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

Dreissig, Isabell; Weiß, Stephan; Hennig, Christoph; Bernhard, Gert; Zänker, Harald

doi:10.1016/j.gca.2010.10.011

Cited by 61 publications

(94 citation statements)

References 79 publications

(96 reference statements)

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“…To explain their results, they speculated that U(IV) colloids enhanced the observed U(IV) solubility in experiments with groundwater from granitic bedrock, a uranium ore deposit or porewater from Boom Clay, respectively. While U(VI) mobility in association with colloids has been documented in the field [23][24][25] , and recent laboratory studies evidenced the formation of U(IV) silicate colloids r20 nm in size 26 and that of U IV O 2 colloids 27 , this study is the first to demonstrate the association of U(IV) with colloids in natural environments and its resulting increased mobility.…”

Section: Discussionmentioning

confidence: 59%

Mobile uranium(IV)-bearing colloids in a mining-impacted wetland

et al. 2013

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Section: Discussionmentioning

confidence: 59%

Mobile uranium(IV)-bearing colloids in a mining-impacted wetland

et al. 2013

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“…The autocorrelation functions, C ( τ ), were calculated from the fluctuations of the scattered light intensity to estimate the hydrodynamic radii (i.e., Stokes radii) of the particles in the samples 18. The Cumulant expansion and the CONTIN analysis were employed to derive the particle size information based on the obtained C ( τ ) 41. For the measurements of aging effect, the samples were triply sealed in a glass cuvette and stored in a N 2 ‐filled inert glove box between the measurements, to avoid possible penetration of air into the samples.…”

Section: Methodsmentioning

confidence: 99%

Hydrolysis of Tetravalent Cerium for a Simple Route to Nanocrystalline Cerium Dioxide: An In Situ Spectroscopic Study of Nanocrystal Evolution

Ikeda‐Ohno

Hennig

Weiß

et al. 2013

Chemistry A European J

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Despite the rapid developments in recent nanocrystal research and their expanding applications, the evolution mechanism of nanocrystals remains veiled for the most part due to the lack of appropriate analytical techniques. Here we demonstrate one promising multi-spectroscopic approach for the in situ investigation of nanocrystal evolution. That is, the formation of nanocrystalline cerium dioxide (NC-CeO2) has been probed by dynamic light scattering (DLS), X-ray absorption spectroscopy (XAS) and high-energy X-ray scattering (HEXS). The obtained results indicate that the fine colloidal particles of NC-CeO2 are formed in an acidic aqueous solution simply through the hydrolysis of the initial precursor of small oligomer Ce(IV) species. This information on how NC-CeO2 evolves is fundamental to simplifying and alleviating the synthetic strategy for NC-CeO2 production.

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“…Furthermore: (a) the precipitation of U VI ? U IV depending on concentration of silicates in sediments may caused the formation of U IV -silica colloids (Dreissig et al 2011). The U-O-Si bond formation has been observed in those forms, where the coordination environment has been found comparable to coffinite (USiO 4 ); and (b) study of the uranium distribution in sediments in the environmental area near to nuclear waste storage has been shown that the uranium mobility curtailed via the precipitation of silicates and phosphates (Um et al 2010).…”

Section: Introductionmentioning

confidence: 97%

Environmental modeling of uranium interstitial compositions of non-stoichiometric oxides: experimental and theoretical analysis

Ivanova

Spiteller

2015

Environ Geochem Health

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Study of uranium interstitial compositions of non-stoichiometric oxides UO2+x (x ∈ 0.1-0.02) in gas and condense phases has been presented, using various soft-ionization mass spectrometric methods such as ESI-, APCI-, and MALDI-MS at a wide dynamic temperature gradient (∈ 25-300 °C). Linearly polarized vibrational spectroscopy has been utilized in order to assign unambiguously, the vibrational frequencies of uranium non-stoichiometric oxides. Experimental design has involved xUO2.66·yUO2.33, xUO2.66·yUO2.33/SiO2, xUO2.66·yUO2.33/SiO2 (NaOH) and SiO2/x'NaOH·y'UO2(NO3)2·6H2O, multicomponent systems (x = 1, y ∈ 0.1-1.0 and x' = 1, y' ∈ 0.1-0.6) as well as phase transitions UO2(NO3)2·6H2O → {U4O9(UO2.25)} → U3O7(UO2.33) → U3O8(UO2.66) → {UO3}, thus ensuring a maximal representativeness to real environmental conditions, where diverse chemical, geochemical and biochemical reactions, including complexation and sorption onto minerals have occurred. Experimental factors such as UV-irradiation, pH, temperature, concentration levels, solvent types and ion strength have been taken into consideration, too. As far as uranium speciation represents a challenging analytical task in terms of chemical identification diverse coordination species, mechanistic aspects relating incorporation of oxygen into UO 2+x form the shown full methods validation significantly impacts the field of environmental radioanalytical chemistry. UO2 is the most commonly used fuel in nuclear reactors around the globe; however, a large non-stoichiometric range ∈ UO1.65-UO2.25 has occurred due to radiolysis of water on UO2 surface yielding to H2O2, OH(·), and more. Each of those compositions has different oxygen diffusion. And in this respect enormous effort has been concentrated to study the potential impact of hazardous radionuclide on the environment, encompassing from the reprocessing to the disposal stages of the fuel waste, including the waste itself, the processes in the waste containers, the clay around the containers, and geological processes. In a broader sense, thereby, this study contributes to field of environmental analysis highlighting the great ability of various soft-ionization MS methods, particularly, MALDI-MS one, for direct assay of complex multicomponent heterogeneous mixtures at fmol-attomol concentration ranges, along with it the great instrumental features allowing, not only meaningful quantitative, but also structural information of the analytes, thus making the method indispensable for environmental speciation of radionuclides, generally.

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

Cited by 61 publications

References 79 publications

Mobile uranium(IV)-bearing colloids in a mining-impacted wetland

Mobile uranium(IV)-bearing colloids in a mining-impacted wetland

Hydrolysis of Tetravalent Cerium for a Simple Route to Nanocrystalline Cerium Dioxide: An In Situ Spectroscopic Study of Nanocrystal Evolution

Environmental modeling of uranium interstitial compositions of non-stoichiometric oxides: experimental and theoretical analysis

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