Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants

Pekka Sten, Markus Olin, Jarmo Lehikoinen

Research output: Book/ReportReport

1 Citation (Scopus)

Abstract

The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous coolant. The present work belongs to a research programme on the properties of such films and especially on the transport of inorganic species through the films. The focus is on the incorporation of the highly energetic long-lived cobalt isotope 60Co in the films causing build-up of radiation fields in the out-of-core system. The first step in 60Co incorporation in the oxide films on the primary circuit surfaces is assumed to be adsorption which can be modelled using the surface complexation approach. The review begins with a general discussion of surface complexation on various iron oxides. After introducing the main concepts of surface complexation modelling, three of the most common models (the constant capacitance model, the diffuse layer model and the triple layer model) are discussed and compared. The very outermost layer of the oxide film is assumed to be more or less hydrated and poorly ordered resembling ferrihydrite known also as hydrous ferric oxide. Consequently, the surface chemical properties of and adsorption on ferrihydrite are reviewed. Using the known and estimated physical properties of the cooling system, chemical composition of the coolant and literature data on the surface and solution reactions, equilibrium calculations are conducted by the HYDRAQL programme to predict adsorption behaviour of cobalt and zinc on ferrihydrite at 25 °C. Except temperature, the conditions simulated in these calculations are similar to those prevailing in the cooling systems. The calculations correctly predict the diminishing effect of zinc on cobalt adsorption. The published surface complexation studies on iron oxides at elevated temperatures are reviewed. Despite the importance of the temperature on adsorption, surface complexation studies at other than room temperature are rare and the high-temperature, high-pressure regime is almost unexplored. The few studies found in the literature indicate that at the elevated temperatures, the charging of the oxide surface will play a much more significant role in the adsorption of ions than at room temperature. Increasing the temperature of the system is known to promote significantly cation uptake. Another general trend is the decrease of the point of zero charge of oxides with increasing temperature.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages73
ISBN (Electronic)951-38-5752-2
ISBN (Print)951-38-5749-2
Publication statusPublished - 2000
MoE publication typeD4 Published development or research report or study

Publication series

SeriesVTT Tiedotteita - Meddelanden - Research Notes
Number2055
ISSN1235-0605

Fingerprint

Complexation
Nuclear power plants
Oxide films
Adsorption
Coolants
Temperature
Cobalt
Cobalt Isotopes
Cooling systems
Oxides
Zinc
ferric oxide
Chemical properties
Cations
Capacitance
Physical properties
Ions
Radiation
Networks (circuits)
Chemical analysis

Keywords

  • nuclear power plants
  • adsorption
  • surface complexation
  • iron oxides
  • oxide films
  • ferrihydrite
  • hydrous ferric oxide
  • zinc
  • cobalt

Cite this

Sten, P., Olin, M., & Lehikoinen, J. (2000). Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants. Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Meddelanden - Research Notes, No. 2055
Sten, Pekka ; Olin, Markus ; Lehikoinen, Jarmo. / Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants. Espoo : VTT Technical Research Centre of Finland, 2000. 73 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2055).
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abstract = "The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous coolant. The present work belongs to a research programme on the properties of such films and especially on the transport of inorganic species through the films. The focus is on the incorporation of the highly energetic long-lived cobalt isotope 60Co in the films causing build-up of radiation fields in the out-of-core system. The first step in 60Co incorporation in the oxide films on the primary circuit surfaces is assumed to be adsorption which can be modelled using the surface complexation approach. The review begins with a general discussion of surface complexation on various iron oxides. After introducing the main concepts of surface complexation modelling, three of the most common models (the constant capacitance model, the diffuse layer model and the triple layer model) are discussed and compared. The very outermost layer of the oxide film is assumed to be more or less hydrated and poorly ordered resembling ferrihydrite known also as hydrous ferric oxide. Consequently, the surface chemical properties of and adsorption on ferrihydrite are reviewed. Using the known and estimated physical properties of the cooling system, chemical composition of the coolant and literature data on the surface and solution reactions, equilibrium calculations are conducted by the HYDRAQL programme to predict adsorption behaviour of cobalt and zinc on ferrihydrite at 25 °C. Except temperature, the conditions simulated in these calculations are similar to those prevailing in the cooling systems. The calculations correctly predict the diminishing effect of zinc on cobalt adsorption. The published surface complexation studies on iron oxides at elevated temperatures are reviewed. Despite the importance of the temperature on adsorption, surface complexation studies at other than room temperature are rare and the high-temperature, high-pressure regime is almost unexplored. The few studies found in the literature indicate that at the elevated temperatures, the charging of the oxide surface will play a much more significant role in the adsorption of ions than at room temperature. Increasing the temperature of the system is known to promote significantly cation uptake. Another general trend is the decrease of the point of zero charge of oxides with increasing temperature.",
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Sten, P, Olin, M & Lehikoinen, J 2000, Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants. VTT Tiedotteita - Meddelanden - Research Notes, no. 2055, VTT Technical Research Centre of Finland, Espoo.

Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants. / Sten, Pekka; Olin, Markus; Lehikoinen, Jarmo.

Espoo : VTT Technical Research Centre of Finland, 2000. 73 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2055).

Research output: Book/ReportReport

TY - BOOK

T1 - Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants

AU - Sten, Pekka

AU - Olin, Markus

AU - Lehikoinen, Jarmo

N1 - Project code: K9SU00195

PY - 2000

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N2 - The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous coolant. The present work belongs to a research programme on the properties of such films and especially on the transport of inorganic species through the films. The focus is on the incorporation of the highly energetic long-lived cobalt isotope 60Co in the films causing build-up of radiation fields in the out-of-core system. The first step in 60Co incorporation in the oxide films on the primary circuit surfaces is assumed to be adsorption which can be modelled using the surface complexation approach. The review begins with a general discussion of surface complexation on various iron oxides. After introducing the main concepts of surface complexation modelling, three of the most common models (the constant capacitance model, the diffuse layer model and the triple layer model) are discussed and compared. The very outermost layer of the oxide film is assumed to be more or less hydrated and poorly ordered resembling ferrihydrite known also as hydrous ferric oxide. Consequently, the surface chemical properties of and adsorption on ferrihydrite are reviewed. Using the known and estimated physical properties of the cooling system, chemical composition of the coolant and literature data on the surface and solution reactions, equilibrium calculations are conducted by the HYDRAQL programme to predict adsorption behaviour of cobalt and zinc on ferrihydrite at 25 °C. Except temperature, the conditions simulated in these calculations are similar to those prevailing in the cooling systems. The calculations correctly predict the diminishing effect of zinc on cobalt adsorption. The published surface complexation studies on iron oxides at elevated temperatures are reviewed. Despite the importance of the temperature on adsorption, surface complexation studies at other than room temperature are rare and the high-temperature, high-pressure regime is almost unexplored. The few studies found in the literature indicate that at the elevated temperatures, the charging of the oxide surface will play a much more significant role in the adsorption of ions than at room temperature. Increasing the temperature of the system is known to promote significantly cation uptake. Another general trend is the decrease of the point of zero charge of oxides with increasing temperature.

AB - The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous coolant. The present work belongs to a research programme on the properties of such films and especially on the transport of inorganic species through the films. The focus is on the incorporation of the highly energetic long-lived cobalt isotope 60Co in the films causing build-up of radiation fields in the out-of-core system. The first step in 60Co incorporation in the oxide films on the primary circuit surfaces is assumed to be adsorption which can be modelled using the surface complexation approach. The review begins with a general discussion of surface complexation on various iron oxides. After introducing the main concepts of surface complexation modelling, three of the most common models (the constant capacitance model, the diffuse layer model and the triple layer model) are discussed and compared. The very outermost layer of the oxide film is assumed to be more or less hydrated and poorly ordered resembling ferrihydrite known also as hydrous ferric oxide. Consequently, the surface chemical properties of and adsorption on ferrihydrite are reviewed. Using the known and estimated physical properties of the cooling system, chemical composition of the coolant and literature data on the surface and solution reactions, equilibrium calculations are conducted by the HYDRAQL programme to predict adsorption behaviour of cobalt and zinc on ferrihydrite at 25 °C. Except temperature, the conditions simulated in these calculations are similar to those prevailing in the cooling systems. The calculations correctly predict the diminishing effect of zinc on cobalt adsorption. The published surface complexation studies on iron oxides at elevated temperatures are reviewed. Despite the importance of the temperature on adsorption, surface complexation studies at other than room temperature are rare and the high-temperature, high-pressure regime is almost unexplored. The few studies found in the literature indicate that at the elevated temperatures, the charging of the oxide surface will play a much more significant role in the adsorption of ions than at room temperature. Increasing the temperature of the system is known to promote significantly cation uptake. Another general trend is the decrease of the point of zero charge of oxides with increasing temperature.

KW - nuclear power plants

KW - adsorption

KW - surface complexation

KW - iron oxides

KW - oxide films

KW - ferrihydrite

KW - hydrous ferric oxide

KW - zinc

KW - cobalt

M3 - Report

SN - 951-38-5749-2

T3 - VTT Tiedotteita - Meddelanden - Research Notes

BT - Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Sten P, Olin M, Lehikoinen J. Surface complexation on iron oxides with reference to the oxide films formed on material surfaces in nuclear power plants. Espoo: VTT Technical Research Centre of Finland, 2000. 73 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2055).