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International Journal of Electrochemistry
Volume 2011, Article ID 235360, 5 pages
http://dx.doi.org/10.4061/2011/235360
Research Article

Corrosion Inhibition Effect of 4-(2-Diethylamino-Ethylsulfonyl)-Phthalonitrile and 4,5-Bis(Hexylsulfonyl)-Phthalonitrile

Chemistry Department, Faculty of Science and Letters, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey

Received 1 July 2010; Revised 1 November 2010; Accepted 5 December 2010

Academic Editor: Kenneth I. Ozoemena

Copyright © 2011 Esma Sezer et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Inhibition of stainless steel corrosion in a 3.0 M NaCl solution by 4-(2-diethylamino-ethylsulfanyl)-phthalonitrile (DAESPN) and 4,5-bis(hexylsulfonyl)-phthalonitrile (Bis-HSPN) was investigated by polarization and electrochemical impedance spectroscopy (EIS) measurements. The values of cathodic (βc) and anodic (βa) Tafel slopes, 𝑖 c o r r , 𝐸 c o r r , corrosion rate (CR), and inhibition efficiences (IE%) obtained from polarization curves and polarization resistance ( 𝑅 P ), double-layer capacitance ( 𝐶 d l ), specific capacitance ( 𝐶 s p ) values were obtained from EIS. Double-layer capacitance differences in the presence and absence of inhibitors were also obtained from EIS measurements as suggested in the literature in order to investigate the interaction of them with metal surface. Results show that both DAESPN and Bis-HSPN are effective in cathodic reaction. Impedance measurements suggest higher surface coverage for DAESPN. The interaction between the inhibitor and the stainless steel was investigated by the adsorption isotherm. Langmuir adsorption isotherm 𝐾 a d s was applied and Δ 𝐺 values were obtained and found as 4 . 3 2 × 1 0 4 , 1 . 1 7 × 1 0 4 and 9.2 kJ, 12.5 kJ for DAESPN and Bis-HSPN, respectively, which suggests the electrostatic interaction between charged metal surface and charged organic molecules.