Theoretical study using DFT calculations on inhibitory action of two pyrazole compounds on corrosion of Steel in phosphoric acid

TOUZANI RACHID, Benhadou I, HAMMOUTI Belkheir, Merad N., Ghalem S

Abstract


The inhibitive effect of three substituted pyrazoles, 1H-pyrazole (P1) and ethyl 5-methyl-1H-pyrazole-3-carboxylate (P2) against the steel corrosion in phosphoric acid solution is investigated using density functional approach B3LYP/ 3-21G* calculations. Results obtained by weight loss in part 1, show that P2 is the best inhibitor.The kinetic and adsorption parameters obtained in part 2 indicated that these pyrazoles acted preferentially by chemical adsorption. The calculated quantum chemical parameters are the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the separation energy (DE), dipole moment (µ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), and the total energy. The obtained data are discussed according to the inhibition efficiencies (E %) obtained.


Keywords


Corrosion, H3PO4, Inhibitors, Pyrazole, DFT calculations

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