Sorption Characteristics of Neptunium by Sodium-Smectite

Kozai, Naofumi; Ohnuki, Toshihiko; Muraoka, Susumu

doi:10.1080/18811248.1993.9734601

Cited by 27 publications

(22 citation statements)

References 5 publications

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“…Despite the wide range in reported Ko values, however, several consistent trends are observed. In general, with the exception of the studies by Ohe et al (1993), sorption tends to decrease with increasing pH Kozai 1994) to pH = 5. Sorption remains relatively constant with further increases in pH.…”

Section: Previous Studiesmentioning

confidence: 93%

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Neptunium(V) Sorption on Montmorillonite: An Experimental and Surface Complexation Modeling Study

Turner

1998

Clays and clay miner.

118

121

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Abstract--Batch sorption experiments at fixed initial Np(V) concentration (-1 • 10 6 M 237Np), M/V ratio (4 g L-l), and ionic strength (0.1 molal NaNO3) were conducted to determine the effects of varying pH and Pco2 on Np(V) sorption on SAz-1 montmorillonite. The results show that Np(V) sorption on montmorillonite is strongly influenced by pH and Pco2. In the absence of CO2, Np(V) sorption increases over the entire pH range examined (~3 to --10), with measured sorption coefficients (Ko) of about 10 mL g-1 at pH < 6 to K o ~ 1000 mL g-~ at a pH of 10.5. However, for experiments open to atmospheric CO2 (Pco2 = 10 3.5 arm), Np(V) sorption peaks at Ko -100 mL g-1 at pH of 8 to 8.5 and decreases at higher or lower pH. A comparison of the pH-dependence of Np(V) sorption with that of Np(V) aqueous speciation indicates a close correlation between Np(V) sorption and the stability field of the Np(V)-hydroxy complex NpO2OH ~ (aq). In the presence of CO2 and aqueous carbonate, sorption is inhibited at pH > 8 due to formation of aqueous Np(V)-carbonate complexes. A relatively simple 2-site DiffuseLayer Model (DLM) with a single Np(V) surface complexation reaction per site effectively simulates the complex sorption behavior observed in the Np(V)-H20-CO2-montmorillonite system. The good agreement between measured and DLM-predicted sorption values suggests that surface complexation models based on parameters derived from a limited set of data could be useful in extrapolating radionuclide sorption over a range of geochemical conditions. Such an approach could be used to support transport modeling and could provide a better alternative to the current use of constant K o values in performance assessment transport calculations.

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Section: Previous Studiesmentioning

confidence: 93%

“…(1) Beall and Allard (1981); (2) Allard et al (1984); (3) Torstenfelt et al (1988); (4) Sakamoto et al (1990); (5) Triay et al (1993); (6) Ohe et al (1993); (7) Kozai (1994).…”

Section: Introductionmentioning

confidence: 99%

Neptunium(V) Sorption on Montmorillonite: An Experimental and Surface Complexation Modeling Study

Turner

1998

Clays and clay miner.

118

121

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“…Among the most ubiquitous inorganic colloids are aluminosilicate clays that are commonly observed as mobile colloids due to their inherently small particle size and prevalence as alteration minerals from original host rock material (Kersting et al, 1999). Clays are known to sorb Pu Keeney-Kennicutt and Morse, 1985;Kozai et al, 1996;Kozai et al, 1993;Lujaniene et al, 2007;Powell et al, 2004Powell et al, , 2005Powell et al, 2008;Sabodina et al, 2006;Sanchez et al, 1985;Turner et al, 1998). In addition, the proposed use of bentonite within some engineered barrier systems scenarios for high-level nuclear waste repositories provides additional importance to understanding Pu interaction with smectite aluminosilicate clays (Sabodina et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Pu(IV) Intrinsic Colloid Stability in the Presence of Montmorillonite at 25 & 80 C

Zhao¹,

Kersting²,

Dai³

et al. 2012

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“…However, up to now no sorption data for americium and plutonium on OPA have been published. More sorption studies have been reported for the uptake of actinides by pure clay minerals, that are the main constituents of OPA (e. g., montmorillonite [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], illite [32][33][34][35][36][37][38][39][40], kaolinite [31,[41][42][43][44][45][46][47][48][49][50][51] , the cation exchange capacity was equal to 10 ± 4 meq/100 g for both powders [9,11]. The mineral composition and the content of the trace elements of the used OPA measured by X-ray fluorescence analysis are given elsewhere [11].…”

Section: Introductionmentioning

confidence: 99%

Distribution coefficients for the sorption of Th, U, Np, Pu, and Am on Opalinus Clay

Amayri

Fröhlich²,

Kaplan³

et al. 2015

Radiochimica Acta

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Sorption Characteristics of Neptunium by Sodium-Smectite

Cited by 27 publications

References 5 publications

Neptunium(V) Sorption on Montmorillonite: An Experimental and Surface Complexation Modeling Study

Neptunium(V) Sorption on Montmorillonite: An Experimental and Surface Complexation Modeling Study

Pu(IV) Intrinsic Colloid Stability in the Presence of Montmorillonite at 25 & 80 C

Distribution coefficients for the sorption of Th, U, Np, Pu, and Am on Opalinus Clay

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