Stimulated Decomposition of Fe(OH)₂in the Presence of AVT Chemicals and Metallic Surfaces—Relevance to Low-Temperature Feedwater Line Corrosion

Abstract

Alkalizing agents cyclohexylamine, morpholine, and hydrazine accelerate the base-induced decomposition of Fe(OH) 2 even at high pH levels by lowering the activation energy of the reaction. Efficient evolution of hydrogen is observed from Fe(OH) 2 suspension in the presence of hydrazine, while weakly stimulated evolution is observed in the presence of cyclohexylamine and morpholine. It appears that the concentration and complexing abilities of the additives critically determine the yield of hydrogen. Nickelcontaining surfaces such as NiO and Monel 400 † alloy (UNS N04400) apart from pure nickel also increase the H 2 yield from Fe(OH) 2 suspensions. These observations are related to corrosion occurring in the low-temperature portion of feedwater circuits of power plants.

Anaerobic Corrosion of Granular Iron: Measurement and Interpretation of Hydrogen Evolution Rates

“…The resulting internal pressure buildup at these locations is believed to be the principal cause for embrittlement and blistering of iron and steel exposed to anaerobic environments. The rate of uptake at the surface is reaction-controlled but is proportional to the square root of the hydrogen partial pressure (Sievert's law): R = kPH°•5 (11) indicating that H2 molecules disproportionate at the iron surface and enter the iron as individual atoms rather than as diatomic molecules (26).…”

“…At lower temperatures, it proceeds slowly because of kinetic restraints, and Fe(OH)2 may be a metastable phase in lowtemperature anaerobic groundwater environments. However, there are known inorganic and organic compounds that can catalyze this mineralogic transformation (10,11). None of these identified catalysts, however, are major constituents of groundwater.…”

Facile synthesis of ultrathin magnetic iron oxide nanoplates by Schikorr reaction

“…The Schikorr reaction usually occurs in the process of anaerobic corrosion of iron and carbon steel in various conditions [21,22]. Herein, this reaction was used to prepare magnetite nanoplates.…”

Characterisation and comparison of corrosion products originated in steel pipelines transporting sour gas and crude oil

“…The denoted hydroxide has been identified in both sediments obtained from gas and crude oil pipelines in whichever of its forms: α-FeO(OH), β-FeO(OH) or γ-FeO(OH). It has been suggested that the hydroxide is transformed, at the same time, into magnetite 39 : …”