Uranium(VI) adsorption on montmorillonite colloid

Yu, Shujuan; Ma, Jianqing; Shi, Yinming; Du, Zuoyong; Zhao, Yuting; Tuo, Xianguo; Leng, Yangchun

doi:10.1007/s10967-020-07083-y

Cited by 28 publications

(4 citation statements)

References 38 publications

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“…Complete exchange of uranium atoms between U(VI) adsorbed to montmorillonite and aqueous U(VI) was observed at both pH 5 and pH 7 within 3.5 h (Figure ). A considerable fraction of adsorbed U(VI) was expected to be adsorbed by cation exchange at pH 5, whereas at pH 7, the adsorbed U(VI) will be predominantly as inner-sphere surface complexes at edge sites. − The timescales of isotope exchange for both pH conditions are larger than the adsorption equilibration time, reported to be ∼30 min . Isotope exchange at pH 5 was slightly faster than that at pH 7 as indicated by the extent of isotope exchange in first 1 h. The intrinsic rate of sorption can be very fast leading to sorption–desorption equilibrium within a few seconds .…”

Section: Resultsmentioning

confidence: 99%

“…47−49 The timescales of isotope exchange for both pH conditions are larger than the adsorption equilibration time, reported to be ∼30 min. 50 Isotope exchange at pH 5 was slightly faster than that at pH 7 as indicated by the extent of isotope exchange in first 1 h. The intrinsic rate of sorption can be very fast leading to sorption−desorption equilibrium within a few seconds. 51 However, the mass transfer rate could be different for the two pH conditions, determining the overall difference in the rate of isotope exchange.…”

Section: ■ Materials and Methodsmentioning

confidence: 93%

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Exchange between Dissolved U(VI) and Adsorbed and Precipitated Forms of Solid-Associated U

Satpathy

Sharma

Pan

et al. 2023

ACS Earth Space Chem.

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The mobility of uranium(VI) in subsurface environments can be limited by its adsorption to clay minerals and by chemical reduction to less mobile U(IV) solid phases. Even for adsorbed and precipitated U species that control the net release of U(VI) to the aqueous phase, dynamic exchange between phases at equilibrium conditions can occur with a pool of exchangeable solid-associated uranium considered as the labile fraction. In this study, the lability of uranium adsorbed to montmorillonite and uranium present in UO2(s) was examined by an isotope exchange technique. Crystalline UO2(s) containing depleted uranium (predominantly 238U and with small amounts of 235U) was contacted with a U(VI) aqueous solution enriched in 236U under oxygen-free (95% N2(g) + 5% H2(g)) conditions that altered the aqueous phase isotopic composition while minimally affecting the overall aqueous U(VI) concentration. Complete isotope exchange between U(VI) adsorbed onto montmorillonite and aqueous U(VI) was observed within 3.5 h. In contrast, no isotope exchange of aqueous U(VI) with UO2(s) was observed even after 47 days of contact. X-ray photoelectron spectroscopy of the UO2(s), both before and after its reaction with aqueous U(VI), showed the presence of U(VI), U(V), and U(IV) on the surface. Although U(VI) was present on the UO2(s) surface, it was nonlabile over a timescale of weeks. This study highlights the difference in lability between adsorbed and precipitated U-containing species, and it illustrates that U(VI) at the surface of a UO2 precipitate does not behave the same as U(VI) adsorbed to minerals not composed of U.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 93%

Exchange between Dissolved U(VI) and Adsorbed and Precipitated Forms of Solid-Associated U

Satpathy

Sharma

Pan

et al. 2023

ACS Earth Space Chem.

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“…UO OH + can interact with neutral (=S-OH) and deprotonated (=S-O -) hydroxyl groups on the surface. In this way, surface complexes of various compositions are formed [23]. In the pH range of 6.5-9, a decrease in sorption is observed due to the formation of negatively charged carbonate and hydroxyl complexes of uranium (VI).…”

Section: Effect Of Solution Ph and Ratio Of Iron And Zirconium Ions O...mentioning

confidence: 99%

Development of granular composites based on laponite and Zr/Fe-alginate for effective removal of uranium (VI) from sulfate solutions

Pylypenko,

Kovalchuk,

Tsyba

2023

EEJET

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The object of research is granular composites based on zirconium-iron alginates and laponite. The task of research is to determine the influence of the Zr:Fe ratio on the structure of granular composites and efficiency of uranium (VI) removal from aqueous solutions. The influence of the zirconium and iron ratio on the parameters of the material's pore structure has been established, particularly on the change in the content of micropores within the matrix. The specific surface area of the materials ranges from 86 to 112 m²/g. The sorption properties of the composites regarding uranium (VI) have been investigated. The impact of the charge of surface groups and the form of uranium (VI) presence in sulfate solutions on their sorption characteristics has been demonstrated. The maximum adsorption capacity reaches 265.1 µmol/g at pH 6. It is shown that an elevated electrolyte content positively affects the efficiency of uranium (VI) removal in neutral and alkaline medium. It has been established that structural changes in the materials occur due to the intensive interaction of iron ions and alginate molecules, resulting in the formation of a dense gel-like structure. The mechanism of uranium (VI) removal is associated with the formation of surface complexes in the presence of electrolytes. The synthesized granulated composites exhibit improved removal efficiency of uranium (VI) under conditions of high mineralization of solutions, making them attractive for potential use as sorbents. The obtained results can be utilized in the development of effective methods for purifying water environments from uranium (VI) in high mineralization conditions, which is a relevant issue in the field of nuclear energy and the removal of radioactive substances from water systems

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“…Clay and silt particles tend to behave as colloids. Their elevated specific surface area is responsible for the cation's adsorption (e.g., K + , U 4+ , U 6+ and Th 4+ ) that increases with the grade of weathering [21,22]. Focusing on the mineral structure, as a general rule, the natural radioelements are more abundant in clay minerals (typical of the fine fraction) than in quartz (the main constituent of sand) [23].…”

Section: Introductionmentioning

confidence: 99%

Airborne Radiometric Surveys and Machine Learning Algorithms for Revealing Soil Texture

Maino

Albéri

Anceschi³

et al. 2022

Remote Sensing

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Soil texture is key information in agriculture for improving soil knowledge and crop performance, so the accurate mapping of this crucial feature is imperative for rationally planning cultivations and for targeting interventions. We studied the relationship between radioelements and soil texture in the Mezzano Lowland (Italy), a 189 km2 agricultural plain investigated through a dedicated airborne gamma-ray spectroscopy survey. The K and Th abundances were used to retrieve the clay and sand content by means of a multi-approach method. Linear (simple and multiple) and non-linear (machine learning algorithms with deep neural networks) predictive models were trained and tested adopting a 1:50,000 scale soil texture map. The comparison of these approaches highlighted that the non-linear model introduces significant improvements in the prediction of soil texture fractions. The predicted maps of the clay and of the sand content were compared with the regional soil maps. Although the macro-structures were equally present, the airborne gamma-ray data permits us shedding light on finer features. Map areas with higher clay content were coincident with paleo-channels crossing the Mezzano Lowland in Etruscan and Roman periods, confirmed by the hydrographic setting of historical maps and by the geo-morphological features of the study area.

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Uranium(VI) adsorption on montmorillonite colloid

Cited by 28 publications

References 38 publications

Exchange between Dissolved U(VI) and Adsorbed and Precipitated Forms of Solid-Associated U

Exchange between Dissolved U(VI) and Adsorbed and Precipitated Forms of Solid-Associated U

Development of granular composites based on laponite and Zr/Fe-alginate for effective removal of uranium (VI) from sulfate solutions

Airborne Radiometric Surveys and Machine Learning Algorithms for Revealing Soil Texture

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