Corrosion inhibition performance of 4-(4-methoxybenzylideneamino)-5-(4-pyridinyl)-2,4-dihydro-1,2,4-triazole-3-thione (MPDTT) for mild steel in acidic media: Experimental and theoretical insights

• M.M. Khalaf¹, A.N. Jasim², M.A.I. Al-Hamid³, A.M. Mustafa⁴, F.F. Sayyid⁴, A.H. Kadhum⁵ and A. Alamiery⁶

¹ Materials Techniques Engineering Department, Technical Engineering College-Baghdad, Middle Technical University, Baghdad 10001, Iraq
² Materials engineering department, Diyala university, Diyala 32001, Iraq
³ Department of Production Engineering and Metallurgical, University of Technology, Baghdad 10001, Iraq
⁴ Energy and Renewable Energies Technology Centre, University of Technology, Baghdad 10001, Iraq
⁵ Faculty of Medicine, University of Al-Ameed, P.O. Box: 56001, Karbala, Iraq
⁶ Al-Ayen Scientific Research Center, Al-Ayen Iraqi University, AUIQ, An Nasiriyah, P.O. Box: 64004, Thi Qar, Iraq

Abstract: This study investigates the corrosion inhibition efficiency of a novel triazole-based compound, 4-(4-methoxybenzylideneamino)-5-(4-pyridinyl)-2,4-dihydro-1,2,4-triazole-3-thione (MPDTT), for mild steel in 1 M HCl, integrating both experimental and theoretical analyses. Unlike conventional triazole inhibitors, MPDTT features a unique molecular structure incorporating methoxy and pyridinyl groups, which enhance its adsorption capacity and corrosion inhibition performance. Weight loss experiments were performed across varying MPDTT concentrations (0.1–1.0 mM) and immersion times (1–48 hours) to evaluate its protective capabilities. The results revealed that inhibition efficiency increased with MPDTT concentration, achieving a maximum of 96.1% at 0.5 mM after 48 hours, with efficiency stabilizing after 10 hours of immersion. Temperature studies (303–333 K) over a 5-hour immersion indicated a slight enhancement in inhibition efficiency with rising temperature, suggesting a robust inhibitor-metal interaction. Adsorption behavior followed the Langmuir isotherm, confirming monolayer formation and indicating a mixed chemisorption and physisorption mechanism. Quantum chemical parameters derived from Density Functional Theory (DFT) calculations, such as HOMO and LUMO energy levels, provided insights into the electronic properties of MPDTT and its potential interaction with the mild steel surface, supporting the experimentally observed inhibition efficiency. This combined experimental-theoretical approach demonstrates MPDTT’s enhanced efficiency, thermal stability, and potential as a highly effective and reliable corrosion inhibitor for mild steel in acidic environments, offering a significant advancement over existing triazole-based compounds.

Keywords: corrosion, mild steel, weight loss, Langmuir isotherm, DFT

Int. J. Corros. Scale Inhib., 2025, 14, no. 2, 437-459
doi: 10.17675/2305-6894-2025-14-2-2

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