COLL 455 |
| Diffuse reflectance spectroscopy in the visible and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) were used to investigate the adsorption of Fe2+(aq) to iron-bearing clay minerals. The diffuse reflectance spectra of a clay suspension in dilute Fe2+(aq) are pH-dependent with new intervalence charge transfer (IVCT) bands appearing at pH values above ~6. These data suggest that that the ferrous iron binds to the mineral at higher pH values in such a way that it is able to exchange charge with the ferric iron within the mineral structure. ATR-FTIR spectra of these same suspensions indicate that a significant change in the Si-O stretching region accompanies this pH-dependent adsorption, confirming a structural modification of the clay mineral lattice. Taken together, the spectral data support a mechanism by which Fe2+(aq) binds to deprotonated edge sites of the clay mineral. |
|
Environmental Interfaces
8:30 AM-12:40 PM, Wednesday, 13 September 2006 Sir Francis Drake -- Empire Room, Oral
Division of Colloid & Surface Chemistry |