Synthesis, Characterization, and Comparative Study of Pyridine Derivatives as Corrosion Inhibitors of Mild Steel in HCl Medium

摘要

Radical catalysis has been used to achieve addition of dodecanethiol and mercaptoa-cetic 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 ~(13)C NMR spectroscopy. Inhibition of the corrosion of mild steel in 1M 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.