SYNTHESIS, CHARACTERIZATION, AND COMPARATIVE STUDY OF PYRIDINE DERIVATIVES AS CORROSION INHIBITORS OF MILD STEEL IN HCl MEDIUM

Abstract

Radical catalysis has been used to achieve addition of dodecanethiol and mercaptoacetic acid to 4-vinylpyridine (4VP), giving 4-(dodecylthiaethyl)pyridine (DTEP) and 4-pyridylethylthia-acetic acid (PETAA). The purified monoadducts have been characterized using ¹H NMR and ¹³C NMR spectroscopy. Inhibition of the corrosion of mild steel in 1 M HCl by 4VP, DTEP, and PETAA has been investigated at 308 K using weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results obtained show that PETAA is the best inhibitor and its inhibition efficiency (E %) increases with the inhibitor concentration, reaching up to 93% for DTEP at 10⁻³ M. Potentiodynamic polarization studies clearly revealed that the inhibitors changed the mechanism of hydrogen evolution and that they acted as mixed inhibitors but most effectively in the cathodic range.

Keywords:

• 4-vinylpyridine
• Corrosion inhibition
• Gravimetry
• Surface electrochemistry
• Thiol addition

Acknowledgment

The authors thank Dr. Jack Harrowfield, Université Louis Pasteur de Strasbourg, for reading this article.