EDTA as a corrosion inhibitor for Al in 0.5 M HCl: adsorption, thermodynamic and theoretical study

Abstract

<p class="Default"><span lang="EN-US">In this study; EDTA is used in very small amount (10<sup>-10</sup> 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 con­centration, unstable complex is formed and acceleration of corrosion occurs. The adsorp­tion 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.</span></p>