Nelson, Y. M. Cornell University, YMN1@cornell.edu
Lion, L. W. Cornell University, LWL3@cornell.edu
Costello, E. K. Cornell University, EKC6@cornell.edu
Koster van Groos, P. G. Cornell University, PGK2@cornell.edu
Shuler, M. L. Cornell University, MLS@cheme.cornell.edu

 
INFLUENCE OF MINERAL FORMATION MECHANISMS ON THE TRACE METAL ADSORPTION PROPERTIES OF IRON AND MANGANESE OXIDES
 
Oxides of Fe and Mn were prepared under controlled laboratory conditions chosen to represent field conditions, and Pb binding by these oxides was measured and compared to that of Fe and Mn oxides prepared by conventional methods. Fe oxides were prepared by slow, diffusion-controlled oxidation of Fe(II) to mimic Fe oxidation at the oxic/anoxic boundary in natural waters. These Fe oxides adsorbed twice as much Pb as Fe oxides prepared by rapid titration of Fe(III) with NaOH. Mn oxides were oxidized by the bacterium Leptothrix discophora to mimic biologically-mediated Mn(II) oxidation that is expected to prevail in circumneutral lakes. The biogenic Mn(III/IV) oxide adsorbed four times more Pb than fresh Mn(IV) oxide precipitates and several orders of magnitude more Pb than aged Mn(IV) oxide minerals. Use of the observed Pb adsorption isotherms of these materials in a composition-based adsorption model for freshwater surface coatings (biofilms and associated mineral phases) suggests a much greater role for Mn oxides in governing Pb adsorption than previously thought. Results of this model are also supported by selective extraction experiments with surface coating materials obtained from the oxic region of natural freshwater aquatic environments.
 
Day: Wednesday, Feb. 3
Time: 04:15 - 04:30pm
Location: Sweeney Center
 
Code: SS28WE0415S