Surface complexation and proton/ligand promoted dissolution in aqueous fluoro- and hydroxyapatite systems

GEOC 64

Åsa Bengtsson, asa.bengtsson@chem.umu.se, Per Persson, per.persson@chem.umu.se, and Staffan Sjöberg, staffan.sjoberg@chem.umu.se. Department of Chemistry, Umeå University, Inorganic Chemistry, SE-901 87 Umeå, Sweden
Apatites (Ca5(PO4)3F,Cl,OH) are the most abundant phosphorus-bearing minerals in nature and they are very important in agriculture as phosphorus containing fertilisers, as well as in medicine as main constituents of mammalian bones and teeth enamel. The surface chemistry of these minerals is very much unexplored, and the dissolution mechanisms are still debated. The objectives with our studies are to clarify the surface acid/base properties and ligand complexation reactions of these apatites with different organic polycarboxylic acids. Studies are being made in pH ranges with/without extensive dissolution and phase transformations. The strategy in modelling surface complexation and apatite dissolution is to combine information provided by i) macroscopic techniques (e. g. potentiometry, adsorption studies, zeta potential measurements) with ii) molecular level characterisations from FTIR, and XPS measurements.
 

Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
8:15 AM-11:55 AM, Monday, 11 September 2006 Moscone Center -- Room 256, Oral

Division of Geochemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006