Theoretical and Experimental Studies of Different Amine Compounds as Corrosion Inhibitors for Aluminum in Hydrochloric Acid

Density Functional Theory investigations using the B3LYP/6-31G* model have been carried out. Several quantum chemical parameters have been computed to interpret the inhibition activity of 2, 4-dinitrophenylhydrazine, o-phenylenediamine, and hydrazine hydrate. The ranking of the quantum chemical calculations classifies 2, 4-Dinitrophenylhydrazine as high efficient inhibitor among the studied molecules. The correspondence of the lowest energy gap (ΔE = 4.27 eV) for the calculated value (88.9%) of the highest inhibition efficiency (%IE) of 2, 4 Dinitrophenylhydrazine. Therefore, in parallel, the experimental inhibition of aluminum corrosion was tested using amine compounds in 1M hydrochloric acid solution by means of gravimetry and gasometry measurements. These compounds have been found to act as effective corrosion inhibitors for aluminum in the acid solution, and the best one was 2, 4-dinitrophenylhydrazine, represent one of the salient agreements between experimental and theoretical measurements. The data are showing that this inhibitor is appropriate for Langmuir adsorption isotherm. SEM micrographs indicate that the surface coverage increases in the presence of 0.5 mM of 2, 4-dinitrophenylhydrazine inhibitor, which in turn results in the formation of the adsorbed compound on the metal surface and the surface is covered by an inhibitor layer that effectively controls the dissolution of aluminum.