The aim with this project was to investigate the role of dissolved phosphate for the adsorption of lead(II), copper(II), cadmium(II) and uranium(VI) onto ferrihydrite and to soils. The methods involved batch studies, EXAFS spectroscopy, and equilibrium modelling. Phosphate was found to significantly enhance the adsorption of all investigated metals onto ferrihydrite. Results obtained so far show that the results are consistent with the formation of ternary surface complexes at low pH, but additional research is required to understand the processes in more detail. Similar enhancements were not observed in soil samples to which phosphate is added, and the reasons for this remain to be fully elucidated. In any case, this research shows that the presence of phosphate may restrict the mobility of many trace metals in environments that contain iron(III) (hydr)oxides.
Uppsala, 2013. , 8 p.