Interfacial behavior of cysteine between mild steel and sulfuric acid as corrosion inhibitor


ÖZCAN M. , KARADAĞ F. , DEHRİ İ.

ACTA PHYSICO-CHIMICA SINICA, vol.24, no.8, pp.1387-1392, 2008 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 24 Issue: 8
  • Publication Date: 2008
  • Doi Number: 10.1016/s1872-1508(08)60059-5
  • Title of Journal : ACTA PHYSICO-CHIMICA SINICA
  • Page Numbers: pp.1387-1392

Abstract

Interfacial behavior of cysteine (Cys) between mild steel and sulfuric acid solution as a corrosion inhibitor has been studied with electrochemical AC (alternating current) and DC (direct current) techniques at (25.0 +/- 0.1) degrees C. The AC impedance results were evaluated using equivalent circuits in which a constant phase element (CPE) has been replaced with double layer capacitance (C(dl)) to represent the frequency distribution of experimental data. Changes in impedance parameters (charge transfer resistance and double layer capacitance) indicated that cysteine molecules acted by accumulating at the metal/solution interface. The fractional coverage of the metal surface (theta) was determined using AC impedance results and it was found that the adsorption of cysteine on the mild steel surface followed a Langmuir isotherm model with a standard free energy of adsorption (Delta G(ads)(0)) of -35.1 kJ center dot mol(-1).