Ionic Competition Effects in a Continuous Uranium Biosorptive Recovery Process

Tsezos, M.; Georgousis, Zoe; Remoudaki, E.

doi:10.1002/(sici)1097-4660(199710)70:2<198::aid-jctb751>3.3.co;2-w

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“…It has been reported that some saprotrophic fungi were able to leach uranium from its ores (Hefnawy et al ., 2002). However, most fungal studies have focussed only on uranium biosorption and bioaccumulation by yeasts, filamentous fungi and lichens (Milodowski et al ., 1990; de Rome and Gadd, 1991; Nakajima and Sakaguchi, 1993; Bengtsson et al ., 1995; Guibal et al ., 1995; Tsezos et al ., 1997; Haas et al ., 1998; McLean et al ., 1998; Genc et al ., 2003).…”

Section: Introductionmentioning

confidence: 99%

Fungal transformations of uranium oxides

Fomina

Charnock

Hillier³

et al. 2007

Environmental Microbiology

107

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The biogeochemical activities of free-living and symbiotic fungi must be acknowledged in attempts to understand uranium cycling and dispersal in the environment. Although the near-surface geochemistry of uranium is very complex and a wide variety of mineral phases is known, uranium trioxide (UO3) and triuranium octaoxide (U(3)O(8)) can be used as well characterized models in the study of biotransformations. We have used a complex methodological approach involving advanced solid state speciation and scanning electron microscopy to study the ability of saprotrophic, ericoid and ectomycorrhizal fungi to transform these model oxides. This study has revealed that fungi exhibit a high uranium oxide tolerance, and possess the ability to solubilize UO3 and U(3)O(8) and to accumulate uranium within the mycelium to over 80 mg (g dry weight)(-1) biomass. X-ray absorption spectroscopy of uranium speciation within the biomass showed that in most of the fungi the uranyl ion was coordinated to phosphate ligands, but in ectomycorrhizal fungi mixed phosphate/carboxylate coordination was observed. Abundant uranium precipitates associated with phosphorus were found in the mycelium and encrusted the hyphae. Some of the fungi caused the biomineralization of well-crystallized uranyl phosphate minerals of the meta-autunite group. This is the first experimental evidence for fungal transformations of uranium solids and the production of secondary mycogenic uranium minerals.

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Section: Introductionmentioning

confidence: 99%

Fungal transformations of uranium oxides

Fomina

Charnock

Hillier³

et al. 2007

Environmental Microbiology

107

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“…Treatment of the bacteria with a buffer of pH 4 results in desorption. The uranium uptake using this substance is believed to be attributed to active groups or capillary action in the cell wall capturing the uranium.An immobilized biomass known as Rhizopus arrhizus has also been tested for its ability to adsorb uranium[29]. Tests were conducted using both synthetic and industrial wastes.…”

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confidence: 99%

Removal of uranium from aqueous wastes using electrically charged carbon nanofibers

Stover¹

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The presence of aqueous uranium wastes is a problem in the United States and their treatment/disposal is desirable. Treatment methods have been developed but result in concentration opposed to conversion to a disposable form. This technique involves recovery of uranium as a solid, providing an advantage over other methods. The technique utilizes carbon nanofibers as electrodes which successfully electrosorb uranium ions. Fibers with varying surface characteristics were evaluated in the removal process and all were determined to be equally and extremely effective. Various experimental parameters were evaluated including applied potential, pH, and flow rate. The critical applied potential at which significant removal is achieved is between-0.3 and-0.4 V. Decreasing pH hinders the electrosorption process while increasing it enhances the process. As expected, an increase in flow rates results in decreased removal. It was determined that cyclic loading/unloading increased fiber performance and a capacity of at least 5.45 g uranium /g carbon can be achieved. These results illustrate that this technique can be effectively implemented to solve current waste management problems.

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Ionic Competition Effects in a Continuous Uranium Biosorptive Recovery Process

Cited by 2 publications

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Fungal transformations of uranium oxides

Fungal transformations of uranium oxides

Removal of uranium from aqueous wastes using electrically charged carbon nanofibers

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