Anti-corrosive Properties and Quantum Chemical Study of (E)-4-Methoxy-N-(Methoxybenzylidene)Aniline and (E)-N-(4-Methoxybenzylidene)-4-Nitroaniline Coating on Mild Steel in Molar Hydrochloric.

摘要

The effect of (E)-4-methoxy-N-(methoxybenzylidene)aniline (P1) and (E)-N-(4-methoxybenzylidene)-4-nitroaniline (P2) on the corrosion of steel in molar hydrochloric acid studied by weight loss andelectrochemical polarisation. The results obtained reveal that the compounds reduce the corrosion rate.The inhibition efficiency increases with the increase of inhibitor concentration. Potentiodynamicpolarisation studies clearly reveal that the presence of the inhibitors does not change the mechanism ofthe hydrogen evolution reaction and acts essentially as mixed inhibitors. We note good agreementbetween gravimetric and electrochemical methods. The influence of temperature and inhibitorconcentration on the corrosion of mild steel has also been investigated in the temperature range 308 -353K, indicates that inhibition efficiency remains almost constant with temperature. The adsorption ofthe inhibitors on the mild steel surface in both acids obeys the Langmuir' adsorption isotherm. Thethermodynamic parameters of adsorption deduced reveal a strong interaction and spontaneousadsorption of P1 and P2 on the mild steel surface. Also the objective of this work is to attempt to findrelationships between their molecular and electronic structures and inhibition efficiency. The structuralparameters, such as the frontier molecular orbital energies (EHOMO and ELUMO), gap of energy , thecharge distribution, the absolute hardness and the softness , the fraction of electrons 凬 transferredfrom the molecules to iron as well as electronic parameters such as Mulliken atomic populations andFukui indices were calculated and discussed.Int. J. Electrochem.