent, 111221, Uzbekistan
⁸ Euromed University of Fes, UEMF, 30 000 Fes, Morocco
⁹ Dept. of Mechanical Industrial Engineering, Vocational Faculty, Institut Teknologi Sepuluh Nopember Surabaya, 60111, East Java, Indonesia
¹⁰ Department of Chemistry, Srinivas University Institute of Engineering and Technology, Mukka, Mangalore, Karnataka, India
¹¹ Interdisciplinary Research Center for Refining & Advanced Chemicals, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
¹² Division of Research and Development, Lovely Professional University, Phagwara, Punjab, 144411, India

Abstract: This study systematically evaluates the corrosion inhibition potential of 3-benzylsulfanyl-4H-(1,2,4) triazole (BST) on mild steel in a 1.0 M HCl environment. The investigation utilized a multi-faceted approach combining weight loss analysis, potentiodynamic polarization (PDP), scanning electron microscopy (SEM), and density functional theory (DFT). Gravimetric results indicated that inhibition efficiency is temperature- and concentration-dependent, peaking at 93.0% with a 0.5 mM concentration after 5 hours at 303 K. Adsorption analysis confirmed the data fits the Langmuir isotherm, suggesting a mechanism driven by both physisorption and chemisorption. PDP measurements corroborated these findings, showing a mixed-type inhibition behavior that suppresses both anodic and cathodic reactions, achieving a maximum efficiency of 96.3%. Surface analysis via SEM revealed that a protective layer was formed by the inhibitor, significantly reducing surface damage compared to the uninhibited acid solution. Furthermore, DFT calculations provided molecular-level evidence of strong interaction between the inhibitor and the steel surface, characterized by favorable HOMO-LUMO energy levels. These findings establish BST as a highly effective corrosion inhibitor that performs comparably to or better than existing triazole derivatives.

Keywords: triazole, corrosion inhibitor, DFT calculations, Langmuir, potentiodynamic method

Int. J. Corros. Scale Inhib., 2026, 15, no. 1, 278-303
doi: 10.17675/2305-6894-2026-15-1-14

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