Investigation of Azo-Azomethine Compounds for Corrosion Protection of A516 Steel in Hydrochloric Acid Solution

Document Type : Original Article

Authors

1 Department of Inorganic Chemistry, Faculty of Chemistry and Petroleum Sciences, Bu-Ali Sina University, Hamedan, Iran

2 Department of Chemistry, Faculty of Science, Arak University, Arak 384817758, Iran

Abstract

Two new azo-azomethine compounds, L1, with a planar structure, and L2, with a tripodal structure, were synthesized from the condensation reaction of 1-(3-formyl-4-hydroxyphenylazo)-4-chlorobenzene with 2-aminonaphthalene and tris(2-aminoethyl)amine, respectively, and characterized using FT-IR, 1H NMR, and elemental analysis. The inhibitory behaviour of L1 and L2 for corrosion protection of A516 steel in 0.1 M hydrochloric acid solution was studied by weight loss measurements, electrochemical impedance spectroscopy, and Tafel polarization at different concentrations and temperatures. FE-SEM and AFM studies of the steel surface before and after exposure to an acidic environment, in the presence or absence of the current inhibitor, show that L1 forms a suitable coating layer on the steel surface due to its planar structure and, as a suitable inhibitor, effectively protects A516 steel against hydrochloric acid solution compared to L2. The inhibition efficiency of steel corrosion reaches 73.7 % with an increase L1 concentration up to the optimum value of 40 µmol/lit. After further increases in inhibitor concentration, the inhibition efficiency decreases. Electrochemical impedance analysis of the HCl/L1/steel interface reveals that at concentrations above the optimum, charge-transfer resistance of the steel surface declines, resulting in an increased corrosion rate. Tafel polarization curves indicate that the inhibition mechanism of L1 is mixed type, with a slight inclination toward cathodic inhibition.

Keywords

Main Subjects

Applied Chemistry Today
Volume 21, Issue 78
May 2026
Pages 179-196

Files

Share

How to cite

Statistics