Adsorption and colloidal properties of radioactive elements in trace concentrations

Kepák, F.

doi:10.1021/cr60272a002

Cited by 27 publications

(6 citation statements)

References 10 publications

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“…These solids are known to have a large exchange capacity for many metals and they are used along with ferric oxyhydroxides to remove trace metals from water in numerous water treatment processes. See Clark (1990), Kepak (1971), Kinniburgh and Jackson (1981), Righetto et al (1988), and Schindler (1981) for discussions on Al oxide adsorption properties.…”

Section: 6mentioning

confidence: 99%

Chemical information on tank supernatants, Cs adsorption from tank liquids onto Hanford sediments, and field observations of Cs migration from past tank leaks

Serne¹,

Zachara²,

Burke³

1998

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Section: 6mentioning

confidence: 99%

Chemical information on tank supernatants, Cs adsorption from tank liquids onto Hanford sediments, and field observations of Cs migration from past tank leaks

Serne¹,

Zachara²,

Burke³

1998

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“…The mechanisms for the nucleation and growth of intrinsic colloids are thought to be similar to those of precipitation [54,55,67,68]. Thus, the process assumes that the concentration of the actinide is sufficiently large so as to exceed the solubility product constant for the formation of a solid phase [54,68,69]. Because actinide oxides and hydroxides are very insoluble, they are frequently the source of intrinsic colloids.…”

Section: Actinide Intrinsic Colloidsmentioning

confidence: 99%

Actinide Environmental Chemistry

1995

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In order to predict release and transport rates, as well as design cleanup and containment methods, it is essential to understand the chemical reactions and forms of the actinides under aqueous environmental conditions. Four important processes that can occur with the actinide cations are: precipitation, complexation, sorption and colloid formation. Precipitation of a solid phase will limit the amount of actinide in solution near the solid phase and have a retarding effect on release and transport rates. Complexation increases the amount of actinide in solution and tends to increase release and migration rates. Actinides can sorb on to mineral or rock surfaces which tends to retard migration. Actinide ions can form or become associated with colloidal sized particles which can, depending on the nature of the colloid and the solution conditions, enhance or retard migration of the actinide. The degree to which these four processes progress is strongly dependent on the oxidation state of the actinide and tends to be similar for actinides in the same oxidation state.In order to obtain information on the speciation of actinides in solution, i.e., oxidation state, complexation form, dissolved or colloidal forms, the use of absorption spectroscopy has become a method of choice. The advent of the ultrasensitive, laser induced photothermal and fluorescence spectroscopies has made possible the detection and study of actinide ions at the parts per billion level. With the availability of third generation synchrotrons and the development of new fluorescence detectors, X-ray absorption spectroscopy (XAS) is becoming a powerful technique to study the speciation of actinides in the environment, particularly for reactions at the solid/solution interfaces.

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“…These interactions are strongly dependent on the electrokinetic properties, concentration and size of the Pu(IV) colloids. The published data on these parameters are scarce, and the reported values were only qualitative or provide a wide range of values. − Grebenshchikova and Davydov reported a value of the isoelectric point (IEP) for Pu(IV) colloids of ∼8 to 8.5 based on qualitative observations of the migration of Pu(IV) colloids in an electric field, without surface charge . Kepak summarized data on the isoelectric point (IEP) of Pu(IV) from previous literature indicating a range of IEPs from 3.1 to 8.5, depending on the concentration of Pu(IV) in solution.…”

Section: Introductionmentioning

confidence: 99%

Dispersion Stability and Electrokinetic Properties of Intrinsic Plutonium Colloids: Implications for Subsurface Transport

Abdel‐Fattah

Zhou

Boukhalfa

et al. 2013

Environ. Sci. Technol.

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Subsurface transport of plutonium (Pu) may be facilitated by the formation of intrinsic Pu colloids. While this colloid-facilitated transport is largely governed by the electrokinetic properties and dispersion stability (resistance to aggregation) of the colloids, reported experimental data is scarce. Here, we quantify the dependence of ζ-potential of intrinsic Pu(IV) colloids on pH and their aggregation rate on ionic strength. Results indicate an isoelectric point of pH 8.6 and a critical coagulation concentration of 0.1 M of 1:1 electrolyte at pH 11.4. The ζ-potential/pH dependence of the Pu(IV) colloids is similar to that of goethite and hematite colloids. Colloid interaction energy calculations using these values reveal an effective Hamaker constant of the intrinsic Pu(IV) colloids in water of 1.85 × 10(-19) J, corresponding to a relative permittivity of 6.21 and refractive index of 2.33, in agreement with first principles calculations. This relatively high Hamaker constant combined with the positive charge of Pu(IV) colloids under typical groundwater aquifer conditions led to two contradicting hypotheses: (a) the Pu(IV) colloids will exhibit significant aggregation and deposition, leading to a negligible subsurface transport or (b) the Pu(IV) colloids will associate with the relatively stable native groundwater colloids, leading to a considerable subsurface transport. Packed column transport experiments supported the second hypothesis.

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Adsorption and colloidal properties of radioactive elements in trace concentrations

Cited by 27 publications

References 10 publications

Chemical information on tank supernatants, Cs adsorption from tank liquids onto Hanford sediments, and field observations of Cs migration from past tank leaks

Chemical information on tank supernatants, Cs adsorption from tank liquids onto Hanford sediments, and field observations of Cs migration from past tank leaks

Actinide Environmental Chemistry

Dispersion Stability and Electrokinetic Properties of Intrinsic Plutonium Colloids: Implications for Subsurface Transport

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