Conference paper

A Ligand Exchange Model for the Adsorption of Inorganic and Organic Ligands at Hydrous Oxide Interfaces

Werner Stumm ; Institute of Aquatic Sciences (EAWAG), Swiss F ederal Institute of Technology (ETH), Zurich, Switzerland
Robert Kummert ; Institute of Aquatic Sciences (EAWAG), Swiss F ederal Institute of Technology (ETH), Zurich, Switzerland
Laura Sigg ; Institute of Aquatic Sciences (EAWAG), Swiss F ederal Institute of Technology (ETH), Zurich, Switzerland

Abstract

Specific adsorption of organic and inorganic weak acids and
of anions on hydrous oxide surfaces and the concomitant influences
upon surface charge can be interpreted as ligand exchange reactions
at the reactive surface sites. Direct (inner sphere) binding of
the ligands to the surface is postulated. The extent of adsorption
and its pH dependence can be explained by considering the affinity
of the surface sites and those of the ligands. Surface equilibrium
constants have been determined experimentally for various surface
reactions; they can be used to predict extent of adsorption and
resulting surface charge. The adsorption of simple weak acids or
their anions is largest around the pH value of pH = pK. The surface
complex formation constants show the same trend in stability
as the corresponding solute complex formation constants; thus
surface coordination equilibrium constants can be estimated from
the corresponding complex formation constants in solution.

Keywords

Hrčak ID:

194579

URI

https://hrcak.srce.hr/194579

Publication date:

5.11.1980.

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