Sequestration of As and Mo in uranium mill precipitates (pH 1.5–9.2): An XAS study

Bissonnette, Jocelyn; Essilfie-Dughan, Joseph; Moldovan, B.; Hendry, M. Jim

doi:10.1016/j.apgeochem.2016.06.007

Cited by 9 publications

(5 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Due to its remarkable sorption capacity and high surface area, − 2-line ferrihydrite readily adsorbs groundwater contaminants − and is commonly used in a range of industrial applications including heavy metal sequestration and nitrogen removal from wastewater. − Its formation and transformation to other iron (hydr)oxides dictate the amount of iron that remains mobile in the aqueous phase, prospectively impacting the long-term performance of nuclear waste repositories and reinforced concrete structures. − Moreover, iron is present in significant quantities (>1 g L –1 ) in uranium mill raffinates . Precipitation as amorphous Fe(OH) 3 (s), ferric arsenate, and hydrotalcite/layered double hydroxide and subsequent adsorption of As are an important mechanism controlling the solubility of elements of concern (EOCs) during raffinate neutralization. − Since most of the highly crystalline ferric (hydr)oxide phases can coexist with or be synthesized from 2-line ferrihydrite, ,− it can be considered a gateway compound that plays an important role in the kinetic mechanism leading to their formation.…”

Section: Introductionmentioning

confidence: 99%

Transformation of 2-Line Ferrihydrite to Goethite at Alkaline pH

Furcas,

Lothenbach,

Mundra

et al. 2023

Environ. Sci. Technol.

View full text Add to dashboard Cite

The transformation of 2-line ferrihydrite to goethite from supersaturated solutions at alkaline pH ≥ 13.0 was studied using a combination of benchtop and advanced synchrotron techniques such as X-ray diffraction, thermogravimetric analysis, and X-ray absorption spectroscopy. In comparison to the transformation rates at acidic to mildly alkaline environments, the half-life, t 1/2 , of 2-line ferrihydrite reduces from several months at pH = 2.0, and approximately 15 days at pH = 10.0, to just under 5 h at pH = 14.0. The calculated-first order rate constants of transformation, k, increase exponentially with respect to the pH and follow the progression log 10 k = log 10 k 0 + a•pH 3 . Simultaneous monitoring of the aqueous Fe(III) concentration via inductively coupled plasma optical emission spectroscopy demonstrates that (i) goethite likely precipitates from solution and (ii) its formation is rate-limited by the comparatively slow redissolution of 2-line ferrihydrite. The analysis presented can be used to estimate the transformation rate of naturally occurring 2-line ferrihydrite in aqueous electrolytes characteristic to mine and radioactive waste tailings as well as the formation of corrosion products in cementitious pore solutions.

show abstract

Section: Introductionmentioning

confidence: 99%

Transformation of 2-Line Ferrihydrite to Goethite at Alkaline pH

Furcas,

Lothenbach,

Mundra

et al. 2023

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…13 The precipitation of molybdate minerals including powellite [CaMoO 4 ], ferrimolybdite [Fe 2 (MoO 4 ) 3 ], wulfenite [PbMoO 4 ], and nickel(II) molybdate [NiMoO 4 ] constitutes another mechanism of Mo removal in mine wastes. 10,12,13,[15][16][17]25 Under anoxic and sulfidic conditions, Mo attenuation can arise through molybdate conversion to (oxo)thiomolybdate (MoO x S 4−x 2− ), which precipitates from solution through complexation with Fe(II), S, and organic matter. 26 Metal stable isotope analyses provide a promising means to trace metal geochemical attenuation.…”

Section: Introductionmentioning

confidence: 99%

“…The World Health Organization (WHO) health-based maximum concentration is 70 μg L –1 (0.73 mM) for drinking water . Although natural waters rarely exceed the WHO criterion, dissolved Mo concentrations exceeding 13 000 μg L –1 (137 mM) have been reported in water influenced by mine wastes. , Effective environmental management at mine sites requires a detailed understanding of processes controlling element mobility, but relatively few studies have examined the fate of Mo in mine wastes. ,− …”

Section: Introductionmentioning

confidence: 99%

“…With increasing pH, molybdate sorption involves weaker outer-sphere complexation ,, which can lead to enhanced Mo mobility in circumneutral to alkaline-pH mine waters . The precipitation of molybdate minerals including powellite [CaMoO 4 ], ferrimolybdite [Fe 2 (MoO 4 ) 3 ], wulfenite [PbMoO 4 ], and nickel(II) molybdate [NiMoO 4 ] constitutes another mechanism of Mo removal in mine wastes. ,,,− , Under anoxic and sulfidic conditions, Mo attenuation can arise through molybdate conversion to (oxo)thiomolybdate (MoO x S 4– x 2– ), which precipitates from solution through complexation with Fe(II), S, and organic matter …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tracing Molybdenum Attenuation in Mining Environments Using Molybdenum Stable Isotopes

Skierszkan

Robertson

Lindsay

et al. 2019

Environ. Sci. Technol.

View full text Add to dashboard Cite

Molybdenum contamination is a concern in mining regions worldwide. Better understanding of processes controlling Mo mobility in mine wastes is critical for assessing potential impacts and developing water-quality management strategies associated with this element. Here, we used Mo stable isotope (δ98/95Mo) analyses to investigate geochemical controls on Mo mobility within a tailings management facility (TMF) featuring oxic and anoxic environments. These isotopic analyses were integrated with X-ray absorption spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and aqueous chemical data. Dissolved Mo concentrations were inversely correlated with δ98/95Mo values such that enrichment of heavy Mo isotopes in solution reflected attenuation processes. Inner-sphere complexation of Mo(VI) with ferrihydrite was the primary driver of Mo removal and was accompanied by a ca. 1‰ isotope fractionation. Limited Mo attenuation and isotope fractionation were observed in Fe(II)- and Mo-rich anoxic TMF seepage, while attenuation and isotope fractionation were greatest during discharge and oxidation of this seepage after discharge into a pond where Fe-(oxyhydr)oxide precipitation promoted Mo sorption. Overall, this study highlights the role of sorption onto Fe-(oxyhydr)oxides in attenuating Mo in oxic environments, a process which can be traced by Mo isotope analyses.

show abstract

“…The study highlights that U ore deposit bacterias have the great capacity to interact with U and these bacterias can be utilized for U contaminated sites and wastes through bioremediation. Bissonnette et al, (2016) considered a lab-scale plant in order to characterize secondary precipitates originating from number of ore blends. Different ratios of contributing phases were determined through precipiates total elemental analysis, Arsenic (As) and molybdenum (Mo) K-edge X-ray absorption spectroscopy that are determined for each pH stage in the process of neutralization.…”

Section: Decommission and Decontamination Of Nuclearmentioning

confidence: 99%

Radioactive Wastes

Choudri¹,

Charabi²,

Baawain³

et al. 2017

Water Environment Research

View full text Add to dashboard Cite

Papers reviewed herein present a general overview of radioactive waste related activities around the world in 2016. The current reveiw include studies related to safety assessments, decommission and decontamination of nuclear facilities, fusion facilities, transportation. Further, the review highlights on management solutions for the final disposal of low and high level radioactive wastes (LLW and HLW), interim storage and final disposal options for spent fuel (SF), and tritiated wastes, with a focus on environmental impacts due to the mobility of radionuclides in ecosystem, water and soil alongwith other progress made in the management of radioactive wastes.

show abstract

Sequestration of As and Mo in uranium mill precipitates (pH 1.5–9.2): An XAS study

Cited by 9 publications

References 58 publications

Transformation of 2-Line Ferrihydrite to Goethite at Alkaline pH

Transformation of 2-Line Ferrihydrite to Goethite at Alkaline pH

Tracing Molybdenum Attenuation in Mining Environments Using Molybdenum Stable Isotopes

Radioactive Wastes

Contact Info

Product

Resources

About