Halogen-substituted thiazole-2-formaldehyde derivatives as corrosion inhibitors for carbon steel in acidic media: a comparative study of adsorption behavior and inhibition efficiency

• D.M. Jamil¹, N. Betti², E.M. Ali³, A.H. Kadhum⁴ and A. Alamiery^5,6

¹ Chemistry Department, College of Science, Al-Nahrain University, P.O. Box: 10001, Baghdad, Iraq
² Materials Engineering College, University of Technology-Iraq, P.O. Box: 10001, Baghdad, Iraq
³ College of Oil and Gas Engineering, University of Technology, Baghdad, Iraq
⁴ Faculty of Medicine, University of Al-Ameed, P.O. Box: 56001, Karbala, Iraq
⁵ AUIQ National Center for Research and Innovation, Al-Ayen Iraqi University, AUIQ, An Nasiriyah, P.O. Box: 64004, Thi Qar, Iraq
⁶ Energy and renewable energies technology center, University of Technology, Baghdad, 10001 Iraq

Abstract: This study explores the influence of halogen substitution on the adsorption behavior and corrosion inhibition performance of thiazole-2-formaldehyde derivatives, chiefly 4-(4-chlorophenyl)thiazole-2-formaldehyde (CTF) and 4-(4-bromophenyl)thiazole-2-formaldehyde (BTF), for carbon steel in 1 M HCl solution. Compounds were acquired from commercial sources and used as received. Weight loss measurements were taken at different concentrations (0.1–0.5 mM) and temperatures (303–333 K) to determine corrosion rates and inhibition efficiencies for immersion times up to 48 hours. It was revealed that BTF exhibits better protective properties at all times with a maximum inhibition of 93.8%. The increase in inhibition efficiency of both inhibitors was due to an increase in concentration and immersion time but decreased slightly with an increase in temperature, indicating the adsorption mechanism to be mainly through physisorption. The adsorption behavior obeyed the Langmuir adsorption isotherm, while the standard Gibbs free adsorption energies (–9.01 and –9.28 kJ·mol^–1 for CTF and BTF, respectively) confirm the spontaneous adsorption with the main physical and a small chemical adsorption contribution. In support of the experiments, the DFT results revealed that BTF has slightly better electronic properties, such as polarizability, energy gap, and electron transfer ability, that favor the interaction between BTF and the carbon steel surface. In general, this indicates that the extent of halogen substitution affects the corrosion inhibition features. The brilliant improvement of BTF gives a stronger hint that electronic structure and polarizability should be considered in the design of inhibitors. The findings contribute to the development of more effective, temperature-tolerant, and environmentally sustainable corrosion inhibitors for industrial applications.

Keywords: thiazoles, corrosion inhibition, low carbon steel, HCl solution, adsorption isotherm, DFT

Int. J. Corros. Scale Inhib., 2025, 14, no. 4, 2312-2333
doi: 10.17675/2305-6894-2025-14-4-32

Download PDF (Total downloads: 9)

Back to this issue content: 2025, Vol. 14, Issue 4 (pp. 1685-... (in progress))