Molecular approach towards understanding the biogenic formation of CeO2 and its interactions with biomolecules

GEOC 90

Javiera Cervini-Silva, jcervini@nature.berkeley.edu, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico City, C.P. 01450, Mexico, Benjamin Gilbert, BGilbert@lbl.gov, Earth Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 90R1116, Berkeley, CA 94720, Sirine C. Fakra, Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, Stephan Dietrich, Lawrence Livermore National Laboratory, and Jillian Banfield, Department of Earth & Planetary Science, University of California at Berkeley, 307 McCone Hall #4767, Berkeley, CA 94720.
Cerium is the most abundant lanthanide and generally the only one to undergo redox reactions at the Earth's surface. The oxidation state influences the environmental chemistry and toxicology of Ce because it alters the mechanisms of interaction between Ce and biomolecules. Here, we study molecular interactions between CeO2 and biomolecules (e.g., catechol) using carbon and cerium, XRD, and IR spectroscopy. Results show a progressive increase in catechol transformation (as % carbon) with decreasing CeO2 particle diameter (13 < d < 84 Å), which substantiates an intimate relation between CeO2 unit cell expansion and reactivity towards organics susceptible to undergo redox transformations. As shown by C and Ce spectroscopy, organic polymers that form because of catechol oxidation are distributed next to the mineral surface and its occurrence is coupled to Ce reduction-oxidation.
 

Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
8:15 AM-11:55 AM, Tuesday, 12 September 2006 Moscone Center -- Room 256, Oral

Division of Geochemistry

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