Iron dissolution and passivation in K2CO3-KHCO3 solutions. rotating ring disc electrode and XPS studies

Abstract

Rotating ring-disc electrode studies on the anodic dissolution and passivation of iron in potassium carbonate/bicarbonate buffers at 25°C show that in the active anodic dissolution potential range Fe(II) soluble species are generated. This reaction is favoured by the presence of bicarbonate ions in solution and it is explained through the formation of an unstable soluble complex containing Fe(lI) and HCO3 ions. This suggests that the anodic layer at a certain stage of its formation contains some amount of carbonate species. XPS data of surface layers produced at different anodic potentials confirm the presence of the carbonate species in thick anodic layers grown in the prepassive potential region in still solutions, whereas the opposite result is found for the thin passive layers formed at high positive potentials.

Flow-Assisted Corrosion in Coal Seam Gas Infrastructure

“…-concentration results in iron dissolution (Castro, Vilche, & Arvia, 1991;Davies & Burstein, 1980;Linter & Burstein, 1999). In addition, Moreno, Morris, Alvarez, and Duffó (2004) demonstrated that high bicarbonate and carbonate increased localised corrosion of carbon steel.…”

“…To date, its effect has been underestimated because most failures in oil and gas infrastructure are attributed to CO 2 corrosion processes. However, studies show that increasing bicarbonate ion concentration accelerates iron dissolution (Castro, et al, 1991;Davies & Burstein, 1980;Linter & Burstein, 1999) and can influence both the anodic and cathodic reactions (Honarvar Nazari, et al, 2010). The bicarbonate ion (Moreno, et al, 2004) contributes to pitting corrosion (Mao, Liu, & Revie, 1994) and stress corrosion cracking (Might & Duquette, 1996;Pilkey, et al, 1995) in carbon steel pipelines.…”

“…-concentration exacerbates iron dissolution (Castro, et al, 1991;Davies & Burstein, 1980;Linter & Burstein, 1999). To date, the role of bicarbonate ions in the corrosion process of carbon steel is still debated (Tan, et al, 2014) Moreno et al (Moreno, et al, 2004) confirmed that high bicarbonate increased localized corrosion contributing to stress corrosion cracking (Might & Duquette, 1996;Pilkey, et al, 1995) and pitting corrosion (Mao, et al, 1994) in carbon steel pipelines.…”

“…Studies indicate that chloride (Alves & Brett, 2002) and HCO 3 -concentrations are correlated with carbon steel dissolution (Castro, et al, 1991;Davies & Burstein, 1980;Linter & Burstein, 1999), with consequences for service life. Many methods such as cathodic protection, phosphating, coating and the use of inhibitors (El-Etre & Abdallah, 2000;Galliano & Landolt, 2002;Kim & Kim, 2001;Lin, Lu, & Kong, 2008) have been adopted to reduce corrosion.…”

“…Bicarbonate plays a major role in the dissolution reactions of steel pipelines (King, 2007).Studies indicate that increasing HCO 3 -concentration exacerbates iron dissolution (Castro, et al, 1991;Davies & Burstein, 1980;Linter & Burstein, 1999).…”