Author(s)

Juliana Panceri Franco, Josimar Ribeiro^*

Laboratório de Pesquisa e Desenvolvimento em Eletroquímica, Departamento de Química do Centro de Ciências Exatas da Universidade Federal do Espírito Santo, Vitória, Brazil.

The novelty of this paper is the analysis in a medium containing sulfide ion due to the generation of this ion in petroleum industries, in the refining stage (the sulfide ion is also present on the produced water). The performance of 1-hydroxyethylidene-1,1-diphosphonic acid inhibitor (HEDP) was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurements in a dissolution of AISI 304 stainless steel immersed in a solution containing chloride and sulfide ions. The protection of the stainless was increased with the addition of divalent cations (Ca²⁺, Zn²⁺, and Mg²⁺). Potentiodynamic polarization studies have shown that the inhibitor alone has anodic protection, but the addition of Ca²⁺ (10 mg·L^-1) favors the cathodic protection, and the addition of Zn²⁺ (20 mg·L^-1) and Mg²⁺ (10 mg·L^-1) mixed-type is observed. Electrochemical impedance spectroscopy was performed at three distinct potentials: -0.3 [V vs. SCE], E_corr [V vs. SCE], and 0.1 [V vs. SCE]. This revealed that calcium is responsible for favoring the formation of the film and the other elements (zinc and magnesium) favor the stabilization of the protective film. Scanning electron microscopy analysis revealed that the addition of cations provided the adsorption of HEDP on the metal surface. Weight loss results showed that the presence of zinc in a solution containing HEDP favored greater inhibitor efficiency (Zn²⁺ η_m = 85.2% and for Mg²⁺ η_m = 70.4%).

AISI 304 Stainless Steel, HEDP, Corrosion Inhibitor, Chloride and Sulfide Ions, Electrochemical Impedance Spectroscopy

Franco, J. and Ribeiro, J. (2020) 1-Hydroxyethylidene-1,1-diphosphonic Acid (HEDP) as a Corrosion Inhibitor of AISI 304 Stainless Steel in a Medium Containing Chloride and Sulfide Ions in the Presence of Different Metallic Cations. Advances in Chemical Engineering and Science, 10, 225-257. doi: 10.4236/aces.2020.103017.