TITLE:
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
AUTHORS:
Juliana Panceri Franco, Josimar Ribeiro
KEYWORDS:
AISI 304 Stainless Steel, HEDP, Corrosion Inhibitor, Chloride and Sulfide Ions, Electrochemical Impedance Spectroscopy
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.10 No.3,
July
31,
2020
ABSTRACT: 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], Ecorr [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+ ηm = 85.2% and for Mg2+ ηm = 70.4%).