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Corresponding Author

ATTIA, E.

Document Type

Original Article

Subject Areas

Chemistry

Keywords

triazole thione; Corrosion; molybdenum; galvanostatic; Potentiodynamic; potentiostatic; Polarization; Adsorption

Abstract

4N- (2- hydroxy -3- triethyl ammonio- propyl-) fatty- 1, 2, 4 triazole -3- thione (12AB) and 2,4N- (bis- 2- hydroxy -3- triethyl ammonio- propyl-) fatty- 1, 2, 4 triazole -3- thione (12ABB) were synthesized, characterized and tested as surfactant corrosion inhibitors for Mo in 0.01 M HCl solution using galvanostatic, potentiodynamic and potentiostatic polarization techniques. Concentrations of the inhibitors were ranged from 1x10−6 to 1 (wt. %). The obtained results using galvanostatic polarization on bare metal showed that thickness of adsorbed layer decreased with increasing concentration of 12AB while adverse trend was observed with 12ABB. On the other hand the anodic oxide film formed at 100mAcm-2 up to 0.268V (SCE) was susceptible to a dissolution process with the presence of two corrosion rates for each concentration of the two additives. Potentiodynamic polarization illustrated that increase of additive concentration lowered corrosion current densities affecting anodic reaction more than cathodic one. The protection efficiency increased with increasing inhibitor concentration. The low values of IE. % indicated the presence of electrostatic attraction between inhibiting molecules and the electrically charged surface of metal. Adsorption followed the kinetic thermodynamic model, Langmuir and Flory–Huggins adsorption isotherms. 12ABB showed better inhibiting action than that of 12AB due to the presence of two side chains in its structure. Potentiostatic polarizations indicated that when the concentration of the additives 12AB and 12ABB exceeded a critical value, ≥0.1Wt.%, no inhibition effect.

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