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

The inhibition effect of 3,6-bis(2-methoxyphenyl)-1,2-dihydro-1,2,4,5-tetra rine (2-MDHT) on the corrosion of mild steel in acidic media has been inves tigated by weight loss and various electrochemical techniques. Results obta ined 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 H2SO4. Potentiodynamic polarisation studies showed that 7-MDHT is a mi xed-type inhibitor in 1 M HCl and cathodic-type in 0.5 M H2SO4. 2-MDHT acts on the cathodic reaction without changing the mechanism of the hydrogen ev olution reaction. Surface analyses were also carried out to establish the m echanism of corrosion inhibition of mild steel in acidic media. The adsorpt ion of this inhibitor on the mild steel surface in both acids obeys the Lan gmuir absorption isotherm. The effect of temperature on the corrosion behav iour of mild steel in 1 M HCl with addition of 100 mg 1(-1) of 2-MDHT was s tudied in the temperature range 25-60 degrees C, The associated activation corrosion and free adsorption energies have been determined. (C) 2000 Elsev ier Science Ltd. All rights reserved.