The inhibition effect of o-nitrophenol and Zn2+ system on corrosion of aluminium

Abstract

Corrosion inhibition of aluminum (6061) in aqueous solution at pH 11 by o-nitrophenolZn 2+ systems has been reported. The study was carried out using classical weight loss method, potentiodynamic polarization study and Fourier Transform Infra-red Spectrocopy (FTIR) Technique. Experimental results indicated that the presence of o-nitrophenol-Zn 2+ inhibit the corrosion of Al(6061). The inhibition efficiency (IE) has been determined by the classical weight loss method. The maximum inhibition efficiency offered by the onitrophenol 250 ppm and Zn 2+ 50 ppm system is 94%. To determine the values of Linear polarization resistance (LPR) and corrosion current (I corr ), potentiodynamic polarization study has been used and it reveal that the inhibitor act as anodic inhibitor and it controls the anodic reaction. The protective film has been characterized by FTIR, SEM, EDAX and AFM. The protective film consists of Al 3+ -o-nitrophenol complex on the anodic metal surface. By using Density Functional Theory (DFT) various quantum chemical parameters such as E HOMO (highest occupied molecular orbital energy), E LUMO (lowest unoccupied molecular orbital energy), energy gap (ΔE), electron affinity (A), ionization potential (I), absolute electronegativity (χ), global hardness (η), softness (S), fraction of electrons transferred (ΔN) have been calculated and discussed. The theoretical results were found to be consistent with the experimental data generated. The inhibition efficiency of the inhibitor is evaluated by weight loss method.