Thiourea and N-Methylthiourea as Corrosion Inhibitors for Steel in Phosphoric Acid

The effect of thiourea (TU) and N-methylthiourea (MTU) on the corrosion of mild steel in 0.5 M H3PO4 was examined using potentiodynamic polarization curve measurements, electrochemical impedance spectroscopy techniques and quantum chemical calculations. Results obtained revealed that MTU is more eff...

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Bibliographic Details
Published inJournal of failure analysis and prevention Vol. 18; no. 5; pp. 1293 - 1299
Main Authors Saad, I. R., Abdel-Gaber, A. M., Younes, G. O., Nsouli, B.
Format Journal Article
LanguageEnglish
Published Materials Park Springer Nature B.V 01.10.2018
Subjects
Adsorption
Corrosion effects
Corrosion inhibitors
Electrochemical impedance spectroscopy
Low carbon steels
Organic chemistry
Parameters
Phosphoric acid
Quantum chemistry
Thermodynamic models
Thioureas
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Summary:The effect of thiourea (TU) and N-methylthiourea (MTU) on the corrosion of mild steel in 0.5 M H3PO4 was examined using potentiodynamic polarization curve measurements, electrochemical impedance spectroscopy techniques and quantum chemical calculations. Results obtained revealed that MTU is more effective than TU in 0.5 M H3PO4.Theoretical fitting of different adsorption isotherms such as Langmuir, Flory–Huggins, Temkin, and the kinetic-thermodynamic models was tested. The thermodynamic activation parameters were calculated. Quantum chemical parameters were calculated and explained. The data explained that the inhibition of mild steel by TU in 0.5 M H3PO4 take place through chemical adsorption mechanism, while physicochemical adsorption mechanism is suggested for MTU.
ISSN:1547-7029
1864-1245
DOI:10.1007/s11668-018-0522-5