abgeschlossene Projekte

Effect of temperature on selenate adsorption by goethite

DFG-Project KE508/6

N.N. Vlasova & M. Kersten Geoscience Institute, D.A. Kulik Paul-Scherrer-Institute, 5232 Villigen, Switzerland

Experimental closed-system Delta-T acid-base titrations between 20 and 75°C were used to constrain a temperature-dependent basic Stern model (BSM) of the surface properties of goethite. Modeling was performed using the new Gibbs-energy-minimization model GEMS. With the latter, So298 and Cpo298 values could be fitted for the goethite surface acidity and background electrolyte outer-sphere complexes. Based on these BSM parameters, an adsorption model could be established for the pH-dependent selenate sorption continuum involving both an inner- and outer-sphere surface complex, where only the latter is affected by ionic strength and temperature.

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