Recovery Of Radionuclides Research Articles

Synthesis and characterization of an analogue of heulandite: Sorption applications for thorium(IV), europium(III), samarium(II) and iron(III) recovery from aqueous waste

The synthesis of needle/fibrous particles of analogue of heulandite with particle diameter of 0.08 μm, length 4–8 μm and high specific surface area (478 m 2 g −1) with cation exchange capacity (3.27 mequiv g −1) have been achieved. The heulandite needles were obtained by using inorganic salts as a source for silicon and aluminum in the hydrothermal synthesis of the material. Alkalinity of the medium played an important role in the formation of heulandite fibers, as it affects the nucleation rate of zeolite synthesis. The analogue of heulandite was characterized using spectroscopic, thermal analysis, scanning and adsorption techniques. After mechanical grinding of crystals of heulandite, obtained powder was used for the study of radionuclide recovery from aqueous waste. The adsorption experiments were carried out under batch process with, pH of medium, amount of sorbent, time of contact between sorbate and sorbent, metal ion concentration and temperature as the variables. The adsorption was strongly dependent on pH of the medium and the uptake of all the metal ions increased from pH 1.0 to 9.0 and the maximum sorption was noticed in the pH range of 5.0–7.0. The optimum condition for these metal ions (Th(IV), Eu(III), Sm(II), and Fe(III)) sorption on self synthesized analogue of heulandite was; 0.001 N metal ion concentration, equilibration time of 4 h, 100 mg sorbent dose and 313–323 K temperature. This sorption process is fit to both Langmuir and Freundlich sorption isotherm. Thermodynamic studies predict the endothermic and spontaneous nature of the same.

Sorption recovery of radionuclides from alkaline solutions using fibrous “filled” sorbents

The possibility of using POLIORGS 33-n and 34-n fibrous “filled” sorbents with amidoxime groups for recovering U(VI), Am(III), and Pu(IV) from alkaline solutions of various compositions was studied. These sorbents exhibit high performance and excellent kinetic properties in recovery of uranium and transuranium elements from alkaline solutions. The distribution coefficients in their sorption from alkaline solutions at various (even high) values of pH and salt content were determined.

Time‐Dependent Distribution of Surface‐Applied Radionuclides and their Recovery in Maize during the Growing Season

The spatial and temporal heterogeneity of field soils influences the fate and behavior of strongly sorbing pollutants and their entry into the food chain. We studied the redistribution of surface-applied 54Mn, 65Zn, 57Co, and 134Cs in the soil profile and their recovery in the aerial parts of maize grown on an untilled agricultural soil during the growing season. Radionuclides were more concentrated in the preferential flow paths (PFP) than in the soil matrix and their concentration decreased with time. The recovery of 54Mn in the aerial plant parts increased between pollen shed and maturity, while the recovery of 65Zn and 57Co did not show any significant difference, and the recovery of 134Cs decreased with time. The amount and distribution of rainfall, and the chemical, physical, and microbiological soil characteristics are the major factors influencing the variation of radionuclide recovery with time.

Determination of 90Sr, 238Pu, 239,240Pu, 241Pu, and 241Am in soils of chernobyl region using various sample preparation techniques

Radiochemical analysis is made of soddy-podzolic sandy and peaty gley soils collected from the Chernobyl zone. Radionuclides were separated by extraction chromatography or ion exchange, and then determined using an α-ray spectrometer and liquid scintillation and proportional gas counters. Leaching from the preliminarily calcined sample with 8 M HNO3 does not ensure 100% recovery of radionuclides from peaty gley soil.

Total dissolution of environmental and biological samples by closed-vessel microwave digestion for radiometric analysis

Dry soil, fish-fillet ash, and grass ash were dissolved with a closed-vesselmicrowave oven system and mineral acids. Reagents and dissolution conditionswere varied to ensure total dissolution and recovery of radionuclides. Solventsto dissolve 99.9% of the mass of 3 g samples satisfactorily were 45 ml 14NHF followed by 60 ml 4N HNO3 saturated with H3BO3 for soil, 60 ml 9N HNO3 followed by 60 ml 14N HF for grass,and 60 ml 9N HNO3 for fish. The reliability of the dissolutionwas tested with samples from the DOE Quality Assurance Program.

Continuous radionuclide recovery from wastewater using magnetotactic bacteria

Magnetotactic bacteria (MTB) can be magnetically removed and harvested from samples collected from ponds and streams. This is achieved by placing a permanent magnet at the sediment/water interface of a sample container. The bacteria swim along field lines, accumulating at regions close to the pole of the magnet. This is the basic principle of Orientation Magnetic Separation (OMS), where the applied magnetic field is utilised to orientate the bacteria to swim in a specific direction. This paper describes the use of MTB for bioaccumulation and radionucleide removal from wastewater using an OMS system.

Use of pelleted and immobilized yeast and fungal biomass for heavy metal and radionuclide recovery

The biosorption of uranium, strontium and caesium by pelleted mycelium of two species of fungi,Rhizopus arrhizus andPenicillium chrysogenum and immobilizedSaccharomyces cerevisiae was evaluated in both batch and continuous flow systems where the presence of competing cations affected accumulation. The uptake mechanism for the pelleted fungal biomass differed from that of the immobilized yeast, the former being metabolism-independent biosorption of the metals while, in the presence of glucose, uptake in the latter organism was biphasic, surface biosorption being followed by energy-dependent influx. Removal of surface-bound metals was achieved by eluting with mineral acids or carbonate/bicarbonate solutions; a high degree of metal recovery was observed for uranium.

Intestinal permeability in gastrointestinal disorders

This study examined intestinal permeability in gastrointestinal disorders by measuring urinary recovery following oral administration of [99mTc]DTPA in 117 subjects. The mean percent of the ingested dose excreted in a 24-hr urine sample was 2.8 +/- 1.6% in 11 healthy controls, 10.8 +/- 10.2% (P less than 0.001) in 21 ulcerative colitis patients, 8.0 +/- 4.7% (P less than 0.001) in 35 Crohn's disease patients, 5.1 +/- 2.9% (P less than 0.01) in 17 patients with heterogeneous digestive disease diagnoses, and 3.2 +/- 4.7% (P greater than 0.05) in 33 patients with hepatobiliary diagnoses. Among ambulatory patients, Crohn's disease subjects, but not ulcerative colitis patients, had greater urinary recovery than the controls (P less than 0.05). The Crohn's disease activity index correlated positively with the radionuclide recovery in Crohn's subjects (r = 0.455, P less than 0.02). In a heterogeneous sample of subjects simultaneous ingestion of [99mTc]DTPA and [51Cr]EDTA produced urinary levels that were correlated positively (r = 0.556, P less than 0.001). Increased absorption of [99mTc]DTPA relative to [51Cr]EDTA, however, was noted in ulcerative colitis patients (P less than 0.05). In conclusion, increased intestinal permeability has been demonstrated by utilizing [99mTc]DTPA in Crohn's disease and ulcerative colitis patients. Although this observation appears to be a nonspecific indicator of injury, the test provides a simple objective means of establishing disease activity, which possibly may be utilized for therapeutic and investigative studies.

Quantitative determination of radionuclides deposited on surfaces of contaminated environmental materials

A standardised technique for transferring radionuclides deposited on non-porous solid materials, into a liquid system by means of a two step process, involving the use of suspensions obtained by mixing attapulgus clay with nitric acid solutions, is described. Possible applications of the methodology are the recovery of radionuclides of particular interest, dispersed or deposited on nonporous surfaces and the quantitative determination of radionuclides present on the same kind of surface.

Selection and evaluation of ion-exchange processes for the recovery of radionuclides from coolant water : Gy. Várterész, “F.J.C.” National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary:

Selection and evaluation of ion-exchange processes for the recovery of radionuclides from coolant water : Gy. Várterész, “F.J.C.” National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary: