Rengamani, S. (1987) Electrochemical studies at the metal-solution-interface-amines as corrosion inhibitors for mild steel in acidic solutions. PhD thesis, Madurai-Kamaraj University.

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Abstract

The influence of a few amines like aniline, isomers of aminophenol, isomers of anisidine, isomers of aminobenzoic acid and beta phenylethyl amine has been studied by different techniques like weight loss measurements, gasometric studies, galvanostatic polarization, small amplitude cyclic voltametry and impedance technique. To correlate the extent of adsorption with corrosion inhibition, capillary electrometric studies have been carried out. The surface of the specimen has been examined using UV reflectance spectro-photometer, scanning electron microscope and ellipsometry. Solution was also analysed to detect the chemical species which accelerate corrosion. Gasometric and weight loss measurements clearly bring out the fact that all amines under study act as corrosion inhibitor for mild steels in HCl. But in H2SO4 with the exception of isomers of aminobenzoic acid, beta phenyl ethylamine and orthoanisidine, all the amines accelerate the corrosion of mild steel. Galvanostatic polarization studies reveal the fact that all the amines are cathodic inhibitors. Adsorption studies using capillary electrometer bring out the fact that almost all amines adsorb more from HCl than from H2SO4. In the present study, all the amines except 0-amino-phenol and m-aminophenol bring down the hydrogen permeation current in HCl, whereas in H2SO4 all the amines except beta phenylethyl amine enhance the permeation current. Values of icorr obtained from linear polarization data and from Tafel extrapolation method clearly show some agreement for HCl. But in the case of H2SO4 values of Rp fail to indicate the stimulation of corrosion shown by some compounds. Double layer capacitance values obtained from small amplitude cyclic voltametry show the effectiveness of various amines in bringing down the values of capacitance by adsorption. Double layer capacitance values obtained using effectiveness of various amines as corrosion inhibitors. Surface of specimens were examined to ascertain whether the high inhibition of corrosion of mild steel by beta phenyl amine is due to physical adsorption or chemisorption. Acceleration of corrosion by some amines in H2SO4 was also examined by UV spectrophotometer. The enhanced inhibitors of corrosion of all amines HCl can be explained to be due to the stronger specific adsorption of chloride ion on the iron surface, which favour more adsorption of organic molecules.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Corrosion inhibitors; mild steel
Subjects:	Corrosion Science and Engineering
Divisions:	UNSPECIFIED
Depositing User:	Dr. N Meyyappan
Date Deposited:	11 Jun 2012 09:59
Last Modified:	11 Jun 2012 09:59
URI:	http://cecri.csircentral.net/id/eprint/2796

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