Experimental and theoretical investigations of a newly synthesized azomethine compound as inhibitor for mild steel corrosion in aggressive media: A comprehensive study

A new azomethine compound viz. 3-(2-amino-4,5-dimethylphenyl)imino)methyl) benzaldehyde (ADMB) was synthesized following a greener approach at room temperature and its anti-corrosion characteristics for mild steel (MS) corrosion were examined at various temperatures (298 K to 328 K) and concentrations (1 mM to 0.001 mM) in 0.5 M H2SO4 via electrochemical methods allied with surface characterization techniques. The adsorption of the ADMB molecules on the metal surface follows Langmuir's adsorption isotherm. To ascertain the mode of adsorption process, various adsorption and activation parameters were evaluated. Surface characterization studies viz. ATR-FTIR, SEM, AFM and EDS depict the formation of protective layer of ADMB on MS specimen. Density functional theory (DFT) treatment of ADMB established that the lower energy gap (Delta E) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) resulted in significantly high inhibition efficiency. These results have shown that ADMB act as an effective inhibitor for MS corrosion in H2SO4. The inhibition efficiencies predicted from experimental measurements are in agreement with the theoretically evaluated parameters and results of spectroscopic techniques. (C) 2018 Elsevier B.V. All rights reserved.