In situ spectroscopic evidence for neptunium(V)-carbonate inner-sphere and outer-sphere ternary surface complexes on hematite surfaces

Yuji Arai; P B Moran; B D Honeyman; J A Davis

doi:10.1021/es062468t

In situ spectroscopic evidence for neptunium(V)-carbonate inner-sphere and outer-sphere ternary surface complexes on hematite surfaces

Environ Sci Technol. 2007 Jun 1;41(11):3940-4. doi: 10.1021/es062468t.

Authors

Yuji Arai¹, P B Moran, B D Honeyman, J A Davis

Affiliation

¹ Department of Entomology, Soils and Plant Sciences, 270 Poole Agricultural Center, Clemson University, Clemson, South Carolina 29634-0315, USA. yarai@clemson.edu

PMID: 17612172
DOI: 10.1021/es062468t

Abstract

Np(V) surface speciation on hematite surfaces at pH 7-9 under pC2 = 10(-3.45) atm was investigated using X-ray absorption spectroscopy (XAS). In situ XAS analyses suggest that bis-carbonato inner-sphere and tris-carbonato outer-sphere ternary surface species coexist at the hematite-water interface at pH 7-8.8, and the fraction of outer-sphere species gradually increases from 27 to 54% with increasing pH from 7 to 8.8. The results suggest that the heretofore unknown Np(V)-carbonato ternary surface species may be important in predicting the fate and transport of Np(V) in the subsurface environment down gradient of high-level nuclear waste respositories.

Publication types

Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Carbonates / chemistry*
Ferric Compounds / chemistry*
Models, Chemical
Models, Molecular
Molecular Structure
Neptunium / chemistry*
Spectrum Analysis
Surface Properties

Substances

Carbonates
Ferric Compounds
ferric oxide
Neptunium