Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils

Bots, Pieter; Comarmond, M. Josick; Payne, Timothy E.; Gückel, Katharina; Lunn, Rebecca; Rizzo, Luca; Schellenger, Alexandra E. P.; Renshaw, Joanna C.

doi:10.1039/d1em00121c

Cited by 3 publications

(6 citation statements)

References 68 publications

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“…With hot particles (fuel particles in Chernobyl [ 5 , 7 , 27 , 33 , 34 , 36 ] and CsMPs in Fukushima [ 52 , 53 , 54 ]) disintegrated, radiocesium incorporated in these particles transfers to the solution. In the solution, radiocesium is sorbed by the soil and sediment particles by ion exchange [ 5 , 7 , 27 , 53 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ]. Exchangeably sorbed radiocesium is fixed by micaceous clay minerals due to the replacement of the interlayer K-cations by Cs-cations [ 5 , 7 , 55 , 57 , 58 , 64 , 65 ].…”

Section: Speciation Of Radiocesium and Its Transformation In Soil–wat...mentioning

confidence: 99%

“…Fixation of radionuclides is the transformation of their exchangeable form to nonexchangeable. It is believed that the mechanism of radiocesium fixation is the replacement of interlattice K + by Cs + ions due to the collapse of the expanded edges of the mineral’s crystal interlayers and/or the slow long-term solid-state diffusion of Cs + ions along the interlayer inside the particle [ 27 , 58 , 59 ].…”

Section: Speciation Of Radiocesium and Its Transformation In Soil–wat...mentioning

confidence: 99%

“…As it appears from laboratory experiments with a variety of soils and sediments [ 59 , 64 , 77 ] and post-Chernobyl field studies [ 5 , 27 ], the timescale of radiocesium fixation equals to weeks or months ( k f = 4–20 yr −1 ), depending on environmental conditions, whereas the timescale of remobilization can be up to a few years ( k r = 0.4–2 yr −1 ). These processes can be expected to show comparable rates in Fukushima soils and sediments.…”

Section: Speciation Of Radiocesium and Its Transformation In Soil–wat...mentioning

confidence: 99%

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Fukushima and Chernobyl: Similarities and Differences of Radiocesium Behavior in the Soil–Water Environment

Konoplev

2022

Toxics

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In the wake of Chernobyl and Fukushima accidents, radiocesium has become a radionuclide of most environmental concern. The ease with which this radionuclide moves through the environment and is taken up by plants and animals is governed by its chemical forms and site-specific environmental characteristics. Distinctions in climate and geomorphology, as well as 137Cs speciation in the fallout, result in differences in the migration rates of 137Cs in the environment and rates of its natural attenuation. In Fukushima areas, 137Cs was strongly bound to soil and sediment particles, with its bioavailability being reduced as a result. Up to 80% of the deposited 137Cs on the soil was reported to be incorporated in hot glassy particles (CsMPs) insoluble in water. Disintegration of these particles in the environment is much slower than that of Chernobyl-derived fuel particles. The higher annual precipitation and steep slopes in Fukushima-contaminated areas are conducive to higher erosion and higher total radiocesium wash-off. Among the common features in the 137Cs behavior in Chernobyl and Fukushima are a slow decrease in the 137Cs activity concentration in small, closed, and semi-closed lakes and its particular seasonal variations: increase in the summer and decrease in the winter.

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Section: Speciation Of Radiocesium and Its Transformation In Soil–wat...mentioning

confidence: 99%

Section: Speciation Of Radiocesium and Its Transformation In Soil–wat...mentioning

confidence: 99%

Section: Speciation Of Radiocesium and Its Transformation In Soil–wat...mentioning

confidence: 99%

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Fukushima and Chernobyl: Similarities and Differences of Radiocesium Behavior in the Soil–Water Environment

Konoplev

2022

Toxics

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“…Extended X-ray Absorption fine Structure (EXAFS) is one such technique that has been employed to successfully elucidate the binding environment of a range of metals adsorbed to surfaces [13,14]. While a number of EXAFS studies have examined strontium binding environment in a range of inorganic materials, very few studies show direct proof of inner sphere binding [15,16], and we are unaware of any previous EXAFS study on biopolymer adsorbents examining the binding mechanism of strontium.…”

Section: Introductionmentioning

confidence: 99%

Binding mechanism of strontium to biopolymer hydrogel composite materials

Foster

Ramanan

Hanson

et al. 2022

J Radioanal Nucl Chem

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Strontium-90 is a radionuclide of concern that is mobile in soil and groundwater and is a threat to life. Activated hydrogel biopolymer composites were fabricated for strontium remediation from groundwater. Batch uptake demonstrated a maximal stontium uptake capacity of 109 mg g−1, much higher than unactivated hydrogel controls. Activation also more than doubled the decontamination factor at environmentally relevant concentrations. EXAFS was used to investigate the binding mechanism, revealing inner sphere complexation of strontium for the first time. Biopolymer composities synthesized for these studies are sustainable and cheap remediation materials that exhibit good strontium uptake and inner sphere binding.

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“…90 Sr is more relevant in the context of fallout from nuclear accidents [10] and nuclear weapons [11]. Various comprehensive papers on Sr interaction with mineral surfaces have been recently published [12,13]. In terms of solute mineral surface interaction, Sr adsorbs on oxides at relatively high pH values corresponding to its weak hydrolysis [14].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Garcia

Lützenkirchen

Huguenel³

et al. 2021

Minerals

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In this work, the adsorption behavior of Sr onto a synthetic iron(III) oxide (hematite with traces of goethite) has been studied. This solid, which might be considered a representative of Fe3+ solid phases (iron corrosion products), was characterized by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS), and its specific surface area was determined. Both XRD and XPS data are consistent with a mixed solid containing more than 90% hematite and 10% goethite. The solid was further characterized by fast acid-base titrations at different NaCl concentrations (from 0.1 to 5 M). Subsequently, for each background NaCl concentration used for the acid-base titrations, Sr-uptake experiments were carried out involving two different levels of Sr concentration (1·10−5 and 5·10−5 M, respectively) at constant solid concentration (7.3 g/L) as a function of −log([H+]/M). A Surface Complexation Model (SCM) was fitted to the experimental data, following a coupled Pitzer/surface complexation approach. The Pitzer model was applied to aqueous species. A Basic Stern Model was used for interfacial electrostatics of the system, which includes ion-specific effects via ion-specific pair-formation constants, whereas the Pitzer-approach involves ion-interaction parameters that enter the model through activity coefficients for aqueous species. A simple 1-pK model was applied (generic surface species, denoted as >XOH−1/2). Parameter fitting was carried out using the general parameter estimation software UCODE, coupled to a modified version of FITEQL2. The combined approach describes the full set of data reasonably well and involves two Sr-surface complexes, one of them including chloride. Monodentate and bidentate models were tested and were found to perform equally well. The SCM is particularly able to account for the incomplete uptake of Sr at higher salt levels, supporting the idea that adsorption models conventionally used in salt concentrations below 1 M are applicable to high salt concentrations if the correct activity corrections for the aqueous species are applied. This generates a self-consistent model framework involving a practical approach for semi-mechanistic SCMs. The model framework of coupling conventional electrostatic double layer models for the surface with a Pitzer approach for the bulk solution earlier tested with strongly adsorbing solutes is here shown to be successful for more weakly adsorbing solutes.

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Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils

Abstract: Strontium and caesium are fission products of concern at many nuclear legacy sites and Cs is additionally a significant consideration at sites in the aftermath of nuclear accidents and incidents....

Cited by 3 publications

References 68 publications

Fukushima and Chernobyl: Similarities and Differences of Radiocesium Behavior in the Soil–Water Environment

Fukushima and Chernobyl: Similarities and Differences of Radiocesium Behavior in the Soil–Water Environment

Binding mechanism of strontium to biopolymer hydrogel composite materials

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

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