Uranium(VI) sorption complexes on silica in the presence of calcium and carbonate

Saleh, Asri; Lee, Jun-Yeop; Jo, Yongheum; Yun, Jong-Il

doi:10.1016/j.jenvrad.2017.11.006

Cited by 41 publications

(9 citation statements)

References 39 publications

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“…Arsenic adsorption on soils increased significantly with decreasing H 2 SiO 3 colloid concentration, but the effect of Fe(OH) 3 colloid on the adsorption behaviour of arsenic in soils is complicated. e common colloids present in natural water are based on oxides of Si, Al, and Fe [23,24]. Ultrafiltration analysis confirmed that the elemental composition of colloids in the groundwater of the study area was Si, Fe, Na, etc.…”

Section: Introductionmentioning

confidence: 63%

Effect of Colloidal Silicate on the Migration Behaviour of Strontium in Groundwater Environment of Geological Disposal Candidate Site

Zuo

Han

Shi

et al. 2019

Journal of Chemistry

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Various colloids are present in the natural groundwater environment, and colloids act on the processes involved when radionuclides leak from a repository in a high-level waste disposal site. is paper investigates the effect of colloidal silicate in natural groundwater environments on the migration behaviour of Sr(II). ree different experimental cases have been designed: (1) effect in the presence of colloidal silicate, (2) effect in the presence of a porous medium, and (3) effect in the presence of both colloidal silicate and porous medium (referred to as CS, PM, and PC, respectively). Batch experiments were used to study the effect of influencing factors on Sr(II) migration behaviour, such as the amount of CS, solid-to-liquid ratio, pH, contact time, and initial concentration of Sr(II). e experiments showed that the effect of PC on the migration behaviour of Sr(II) was greatest, and the presence of CS enhanced the sorption. e colloid amount, pH, and solid-to-liquid ratio significantly affected the migration behaviour. e more the colloids were added, the better the adsorption effect. e optimal pH and solid-to-liquid ratio were 6 and 20 : 1, respectively. e alkaline environment is more conductive to colloid sorption. When the solid-to-liquid ratio was 20 : 1, the sorption percentage of PC is 0.5 times larger than PM. Although the PC has a longer adsorption equilibrium time, the percentage of adsorption can be larger than that in the other two cases. e kinetics and isotherms of Sr(II) were best described by the pseudosecond-order and Langmuir models. It was inferred that strong chemical interactions and/or surface complexation contributed primarily to Sr(II) sorption, and the process was on the monolayer adsorption of the outer surface. ese findings provide valuable information for the migration behaviour of strontium in groundwater environments of geological disposal site. At the same time, it provides information for the implementation of permeable reactive barrier technology to control the transport of radioactive Sr(II) and its species in natural surface and groundwater.

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Section: Introductionmentioning

confidence: 63%

Effect of Colloidal Silicate on the Migration Behaviour of Strontium in Groundwater Environment of Geological Disposal Candidate Site

Zuo

Han

Shi

et al. 2019

Journal of Chemistry

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“…However, the luminescence spectral shapes of these U(VI)-hydroxo surface species have not yet been compared in detail. It is also of interest to note that the luminescence spectral shapes observed in other studies differ markedly for U(VI) surface species under near-neutral pH conditions [18,23,24]. Moreover, a wide range of luminescence lifetimes has been reported.…”

Section: Introductionmentioning

confidence: 83%

“…Recent reviews have described related studies of several mineral surfaces [5][6][7]. The adsorption characteristics of U(VI) onto SiO 2 surfaces have been investigated at the molecular scale using spectroscopic techniques, such as extended X-ray absorption fine structure (EXAFS) spectroscopy [8][9][10][11][12], X-ray photoelectron spectroscopy [13,14], and time-resolved laser-induced fluorescence spectroscopy (TRLFS) [13][14][15][16][17][18][19][20][21][22][23][24]. Among these techniques, TRLFS has received considerable attention because of its high sensitivity.…”

Section: Introductionmentioning

confidence: 99%

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Surface Coverage- and Excitation Laser Wavelength-Dependent Luminescence Properties of U(VI) Species Adsorbed on Amorphous SiO2

Jung

Kim

et al. 2022

Minerals

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Time-resolved luminescence spectroscopy is usefully used to identify U(VI) surface species adsorbed on SiO2. However, the cause of the inconsistent luminescence lifetimes and spectral shapes reported previously remains undetermined. In this study, the U(VI) surface coverage (Γ) and excitation laser wavelength (λex) were examined as the predominant factors governing the luminescence properties of U(VI) surface species. At neutral pH, the luminescence lifetimes of U(VI) surface species increased with decreasing Γ. In the low-Γ region, where a relatively large number of adjacent surface sites are involved in the formation of multidentate surface complexes, the displacement of more number of coordinated water molecules in the equatorial plane of U(VI) results in a longer lifetime. The pH-dependent luminescence lifetimes of U(VI) surface species at the same U(VI) to SiO2 concentration ratio in the pH range of 4.5–7.5 also explain the effect of the surface binding sites on the luminescence lifetime. The time-resolved luminescence properties of the U(VI) surface species were also investigated at different excitation wavelengths. Continued irradiation of the SiO2 surface with a UV laser beam at λex = 266 nm considerably reduced the luminescence intensities of the U(VI) surface species. The higher the laser pulse energy, the greater the decrease in luminescence intensity. Laser-induced thermal desorption (LITD) of U(VI) surface species is suggested to be the origin of the decrease in luminescence intensity. LITD effects were not observed at λex = 355 and 422 nm, even at high laser pulse energies.

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“…Dissolved concentrations increase with pH above 6, which could be due to the formation of soluble carbonate complexes (c.f. Saleh et al 2018;Stewart et al 2010), reaching a final concentration of 30-35 µg/L at pH above 7. Concentrations in Pölen are less than in Norrtorpssjön and G3, which might indicate differences between the two lakes in addition to the influence of the deposit.…”

Section: Water Chemistry: Minor Componentsmentioning

confidence: 99%

Chemistry of Acidic and Neutralized Alum Shale Pit Lakes 50 Years After Mine Closure, Kvarntorp, Sweden

et al. 2020

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Several large pits were left after alum shale was mined from 1942 to 1966 in the Kvarntorp area of Sweden. Of these, the pit lakes Pölen and Norrtorpssjön are the focus of this study. They have elevated levels of Na, K, Mg, Ca, Al, Mn, Fe, and sulphate, as well as trace elements, from weathering of the exposed shale. Both lakes had a stable pH below 4 until 1996 when the pH in Norrtorpssjön started to increase, exceeding 8 in 2010, due to inflow of leachates from alkaline waste dumped in an adjacent waste deposit, similar to a large scale anoxic limestone drain (ALD). Iron and Al concentrations decreased as the pH increased, indicating formation of particulate species which accumulate as sediments. The Co, Ni, and Zn concentrations also decreased, probably due to association with the solid phases, while Cu was less affected by the increase in pH, possibly due to formation of complexes with dissolved organic matter. Vanadium concentrations show limited solubility, while Mo concentrations increased at higher pH. Uranium concentrations decreased from above 80 μg/L to below 10 μg/L before rising to 30-35 μg/L due to the formation of soluble carbonate complexes at higher pH levels. The elevated levels of Li, Sr, and U indicate that weathering has continued despite the pH change. Both pit lakes are stratified, but no seasonal overturn has been observed. Long-term behaviour of this large-scale ALD and its implications are also discussed.

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Uranium(VI) sorption complexes on silica in the presence of calcium and carbonate

Cited by 41 publications

References 39 publications

Effect of Colloidal Silicate on the Migration Behaviour of Strontium in Groundwater Environment of Geological Disposal Candidate Site

Effect of Colloidal Silicate on the Migration Behaviour of Strontium in Groundwater Environment of Geological Disposal Candidate Site

Surface Coverage- and Excitation Laser Wavelength-Dependent Luminescence Properties of U(VI) Species Adsorbed on Amorphous SiO2

Chemistry of Acidic and Neutralized Alum Shale Pit Lakes 50 Years After Mine Closure, Kvarntorp, Sweden

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