Edta as a corrosion inhibitor for al in 0.5 m hcl: Adsorption, thermodynamic and theoretical study

Abstract

In this study; EDTA is used in very small amount (10-10 M) as an inhibitor for the Al corrosion in 0.5 M HCl. Thermodynamic and adsorption parameters are calculated. The result shows that, in this range of concentrations, EDTA is chemisorbed at the Al surface, forming a stable complex with Al and give inhibition efficiency up to 89 %. For more con-centration, unstable complex is formed and acceleration of corrosion occurs. The adsorp-tion fit well to Langmuir, Temkin isotherms and El-awady model. Density functional theory (DFT) is used to study the geometrical optimizations of EDTA. From the obtained optimized structure, The highest occupied molecular orbital (EHOMO), the lowest unoccupied molecular orbital (ELUMO and their energy difference (ΔE), the total energy (TE), electronegativity (χ), dipole moment (µ), global hardness (η), global softness (σ), electron affinity (A), ionization potential (I), the fraction of electrons transferred (∆N) and were determined using B3LYP/6-31G(d,p) basis set.