Corrosion Inhibition Mechanism Concerning Adsorption of Sulfate, Hydrogen Sulfate Anions and Benzotriazol from Sulfuric Acid Solutions on Heterogeneous Steel Surface

Abstract

The adsorption of benzotriazol on heterogeneous steel surface from H₂SO₄ solutions of different concentrations was studied by its corrosion inhibition effectiveness. A mechanism of corrosion and corrosion inhibition of carbon steel by benzotriazol illustrate the dual effect of enhancing and competitive influences of sulfate and hydrogen sulfate anions with benzotriazol for adsorption on steel surface. Ismaeel adsorption isotherm for adsorption of multicomponent with different molecular sizes and action on heterogeneous surface is applicable to experimental results at all H₂SO₄ and benzotriazol concentrations. It gives values of adsorption free energy change (ΔG) and heterogeneity parameter (m), which agree with inhibition mechanism and explain the decrease of surface coverage (θ) with benzotriazol as acid concentration increase.