The inhibition action of 3,6-bis(2-methoxyphenyl)-1,2-dihydro-1,2,4,5-tetrazine on the corrosion of mild steel in acidic media

Abstract

The inhibition effect of 3,6-bis(2-methoxyphenyl)-1,2-dihydro-1,2,4,5-tetrazine (2-MDHT) on the corrosion of mild steel in acidic media has been investigated by weight loss and various electrochemical techniques. Results obtained reveal that this organic compound is a very good inhibitor. 2-MDHT is able to reduce the corrosion of steel more effectively in 1 M HCl than in 0.5 M H 2SO 4. Potentiodynamic polarisation studies showed that 2-MDHT is a mixed-type inhibitor in 1 M HCl and cathodic-type in 0.5 M H 2SO 4. 2-MDHT acts on the cathodic reaction without changing the mechanism of the hydrogen evolution reaction. Surface analyses were also carried out to establish the mechanism of corrosion inhibition of mild steel in acidic media. The adsorption of this inhibitor on the mild steel surface in both acids obeys the Langmuir absorption isotherm. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of 100 mg l −1 of 2-MDHT was studied in the temperature range 25–60°C. The associated activation corrosion and free adsorption energies have been determined.