X-Ray Absorption and EPR Spectroscopic Characterization of Adsorbed Copper(II) Complexes at the Boehmite (AlOOH) Surface
✍ Scribed by Forrest J. Weesner; William F. Bleam
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 179 KB
- Volume
- 196
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
hand, ions that are bound to a surface while retaining their The chemical environment of Cu(II) adsorbed to the boehmite hydration shell are outer-sphere. There has been great inter-(AlOOH) surface at pH 6.5 is examined by electron paramagnetic est in developing modeling approaches to indirectly deterresonance and X-ray absorption spectroscopy. Adsorbed Cu(II) mine the nature and stability of these surface complexes (2).
is always coordinated by four oxygens in an axially symmetric
The use of surface spectroscopy to directly examine surligand field when adsorbed under our experimental conditions. face complexes is an excellent complement to modeling.
The Cu-O bond distance is approximately 1.94 A ˚. An oriented, Surface complex models are difficult to constrain, particuinner-sphere Cu(II) surface complex is observed at low surface loading (õ0.2 mmol/M 2 ). A second population of Cu(OH) N larly as the complexity of the system increases beyond a
outer-sphere complexes is proposed at higher surface single adsorbate or when new surface phases form concurloadings to explain X-ray absorption fine structure results. Cu(II) rent with or following adsorption. For a model to have the strongly resists any tendency to form a surface precipitate on desired property of prediction, it must be based on the correct boehmite at pH 6.5. The presence of specifically adsorbing anions surface speciation at the outset (3). had little effect on the local chemical environment of adsorbed Electron paramagnetic resonance (EPR) and X-ray ab-Cu(II). ᭧ 1997 Academic Press sorption spectroscopy (XAS) are two techniques that have