Adsorption of monovalent and divalent cations at the TiO2 (110) – aqueous interface studied using resonant anomalous X-ray reflectivity

COLL 355

Vaibhav Kohli, v-kohli@northwestern.edu1, Zhan Zhang2, Changyong Park, cypark@anl.gov3, Paul Fenter, fenter@anl.gov3, Jorgen Rosenqvist4, and David J. Wesolowski4. (1) Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108, (2) Advanced Photon Source, Argonne National Laboratory, 9700 Cass Ave., Argonne, IL 60439, (3) Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, (4) Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
The ability to characterize the electrical double layer structure is critical to understanding interfacial processes that occur at mineral–water interfaces. We report the results of studies on the adsorption profiles of Rb+ and Sr2+ at the Rutile TiO2 (110) – water interface using resonant anomalous x-ray reflectivity (RAXR). Ion adsorption at the rutile–aqueous interface has been previously studied using other x-ray based techniques, such as x-ray reflectivity and x-ray standing waves, which detected a single layer of adsorbed ions that comprised only part of the total interfacial ion distribution. We have therefore used RAXR to obtain further insight into the adsorbed ion structure. Our results show that Rb+ adsorbs as a single adsorbed layer; whereas Sr2+ is distributed in two distinct layers above the surface. We will describe the influence of anions and solution concentration of Sr2+ on the interfacial Sr2+ distribution.

 

The Physical Chemistry of Environmental Interfaces
8:30 AM-12:40 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 225, Oral

Division of Colloid & Surface Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008