Azole Compounds as Corrosion Inhibitors: Part I

• Published in: Journal of materials engineering and performance 2014, Vol.23 (1), p.213-221
• Main Authors: Ergun, Ümit, Emregül, Kaan C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion; Corrosion and Coatings; Corrosion mechanisms; Engineering Design; Exact sciences and technology; Materials Science; Metals. Metallurgy; Quality Control; Reliability; Safety and Risk; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-013-0737-2

The inhibitory effect of 3-amino-1,2,4 triazole (I), 2-aminothiazole (II), and 3-amino-5-mercapto-1,2,4 triazole (III) on the corrosion of steel in 2 M HCl solution has been studied using chemical technique and electrochemical techniques. The inhibition efficiencies (η) obtained from all the methods employed are in good agreement. Results reveal compound (III) to be the most efficient inhibitor with an inhibition efficiency of 91%. The inhibition efficiency increases with increasing concentration in all three compounds. Studies clearly indicate that these compounds act as a mixed type inhibitor without altering the cathodic reaction. The inhibitors are adsorbed on the surface according to the Langmuir adsorption isotherm. Quantum chemical parameters such as highest occupied molecular orbital energy ( E HOMO ), lowest unoccupied molecular orbital energy ( E LUMO ), energy gap (Δ E ), and dipole moment (μ) have been calculated for 3-amino-1,2,4 triazole (I), 2-aminothiazole (II), and 3-amino-5-mercapto-1,2,4 triazole (III) using semi-empirical PM3 and 6-311G(d,p) DFT methods.