Metal Ion (Cr3+, Eu3+, UO22+) Adsorption on Gibbsite Nanoplates 

Hailin Zhang1

Zheming Wang1,Email

Yatong Zhao1

Wenwen Cui1

Xin Zhang1

Suyun Wang1

Eric D. Walter2

Michel J. Sassi1

Carolyn I. Pearce3

Sue B. Clark3,4

Kevin M. Rosso1 

1Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, United States.
2Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, United States.
3Energy and Environmental Division, Pacific Northwest National Laboratory, Richland, WA 99352, United States.
4Savannah River National Laboratory, Aiken, SC 29808, United States.

 

Abstract

Gibbsite is a common and important aluminum hydroxide mineral in natural environments and various industries, but the mechanisms by which metal ions sorb on the gibbsite surface, and their impact on surface reactivity, is not well understood. Here we examined Cr3+, Eu3+ and UO22+ cation sorption on synthetic nanoplatelet gibbsite using vibrational sum frequency generation (VSFG) spectroscopy along with time-resolved laser-induced fluorescence spectroscopy (TRLFS), Raman/Fourier Transform Infrared (FTIR) spectroscopy, and electron microscopy. Batch sorption experiments show uptake across a broad pH range. VSFG spectra reveal cation-specific participation of surface OH groups in metal binding. For Cr3+, uniform loss of spectral intensity with increasing cation loading indicates equal involvement of the six distinct hydroxyls. But sorption of Eu3+ and UO22+ alters its spectral profile where the reduction of the intra-layer OH bands was more pronounced and the correlation between the spectral reduction and metal ion concentration is weaker, indicating differed sorption mechanism. The latter was confirmed by the results of TRLFS analysis of both Eu3+ and UO22+ adsorbed on the gibbsite.

Metal Ion (Cr3+, Eu3+, UO22+) Adsorption on Gibbsite Nanoplates