Diagrams Er-mKOH for Iron at 25-125 °C and at Total Pressure of 1-30 Bar

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Title:Diagrams Er-mKOH for Iron at 25-125 °C and at Total Pressure of 1-30 Bar
Creators:
Balej, Jan
Divisek, Jiri
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 62, 11, pp. 1677-1689
Uncontrolled Keywords:Iron oxo compounds, Iron corrosion products

Abstract

Taking into consideration the water activity <i>a</i><sub>H<sub>2</sub>O</sub>, the equilibrium pressure of water vapour <i>p</i><sub>H<sub>2</sub>O</sub> in or above KOH solutions of different molality (2-18 mol kg<sup>-1</sup>) and temperature (0-200 °C), the relations for the quantitative evaluation of the equilibrium conditions of individual reactions in the Fe-KOH-H<sub>2</sub>O system were derived in potential range from -0.3 to +1.8 V (RHE). With the aid of standard thermodynamic data for individual reaction components, <i>E</i><sub>r</sub>-<i>m</i><sub>KOH</sub> diagrams were constructed for iron at 25, 100 and 125 °C and a total pressure of 1, 10 and 30 bar (0.1, 1 and 3 MPa). Under standard conditions (<i>a</i><sub>H<sub>2</sub>O</sub> = 1.0), Fe(OH)<sub>2</sub>(s) may result at temperatures of up to 63.1 °C, while at higher temperatures solid magnetite, Fe<sub>3</sub>O<sub>4</sub>, is directly formed as the thermodynamically stable primary corrosion product. The region of existence of solid Fe(OH)<sub>2</sub> is influenced by the molality and temperature of KOH solutions in contact with metallic iron. For example, at 25 °C Fe(OH)<sub>2</sub> can only arise as the primary corrosion product in KOH solutions <i>m</i><sub>KOH</sub> ≤ 6.34 mol kg<sup>-1</sup>, which cannot be concluded from the usual <i>E</i><sub>r</sub>-pH diagram after Pourbaix.

Title:Diagrams Er-mKOH for Iron at 25-125 °C and at Total Pressure of 1-30 Bar
Creators:
Balej, Jan
Divisek, Jiri
Uncontrolled Keywords:Iron oxo compounds, Iron corrosion products
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:62
Number:11
Page Range:pp. 1677-1689
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19971677UNSPECIFIED
ID Code:1242
Item Type:Article
Deposited On:06 Feb 2009 17:07
Last Modified:06 Feb 2009 16:07

Citation

Balej, Jan; Divisek, Jiri (1997) Diagrams Er-mKOH for Iron at 25-125 °C and at Total Pressure of 1-30 Bar. Collection of Czechoslovak Chemical Communications, 62 (11). pp. 1677-1689. ISSN 0010-0765

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