Doctor of Philosophy (Ph.D.)
Virginia Institute of Marine Science
The purpose of this work is to investigate the use of planar oxides as tools for metal ion sorption studies that can be used in both laboratory and field settings. to do this, a three-step approach was used. In the first step, the reactivities of the planar gamma-Al2O3 surfaces relative to pure phase gamma alumina was investigated through Pb(II) sorption studies. The relative quantitative uptake of Pb(II) on the planar gamma alumina was found to be comparable to that on the bulk. XAS analysis showed that the coordination geometry and local binding environment of the Pb(II) complexes were similar on the two surfaces over a range of Pb(II) loadings. Second, the complexity of the planar surface was increased by creating mixed Fe-Al oxides of varying elemental composition, morphology and crystallinity. This was accomplished by coating the planar gamma alumina by varying the initial Fe(III) concentrations, reaction times and number of coating sequences. Significant changes in the elemental composition and distribution of Fe(III) were seen with changes in the reaction parameters. These differences should lead to variations in both the chemical and biological reactivities of these surfaces. The third step involved placing the planar gamma aluminas with varying Pb(II) loadings directly into natural sediments. Changes in Pb(II) concentrations as a result of initial Pb(Il) loading, emplacement time and redox conditions were examined as well as changes in the surface morphology of the materials. Lead/Al ratios, as well as interaction between the emplaced planars and the surrounding sediments, varied as a function of time and initial Pb(II) loading as evidenced by the changes in the surface morphologies, Pb(II) surface concentrations and changes in correlations with Fe and S present in the surrounding sediments. Biological controls may be suggested by the presence of clusters of pits found on the planar surfaces after emplacement. Results from these experiments indicate that planar oxides can be used in a variety of ways to better understand factors controlling metal sorption processes in both the laboratory and in natural environments.
© The Author
Conrad, Christine F., "Planar oxides as a novel approach to metal ion sorption studies: from the lab to the field" (2005). Dissertations, Theses, and Masters Projects. Paper 1539616617.