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1.
Inorg Chem ; 57(23): 14872-14881, 2018 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-30427192

RESUMO

In this work, the morphology, composition, crystal, and electronic structure of Ca8Mg(SiO4)4Cl2 (CMSOC) prepared by a high-temperature solid-state reaction technique are characterized first. To investigate the site occupancies of Eu3+ and Ce3+ in CMSOC, the emission spectra under well-chosen wavelength excitations and the corresponding excitation spectra by monitoring of the specific wavelength emissions are measured in detail for singly doped samples with different concentrations. Two kinds of Eu3+ or Ce3+ luminescence spectra are found. On the basis of the chemical environments of two Ca2+ sites and dielectric chemical bond theory, the sites of these two kinds of Eu3+ and Ce3+ luminescence spectra are respectively assigned. Because energy transfer between the two types of luminescent centers, concentration-dependent emission-wavelength shifting, and luminescence concentration quenching are negligible, the emission spectra of Eu3+ and Ce3+ give us a hint of their occupation preferences on two Ca2+ sites. The results indicate that, with an increase of the doping concentration, the Eu3+ ions with smaller cationic size show an occupation preference on the smaller Ca2+(1) sites, but the Ce3+ ions with larger cationic size are inclined to enter the larger Ca2+(2) sites. These opposite occupation preferences of Eu3+ and Ce3+ in CMSOC are thought to be the cationic-size-driven site selection.


Assuntos
Cério/análise , Európio/análise , Luminescência , Substâncias Luminescentes/química , Cálcio/química , Cloretos/química , Transferência de Energia , Íons/análise , Substâncias Luminescentes/síntese química , Medições Luminescentes , Magnésio/química , Tamanho da Partícula , Silicatos/química , Propriedades de Superfície
2.
J Environ Radioact ; 193-194: 75-81, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30218792

RESUMO

Radionuclides-resistant filamentous fungi were isolated from radionuclides' contaminated soils. Effects of contact time, mycelia dosage, pH, ionic strength and thiol compounds on 152+154Eu(III) accumulation on two kinds of filamentous fungi (Aspergillus sydowii and Trichoderma harzianum, denoted as A. sydowii and T. harzianum, respectively) were investigated by batch techniques. The maximum tolerance to Eu(III) concentration of A. sydowii and T. harzianum reached 3000 mg/L and 3500 mg/L, and the Eu(III) accumulation on A. sydowii and T. harzianum can be fitted better with the pseudo-second-order kinetic model, respectively. Filamentous fungi were characterized by FT-IR and acid base titrations, and morphological structures of mycelia changed obviously under Eu(III) stress by SEM and TEM analysis. The results suggested that filamentous fungi could play an important role in the migration and transformation of radionuclides in the environment.


Assuntos
Aspergillus/metabolismo , Európio/análise , Poluentes Radioativos do Solo/metabolismo , Trichoderma/metabolismo , Aspergillus/química , Poluentes Radioativos do Solo/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Trichoderma/química
3.
Environ Pollut ; 236: 835-843, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29462778

RESUMO

The coagulation behaviors of humic acid (HA) with Cs+ (10-500 mM), Sr2+ (0.8-10.0 mM) and Eu3+ (0.01-1.0 mM) at different pH values (2.8, 7.1 and 10.0) were acquired through a dynamic light scattering (DLS) technique combined with spectroscopic analysis and molecular dynamic (MD) simulations. The coagulation rate and the average hydrodynamic diameter () increased significantly as the concentration of nuclides increased. could be scaled to time t as ∝ ta at higher Sr2+ concentrations, which shows that HA coagulation is consistent with the diffusion-limited colloid aggregation (DLCA) model. Trivalent Eu3+ induced HA coagulation at a much lower concentration than bivalent Sr2+ and monovalent Cs+. The coagulation value ratio of Sr2+ and Eu3+ to Cs+ is almost proportional to Z-6, indicating that the HA coagulation process is generally consistent with the Schulze-Hardy rule. Spectroscopic analysis indicated that the complexation between nuclides and carboxylic/phenolic groups of HA molecules played important roles in the coagulation of HA. MD modelling suggested that Sr2+ and Eu3+ ions increased the coagulation process through the formation of intra- or inter-molecular bridges between negatively charged HA molecules, whereas for Cs+, no inter-molecular bridges were formed. This work offers new insight into the interactions between HA and radionuclides and provides a prediction for the roles of HA in the transportation and elimination of radionuclides in severely polluted environments.


Assuntos
Césio/análise , Európio/análise , Modelos Químicos , Estrôncio/análise , Coloides , Substâncias Húmicas/análise , Concentração de Íons de Hidrogênio , Íons , Fenóis
4.
J Nanobiotechnology ; 15(1): 71, 2017 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-29017510

RESUMO

BACKGROUND: Intrinsic iron in biological tissues frequently precludes unambiguous the identification of iron oxide nanoparticles when iron-based detection methods are used. Here we report the full methodology for synthesizing very small iron oxide nanoparticles (VSOP) doped with europium (Eu) in their iron oxide core (Eu-VSOP) and their unambiguous qualitative and quantitative detection by fluorescence. METHODS AND RESULTS: The resulting Eu-VSOP contained 0.7 to 2.7% Eu relative to iron, which was sufficient for fluorescent detection while not altering other important particle parameters such as size, surface charge, or relaxivity. A customized enhancer solution with high buffer capacity and nearly neutral pH was developed to provide an antenna system that allowed fluorescent detection of Eu-VSOP in cells and histologic tissue slices as well as in solutions even under acidic conditions as frequently obtained from dissolved organic material. This enhancer solution allowed detection of Eu-VSOP using a standard fluorescence spectrophotometer and a fluorescence microscope equipped with a custom filter set with an excitation wavelength (λex) of 338 nm and an emission wavelength (λem) of 616 nm. CONCLUSION: The fluorescent detection of Eu-doped very small iron oxide nanoparticles (Eu-VSOP) provides a straightforward tool to unambiguously characterize VSOP biodistribution and toxicology at tissue, and cellular levels, providing a sensitive analytical tool to detect Eu-doped IONP in dissolved organ tissue and biological fluids with fluorescence instruments.


Assuntos
Európio/análise , Compostos Férricos/análise , Nanopartículas/análise , Animais , Európio/farmacocinética , Compostos Férricos/síntese química , Compostos Férricos/farmacocinética , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência/métodos , Nanopartículas/ultraestrutura , Nanotecnologia/métodos , Células RAW 264.7 , Distribuição Tecidual
5.
Luminescence ; 32(8): 1456-1465, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28612390

RESUMO

Potassium fluoro-phosphate (KFP) glass singly doped with different concentrations of europium (Eu3+ ) or samarium (Sm3+ ) or co-doped (Sm3+ /Eu3+ ) was prepared, and their luminescence spectra were investigated. The phase composition of the product was verified by X-ray diffraction analysis. Optical transition properties of Eu3+ in the studied potassium phosphate glass were evaluated in the framework of the Judd-Ofelt theory. The radiative transition rates (AR ), fluorescence branching ratios (ß), stimulated emission cross-sections (σe ) and lifetimes (τexp ) for certain transitions or levels were evaluated. Red emission of Eu3+ was exhibited mainly by the 5 D0 →7 F2 transition located at 612 nm. Concentration quenching and energy transfer were observed from fluorescence spectra and decay curves, respectively. It was found that the lifetimes of the 5 D0 level increased with increase in concentration and then decreased. By co-doping with Sm3+ , energy transfer from Sm3+ to Eu3+ occurred and contributed to the enhancement in emission intensity. Intense orange-red light emission was obtained upon sensitizing with Sm3+ in KFP glass. This approach shows significant promise for use in reddish-orange lighting applications. The optimized properties of the Sm3+ /Eu3+ co-doped potassium phosphate glass might be promising for optical materials.


Assuntos
Európio/análise , Flúor/química , Fosfatos/química , Potássio/química , Samário/análise , Vidro/química , Espectroscopia de Ressonância Magnética , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Chem Commun (Camb) ; 53(52): 7084-7087, 2017 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-28627559

RESUMO

We report a direct imaging tool, HGEu001, for primary cilia in living cells, which is specific, and based on the UV light or near infrared laser (via two-photon excitation) induced long-lived europium luminescence.


Assuntos
Cílios , Európio/análise , Európio/química , Luminescência , Imagem Óptica , Compostos Organometálicos/análise , Compostos Organometálicos/química , Animais , Linhagem Celular , Humanos , Lasers , Camundongos , Compostos Organometálicos/síntese química , Raios Ultravioleta
7.
Talanta ; 167: 532-536, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28340756

RESUMO

The determination of iodine as a main fission product (especially the isotopes I-129 and I-131) of stored HLW in a disposal beside its distribution as a natural ingredient of many different products like milk, food and seawater is a matter of particular interest. The simultaneous ICP-MS determination of iodine as iodide together with other elements (especially higher valent metal ions) relevant for HLW is analytically very problematic. A reliable ICP-MS quantification of iodide must be performed at neutral or alkaline conditions in contrast to the analysis of metal ions which are determined in acidic pH ranges. Herein, we present a method to solve this problem by changing the iodine speciation resulting in an ICP-MS determination of iodide as iodate. The oxidation from iodide to iodate with sodium hypochlorite at room temperature is a fast and convenient method with flexible reaction time, from one hour up to three days, thus eliminating the disadvantages of quantifying iodine species via ICP-MS. In the analysed concentration range of iodine (0.1-100µgL-1) we obtain likely quantitative recovery rates for iodine between 91% and 102% as well as relatively low RSD values (0.3-4.0%). As an additional result, it is possible to measure different other element species in parallel together with the generated iodate, even high valent metals (europium and uranium beside caesium) at recovery rates in the same order of magnitude (93-104%). In addition, the oxidation process operates above pH 7 thus offering a wide pH range for sample preparation. Even analytes in complex matrices, like 5M saline (NaCl) solution or artificial cement pore water (ACW) can be quantified with this robust sample preparation method.


Assuntos
Ácidos/química , Césio/análise , Európio/análise , Iodo/análise , Espectrometria de Massas/métodos , Urânio/análise , Água/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Água/química
8.
Luminescence ; 32(5): 800-805, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28124455

RESUMO

In spectral analysis, a chemical component is usually identified by its characteristic spectra, especially the peaks. If two components have overlapping spectral peaks, they are generally considered to be indiscriminate in current analytical chemistry textbooks and related literature. However, if the intensities of the overlapping major spectral peaks are additive, and have different rates of change with respect to variations in the concentration of the individual components, a simple method, named the 'common-origin ray', for the simultaneous determination of two components can be established. Several case studies highlighting its applications are presented.


Assuntos
Difusão Dinâmica da Luz/métodos , Processamento de Sinais Assistido por Computador , Espectrometria de Fluorescência/métodos , Espectrofotometria Ultravioleta/métodos , Cério/análise , Clorpromazina/análise , Európio/análise , Isomerismo , Modelos Teóricos , Naftóis/análise , Naftóis/química , Fenilalanina/análise , Fenilalanina/química , Prometazina/análise , Pontos Quânticos , Triptofano/análise , Triptofano/química , beta-Ciclodextrinas/química
9.
Bull Environ Contam Toxicol ; 98(3): 407-412, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27999882

RESUMO

Contamination of soil with Americium (241Am) at nuclear sites in China poses a serious problem. We screened six plants, from five families, for their 241Am-enrichment potential. Europium (Eu), which is morphologically and chemically similar to the highly toxic 241Am, was used in its place. Moreover, the effects of sylvite, citric acid (CA), malic acid (MA), and humic acid (HA) on the absorption of 241Am by the plants, and its transport within them, were evaluated along with their effect on plant biomass and 241Am extraction volume. Barley and cabbage showed relatively stronger Eu accumulation capacities. Citric acid promoted the absorption of 241Am by barley roots and its transport within the plants. The effects of sylvite were not obvious and those of HA were the weakest in case of sunflower; HA, however, maximally increased the biomass of the plants. Our results could provide the basis for future radionuclide phytoremediation of contaminated soils.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Ácido Cítrico/farmacologia , Európio/análise , Malatos/farmacologia , Plantas/química , Cloreto de Potássio/farmacologia , Biomassa , China , Substâncias Húmicas , Plantas/efeitos dos fármacos , Poluentes do Solo/análise
10.
Dalton Trans ; 45(46): 18719-18729, 2016 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-27840875

RESUMO

Herein, we report a novel lysosome targetable luminescent bioprobe derived from a europium coordination compound, namely Eu(pfphOCH3IN)3(DDXPO) 4 [where HpfphOCH3IN = 4,4,5,5,5-pentafluoro-3-hydroxy-1-(1-(4-methoxyphenyl)-1H-indol-3-yl)pent-2-en-1-one and DDXPO = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide]. Notably, the newly designed europium complex exhibits significant quantum yield (Φoverall = 25 ± 3%) and 5D0 excited state lifetime (τ = 398 ± 3 µs) values under physiological pH (7.2) conditions when excited at 405 nm. Hence the developed europium complex has been evaluated for live cell imaging applications using mouse pre-adipocyte cell lines (3T3L1). Colocalization studies of the designed bio-probe with commercial Lysosome-GFP in 3T3L1 cells demonstrated the specific localization of the probe in the lysosome with a high colocalization coefficient (A = 0.83). Most importantly, the developed bioprobe exhibits good cell permeability, photostability and non-cytotoxicity.


Assuntos
Complexos de Coordenação/química , Európio/química , Substâncias Luminescentes/química , Lisossomos/ultraestrutura , Imagem Óptica/métodos , Células 3T3-L1 , Animais , Complexos de Coordenação/análise , Európio/análise , Halogenação , Indóis/análise , Indóis/química , Ligantes , Substâncias Luminescentes/análise , Camundongos , Microscopia Confocal/métodos , Xantenos/análise , Xantenos/química
11.
J Environ Manage ; 184(Pt 3): 552-559, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27789090

RESUMO

Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (42). The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths.


Assuntos
Utensílios Domésticos , Ácido Clorídrico/química , Iluminação , Reciclagem/métodos , Térbio/química , Cério/análise , Cério/química , Európio/análise , Európio/química , Lantânio/análise , Lantânio/química , Óxidos/análise , Óxidos/química , Projetos de Pesquisa , Térbio/análise , Ítrio/análise , Ítrio/química
12.
Contrast Media Mol Imaging ; 11(4): 299-303, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27028559

RESUMO

Eu(II) -based contrast agents offer physiologically relevant, metal-based redox sensing that is unachievable with Gd(III) -based contrast agents. To evaluate the in vivo contrast enhancement of Eu(II) as a function of injection type, we performed intravenous, intraperitoneal, and subcutaneous injections in mice. Our data reveal a correlation between reported oxygen content and expected rates of diffusion with the persistence of Eu(II) -based contrast enhancement. Biodistribution studies revealed europium clearance through the liver and kidneys for intravenous and intraperitoneal injections, but no contrast enhancement was observed in organs associated with clearance. These data represent a step toward understanding the behavior of Eu(II) -based complexes in vivo. Copyright © 2016 John Wiley & Sons, Ltd.


Assuntos
Meios de Contraste/farmacocinética , Európio/farmacocinética , Injeções/métodos , Animais , Meios de Contraste/administração & dosagem , Meios de Contraste/análise , Európio/análise , Injeções Intraperitoneais , Injeções Intravenosas , Injeções Subcutâneas , Rim/metabolismo , Fígado/metabolismo , Taxa de Depuração Metabólica , Camundongos , Distribuição Tecidual
13.
Environ Sci Technol ; 50(7): 3706-13, 2016 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-26926621

RESUMO

Europium speciation is investigated by time-resolved luminescence spectroscopy (TRLS) in the presence of Suwannee River fulvic acid (SRFA). From complexation isotherms built at different total Eu(III) concentrations, pH values, ionic strength, and SRFA concentrations, it appears that two luminescence behaviors of Eu(III) are occurring. The first part, at the lowest CSRFA values, is showing the typical luminescence evolution of Eu(III) complexed by humic substances--that is, the increase of the asymmetry ratio between the (5)D0 → (7)F2 and (5)D0 → (7)F1 transitions up to a plateau--, and the occurrence of a biexponential decay--the first decay being faster than free Eu(3+). At higher CSRFA, a second luminescence mode is detected as the asymmetry ratio is increasing again after the previous plateau, and could correspond to the formation of another type of complex, and/or it can reflect a different spatial organization of complexed europium within the SRFA structure. The luminescence decay keeps on evolving but link to hydration number is not straightforward due to quenching mechanisms. The Eu(III) chemical environment evolution with CSRFA is also ionic strength dependent. These observations suggest that in addition to short-range interactions--intraparticulate complexation--, there might be interactions at longer range--interparticulate repulsion--between particles that are complexing Eu(III) at high CSRFA. These interactions are not yet accounted by the different complexation models.


Assuntos
Benzopiranos/química , Európio/química , Análise Espectral/métodos , Európio/análise , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Luminescência , Concentração Osmolar
14.
Environ Sci Technol ; 50(8): 4459-67, 2016 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-26998856

RESUMO

The adsorption mechanism of U(VI) and Eu(III) on carbonaceous nanofibers (CNFs) was investigated using batch, IR, XPS, XANES, and EXAFS techniques. The pH-dependent adsorption indicated that the adsorption of U(VI) on the CNFs was significantly higher than the adsorption of Eu(III) at pH < 7.0. The maximum adsorption capacity of the CNFs calculated from the Langmuir model at pH 4.5 and 298 K for U(VI) and Eu(III) were 125 and 91 mg/g, respectively. The CNFs displayed good recyclability and recoverability by regeneration experiments. Based on XPS and XANES analyses, the enrichment of U(VI) and Eu(III) was attributed to the abundant adsorption sites (e.g., -OH and -COOH groups) of the CNFs. IR analysis further demonstrated that -COOH groups were more responsible for U(VI) adsorption. In addition, the remarkable reducing agents of the R-CH2OH groups were responsible for the highly efficient adsorption of U(VI) on the CNFs. The adsorption mechanism of U(VI) on the CNFs at pH 4.5 was shifted from inner- to outer-sphere surface complexation with increasing initial concentration, whereas the surface (co)precipitate (i.e., schoepite) was observed at pH 7.0 by EXAFS spectra. The findings presented herein play an important role in the removal of radionuclides on inexpensive and available carbon-based nanoparticles in environmental cleanup applications.


Assuntos
Európio/análise , Nanofibras/química , Nanofibras/ultraestrutura , Nitrato de Uranil/análise , Poluentes Radioativos da Água/análise , Adsorção , Európio/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Propriedades de Superfície , Nitrato de Uranil/química , Poluentes Radioativos da Água/química , Espectroscopia por Absorção de Raios X
15.
Anal Chem ; 88(2): 1238-45, 2016 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-26643651

RESUMO

Luminescent lanthanide ion complexes have received increasing attention because of their unique optical properties. Herein, we discovered that the luminescence of europium(III) (Eu(3+)) could be regulated by Ag(+) and SCN(-) in seconds with enoxacin (ENX) as the antenna. Under given conditions, only the simultaneous introduction of Ag(+) and SCN(-) could remarkably enhance the luminescence intensity of Eu(3+)-ENX complexes. This phenomenon has been exploited to design an "AND" logic gate and specific luminescence turn-on assays for sensitively sensing Ag(+) and SCN(-) for the first time. Furthermore, the addition of S(2-) resulted in efficient luminescence quenching of the Eu(3+)/ENX/Ag(+)/SCN(-) system due to the strong affinity between Ag(+) and S(2-). Thus, a new luminescent sensing platform for S(2-) was established, which exhibited excellent selectivity and high sensitivity. S(2-) could be detected within the concentration range of 100 nM to 12.5 µM with a detection limit of 60 nM. Such sensing system features simplicity, rapidity, and flexibility. Moreover, this proposed Eu(3+)-based luminescent assay could be successfully applied in the real environmental water sample analysis.


Assuntos
Enoxacino/química , Európio/análise , Luminescência , Sulfetos/análise , Poluentes Químicos da Água/análise , Computadores Moleculares , Íons/análise , Lagos , Lógica , Medições Luminescentes , Prata/química , Tiocianatos/química
16.
Appl Radiat Isot ; 107: 17-23, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26405840

RESUMO

A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82.


Assuntos
Sedimentos Geológicos/química , Metais Terras Raras/análise , Análise de Ativação de Nêutrons/métodos , Cério/análise , Európio/análise , Lantânio/análise , Malásia , Análise de Ativação de Nêutrons/instrumentação , Oceanos e Mares , Samário/análise , Itérbio/análise
17.
J Environ Radioact ; 151 Pt 1: 218-223, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26519922

RESUMO

Diffusion of Na(I), Cs(I), Sr(II) and Eu(III) in smectite rich natural clay, proposed as a backfill material in the Indian geological repository, was studied using the out-diffusion method. Radiotracers (22)Na, (137)Cs, (85)Sr and (154)Eu were used; the first three are carrier-free enabling experimental work at sub-micromolar metal ion concentration, and Eu(III) tracer (154)Eu was used at sub millimolar concentration. An out-diffusion methodology, wherein a thin planar source of radioactivity placed between two clay columns diffuses out, was used to obtain the apparent diffusion coefficient (Da) values. This methodology enabled determination of diffusion coefficient even for strongly sorbing (154)Eu. Da values for (22)Na, (137)Cs, (85)Sr and (154)Eu were 2.35 (±0.14) × 10(-11), 2.65 (±0.09) × 10(-12), 3.32 (±0.15) × 10(-11) and 1.23 (±0.15) × 10(-13) m(2) s(-1), respectively. Da values were found to be in fair agreement with literature data reported for similar mineralogical sediments. Sorption of radionuclides on the clay was also determined in the present study and differences in Da values were rationalized on the basis of sorption data. Distribution ratios (Kd) for Cs(I) and Eu(III) were higher than that for Sr(II), which in turn was higher than that for Na(I).


Assuntos
Európio/análise , Monitoramento de Radiação , Radioisótopos/análise , Poluentes Radioativos do Solo/análise , Silicatos de Alumínio/análise , Radioisótopos de Césio/análise , Argila , Difusão , Índia , Silicatos/análise , Radioisótopos de Sódio/análise , Radioisótopos de Estrôncio/análise
18.
J Environ Radioact ; 151 Pt 1: 156-165, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26465672

RESUMO

Potential utilization of hematite as a natural material for immobilization of long-lived radionuclides from radioactive liquid waste was investigated. Hematite ore has been characterized by different analytical tools such as Fourier transformer infrared (FTIR), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal (DT) analysis, scanning electron microscopy (SEM) and BET-surface area. In this study, europium was used as REEs(III) and as a homolog of Am(III)-isotopes (such as (241)Am of 432.6 y, (242m)Am of 141 y and (243)Am of 7370 y). Micro particles of the hematite ore were used for treatment of radioactive waste containing (152+154)Eu(III). The results indicated that 96% (4.1 × 10(4) Bq) of (152+154)Eu(III) was efficiently retained onto hematite ore. Kinetic experiments indicated that the processes could be simulated by a pseudo-second-order model and suggested that the process may be chemisorption in nature. The applicability of Langmuir, Freundlich and Temkin models was investigated. It was found that Langmuir isotherm exhibited the best fit with the experimental results. It can be concluded that hematite is an economic and efficient reactive barrier for immobilization of long-lived radio isotopes of actinides and REEs(III).


Assuntos
Recuperação e Remediação Ambiental/métodos , Európio/análise , Compostos Férricos/química , Radioisótopos/análise , Poluentes Radioativos da Água/análise , Adsorção , Recuperação e Remediação Ambiental/economia
19.
J Am Soc Mass Spectrom ; 26(12): 2086-95, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26453417

RESUMO

The analytical utility of a new and simple to use ionization method, matrix-assisted ionization (MAI), coupled with ion mobility spectrometry (IMS) and mass spectrometry (MS) is used to characterize a 2-armed europium(III)-containing poly(ethylene glycol) (Eu-PEG) complex directly from a crude sample. MAI was used with the matrix 1,2-dicyanobenzene, which affords low chemical background relative to matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI). MAI provides high ion abundance of desired products in comparison to ESI and MALDI. Inductively coupled plasma-MS measurements were used to estimate a maximum of 10% of the crude sample by mass was the 2-arm Eu-PEG complex, supporting evidence of selective ionization of Eu-PEG complexes using the new MAI matrix, 1,2-dicyanobenzene. Multiply charged ions formed in MAI enhance the IMS gas-phase separation, especially relative to the singly charged ions observed with MALDI. Individual components are cleanly separated and readily identified, allowing characterization of the 2-arm Eu-PEG conjugate from a mixture of the 1-arm Eu-PEG complex and unreacted starting materials. Size-exclusion chromatography, liquid chromatography at critical conditions, MALDI-MS, ESI-MS, and ESI-IMS-MS had difficulties with this analysis, or failed. Graphical Abstract ᅟ.


Assuntos
Complexos de Coordenação/análise , Európio/análise , Polietilenoglicóis/análise , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Cromatografia Líquida/métodos , Desenho de Equipamento , Nitrilos/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/instrumentação
20.
J Environ Radioact ; 146: 119-24, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25982445

RESUMO

A fully detailed Monte Carlo geometrical model of a High Purity Germanium detector with a (152)Eu source, packed in Marinelli beaker, was developed for routine analysis of large volume environmental samples. Then, the model parameters, in particular, the dead layer thickness were adjusted thanks to a specific irradiation configuration together with a fine-tuning procedure. Thereafter, the calculated efficiencies were compared to the measured ones for standard samples containing (152)Eu source filled in both grass and resin matrices packed in Marinelli beaker. From this comparison, a good agreement between experiment and Monte Carlo calculation results was obtained highlighting thereby the consistency of the geometrical computational model proposed in this work. Finally, the computational model was applied successfully to determine the (137)Cs distribution in soil matrix. From this application, instructive results were achieved highlighting, in particular, the erosion and accumulation zone of the studied site.


Assuntos
Radioisótopos de Césio/análise , Európio/análise , Modelos Teóricos , Monitoramento de Radiação/métodos , Radioisótopos/análise , Poluentes Radioativos do Solo/análise , Germânio , Método de Monte Carlo
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