Experimental and modeling studies on sorption and diffusion of radium in bentonite

Tachi, Yukio; Shibutani, Tomoki; Sato, Haruo; Yui, Mikazu

doi:10.1016/s0169-7722(00)00147-9

Cited by 41 publications

(10 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a previous study (AlAttar et al 2010), bentonite was reported to have a K d for Ra of 40.5 L kg -1 . Other studies reported the sorption and desorption behavior of Ra on bentonite as a function of pH (7-11); K d values were found to be in the range of 10 2 -10 4 L kg -1 (Tachi et al 2001). Much lower values were also reported for Ra and Sr (7.8 L kg -1 ) (Ochs 2006).…”

Section: Resultsmentioning

confidence: 94%

A Study on Sorption of 226Ra on Different Clay Matrices

Alhajji

Al-Masri

Khalily

et al. 2016

Bull Environ Contam Toxicol

View full text Add to dashboard Cite

The sorption of radium 226 ((226)Ra) on different clay materials (bentonite, illite and a mixture of bentonite-illite) was studied. Clay materials are used in the construction of disposal pits for technically enhanced naturally occurring radioactive materials (TENORM) wastes (i.e., contaminated soil and sludge) generated by the oil and gas industry operations. Experimental conditions (pH, clay materials quantity, and activity concentrations of (226)Ra) were changed in order to determine the optimal state for adsorption of (226)Ra. The results showed that the concentration of adsorbed (226)Ra on clay materials increased with time to reach an equilibrium state after approximately 5 h. More than 95 % of the radium was adsorbed. The mixture of bentonite-illite (1/9) exhibited the greatest adsorption of radium under all experimental conditions.

show abstract

Section: Resultsmentioning

confidence: 94%

A Study on Sorption of 226Ra on Different Clay Matrices

Alhajji

Al-Masri

Khalily

et al. 2016

Bull Environ Contam Toxicol

View full text Add to dashboard Cite

show abstract

“…Recent overviews of radium adsorption processes in subsurface systems have been provided in International Atomic Energy Agency (IAEA, 2006), US EPA (2010), and Kaplan et al (2010). Radium uptake onto clay minerals is controlled by ion exchange based on apparent reversibility and selectivity of the adsorption process (Ames et al, 1983a,b;Centeno et al, 2004;Tachi et al, 2001). Amorphous Fe-hydroxides adsorb orders of magnitude more Ra than clay minerals and Ra is preferentially sorbed onto Mn-oxyhydroxides over Feoxyhydroxides (Ames et al, 1983a,b;Moore and Reid, 1973).…”

Section: Geochemical Controls On Ra Concentrationsmentioning

confidence: 99%

Radioactivity, Geochemistry, and Health

Siegel

Bryan

2014

Treatise on Geochemistry

View full text Add to dashboard Cite

“…These solid phases must be methodically characterised, with special emphasis on the identification of sorption sites, the estimation of their concentration and their sorption behaviour towards radionuclides under different conditions. The sorption of U(VI) and, in less extent, Rahave been previously studied for different iron oxyhydroxide, carbonate and clayey minerals (Catalano and Brown Jr, 2005;Jones et al, 2011;Payne et al, 2004;Sajih et al, 2014;Stammose et al, 1992;Tachi et al, 2001;Turner et al, 1996). Clay minerals are abundant in geological formations and soils, and have the distinctive property of retaining ions,with high affinity for cationic species.The sorption process on clays is mainly via ion exchange on the surface, becoming even more important with trace-level concentrations and low ionic strength conditions, as the onesin natural environments.…”

Section: Introductionmentioning

confidence: 99%

“…Turner et al (1996)used an ion exchange model to describe sorption of uranyl on a smectite type clay, and obtained equilibrium constants for the different sorption sites on the surface. An ion exchange model (considering two types of sorption sites) was also more suitable than surface complexation model to describe the retention of U(VI) at trace level on a clay mixture of kaolinite and smectite (Stammose et al, 1992), and the sorption of Ra was also demonstrated to happen via an ion exchange mechanism on purified smectite (Tachi et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Study of uranium(VI) and radium(II) sorption at trace level on kaolinite using a multisite ion exchange model

Reinoso-Maset

2016

Journal of Environmental Radioactivity

View full text Add to dashboard Cite

Uranium and the long-lived decay product radium-226 are abundantly present in mine wastes produced during uranium extraction activities. In the case of release to the surrounding environment, these radionuclides are at trace level compared to groundwater solutes, and the presence, content and properties of clay minerals in the host environment influence the extent of radionuclide sorption and, in turn, migration. Since clays are known to have the distinctive property of retaining ions, the aim of this work was to study the sorption of trace U(VI) and Ra(II) on a common phyllosilicate mineral, kaolinite, in the presence of excess K, a common groundwater cation, in order to obtain a thermodynamic database that describes the ion exchange equilibria occurring at the mineral-solution interface. Following a detailed experimental protocol using chemical and radiochemical analytical techniques, batch experiments over a wide pH range (from 2 to 11) and fixed concentration (ca. 10(-9) M), and additional adsorption isotherms at two different solution pH (6.2 and 10.4) over a concentration range (10(-10) to 10(-4) M) were carried out to measure the distribution coefficient (Kd) of U(VI) and Ra(II) sorption on kaolinite. The experimental sorption data was processed according to a general multisite sorbent/multispecies sorbate ion exchange model, which allowed deducing the charge of adsorbed species and the stoichiometry of the associated adsorption equilibria on kaolinite's surface sites. Aqueous speciation calculations predicted Ra(II) as Ra(2+) over the working pH range, and its adsorption curves and isotherms were explained using three sorption sites. Adsorption of U(VI) occurred on four sorption sites and was governed by its solution speciation, with positively charged hydroxylated (UO2(2+) and UO2(OH)(+)) and silicate (UO2(H3SiO4)(+)) species being adsorbed between pH 2 and 6, whereas its negatively charged forms (UO2(OH)3(-) and UO2(OH)4(2-)) dominated U(VI) sorption at pH > 7. Nonlinear fitting of the experimental data using the ion exchange model provided the associated equilibrium constants as corrected selectivity coefficients.

show abstract

Experimental and modeling studies on sorption and diffusion of radium in bentonite

Cited by 41 publications

References 3 publications

A Study on Sorption of 226Ra on Different Clay Matrices

A Study on Sorption of 226Ra on Different Clay Matrices

Radioactivity, Geochemistry, and Health

Study of uranium(VI) and radium(II) sorption at trace level on kaolinite using a multisite ion exchange model

Contact Info

Product

Resources

About