Modelling of metal cation adsorption on outer oxide film surfaces

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Modelling of metal cation adsorption on outer
oxide film surfaces

• Jarmo Lehikoinen
• ANTIOXI Advisory Board Meeting
• VTT Materials and Building, 6 February, 2007

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Introduction

• In the adsorption studies, we adopt the surface
  complexation approach to elucidate the effects
  that solution conditions (e.g. pH, metal loading)
  have on adsorption. This approach provides a
  thermodynamically consistent framework for
  modelling the distribution of solutes between
  aqueous solution and oxide surfaces and supplies
  a quantifiable basis for assessing the identity
  of those surface species that may act as
  precursors in further surface-controlled
  processes. Mechanistic surface complexation
  modelling has been found an invaluable tool to
  explain and predict the uptake of contaminants on
  (hydr)oxides in various conditions.

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Modelling
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Modelling software

• FITEQL v. 4.0 modified at VTT for
  high-temperature systems

Modelling procedure

• Optimization of surface hydrolysis constants
  (Ka1, Ka2) from titration data (constrained by
  pHPZNPC)
• Optimization of metal adsorption stability
  constant(s) (KMe) from batch adsorption data
• Prediction of metal adsorption on oxide surface
  in various conditions