Uranium(VI) sorption onto kaolinite in the presence and absence of humic acid

Křepelová, Adéla; Sachs, Susanne; Bernhard, Gert

doi:10.1524/ract.2006.94.12.825

Cited by 105 publications

(106 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The decreased U adsorption at pH > ~7.5 is due to competition between dissolved HA, carbonate, and U-carbonate complexes for adsorption onto surface sites, where observed HA adsorption remains high at pH up to 9.5, particularly for SRS sediment and goethite ( Figure S-1). Kaolinite features point of zero charge (PZC) at around pH 5 (18,22).…”

Section: Resultsmentioning

confidence: 99%

Method to Attenuate U(VI) Mobility in Acidic Waste Plumes Using Humic Acids

Wan

Dong

Tokunaga

2011

Environ. Sci. Technol.

View full text Add to dashboard Cite

Abstract. Acidic uranium (U) contaminated plumes have resulted from acid-extraction of plutonium during the Cold War and from U mining and milling operations. A sustainable method for in-situ immobilization of U under acidic conditions is not yet available. Here, we propose to use humic acids (HAs) for in-situ U immobilization in acidic waste plumes. Our laboratory batch experiments show that HA can adsorb onto aquifer sediments rapidly, strongly and practically irreversibly. Adding HA greatly enhanced U adsorption capacity to sediments at pH below 5.0. Our column experiments using historically contaminated sediments from the Savannah River Site under slow flow rates (120 and 12 m/y) show that desorption of U and HA were non-detectable over 100 pore-volumes of leaching with simulated acidic groundwaters.Upon HA-treatment, 99% of the contaminant [U] was immobilized at pH < 4.5, compared to 5% and 58% immobilized in the control columns at pH 3.5 and 4.5, respectively. These results demonstrated that HA-treatment is a promising in-situ remediation method for acidic U waste plumes. As a remediation reagent, HAs are resistant to biodegradation, cost effective, nontoxic, and easily introducible to the subsurface.2

show abstract

Section: Resultsmentioning

confidence: 99%

Method to Attenuate U(VI) Mobility in Acidic Waste Plumes Using Humic Acids

Wan

Dong

Tokunaga

2011

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…Generally, U has a strong binding affinity for NOM, both soluble and insoluble fractions. Soluble HA can complex U(VI), increasing its solubility and reducing its ability to adsorb onto Fe oxides and clays at circumneutral pH (Křepelová et al, 2006). Natural organic matter can also affect the rate and extent of U sorption onto silica sand (Tinnacher et al, 2013).…”

Section: Effect Of Natural Organic Matter On Redox Processesmentioning

confidence: 99%

“…Complexation of U(VI) with HA is strongest between pH 4.5 and 7 in the presence of dissolved inorganic carbon (pCO 2 at least 10 À3.5 atm). At low and high pH (<3 or >8.5), HA can increase adsorption to mineral surfaces, possibly due to low solubility of HA at low pH and the presence of U(VI)-carbonate-HA ternary surface complexes at high pH (Lenhart and Honeyman, 1999;Křepelová et al, 2006;Payne et al, 1996). The presence of HA can affect U(IV) as well by increasing the solubility via the formation of aqueous U(IV)-HA species; increased rate of oxidation has been observed due to this complexation (Gu et al, 2005).…”

Section: Effect Of Natural Organic Matter On Redox Processesmentioning

confidence: 99%

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Campbell¹,

Gallegos²,

Landa

2015

Applied Geochemistry

View full text Add to dashboard Cite

aspects of uranium mineralization, mining, milling, and remediation" (2014 U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling of U-bearing ores is the first step in the nuclear fuel cycle, and the contact of residual waste with natural water is a potential source of contamination of U and associated elements to the environment. Uranium is mined by three basic methods: surface (open pit), underground, and solution mining (in situ leaching or in situ recovery), depending on the deposit grade, size, location, geology and economic considerations (Abdelouas, 2006). Solid wastes at U mill tailings (UMT) sites can include both standard tailings (i.e., leached ore rock residues) and solids generated on site by waste treatment processes. The latter can include sludge or ''mud'' from neutralization of acidic mine/mill effluents, containing Fe and a range of coprecipitated constituents, or barium sulfate precipitates that selectively remove Ra (e.g., Carvalho et al., 2007). In this chapter, we review the hydrometallurgical processes by which U is extracted from ore, the biogeochemical processes that can affect the fate and transport of U and associated elements in the environment, and possible remediation strategies for site closure and aquifer restoration. This paper represents the fourth in a series of review papers from the U.S. Geological Survey (USGS) on geochemical aspects of UMT management that span more than three decades. The first paper (Landa, 1980) in this series is a primer on the nature of tailings and radionuclide mobilization from them. The second paper (Landa, 1999) includes coverage of research carried out under the U.S. Department of Energy's Uranium Mill Tailings Remedial Action Program (UMTRA). The third paper (Landa, 2004) reflects the increased focus of researchers on biotic effects in UMT environs. This paper expands the focus to U mining, milling, and remedial actions, and includes extensive coverage of the increasingly important alkaline in situ recovery and groundwater restoration.Ó 2014 Published by Elsevier Ltd.

show abstract

“…Complete sorption of U onto clay and other surfaces typically occurs within a period of a few days [19]. Krepelova et al (2006) found that U(VI) adsorption to clay (kaolinite) under acidic conditions increases if humic acids are present due to the formation of additional binding sites for U coming from the adsorption of humic acids to kaolinite [20]. Feng et al (2005) showed in batch experiments that peat humic acid is sorbed to different clay minerals (kaolinite and montmorillonite) via cation bridging, ligand exchange and van der Waals forces.…”

Section: +mentioning

confidence: 99%

Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part II: Examples from Literature and a Conceptual Filter Model

Winde

2011

Water

View full text Add to dashboard Cite

Abstract:As the second part of a series of four, this paper reviews a number of case studies of natural uranium attenuation in peat, as well as underlying chemical mechanisms reported in literature. Based on this review, a generic, conceptual, model for peat to act as filter for dissolved uranium (U) is developed for guiding subsequent field investigations. The model consists of a chemical and an hydraulic component which is derived largely from data reported in literature as well as from limited field observations. For the chemical model component 10 different processes, each controlled by factors relating to water chemistry, have been identified to govern the attenuation of U in peat via a net balance of immobilization and remobilization. For the hydraulic aspect of the filter model, five different principal modes of U polluted water coming in contact with peat are discussed, focusing on the associated peat-water contact time as a crucial parameter controlling chemical U attenuation. Moreover, links between the two model components are discussed and, based on the integrated conceptual model, possible effects of natural and anthropogenic events on U attenuation in peatlands are outlined. Guided by the model, various site-specific field and laboratory investigations are finally designed to verify how far the identified generic factors and processes are indeed applicable to the Gerhard Minnebron Peatland.

show abstract

Uranium(VI) sorption onto kaolinite in the presence and absence of humic acid

Abstract: We studied the U(VI) sorption onto kaolinite in batch experiments in the absence and presence of humic acid (HA) under different experimental conditions: [U]

Cited by 105 publications

References 43 publications

Method to Attenuate U(VI) Mobility in Acidic Waste Plumes Using Humic Acids

Method to Attenuate U(VI) Mobility in Acidic Waste Plumes Using Humic Acids

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part II: Examples from Literature and a Conceptual Filter Model

Contact Info

Product

Resources

About