Inhibition of phosphoric acid corrosion of zinc by organic onium compounds and their adsorption characteristics

• Published in: Journal of applied electrochemistry Vol. 29; no. 5; pp. 619 - 626
• Main Author: MORAD, M. S
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-05-1999
• Subjects: Applied sciences; Corrosion; Corrosion prevention; Exact sciences and technology; Metals. Metallurgy; Quaternary ammonium compound; Phosphoric acid; Corrosion; Adsorption isotherm; Equivalent circuit; Transition metal; Corrosion inhibitor; Zinc; Organic compounds; Electrical impedance; Quaternary phosphonium compound
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1023/A:1026445521937

The inhibiting properties of some organic phosphonium and ammonium compounds were studied with respect to the corrosion of zinc in 1M H sub 3 PO sub 4 solution. It was found that onium compounds which have pi -electron system(s) are adsorbed following Frumkin's adsorption isotherm and provide better inhibition efficiency than those containing no pi -electron system. The adsorption of the latter compounds was found to obey Langmuir's isotherm. Both potentiostatic and electrochemical impedance techniques proved that the studied onium compounds act as primary interface inhibitors without changing the mechanism of either hydrogen evolution reaction or zinc dissolution.