Experimental and theoretical studies of thiazoles as corrosion inhibitors for mild steel in sulphuric acid solution

The inhibition effects of 2-amino-5-mercapto-1,3,4-thiadiazole (2A5MT) and 2-mercaptothiazoline (2MT) on mild steel corrosion in 1.0 M H2SO4 were studied with potentiodynamic polarization, linear polarization resistance and electrochemical impedance spectroscopy techniques. It was shown that both 2A5MT and 2MT act as good corrosion inhibitors for mild steel protection. The high inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the steel surface. The effects of the presence of extra NH2 group and N atom in 2A5MT on the ability to act as corrosion inhibitors were investigated by theoretical calculations.

Graphical abstractThe inhibition effect of 2-amino-5-mercapto-1,3,4-thiadiazole and 2-mercaptothiazoline on mild steel corrosion in 1.0 M H2SO4 was studied using electrochemical techniques. The effects of the presence of extra NH2 group and N atom in 2A5MT on the ability to act as corrosion inhibitors were investigated by theoretical calculations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The inhibition effects of thiazoles on mild steel corrosion in 1.0 M H2SO4 were studied. ► It was shown that both thiazole compounds act as excellent corrosion inhibitors for mild steel. ► The high inhibition efficiency was attributed to the adsorption of the inhibitor molecules on the metal surface. ► Langmuir adsorption isotherm exhibited the best fit to the experimental data. ► Quantum chemical calculations show there is a correlation between inhibitive property and molecular parameters.