Interactions Between Np-Doped Synroc and Boom Clay

1994 ◽  
Vol 353 ◽  
Author(s):  
K. P. Hart ◽  
B. J. Robinson ◽  
T. E. Payne ◽  
P. Van Iseghem ◽  
K. Lemmens
Keyword(s):  
Anaerobic Conditions ◽  
Boom Clay ◽  
Reducing Conditions ◽  
Mobile Fraction ◽  
Leaching Experiments

AbstractLeaching experiments with deionised water at 70°C have been carried out to ascertain the effect of oxidising and anaerobic conditions and the presence of Boom clay on Np release from Synroc.The normalised solution leach rates of Np measured in these experiments are about a factor of 10 lower under reducing conditions than oxidising conditions and the presence of Boom clay was found not to enhance the leaching of Np from Synroc. Neptunium was found to be predominantly in the mobile fraction and was not removed from the leaching solutions significantly by filtration or ultrafiltration.

scholarly journals Profiling of human burned bones: oxidising versus reducing conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. P. M. Marques ◽  
D. Gonçalves ◽  
A. P. Mamede ◽  
T. Coutinho ◽  
E. Cunha ◽  
...  
Keyword(s):  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Skeletal Remains ◽  
Anaerobic Conditions ◽  
Human Skeletal Remains ◽  
Human Bones ◽  
Reducing Conditions ◽  
Wide Range ◽  
Burned Bones ◽  
Vibrational Bands

AbstractComplementary optical and neutron-based vibrational spectroscopy techniques (Infrared, Raman and inelastic neutron scattering) were applied to the study of human bones (femur and humerus) burned simultaneously under either aerobic or anaerobic conditions, in a wide range of temperatures (400 to 1000 °C). This is the first INS study of human skeletal remains heated in an oxygen-deprived atmosphere. Clear differences were observed between both types of samples, namely the absence of hydroxyapatite’s OH vibrational bands in bone burned anaerobically (in unsealed containers), coupled to the presence of cyanamide (NCNH2) and portlandite (Ca(OH)2) in these reductive conditions. These results are expected to allow a better understanding of the heat effect on bone´s constituents in distinct environmental settings, thus contributing for an accurate characterisation of both forensic and archaeological human skeletal remains found in distinct scenarios regarding oxygen availability.

Comparison of the Dissolution Behaviour of Various UO2Samples in Saline Solution at 100°C Under Reducing Conditions

1993 ◽  
Vol 333 ◽  
Author(s):  
S. Stroes-Gascoyne ◽  
J.C. Tait ◽  
R.J. Porth ◽  
J.L. McConnell ◽  
A.M. Duclos
Keyword(s):  
Saline Solution ◽  
Radiation Characteristic ◽  
Combined Effects ◽  
Used Nuclear Fuel ◽  
Reducing Conditions ◽  
Dissolution Behaviour ◽  
Gamma Radiolysis ◽  
Leaching Experiments ◽  
Leaching Behaviour ◽  
High Burnup

ABSTRACTThe separate effects of alpha- and gamma-radiolysis on UO2dissolution can be studied with unirradiated UO2, whereas studies vith used nuclear fuel necessarily always include both alpha- and gamma-radiolysis effects. This paper attempts to separate these effects by comparing the leaching behaviour in saline solution of a number of UO2samples (each vith a particular radiation characteristic or chemical property inherent to used fuel) vith the leaching behaviour of used fuel. Data from leaching experiments vith lov- and high-burnup CANDU (CANada Deuterium Uranium) fuels are also compared. The results indicate that the presence of an alpha field at 100°C under reducing conditions does not increase UO2dissolution but suggest that the combined effects of the beta and gamma fields in used CANDU fuel may enhance UO2dissolution.

Dissolution of uranium dioxide in simulated Boom clay water

2002 ◽  
Vol 90 (2) ◽  
Author(s):  
S. Guilbert ◽  
M.J. Guittet ◽  
N. Barré ◽  
P. Trocellier ◽  
M. Gautier-Soyer ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Uranium Dioxide ◽  
Uranium Concentration ◽  
Boom Clay ◽  
Solubility Behavior ◽  
Fuel Pellets ◽  
Reducing Conditions ◽  
Comparable Period

SummaryThe solubility behavior of uranium dioxide was studied under oxidizing and reducing conditions in simulated Belgian Boom clay water at 25 °C, on unirradiated fuel pellets. For a comparable period (1 month), the uranium concentration and the dissolution rate (10

scholarly journals Biodegradability of Trimethylbenzene Isomers under Denitrifying and Sulfate-Reducing Conditions

2019 ◽  
Vol 16 (4) ◽  
pp. 615 ◽  
Author(s):  
Thomas Fichtner ◽  
Axel Fischer ◽  
Christina Dornack
Keyword(s):  
Residence Time ◽  
Strong Dependence ◽  
Experimental Period ◽  
Anaerobic Conditions ◽  
Biodegradation Rate ◽  
First Order ◽  
Sulfate Reducing ◽  
Reducing Conditions ◽  
Benzene Toluene ◽  
Laboratory Investigations

Trimethylbenzene (TMB) isomers (1,2,3-TMB, 1,2,4-TMB, and 1,3,5-TMB) are often used as conservative tracers in anaerobic, contaminated aquifers for assessing BTEX (benzene, toluene, ethylbenzene, xylenes) biodegradation at field sites. However, uncertainties exist about the behavior of these compounds under anaerobic conditions. For this reason, the influence of various parameters (temperature, residence time) on the biodegradability of TMB isomers was investigated under denitrifying and sulfate-reducing conditions in microcosms and 1D-column experiments. Soil and groundwater contaminated with a cocktail of aromatic hydrocarbons including the TMB isomers, both collected from an industrial site in Berlin, Germany, were used for the laboratory investigations. A continuous and complete biodegradation of 1,3,5-TMB and 1,2,4-TMB under denitrifying conditions was observed independent of realized temperature (10–20 °C) and residence time. Biodegradation of 1,2,3-TMB started after longer lag-phases and was not continuous over the whole experimental period; a strong dependence on temperature and residence time was identified. The biodegradability of all TMB isomers under sulfate-reducing conditions was continuous and complete at higher temperatures (20 °C), whereas no degradation was observed for lower temperatures (10 °C). First-order biodegradation rate constants ranged from 0.05 to 0.21 d−1 for 1,3,5-TMB and 1,2,4-TMB and from 0.01 to 0.11 d−1 for 1,2,3-TMB.

Influence of bacteria on rock-water interaction and clay mineral formation in subsurface granitic environments

Clay Minerals ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 599-613 ◽  
Author(s):  
K. Hama ◽  
K. Bateman ◽  
P. Coombs ◽  
V. L. Hards ◽  
A. E. Milodowski ◽  
...  
Keyword(s):  
Hard Rock ◽  
Microbial Interactions ◽  
Anaerobic Conditions ◽  
Crushed Material ◽  
Fine Grained ◽  
Rock Laboratory ◽  
Stirred Reactor ◽  
Reducing Conditions ◽  
Rock Water Interaction ◽  
Reducing Bacteria

AbstractStudies of the subsurface microbiology of the Äspö Hard Rock Laboratory, Sweden have revealed the presence of many different bacteria in the deep groundwaters which appear to maintain reducing conditions. Experiments were conducted to study the rock-water and microbial interactions. These used crushed Äspö diorite, Äspö groundwater and iron- and sulphate-reducing bacteria in flowing systems under anaerobic conditions. In column experiments, there was evidence of loss and mobilization of fine-grained crushed material (<5 μm) which had originally adhered to grain surfaces in the starting material. The mobilized fines were trapped between grains. The degree of mineralogical alteration was greater in the experiments when bacteria were present. In both column and continuously stirred reactor experiments, there is evidence for the formation of a secondary clay. These experiments have shown that microbial activity can influence rock-water interactions even in nutrient-poor conditions.

Biotransformation potential of phytosterols under anoxic and anaerobic conditions

2014 ◽  
Vol 69 (8) ◽  
pp. 1661-1668 ◽  
Author(s):  
C. M. Dykstra ◽  
H. D. Giles ◽  
S. Banerjee ◽  
S. G. Pavlostathis
Keyword(s):  
Free Energy ◽  
Retention Time ◽  
Biological Treatment ◽  
Pulp And Paper ◽  
Standard Gibbs Free Energy ◽  
Group Contribution Method ◽  
Anaerobic Conditions ◽  
Waste Streams ◽  
Sulfate Reducing ◽  
Reducing Conditions

The biotransformation potential of three phytosterols (campesterol, stigmasterol and β-sitosterol) under denitrifying, sulfate-reducing and fermentative/methanogenic conditions was assessed. Using a group contribution method, the standard Gibbs free energy of phytosterols was calculated and used to perform theoretical energetic calculations. The oxidation of phytosterols under aerobic, nitrate-reducing, sulfate-reducing and methanogenic conditions was determined to be energetically feasible. However, using semi-continuously fed cultures maintained at 20–22 °C over 16 weekly feeding cycles (112 days; retention time, 21 days), phytosterol removal was observed under nitrate-reducing and sulfate-reducing conditions, but not under fermentative/methanogenic conditions. Under sulfate-reducing conditions, stigmast-4-en-3-one was identified as an intermediate of phytosterol biotransformation, a reaction more likely carried out by dehydrogenases/isomerases, previously reported to act on cholesterol under both oxic and anoxic (denitrifying) conditions. Further study of the biotransformation of phytosterols under anoxic/anaerobic conditions is necessary to delineate the factors and conditions leading to enhanced phytosterol biodegradation and the development of effective biological treatment systems for the removal of phytosterols from pulp and paper wastewaters and other phytosterol-bearing waste streams.

Uranium release from boom clay in bicarbonate media

2002 ◽  
Vol 90 (9-11) ◽  
Author(s):  
L. Wang ◽  
A. Dierckx ◽  
P. De Cannière ◽  
A. Maes
Keyword(s):  
Natural Uranium ◽  
Bicarbonate Concentration ◽  
Boom Clay ◽  
Dissolved Species ◽  
Leaching Experiments ◽  
Solid Liquid ◽  
Carbonate Complexes

SummaryThe release of natural uranium from Boom Clay was studied to better understand the mechanisms governing the solid-liquid partitioning of uranium. Batch leaching experiments suggested that the portion of natural uranium released from clay is associated with colloids at a low bicarbonate concentration prevailing in Boom Clay. At increased bicarbonate concentrations, uranium was present predominantly as dissolved species indicating a formation of uranium carbonate complexes. The

Static Dissolution of Uo2 in Interstitial Boom Clay Water

1999 ◽  
Vol 556 ◽  
Author(s):  
K. Lemmens ◽  
C. Cachoir ◽  
P. Van Iseghem
Keyword(s):  
Uranium Concentration ◽  
Solid Phase ◽  
Experimental Conditions ◽  
Boom Clay ◽  
Carbonate Concentration ◽  
Reducing Conditions ◽  
Ph Conditions ◽  
The Impact ◽  
Uranium Species ◽  
Sulfide Species

AbstractStatic dissolution experiments were performed with unirradiatcd UO2 in Boom Clay water. The objectives were (1) to measure the solubility of uranium species in Boom Clay water, with UO2 as the solid phase, and (2) to assess the impact of dissolved organic matter and carbonate concentration on this solubility. The tests were supported by calculations with geochemical codes to indicate possibly solubility controlling solid phases. The tests were performed in anoxic and reducing conditions, at 20 and 25°C. The following conclusions could be drawn: (1) Within 2 months in anoxic conditions, the uranium concentrations appear to approach saturation. (2) The “near-saturation” concentrations are between 2.4 and 7.8× 10−7 M. (3) The influence of the carbonate concentration and humic acids on the uranium concentration was apparently small, but the interpretation is hampered by pH and Eh variations. (4) The concentrations tend to be higher than the concentrations found in literature for similar Eh and/or pH conditions; this can probably be explained by small differences in experimental conditions. (5) The measured “near steadystate” uranium concentration in the real clay water agrees relatively well with the solubility calculated for uraninite. (6) Addition of sulfide species reduced the rcdox potential, but not the uranium concentrations, except in real Boom Clay water.

Biohydrometallurgy as a Remediation Strategy for Marine Sediments Contaminated by Heavy Metals

2009 ◽  
Vol 71-73 ◽  
pp. 669-672 ◽  
Author(s):  
F. Beolchini ◽  
A. Dell’Anno ◽  
L. Rocchetti ◽  
Francesco Vegliò ◽  
R. Danovaro
Keyword(s):  
Heavy Metals ◽  
Treatment Time ◽  
Sulfate Reducing Bacteria ◽  
Sulfate Reducing ◽  
First Case ◽  
Remediation Strategies ◽  
Mobile Fraction ◽  
Microbial Strains ◽  
Leaching Experiments ◽  
Reducing Bacteria

This paper deals with biohydrometallurgy applied for the remediation of sediments contaminated by heavy metals. Both metal mobilization by bioleaching and metal stabilization by sulfate reducing bacteria stimulation have been investigated. In the first case, leaching experiments were performed with different microbial strains: i) autotrophic Fe/S-oxidizing bacteria, ii) heterotrophic Fe reducing bacteria, and iii) a mix of them. The highest extraction yields were 90% for Cu, Cd, Hg and Zn and were achieved with a consortium of the autotrophic and the heterotrophic strains. In the second case, anaerobic microcosm experiments were performed according to a full factorial experiment where the main factors were: i) acetate, ii) inoculum of alloctonous sulfate-reducing bacteria and iii) treatment time. Significant changes on metal partitioning were observed in all the investigated treatments: in particular, Cu, Pb and Zn concentrations in the mobile fraction were reduced and the ones in the oxidizable fraction significantly increased. Anaerobic processes where hypothesized to lead to the formation of metal sulfides, relatively stable and less bioavailable than mobile fractions. The obtained results open new perspectives for biohydrometallurgy applied in the context of remediation strategies for sediments contaminated by heavy metals.

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