Reference

Inhibitive action of indole-5-carboxylic acid towards corrosion of mild steel in deaerated 0

All Rights Reserved. Inhibitive action of indole-5-carboxylic acid towards corrosion of mild steel in deaerated 0.5M sulfuric acid solutions. Quartarone, G.; Bonaldo, L.; Tortato, C. (Department of Chemistry, University of Venice, Venice I-30123, Italy). Applied Surface Science, 252(23), 8251-8257 (English) 2006 Elsevier B.V. CODEN: ASUSEE. ISSN: 0169-4332. DOCUMENT TYPE: Journal CA Section: 72 (Electrochemistry) Section cross-reference(s): 55, 66, 69 Inhibition of mild steel corrosion in deaerated 0.5M H2SO4 solns. contg. various concns. of indole-5-carboxylic acid was studied at 25-55° using wt.-loss, potentiodynamic and spectrophotometric tests.Several substances with their cas registry numbers 1670-81-1 and 12753-99-0 may be metioned in this study. The adsorptive behavior of inhibitor was also studied using electrochem. impedance spectroscopy measurements. The indole-5-carboxylic acid is found to shift the corrosion potentials towards more noble values. This shift indicates that the addn. of inhibitor mainly affects the anodic process, raising the anodic overpotential more than that of the cathodic, i.e. the indole-5-carboxylic acid behaves as mixed-type inhibitor. Because the cathodic Tafel slopes for hydrogen evolution (bc) are affected, the inhibitor probably affects the hydrogen evolution mechanism. The activation energy values (Ea) indicate that the indole-5-carboxylic acid increases the activation energy of the corrosion reaction. The adsorption behavior of indole-5-carboxylic acid follows Langmuir's isotherm. Both the low values of - D G°ads and its decrease with temp. suggest phys. adsorption. Double layer capacitance-potential curves indicate considerable adsorption of the inhibitor in the potential range (-400 to -800 mV/SCE). .