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

Esma Sezer,Kerim Çoban,Zehra Altuntaş Bayır,Belkis Ustamehmetoğlu,Ayfer Kalkan

doi:10.4061/2011/235360

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, , , corrosion rate (CR), and inhibition efficiences (IE%) obtained from polarization curves and polarization resistance (), double-layer capacitance (), specific capacitance () 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 was applied and values were obtained and found as , 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.

Highlights

Stainless steel is used in a wide range of industrial applications
The efficiency of an organic compound as a successful inhibitor is mainly dependent on its ability to be adsorbed on the metal surface, which consists of the replacement of water molecule at a corroding interface
Electrochemical polarisation curves and electrochemical impedance spectroscopy measurements were performed in a three-electrode cell using a PAR 2263 model potentiostat

Summary

Introduction

Stainless steel is used in a wide range of industrial applications. Corrosion of steel and its inhibition in chloride solution have attracted the attention of a number of investigators [1,2,3,4]. The efficiency of an organic compound as a successful inhibitor is mainly dependent on its ability to be adsorbed on the metal surface, which consists of the replacement of water molecule at a corroding interface. The adsorption of these compounds is influenced by the electronic structure of the inhibiting molecules [6, 7] and by the steric factors, aromaticity, electron density at the donor atoms, and the presence of functional groups [8,9,10,11,12,13].

Experimental

Result and Discussion

Findings

MHz-1 mHz

Conclusion