Electrochemical and quantum chemical studies of 2-amino-4-methyl-thiazole as corrosion inhibitor for mild steel in HCl solution

• 2-Amino-4-methyl-thiazole (2A4MT) was investigated as a corrosion inhibitor.
• The pores on mild steel were suppressed in presence of 2A4MT, as seen from SEM.
• The thermodynamic data signaled strongly adsorption of protonated 2A4MT.
• The Mulliken and NBO charges correlated 2A4MT is favorable in protonated form.

The application of 2-amino-4-methyl-thiazole (2A4MT) as a corrosion inhibitor for mild steel (MS) protection was investigated in 0.5 M HCl solution. The electrochemical impedance spectroscopy and potentiodynamic measurements were used at various concentrations and temperatures. The surface of MS was analyzed with scanning electron microscope in absence and presence of 2A4MT. Results showed that the correlation between experimental (inhibition efficiency, surface charge, ΔGadso,Ea) and quantum calculation parameters (dipole moment, EHOMO, ELUMO). It was concluded that the high corrosion inhibition efficiency of 2A4MT was associated with its strong adsorption as a barrier film on the MS surface.