Friday, November 6, 2009: 10:40 AM
Charolais (Camino Real Hotel)
The use of plants offers the potential for the selective removal and sequestration of toxic lanthanide and actinide metals from contaminated land. Ideally, this process of phytoextraction transports the metal ions from the soil, through the plant’s root system, and into its shoots and leaves. Unfortunately, metal ions often do not progress further than the plant roots. It is an objective of our laboratory to more fully understand the chemical interactions of heavy metal ions with materials derived from the plant, Datura innoxia. Previous studies have been limited to cultured cells from the anther of the plant’s flower. The present work discusses the extension of that work to the investigation of tissue materials such as the roots. Previously, application of regularized regression analysis to binding isotherms revealed the presence of both “high” affinity and “low” affinity binding sites involving carboxylate and sulfonate functionalities with the potential involvement of electrostatic physisorption interactions. The current work further explores these affinity spectra through the elucidation of both the enthalpies (DH) and entropies (DS) of metal binding. The results of this study and their impact on our understanding of biosorption chemical interactions will be presented. Additionally, implications of those findings on the potential application of this (or other) plant for phytoextraction of lanthanide and actinide metal ions will be discussed.