N-Phenyl-N′-[5-phenyl-1,2,4-thiadiazol-3-yl]thiourea: corrosion inhibition of mild steel in 1 M HCl

• A. Mohammed¹, H.S. Aljibori², M.A.I. Al-Hamid³, W.K. Al-Azzawi⁴, A.A.H. Kadhum⁵ and A. Alamiery^3,6

¹ Department of Electromechanical Engineering, University of Technology-Iraq, P.O. Box: 10001, Baghdad, Iraq
² College of Engineering, University of Warith Al-Anbiyaa, Karbalaa, 56001, Iraq
³ Energy and Renewable Energies Technology Center, University of Technology, Iraq, P.O. Box: 10001, Baghdad, Iraq
⁴ Department of Medical Instruments Engineering Techniques, Al-Farahidi University, P.O. Box:10001, Baghdad, Iraq
⁵ Al-Ameed University College, P.O. Box: 56001, Karbala, Iraq
⁶ Department of Chemical and Process Engineering, Faculty of Engineering and Build Environment, Universiti Kebangsaan Malaysia, P.O. Box: 43600, Bangi, Selangor, Malaysia

Abstract: Corrosion control is of paramount importance in the realm of metals, and the quest for effective inhibitors is ongoing. This study delves into the potential corrosion inhibitory effect of N-phenyl-N′-[5-phenyl-1,2,4-thiadiazol-3-yl]thiourea (NPPTT) on mild steel when exposed to a corrosive 1 M HCl solution. Employing a dual approach, we combine experimental weight loss techniques with Density Functional Theory (DFT) calculations to comprehensively analyze inhibition efficiency and the underlying molecular interactions in the corrosion inhibition process. Our investigation begins with the confirmation of the inhibitor’s structural properties through experimental synthesis and characterization techniques. Subsequently, we assess the corrosion inhibition capability by immersing mild steel samples in the aggressive HCl solution, both with and without the inhibitor. Our findings reveal a significant reduction in the corrosion rate, signifying the potential of NPPTT as an effective corrosion inhibitor. At an inhibitor concentration of 0.5 mM and an immersion time of 5 hours at 303 K, the inhibition efficiency reaches 93.9%. To unravel the mechanistic insights at the molecular level, DFT calculations are employed. Quantum chemical parameters are computed, shedding light on how NPPTT molecules interact with the mild steel surface through a combination of electrostatic interactions, coordination bonds, and other molecular linkages. These theoretical findings corroborate the experimental results, enhancing our comprehension of the inhibitor’s action. Notably, our adsorption isotherm studies align with the Langmuir adsorption model, further confirming the inhibitor’s adherence to the metal surface. In summary, this combined theoretical and experimental investigation explores the corrosion inhibitory potential of NPPTT for mild steel in a corrosive, acidic environment. Our holistic approach not only validates the inhibitor’s efficiency but also advances our understanding of its molecular interactions, offering valuable insights for corrosion prevention strategies and the development of effective corrosion mitigation approaches in industrial settings.

Keywords: corrosion inhibition, mild steel, thiadiazole derivatives, acidic environment, DFT calculations

Int. J. Corros. Scale Inhib., 2024, 13, no. 1, 38-78
doi: 10.17675/2305-6894-2024-13-1-3

Download PDF (Total downloads: 53)

Back to this issue content: 2024, Vol. 13, Issue 1 (pp. 1-629)