Np(V) Retention at the Illite du Puy Surface

被引：0

作者：

Schacherl, Bianca ^{[1
]}

Joseph, Claudia ^{[1
]}

Beck, Aaron ^{[1
]}

Lavrova, Polina ^{[1
]}

Schnurr, Andreas ^{[1
]}

Dardenne, Kathy ^{[1
]}

Geyer, Frank ^{[1
]}

Cherkezova-Zheleva, Zara ^{[2
]}

Goettlicher, Joerg ^{[3
]}

Geckeis, Horst ^{[1
]}

Vitova, Tonya ^{[1
]}

机构：

[1] Karlsruhe Inst Technol KIT, Inst Nucl Waste Disposal INE, D-76021 Karlsruhe, Germany

[2] Bulgarian Acad Sci, Inst Catalysis, Sofia 1113, Bulgaria

[3] Karlsruhe Inst Technol KIT, Inst Photon Sci & Synchrotron Radiat IPS, D-76021 Karlsruhe, Germany

来源：

ENVIRONMENTAL SCIENCE & TECHNOLOGY | 2023年 / 57卷 / 30期

基金：

欧洲研究理事会;

关键词：

neptunium; clay; high-energy resolution X-rayabsorption near-edge structure (HR-XANES) spectroscopy; sorption; diffusion; solvent extraction; BATCH SORPTION; NEPTUNIUM(V) SORPTION; DIFFUSION; MONTMORILLONITE; SPECIATION; CLAY; MECHANISMS; COMPLEXES; ACTINIDES; BEHAVIOR;

D O I：

10.1021/acs.est.2c09356

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

In this study, Np(V)retention on Illite du Puy (IdP) was investigatedsince it is essential for understanding the migration behavior ofNp in argillaceous environments. The presence of structural Fe(III)and Fe(II) in IdP was confirmed by Fe K-edge X-ray absorption near-edgestructure (XANES) and Fe-57 Mo''ssbauer spectroscopy.In batch sorption experiments, a higher Np sorption affinity to IdPwas found than to Wyoming smectite or iron-free synthetic montmorillonite.An increase of the relative Np(IV) ratio sorbed onto IdP with decreasingpH was observed by solvent extraction (up to (24 & PLUSMN; 2)% at pH5, c (0)(Np) = 10(-6) mol/L). Furthermore, up to (33 & PLUSMN; 5)% Np(IV)could be detected in IdP diffusion samples at pH 5. Respective NpM5-edge high-energy resolution (HR-) XANES spectra suggestedthe presence of Np(IV/V) mixtures and weakened axial bond covalencyof the NpO2 (+) species sorbed onto IdP. Np L-3-edge extended X-ray absorption fine structure (EXAFS) analysisshowed that significant fractions of Np were coordinated to Fe Oentities at pH 9. This highlights the potential role of Fe(II/III)clay edge sites as a strong Np(V) surface complex partner and pointsto the partial reduction of sorbed Np(V) to Np(IV) via structuralFe(II). The complementary use of advancedspectroscopic methodsand wet chemical experiments at similar low Np loadings (>20 ppm)highlighted the role of Fe(II) in Np(V) interaction with illite.

引用

页码：11185 / 11194

页数：10

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