Effect of Ethanolamine and Ethylamine on the Entropy Content of the Corrosion of Mild Steel in Tetraoxosulphate (VI) acid Solution

Abstract

The influence of ethanolamine and ethylamine on the corrosion behaviour of mild steel in 1M H₂SO₄ solution was investigated at room temperature (25^oC) by weight loss method. Results obtained show that the compounds are better inhibitors at low concentrations (<0.3M). From the decreasing weights of the metal over time, the concentrations of the metal was evaluated and plots of logarithm of the concentration of metal versus time as well as Erying-type equations facilitated the access of thermodynamic parameters such as equilibrium constant (k), enthalpy (?H*) and entropy (?S*) of the corrosion process. The entropy of the aggressive ions was found to have reduced on introduction of the inhibitors into the corrodent medium. Attempt to correlate the molecular structures of the inhibitors to the mechanism of inhibition was made.

Keywords: corrosion inhibition, mild steel, ethanolamine, ethylamine