Kinetics of neptunium(V) sorption and desorption on goethite: An experimental and modeling study

Tinnacher, Ruth M.; Zavarin, Mavrik; Powell, Brian A.; Kersting, Annie B.

doi:10.1016/j.gca.2011.08.014

Cited by 35 publications

(54 citation statements)

References 67 publications

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“…Guo et al [43,44] showed that the kinetics of U(VI) and Th(IV) on TiO 2 are very fast over a wide pH range, with maximum sorption being reached within 1 day. Furthermore, studies on iron oxides and clays indicate fast Np(V) sorption kinetics (e.g., [45][46][47][48]) supporting the assumption that the sorption kinetics of Np(V) on TiO 2 is fast.…”

Section: Kinetic Test Experimentsmentioning

confidence: 70%

Influence of the redox state on the neptunium sorption under alkaline conditions: Batch sorption studies on titanium dioxide and calcium silicate hydrates

Tits¹,

Laube²,

Wieland

et al. 2014

Radiochimica Acta

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Influence of the redox state on the neptunium sorption under alkaline conditions: Batch sorption studies on titanium dioxide and calcium silicate hydrates Abstract: Wet chemistry experiments were carried out to investigate the effect of the redox state and aqueous speciation on the uptake of neptunium by titanium dioxide (TiO 2 ) and by calcium silicate hydrates (C-S-H) under alkaline conditions. TiO 2 was chosen as a reference sorbent to determine the surface complexation behaviour of neptunium under alkaline conditions. C-S-H phases are important constituents of cement and concrete. They may contribute significantly to radionuclide retention due to their high recrystallization rates making incorporation the dominating sorption mechanism for many radionuclides (e.g. the actinides) on these materials. The sorption of neptunium on both solids was found to depend strongly on the degree of hydrolysis. On TiO In addition to the effect of hydrolysis, the presence of Ca is found to promote Np(V) and Np(VI) sorption on TiO 2 whereas on C-S-H phases, the present wet chemistry data do not give unambiguous evidence. Thus, the aqueous speciation appears to have a similar influence on the sorption of the actinides on both types of solids despite the different sorption mechanism.The similar d values for Np(IV,V,VI) sorption at pH = 10 can be explained qualitatively by invoking inter-ligand electrostatic repulsion between OH groups in the coordination sphere of Np(V) and Np(VI). This mechanism was proposed earlier in the literature for the prediction of actinide complexation constants with inorganic ligands. A limiting coordination number for each Np redox state, resulting from the inter-ligand electrostatic repulsion, allows the weaker sorption of the highest hydrolysed Np(V,VI) species to be explained.

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Section: Kinetic Test Experimentsmentioning

confidence: 70%

Influence of the redox state on the neptunium sorption under alkaline conditions: Batch sorption studies on titanium dioxide and calcium silicate hydrates

Tits¹,

Laube²,

Wieland

et al. 2014

Radiochimica Acta

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show abstract

“…However, to our knowledge only one sorption study using short-lived 239 Np isotopes is reported in the literature [7], compared to the many high concentration sorption studies reported using 237 Np [18,[28][29][30].…”

Section: Introductionmentioning

confidence: 98%

“…As a result, multi-site sorption models are frequently employed [16][17][18][19][20][21]. In such models, the iron oxide surface is modeled as containing a relatively large quantity ($90-99%) of ''low affinity'' sites which characterize bulk sorption behavior and smaller quantities ($1-10%) of ''high affinity'' sites which control sorption behavior at low mineral surface loads [21].…”

Section: Introductionmentioning

confidence: 99%

“…Studies of Np sorption at moderate concentrations (10 À6 -10 À8 M) have suggested Freundlich-like behavior, in that as the Np concentration increases, the distribution coefficient (K d , defined as the concentration of Np associated with the solid divided by the concentration in the aqueous phase) decreases [18]. Fundamentally, the Freundlich isotherm has been shown to be equivalent to a multi-site Langmuir model in which a Gaussian-like distribution of site affinities exists [47].…”

Section: Introductionmentioning

confidence: 99%

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Neptunium(V) sorption to goethite at attomolar to micromolar concentrations

Snow

Zhao

Dai

et al. 2013

Journal of Colloid and Interface Science

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“…The predominant morphology of the geothite particles was "star-shaped". Additional characterization details can be found in Tinnacher et al(2011).…”

Section: Goethitementioning

confidence: 99%

Sorption Behavior and Morphology of Plutonium in the Presence of Goethite at 25 and 80C

Zavarin¹,

Zhao²,

Dai³

et al. 2012

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Kinetics of neptunium(V) sorption and desorption on goethite: An experimental and modeling study

Cited by 35 publications

References 67 publications

Influence of the redox state on the neptunium sorption under alkaline conditions: Batch sorption studies on titanium dioxide and calcium silicate hydrates

Influence of the redox state on the neptunium sorption under alkaline conditions: Batch sorption studies on titanium dioxide and calcium silicate hydrates

Neptunium(V) sorption to goethite at attomolar to micromolar concentrations

Sorption Behavior and Morphology of Plutonium in the Presence of Goethite at 25 and 80C

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