Study of the generation and stability of thorium(IV) colloids by LIBD combined with ultrafiltration

Bitea, C.; Müller, Ralf; Neck, V.; Walther, Clemens; Kim, J.I

doi:10.1016/s0927-7757(02)00559-9

Cited by 50 publications

(26 citation statements)

References 12 publications

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“…In undersaturated solutions, well below the pH of quantitative formation of LIBD-detectable colloids, light scattering and observation of a very small number of breakdown events close to the detection limit of LIBD (∼ 10 4 particles/mL) suggests the presence of colloids sized some tenths of a micron at extremely low number. It might be that the equilibrium and hence coexistence of colloids and solution species which was proven for Th(IV) [58] spans a much wider range in the case of Pu(IV) solutions and that monomeric ions coexist with colloids [6] and polymers of considerable size up to billions of amu [4]. This coexistence would underline the extraordinary role of colloids and polymers in the Pu(IV) chemistry.…”

Section: Discussionmentioning

confidence: 93%

New insights in the formation processes of Pu(IV) colloids

Walther¹,

Rothe

Brendebach

et al. 2009

Radiochimica Acta

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The high tendency of tetravalent plutonium to form polymeric complexes and colloids is well known but the exact processes underlying their formation are still controversially discussed. In the present work, the nucleation of small polynuclear hydroxide complexes, i.e., ionic species containing more than one Pu ion, their aggregation and formation of larger colloids (polymers exceeding some 5 nm in size) and finally ripening processes of freshly formed amorphous Pu(IV) colloids towards more crystalline particles are investigated by use of a combination of various spectroscopic techniques. By electrospray mass-spectrometry small polymers such as dimers, trimers and tetramers containing mixed oxidation states of Pu were observed. These polymers might be responsible for the equilibration between the Pu(III)/Pu(IV) and the plutonyl species Pu(V)/Pu(VI) even in dilute solutions in the absence of colloids or precipitates.

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Section: Discussionmentioning

confidence: 93%

New insights in the formation processes of Pu(IV) colloids

Walther¹,

Rothe

Brendebach

et al. 2009

Radiochimica Acta

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“…If colloid removal (ultrafiltration, ultracentrifugation) is omitted, total actinide concentrations, [An(IV)] tot , higher than those based on true solubility, [An(-OH) 4 (aq)], by a factor of about 100-1000 are found due to the presence of An(IV) colloids. Interestingly, the colloids of amorphous actinide oxyhydroxide responsible for these increased An(IV) concentrations, which are formed via the build-up of An(IV) oligomers and polymers (Walther et al, 2008(Walther et al, , 2009), seem to be in equilibrium with the truly dissolved actinide species Bitea et al, 2003;Altmaier et al, 2004;Rothe et al, 2004). They are hydrophilic and their stability is neither influenced by the ionic strength of the solution nor by the pH (within the pH range in which they do not re-dissolve by chemical dissolution).…”

Section: Introductionmentioning

confidence: 99%

Formation of uranium(IV)-silica colloids at near-neutral pH

Dreissig

Weiß

Hennig

et al. 2011

Geochimica et Cosmochimica Acta

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“…In a series of recent papers of our laboratory [1][2][3] thorium was used as a surrogate for other tetravalent actinides to investigate the solid-liquid equilibria and the effect of colloids on the solubility of An(IV) oxides/hydroxides. These investigations (in 0.5 M NaCl solution) and the solubility studies of numerous other authors [4][5][6][7][8][9][10] have been performed in solutions of low and moderate ionic strength (I < 1 M).…”

Section: Introductionmentioning

confidence: 99%

Solubility and colloid formation of Th(IV) in concentrated NaCl and MgCl₂solution

Altmaier¹,

Neck

Fanghänel³

2004

Radiochimica Acta

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Tetravalent actinides / Thorium(IV) / Solubility / Chloride solution / Ultracentrifugation / Eigencolloids / PseudocolloidsSummary. The solubility of crystalline ThO 2 (cr) and amorphous hydrated Th(IV) oxyhydroxide ThO n (OH) 4−2n ·xH 2 O(am) has been measured in dilute to concentrated NaCl and MgCl 2 solutions equilibrated with magnesium hydroxide or hydroxychloride at 22 ± 2 • C. The contributions of colloids to the total thorium concentrations observed in both overand undersaturation experiments with amorphous Th(IV) precipitates have been analysed by ultracentrifugation. The solubility increasing effect of long-time stable Th(IV) eigencolloids, previously investigated in 0.5 M NaCl solutions, is also observed in concentrated 5 M NaCl. Ionic strength and chloride concentration have no effect on the stability of these hydrophilic Th(IV) oxyhydroxide eigencolloids, which are the predominant species in solution. They cause relatively high total thorium concentration in neutral to alkaline steady state solutions, independent of ionic strength: log[Th] tot ≈ log[Th] coll = −6.3 ± 0.5. In concentrated MgCl 2 solutions saturated with magnesium hydroxychloride colloids, the formation of pseudocolloids, i.e., Th(IV) sorbed onto Mg 2 (OH) 3 Cl·4H 2 O(coll), leads to a further increase of the total thorium concentration up to 10 −5 M. The present results are discussed with regard to maximum Th(IV) and Pu(IV) concentrations in performance assessment calculations.

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Study of the generation and stability of thorium(IV) colloids by LIBD combined with ultrafiltration

Cited by 50 publications

References 12 publications

New insights in the formation processes of Pu(IV) colloids

New insights in the formation processes of Pu(IV) colloids

Formation of uranium(IV)-silica colloids at near-neutral pH

Solubility and colloid formation of Th(IV) in concentrated NaCl and MgCl₂solution

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Study of the generation and stability of thorium(IV) colloids by LIBD combined with ultrafiltration

Cited by 50 publications

References 12 publications

New insights in the formation processes of Pu(IV) colloids

New insights in the formation processes of Pu(IV) colloids

Formation of uranium(IV)-silica colloids at near-neutral pH

Solubility and colloid formation of Th(IV) in concentrated NaCl and MgCl2solution

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Solubility and colloid formation of Th(IV) in concentrated NaCl and MgCl₂solution