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1.
J Fluoresc ; 33(5): 1705-1716, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36826726

RESUMEN

Organic liquid scintillation detectors are widely used to measure the presence of radiation. With these devices, there are advantages in that they are easy to manufacture, large in size, and have a short fluorescence decay time. However, they are not suitable for gamma spectroscopy because they are composed of a low-atomic-number material. In this regard, alternative materials for the secondary solute used in basic organic liquid scintillators have been investigated, and the applicability of alternative materials, the detection characteristics, and neutron/gamma identification tests were all assessed. 7-Diethylamino-4-methylcoumarin (DMC), selected as an alternative material, is a benzopyrone derivative in the form of colorless crystals with high fluorescence, a high quantum yield in the visible region, and excellent light stability. In addition, it has a large Stokes shift, and solubility in a solvent is good. Through an analysis in this study, it was found that the absorption wavelength range of DMC coincides with the emission wavelength range of PPO, which is the primary solute used with DMC. Finally, it was confirmed that the optimal concentration of DMC was 0.08 wt%. As a result of performing gamma and neutron measurement tests using a DMC-based liquid scintillator, it was found to perform well (FOM = 1.42) compared to a commercial liquid scintillator, BC-501A.

2.
Nanomaterials (Basel) ; 11(12)2021 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-34947587

RESUMEN

Anode materials providing a high specific capacity with a high cycling performance are one of the key parameters for lithium ion batteries' (LIBs) applications. Herein, a high-capacity NiFe2O4(NFO) film anode is prepared by E-beam evaporation, and the effect of the heat treatment is studied on the microstructure and electrochemical properties of LIBs. The NiFe2O4 film annealed at 800 °C (NFO-800) showed a highly crystallized structure and different surface morphologies when compared to the electrode annealed at a lower temperature (NFO-600, NFO-700). In the electrochemical measurements, the high specific capacity (1804 mA g-1) and capacity retention ratio (95%) after 100 cycles were also achieved by the NFO-800 electrode. The main reason for the good electrochemical performance of the NFO-800 electrode is a high structure integrity, which could improve the cycle stability with a high discharge capacity. The NiFe2O4 electrode with an annealing process could be further proposed as an alternative ferrite material.

3.
Environ Res ; 191: 110099, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32866495

RESUMEN

A composite adsorbent for the removal of radioactive cesium (137Cs) was synthesized by immobilizing potassium cobalt ferrocyanide in the micro pores of the zeolite chabazite. The synthetically optimized composite adsorbent demonstrates a rapid cesium adsorption rate under both salt-free and high-salt conditions with a high distribution coefficient of cesium (≥105 mL/g). Although both components have the same ion-exchange reaction between potassium and cesium, the reaction by ferrocyanide component was predominant, which derived hundred times higher distribution coefficient of the composite adsorbent than that of pure chabazite. A thermal stabilization process was studied for improving the storage and/or disposal stability of the spent adsorbent. The formation of a eutectic system within the spent adsorbent reduced the stabilization temperature to 1000 °C from 1200 °C. Accordingly, the leaching of cesium was remarkably reduced by the remineralization to the stable pollucite. The stable impregnation of ferrocyanide component in the chabazite pores derived the reduction of cesium volatility enabling the high temperature stabilization method. Our experimental results provide evidence that the composite adsorbent has clear advantages on the cesium removal from contaminated water and its stabilization via thermal-treatment.


Asunto(s)
Cesio , Radiactividad , Adsorción , Agua , Contaminación del Agua
4.
Chemosphere ; 252: 126482, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32222520

RESUMEN

This study investigated the feasibility of using photoheterotrophic microalga, Desmodesmus armatus SCK, for removal of cesium (Cs+) followed by recovery process using magnetic nanoparticles. The comparison of three microalgae results indicated that D. armatus SCK removed the most Cs+ at both 25 °C and 10 °C. The results also revealed that the use of microalga grown in potassium (K+)-starved condition improves the accumulation of Cs+. Heterotrophic mode with addition of volatile fatty acids (VFAs), especially acetic acids (HAc), also enhanced removal of Cs+ by K+-starved D. armatus SCK; maximum removal efficiency of Cs+ was almost 2-fold higher than that of cells grown without organic carbon source. The Cs+ taken up by this microalga was efficiently harvested using magnetic nanoparticles, polydiallyldimethylammonium (PDDA)-FeO3. Finally, this strain eliminated more than 99% of radioactive 137Cs from solutions of 10, 100, and 1000 Bq mL-1. Therefore, use of K+-starved microalga, D. armatus SCK, with VFAs could be promising means to remove the Cs from the liquid wastes.


Asunto(s)
Cesio/metabolismo , Microalgas/metabolismo , Contaminantes Químicos del Agua/metabolismo , Cesio/análisis , Radioisótopos de Cesio , Ácidos Grasos Volátiles , Procesos Heterotróficos , Fenómenos Magnéticos , Potasio , Contaminantes Químicos del Agua/análisis
5.
Sci Rep ; 9(1): 10149, 2019 07 12.
Artículo en Inglés | MEDLINE | ID: mdl-31300718

RESUMEN

We evaluated the potential sequestration of cesium (Cs+) by microalgae under heterotrophic growth conditions in an attempt to ultimately develop a system for treatment of radioactive wastewater. Thus, we examined the effects of initial Cs+ concentration (100-500 µM), pH (5-9), K+ and Na+ concentrations (0-20 mg/L), and different organic carbon sources (acetate, glycerol, glucose) on Cs+ removal. Our initial comparison of nine microalgae indicated that Desmodesmus armatus SCK had removed the most Cs+ under various environmental conditions. Addition of organic substrates significantly enhanced Cs+ uptake by D. armatus, even in the presence of a competitive cation (K+). We also applied magnetic nanoparticles coated with a cationic polymer (polyethylenimine) to separate 137Cs-containing microalgal biomass under a magnetic field. Our technique of combining bioaccumulation and magnetic separation successfully removed more than 90% of the radioactive 137Cs from an aqueous medium. These results clearly demonstrate that the method described here is a promising bioremediation technique for treatment of radioactive liquid waste.


Asunto(s)
Radioisótopos de Cesio/aislamiento & purificación , Microalgas/metabolismo , Contaminantes Radiactivos del Agua/aislamiento & purificación , Bioacumulación , Carbono/metabolismo , Cesio/aislamiento & purificación , Cesio/farmacocinética , Radioisótopos de Cesio/farmacocinética , Chlorophyta/efectos de los fármacos , Chlorophyta/metabolismo , Concentración de Iones de Hidrógeno , Fenómenos Magnéticos , Nanopartículas de Magnetita/química , Microalgas/efectos de los fármacos , Polietileneimina/química , Potasio/farmacología , Sodio/farmacología , Especificidad de la Especie , Contaminantes Químicos del Agua/aislamiento & purificación , Contaminantes Químicos del Agua/farmacocinética , Contaminantes Radiactivos del Agua/farmacocinética
6.
J Hazard Mater ; 327: 127-134, 2017 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-28063370

RESUMEN

We report on a new approach to increase the removal of cesium from contaminated clays based on the intercalation of a cationic polyelectrolyte into the clay interlayers. A highly charged cationic polyelectrolyte, polyethyleneimine (PEI), was shown to intercalate into the negatively charged interlayers and readily replaced Cs ions adsorbed on the interlayers of montmorillonite. The polycation desorbed significantly more Cs strongly bound to the clay than did single cations. Moreover, additional NH4+ treatment following the PEI treatment enhanced desorption of Cs ions that were less accessible by the bulky polyelectrolyte. This synergistic effect of PEI with NH4+ yielded efficient desorption (95%) of an extremely low concentration of radioactive 137Cs in the clay, which is very difficult to remove by simple cation-exchange methods due to the increased stability of the binding of Cs to the clay at low Cs concentrations.

7.
J Hazard Mater ; 326: 69-76, 2017 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-27987452

RESUMEN

We demonstrate a simple method for the visual determination and removal of Co ions using a bead-shaped, capturing probe based on hybridized sodium alginate. For Co ions, the designed protocol consisted of three main constituents: an azopyridine-based Co ion-probe for visual detection; sodium alginate as an adsorbent for the Co ion and a bead construct for removal and structure; silica as a linker for the probe and the alginate, leading to a robust structure. When the composite beads were exposed to Co ions, the yellow color of the beads turned to intensive violet and the color intensity was associated with the Co ion concentration. The color variation was quantified using red-green-blue (RGB) color values that were obtained with a scanner and evaluated with Photoshop. The technique achieved both visual recognition with obvious color change of the beads and efficient removal of the radioactive 60Co ion. The sensing and removal of any radioactive isotope could be achieved with an appropriate sensing probe, to provide a simple and universal platform for remediation.

8.
Chemosphere ; 168: 1068-1074, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-27839883

RESUMEN

We propose a new approach to remediate cesium-contaminated clays based on intercalation of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) into clay interlayers. Intercalation of DTAB was found to occur very rapidly and involved exchanging interlayer cations. The reaction yielded efficient cesium desorption (∼97%), including of a large amount of otherwise non-desorbable cesium ions by cation exchange with ammonium ions. In addition, the intercalation of DTAB afforded an expansion of the interlayers, and an enhanced desorption of Cs by cation exchange with ammonium ions even at low concentrations of DTAB. Finally, the residual intercalated surfactants were easily removed by a decomposition reaction with hydrogen peroxide in the presence of Cu2+/Fe2+ catalysts.


Asunto(s)
Silicatos de Aluminio/química , Cesio/aislamiento & purificación , Compuestos de Amonio Cuaternario , Tensoactivos , Adsorción , Cationes , Arcilla
9.
J Nanosci Nanotechnol ; 16(3): 3067-70, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-27455762

RESUMEN

Copper ferrocyanide-functionalized magnetic nano-adsorbents were successfully synthesized by electrostatic coating of citric acid coated Fe3O4 nanoparticles with polyethyleneimine, and immobilizing copper and ferrocyanide on the surfaces of polyethyleneimine-coated nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the copper ferrocyanide-functionalized magnetic nano-adsorbents toward the removal of radioactive Cs.


Asunto(s)
Radioisótopos de Cesio/química , Ferrocianuros/química , Óxido Ferrosoférrico/química , Magnetismo , Nanopartículas , Polietileneimina/química , Adsorción , Microscopía Electrónica de Transmisión , Espectroscopía Infrarroja por Transformada de Fourier , Termogravimetría , Difracción de Rayos X
10.
J Nanosci Nanotechnol ; 15(2): 1695-9, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26353716

RESUMEN

Copper ferrocyanide-functionalized magnetite nanoparticles (Cu-FC-MNPs) were successfully synthesized by immobilizing copper and ferrocyanide on the surfaces of [1-(2 amino-ethyl)-3-aminopropyl] trimethoxysilane-modified magnetite nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the Cu-FC-MNPS toward the removal of radioactive Cs. The Cu-FC-MNPs showed excellent separation properties using an external magnet in an aqueous solution.


Asunto(s)
Radioisótopos de Cesio/aislamiento & purificación , Ferrocianuros/química , Nanopartículas de Magnetita/química , Contaminantes Radiactivos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Absorción Fisicoquímica , Radioisótopos de Cesio/química , Nanopartículas de Magnetita/ultraestructura , Ensayo de Materiales , Nanoconjugados/química , Nanoconjugados/ultraestructura , Tamaño de la Partícula , Propiedades de Superficie , Contaminantes Radiactivos del Agua/química
11.
J Nanosci Nanotechnol ; 15(10): 8279-84, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26726503

RESUMEN

Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.


Asunto(s)
Glicerol/química , Nanopartículas/química , Ósmosis , Polímeros/química , Ácido Succínico/química , Magnetismo
12.
Nanomaterials (Basel) ; 4(4): 894-901, 2014 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-28344255

RESUMEN

Radioactive cesium (137Cs) has inevitably become a human concern due to exposure from nuclear power plants and nuclear accident releases. Many efforts have been focused on removing cesium and the remediation of the contaminated environment. In this study, we elucidated the ability of Prussian blue-coated magnetic nanoparticles to eliminate cesium from radioactive contaminated waste. Thus, the obtained Prussian blue-coated magnetic nanoparticles were then characterized and examined for their physical and radioactive cesium adsorption properties. This Prussian blue-coated magnetic nanoparticle-based cesium magnetic sorbent can offer great potential for use in in situ remediation.

13.
J Mater Chem B ; 1(24): 3035-3043, 2013 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-32261006

RESUMEN

Superparamagnetic iron oxide nanoparticles are widely used as nanoprobes for magnetic resonance imaging (MRI). In this study, a novel type of cross-linked magnetic nanoparticle was developed in an effort to improve the structural stability of amphiphilic polymer-coated iron oxide nanoparticles. Iron oxide nanocrystals were coated with a cross-linkable amphiphilic graft copolymer, poly(succinimide) grafted with folate-conjugated polyethylene glycol (PEG) and alkyl chains. The tumor-specific targeting ligand, folate, was included to target and detect cancer cells. The hydrophobic portions of the amphiphilic copolymer on the surfaces of the nanoparticles were cross-linked via an aminolysis reaction between the succinimide units and a bifunctional primary amine. The folate-conjugated cross-linked magnetic nanoparticles (F-CLMNPs) were 40 nm in diameter and displayed a low cytotoxicity, even at relatively high concentrations. The F-CLMNPs exhibited highly efficient intracellular uptake into KB cells, which overexpress the folate receptor, as determined by fluorescence microscopy, flow cytometry, and Prussian blue staining. In vivo MR images of a mouse bearing a KB cell tumor displayed a 75% drop in the T2 signal in the tumor tissues within 3 hours. These results indicated that the F-CLMNPs accumulated at the tumor site and were highly effective for tumor detection using in vivo MRI techniques.

14.
J Colloid Interface Sci ; 391: 158-67, 2013 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-23116857

RESUMEN

Water soluble and biocompatible iron oxide nanoparticles coated with poly(aspartic acid) (PAsp), poly(asparagines) (PAsn), poly(2-hydroxy-ethyl L-aspartamide) (PHEA), and poly-α,ß-(N-2-dimethylaminoethyl L-aspartamide) (PDMAEA) were prepared by hydrophobic interaction between hydrophobic iron oxide nanoparticles and each amphiphilic poly(amino acid)s graft polymer. The octadecyl side chain grafted poly(succinimide)(PSI-g-C(18)), used as a precursor polymer, was easily aminolyzed with nucleophilic compounds to form various poly(amino acid)s graft polymer (PAsp-g-C(18), PAsn-g-C(18), PHEA-g-C(18), PDMAEA-g-C(18),) and simultaneously stabilize the dispersion of iron oxide nanoparticles in aqueous solution. The diameters of the poly(amino acid)s coated iron oxide nanoparticles (PAIONs) were smaller than 30 nm in aqueous solution, extremely stable in aqueous solutions with a wide range of pH and salt concentrations. Further, all the PAIONs showed excellent MR signal intensities (high r(2) values) and the cellular uptake property of the PAIONs was also evaluated.


Asunto(s)
Compuestos Férricos/química , Nanopartículas/química , Péptidos/química , Supervivencia Celular , Compuestos Férricos/farmacología , Humanos , Células KB , Imagen por Resonancia Magnética/métodos , Espectroscopía de Resonancia Magnética/métodos , Nanopartículas/ultraestructura , Péptidos/farmacología , Fantasmas de Imagen , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie
15.
Radiat Prot Dosimetry ; 112(2): 287-90, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15280566

RESUMEN

The surface contamination level of a radiation-controlled area is measured periodically according to atomic energy law and connection regulations. The measurement of surface contamination by an indirect method is subject to various kinds of error depending on the sampling person and consumes much time and effort in the sampling of large nuclear facilities. In this research, an automatic smear sampler is developed to solve these problems. The developed equipment is composed of a rotating sampling part, a sample transferring part, a power supply part a control part, and vacuum part. It improved the efficiency of estimation of the surface contamination level achieved periodically in a radiation-controlled area. Using an automatic smear sampler developed in this research, it is confirmed that radioactive contaminated materials are uniformly transferred to smear paper more than any sampling method by an operator.


Asunto(s)
Contaminación de Equipos , Análisis de Falla de Equipo/métodos , Exposición Profesional/análisis , Contaminantes Radiactivos/análisis , Radioisótopos/análisis , Radiometría/instrumentación , Manejo de Especímenes/instrumentación , Descontaminación/instrumentación , Descontaminación/métodos , Polvo/análisis , Diseño de Equipo , Reactores Nucleares , Dosis de Radiación , Radiometría/métodos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Manejo de Especímenes/métodos
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