High density Gd-substituted yttrium iron garnets by coprecipitation

International Nuclear Information System (INIS)

Lamastra, Francesca Romana; Bianco, Alessandra; Leonardi, Federica; Montesperelli, Giampiero; Nanni, Francesca; Gusmano, Gualtiero

2008-01-01

Gadolinium-substituted yttrium iron garnets are ferrite materials of primary importance in microwave engineering. Stoichiometric powders of nominal composition Y 2.6 Gd 0.4 Fe 5 O 12 (i.e. Fe/(Y + Gd) = 1.67) were prepared by reverse strike coprecipitation of metal nitrates. In order to investigate the influence of composition on phase formation, non-stoichiometric powders were also synthesised. On the basis of DTA/TGA analysis, dried coprecipitates were calcined between 600 deg. C and 1200 deg. C and then characterised by ICP, XRD and HT-XRD. Amorphous coprecipitates crystallise around 700 deg. C in cubic garnet phase along with small amounts of YFeO 3 and/or α-Fe 2 O 3 . Only iron-rich garnets, either pure or Gd-substituted, calcined at 1200 deg. C or above display a single-phase cubic garnet. According to thermal dilatometry results, calcined powders were sintered in air up to 1470 deg. C. The microstructure of sintered ceramics is made up of fine grains, the average size ranging between 3 μm and 13 μm. Density of sintered bodies ranged from 88% to 98%. Ferromagnetic resonance linewidth (ΔH -3dB ) ranged between 4352.9 A m -1 and 4392.7 A m -1 , depending on composition and microstructure

Study of calcium carbonate and sulfate co-precipitation

KAUST Repository

Zarga, Y.

2013-06-01

Co-precipitation of mineral based salts in scaling is still not well understood and/or thermodynamically well defined in the water industry. This study focuses on investigating calcium carbonate (CaCO3) and sulfate mixed precipitation in scaling which is commonly observed in industrial water treatment processes including seawater desalination either by thermal-based or membrane-based processes. Co-precipitation kinetics were studied carefully by monitoring several parameters simultaneously measured, including: pH, calcium and alkalinity concentrations as well as quartz microbalance responses. The CaCO3 germination in mixed precipitation was found to be different than that of simple precipitation. Indeed, the co-precipitation of CaCO3 germination time was not anymore related to supersaturation as in a simple homogenous precipitation, but was significantly reduced when the gypsum crystals appeared first. On the other hand, the calcium sulfate crystals appear to reduce the energetic barrier of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic Microscopy (SEM) were used to identify the nature of scales structures. Gypsum was found to be the dominant precipitate while calcite and especially vaterite were found at lower proportions. These analyses showed also that gypsum crystals promote calcite crystallization to the detriment of other forms. © 2013 Elsevier Ltd.

Effect of organic complexing compounds and surfactants on coprecipitation of cesium radionuclides with nickel ferrocyanide precipitate

International Nuclear Information System (INIS)

Milyutin, V.V.; Gelis, V.M.; Ershov, B.G.; Seliverstov, A.F.

2008-01-01

One studied the effect of the organic complexing compounds and of the surfactants on the coprecipitation of Cs trace amounts with the nickel ferrocyanide precipitate. The presence of the oxalate- and ethylenediamin-tetraacetate-ions in the solutions is shown to result in the abrupt reduction of Cs coprecipitation degree. The effect of the various surfactants manifested itself not so explicitly. To reduce the negative effect of the organic compounds on the intimacy of Cs coprecipitation one tried out the procedure of their chemical destruction by ozon. Pre-ozonization of the solutions enabled to prevent the negative effect of the organic complexing compounds and of the surfactants on Cs coprecipitation with nickel ferrocyanide precipitate [ru

Application of Micro-coprecipitation Method to Alpha Source Preparation for Measuring Alpha Nuclides

International Nuclear Information System (INIS)

Lee, Myung Ho; Park, Jong Ho; Oh, Se Jin; Song, Byung Chul; Song, Kyuseok

2011-01-01

Among the source preparations, an electrodeposition is a commonly used method for the preparation of sources for an alpha spectrometry, because this technique is simple and produces a very thin deposit, which is essential for a high resolution of the alpha peak. Recently, micro-coprecipitation with rare earths have been used to yield sources for -spectrometry. In this work, the Pu, Am and Cm isotopes were purified from hindrance nuclides and elements with an a TRU resin in radioactive waste samples, and the activity concentrations of the Pu, Am and Cm isotopes were determined by radiation counting methods after alpha source preparation like micro coprecipitation. After the Pu isotopes in the radioactive waste samples were separated from the other nuclides with an anion exchange resin, the Am isotopes were purified with a TRU resin and an anion exchange resin or a TRU resin. Activity concentrations and chemical recoveries of 241 Am purified with the TRU resin were similar to those with the TRU resin and anion exchange resin. In this study, to save on the analytical time and cost, the Am isotopes were purified with the TRU resin without using an additional anion exchange resin. After comparing the electrodeposition method with the micro-coprecipitation method, the micro-coprecipitation method was used for the alpha source preparation, because the micro-coprecipitation method is simple and more reliable for source preparation of the Pu, Am and Cm isotopes

Co-precipitation of plutonium(IV) and americium(III) from nitric acid-oxalic acid solutions with bismuth oxalate

International Nuclear Information System (INIS)

Pius, I.C.; Noronha, D.M.; Chaudhury, Satyajeet

2017-01-01

Co-precipitation of plutonium and americium from nitric acid-oxalic acid solutions with bismuth oxalate has been investigated for the removal of these long lived α-active nuclides from waste solutions. Effect of concentration of bismuth and oxalic acid on the co-precipitation of Pu(IV) from 3 M HNO_3 has been investigated. Similar experiments were also carried out from 3.75 M HNO_3 on co-precipitation of Am(III) to optimize the conditions of precipitation. Strong co-precipitation of Pu(IV) and Am(III) with bismuth oxalate indicate feasibility of treatment of plutonium and americium bearing waste solutions. (author)

Coprecipitation of mono-, di-, tri-, tetra- and hexavalent ions with Na-polyuranates

International Nuclear Information System (INIS)

Diaz Arocas, P.; Garcia-Serrano, J.; Quinones, J.; Geckeis, H.; Grambow, B.

1996-01-01

The objective of this work is to study the solubility and coprecipitation phenomena related to spent fuel dissolution under anoxic conditions in order to identify potential upper limits of radionuclide release. In the present work it is attempted to identify those elements for which coprecipitation phenomena are significant. The pH dependent precipitation behaviour of minor elements with Na-polyuranates is studied in carbonate-free 5 m NaCl solutions. Three different systems were investigated: ''System A'' NaCl-Cs-Sr-Eu-Mo-Th-U(VI)-H 2 O. ''System B'' NaCl-Cs-Sr-Eu-Mo-Th-H 2 O. ''System C'' an aqueous solution of dissolved SIMulated FUEL (SIMFUEL) containing: NaCl-Sr-Ba-Y-La-Ce-Nd-Zr-Pd-Mo-Rh-Ru-U(VI)-H 2 O. The experimental results obtained in this work show that: (1) The presence of minor elements do not influence the precipitation of Na-polyuranate, (2) Solution concentration of trivalent rare Earth elements reveal a strong decrease with pH, possibly controlled by coprecipitation, (3) Tetravalent elements such as Th (Sys. A and B) and Zr (sys. C) show a strong decrease in their concentration independent of pH. Th concentrations were not controlled by coprecipitation but probably by formation of individual solubility controlling phase such as Th(OH) 4 , (4) Sr and Cs stay in solution during the precipitation process. (orig.)

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

International Nuclear Information System (INIS)

Thorat, J. H.; Kanade, K. G.; Nikam, L. K.; Chaudhari, P. D.; Panmand, R. P.; Kale, B. B.

2012-01-01

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 °C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 °C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 °C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50–60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25–50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

Energy Technology Data Exchange (ETDEWEB)

Thorat, J. H. [Mahatma Phule College, Department of Chemistry (India); Kanade, K. G. [Annasaheb Awate College (India); Nikam, L. K. [B.G. College (India); Chaudhari, P. D.; Panmand, R. P.; Kale, B. B., E-mail: kbbb1@yahoo.com [Center for Materials for Electronics Technology (C-MET) (India)

2012-02-15

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 Degree-Sign C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 Degree-Sign C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 Degree-Sign C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50-60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25-50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.

Coprecipitation of thorium and uranium peroxides from acid solutions

Energy Technology Data Exchange (ETDEWEB)

McTaggart, D.R.; Mailen, J.C.

1981-01-01

The factors affecting successful coprecipitation of thorium and uranium peroxides from acid media were studied. Variables considered in this work were H/sup +/ concentration, H/sub 2/O/sub 2/ concentration, duration of contact, and rate of feed solution addition. In all experiments, stock solutions of Th(NO/sub 3/)/sub 4/ and UO/sub 2/(NO/sub 3/)/sub 2/ were fed at a controlled rate into H/sub 2/O/sub 2/ solutions with constant stirring. Samples were taken as a function of time to follow the H/sup +/ concentration of the solution, uranium precipitation, thorium precipitation, precipitant weight/volume of solution, and crystalline structure and growth. The optimum conditions for maximum coprecipitation are low H/sup +/ concentration, high H/sub 2/O/sub 2/ concentration, and extended contact time between the solutions.

Solid-state 29Si NMR and FTIR analyses of lignin-silica coprecipitates

DEFF Research Database (Denmark)

Cabrera Orozco, Yohanna; Cabrera, Andrés; Larsen, Flemming Hofmann

2016-01-01

When agricultural residues are processed to ethanol, lignin and silica are some of the main byproducts. Separation of these two products is difficult and the chemical interactions between lignin and silica are not well described. In the present study, the effect of lignin-silica complexing has been...... investigated by characterizing lignin and silica coprecipitates by FTIR and solid state NMR. Silica particles were coprecipitated with three different lignins, three lignin model compounds, and two silanes representing silica-in-lignin model compounds. Comparison of 29Si SP/MAS NMR spectra revealed differences...

Formation of Silica-Lysozyme Composites Through Co-Precipitation and Adsorption

Directory of Open Access Journals (Sweden)

Daniela B. van den Heuvel

2018-04-01

Full Text Available Interactions between silica and proteins are crucial for the formation of biosilica and the production of novel functional hybrid materials for a range of industrial applications. The proteins control both precipitation pathway and the properties of the resulting silica–organic composites. Here, we present data on the formation of silica–lysozyme composites through two different synthesis approaches (co-precipitation vs. adsorption and show that the chemical and structural properties of these composites, when analyzed using a combination of synchrotron-based scattering (total scattering and small-angle X-ray scattering, spectroscopic, electron microscopy, and potentiometric methods vary dramatically. We document that while lysozyme was not incorporated into nor did its presence alter the molecular structure of silica, it strongly enhanced the aggregation of silica particles due to electrostatic and potentially hydrophobic interactions, leading to the formation of composites with characteristics differing from pure silica. The differences increased with increasing lysozyme content for both synthesis approaches. Yet, the absolute changes differ substantially between the two sets of composites, as lysozyme did not just affect aggregation during co-precipitation but also particle growth and likely polymerization during co-precipitation. Our results improve the fundamental understanding of how organic macromolecules interact with dissolved and nanoparticulate silica and how these interactions control the formation pathway of silica–organic composites from sodium silicate solutions, a widely available and cheap starting material.

Formation of Silica-Lysozyme Composites Through Co-Precipitation and Adsorption

Science.gov (United States)

van den Heuvel, Daniela B.; Stawski, Tomasz M.; Tobler, Dominique J.; Wirth, Richard; Peacock, Caroline L.; Benning, Liane G.

2018-04-01

Interactions between silica and proteins are crucial for the formation of biosilica and the production of novel functional hybrid materials for a range of industrial applications. The proteins control both precipitation pathway and the properties of the resulting silica-organic composites. Here we present data on the formation of silica-lysozyme composites through two different synthesis approaches (co-precipitation vs. adsorption) and show that the chemical and structural properties of these composites, when analyzed using a combination of synchrotron-based scattering (total scattering and SAXS), spectroscopic, electron microscopy and potentiometric methods vary dramatically. We document that while lysozyme was not incorporated into nor did its presence alter the molecular structure of silica, it strongly enhanced the aggregation of silica particles due to electrostatic and potentially hydrophobic interactions, leading to the formation of composites with characteristics differing from pure silica. The differences increased with increasing lysozyme content for both synthesis approaches. Yet, the absolute changes differ substantially between the two sets of composites, as lysozyme did not just affect aggregation during co-precipitation but also particle growth and likely polymerization during co-precipitation. Our results improve the fundamental understanding of how organic macromolecules interact with dissolved and nanoparticulate silica and how these interactions control the formation pathway of silica-organic composites from sodium silicate solutions, a widely available and cheap starting material.

Supercritical antisolvent co-precipitation of rifampicin and ethyl cellulose

CSIR Research Space (South Africa)

Djerafi, R

2017-05-01

Full Text Available . Using the solvent mixture, co-precipitates with particle sizes ranging between 190 and 230 nm were obtained with drug loading and drug precipitation yield from respectively 8.5 to 38.5 and 42.4 to 77.2% when decreasing the ethyl cellulose...

Dissolution of ibuprofen enantiomers from coprecipitates and suspensions containing chiral excipients.

Science.gov (United States)

Janjikhel, R K; Adeyeye, C M

1999-01-01

The purpose of this research was to evaluate the stereospecific interaction of ibuprofen with chiral excipients such as hydroxypropyl-beta-cyclodextrin (HPCD), tartaric acid, sucrose, hydroxypropylmethylcellulose (HPMC), methylcellulose (MC), and a nonchiral excipient, citric acid. Coprecipitates of ibuprofen were prepared in molar ratios ranging between 1:0.5 and 1:10 by a solvent evaporation method and characterized using x-ray diffraction, Fourier-transform infrared (FTIR) spectroscopy, and dissolution testing. Phase solubility studies of ibuprofen were carried out by adding excess amount of ibuprofen to aqueous excipient solutions of varying concentrations. Interaction was studied in suspensions of ibuprofen with HPMC, MC, and sucrose stored at room temperature and 60 degrees C for 12 weeks. Solubility of ibuprofen in HPCD solutions increased 10-fold, whereas solubility decreased in the tartaric and citric acid solutions, a result of decreased pH with increased amount of the acids in which ibuprofen (pKa 4.8) is less soluble. Phase solubility diagrams of ibuprofen in aqueous HPCD, citric acid, and tartaric acid solutions showed no stereospecific differences in solubility of the two enantiomers. X-ray diffraction studies showed that ibuprofen exists in a crystalline form at low ibuprofen-to-excipient ratios, whereas at the higher ratios, it exists in an amorphous form. FTIR spectroscopy for HPCD coprecipitates showed a shift of the carbonyl stretching band of ibuprofen to a higher wavelength with a markedly decreased intensity, probably because of a breakdown in the intermolecular hydrogen bonding with ibuprofen and restriction of the drug molecule in the HPCD cavity, respectively. Dissolution profiles of the coprecipitates demonstrated higher dissolution rates than those of pure ibuprofen. The presence of chiral excipients did not appear to cause stereoselective release of the drug from the coprecipitates and the suspensions.

Co-precipitation and solubility studies of cesium, potassium and sodium tetraphenylborate

International Nuclear Information System (INIS)

Peterson, R.A.

1999-01-01

This report contains the results from a study requested by High Level Waste Division on the co-precipitation and solubility of cesium, potassium, and sodium tetraphenylborate. Co-precipitation of cesium (Cs), potassium (K), and sodium (Na) tetraphenylborate (TPB) helps determine the efficiency of reagent usage in the Small Tank Precipitation Process. This process uses NaTPB to remove cesium from waste by means of precipitation. Previous studies by McCabe suggested that if the sodium ion concentration [Na+] increased the rate at which cesium tetraphenylborate (KTPB) in the presence of high [Na+] (∼5M) appears to produce a mixed solid phase composed of NaTPB and KTPB together in the crystal lattice

Exafs studies of coprecipitation and adsorption reactions of Tc

Energy Technology Data Exchange (ETDEWEB)

Bunker, D.J.; Jones, M.J.; Livens, F.R.; Collison, D. [Manchester Univ. (United Kingdom). Dept. of Chemistry; Pattrick, R.A.D. [Manchester Univ., Dept. of Earth Sciences (United Kingdom); Charnock, J.M. [CLRC Daresbury Laboratoire, Warrington Cheshire (United Kingdom)

2000-07-01

Adsorption and coprecipitation reactions may be a simple way of removing [TcO{sub 4}]{sup -} from aqueous solution. The effectiveness of a range of potential adsorbents and precipitants has been evaluated and some are capable of near quantitative (>98%) removal of [TcO{sub 4}){sup -} from solution. X-ray absorption near edge structure (XANES) has been used to determine Tc oxidation states and extended X-ray absorption fine structure spectroscopy (EXAFS) has been used to identify the local environment of Tc. The absorption edge position has been determined, using [PPh{sub 4}][TcO{sub 4}], TcS{sub 2} and Tc{sub 2}S{sub 7} as model compounds, and is diagnostic of Tc oxidation state. In a series of experiments investigating FeS coprecipitation, Tc was reduced to oxidation state (IV) and its local environment resembled that in TcO{sub 2} (6 O atoms at approximately 2.0 Angstrom). (authors)

Synthesis of alumina/YAG 20 vol% composite by co-precipitation

Directory of Open Access Journals (Sweden)

Radosław Lach

2011-12-01

Full Text Available Co-precipitation of alumina/YAG precursor from aluminum and yttrium nitrate solution with ammonium carbonate results in dawsonite. Its crystallographic parameters differ from the compound precipitated with no yttrium additive. It suggests that yttrium ions become incorporated into the dawsonite structure. The DSC/TG and X-ray diffraction measurements show decomposition of dawsonite at elevated temperatures resulting in γ-Al2O3 and then δ- and θ-alumina modifications. Full transformation to α-Al2O3 and YAG occurs at temperatures higher than 1230°C. Starting powder for the sintering experiments was prepared using the coprecipitated precursor calcined at 600°C. Seeding of such powder with 5 wt.% α-Al2O3 results in material of 98% density at 1500°C. Much lower densification show compacts of unseeded powder.

Enhanced removal of arsenic from a highly laden industrial effluent using a combined coprecipitation/nano-adsorption process.

Science.gov (United States)

Jiang, Yingnan; Hua, Ming; Wu, Bian; Ma, Hongrui; Pan, Bingcai; Zhang, Quanxing

2014-05-01

Effective arsenic removal from highly laden industrial wastewater is an important but challenging task. Here, a combined coprecipitation/nano-adsorption process, with ferric chloride and calcium chloride as coprecipitation agents and polymer-based nanocomposite as selective adsorbent, has been validated for arsenic removal from tungsten-smelting wastewater. On the basis of operating optimization, a binary FeCl3 (520 mg/L)-CaCl2 (300 mg/L) coprecipitation agent could remove more than 93% arsenic from the wastewater. The resulting precipitate has proved environmental safety based on leaching toxicity test. Fixed-bed column packed with zirconium or ferric-oxide-loaded nanocomposite was employed for further elimination of arsenic in coprecipitated effluent, resulting in a significant decrease of arsenic (from 0.96 to less than 0.5 mg/L). The working capacity of zirconium-loaded nanocomposite was 220 bed volumes per run, much higher than that of ferric-loaded nanocomposite (40 bed volumes per run). The exhausted zirconium-loaded nanocomposite could be efficiently in situ regenerated with a binary NaOH-NaCl solution for reuse without any significant capacity loss. The results validated the combinational coprecipitation/nano-adsorption process to be a potential alternative for effective arsenic removal from highly laden industrial effluent.

and aluminum-substituted cobalt ferrite prepared by co-precipitation

Indian Academy of Sciences (India)

Structural and magnetic properties of zinc- and aluminum-substituted cobalt ferrite prepared by co-precipitation method. S T ALONE1,∗ and K M JADHAV2. 1Shiv Chhatrapati College, Aurangabad 431 004, India. 2Department of Physics, Dr. B. A. Marathwada University, Aurangabad 431 004, India. ∗Corresponding author.

Encapsulation of albumin in self-assembled layer-by-layer microcapsules: comparison of co-precipitation and adsorption techniques.

Science.gov (United States)

Labala, Suman; Mandapalli, Praveen Kumar; Bhatnagar, Shubhmita; Venuganti, Venkata Vamsi Krishna

2015-01-01

The objective of this study is to prepare and characterize polymeric self-assembled layer-by-layer microcapsules (LbL-MC) to deliver a model protein, bovine serum albumin (BSA). The aim is to compare the BSA encapsulation in LbL-MC using co-precipitation and adsorption methods. In co-precipitation method, BSA was co-precipitated with growing calcium carbonate particles to form a core template. Later, poly(styrene sulfonate) and poly(allylamine hydrochloride) were sequentially adsorbed onto the CaCO3 templates. In adsorption method, preformed LbL-MC were incubated with BSA and encapsulation efficiency is optimized for pH and salt concentration. Free and BSA-encapsulated LbL-MC were characterized using Zetasizer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and differential scanning calorimeter. Later, in vitro release studies were performed using dialysis membrane method at pH 4, 7.4 and 9. Results from Zetasizer and SEM showed free LbL-MC with an average size and zeta-potential of 2.0 ± 0.6 μm and 8.1 ± 1.9 mV, respectively. Zeta-potential of BSA-loaded LbL-MC was (-)7.4 ± 0.7 mV and (-)5.7 ± 1.0 mV for co-precipitation and adsorption methods, respectively. In adsorption method, BSA encapsulation in LbL-MC was found to be greater at pH 6.0 and 0.2 M NaCl. Co-precipitation method provided four-fold greater encapsulation efficiency (%) of BSA in LbL-MC compared with adsorption method. At pH 4, the BSA release from LbL-MC was extended up to 120 h. Polyacrylamide gel electrophoresis showed that BSA encapsulated in LBL-MC through co-precipitation is stable toward trypsin treatment. In conclusion, co-precipitation method provided greater encapsulation of BSA in LbL-MC. Furthermore, LbL-MC can be developed as carriers for pH-controlled protein delivery.

Coprecipitation of cadmium with calcite

International Nuclear Information System (INIS)

Fujino, Osamu; Kumagai, Tetsu; Shigematsu, Tsunenobu; Matsui, Masakazu

1976-01-01

The distribution of cadmium between precipitates of calcite and saturated aqueous solution was measured at 25 0 C to understand the distribution of cadmium in the bivalves. Calcite was precipitated from calcium bicarbonate solution by the gradual release of carbon dioxide. The cadmium ions were coprecipitated in calcite, obeying the logarithmic distribution law. The apparent distribution coefficient was decreased as α, α'-dipyridyl increased, but the true distribution coefficient was found to be an almost constant value, 560. This value is fairly close to the ratio of solubility product constants K sub(calcite)/K sub(CdCO 3 ), 890. This suggests that the deviation of the present solid solution from ideality is not very large. (auth.)

The removal of 134Cs from radioactive process waste water by coprecipitate flotation

International Nuclear Information System (INIS)

Aziz, M.; Shakir, K.; Benyamin, K.

1986-01-01

The coprecipitate flotation of 134 Cs from radioactive process waste water using copper ferrocyanide as a coprecipitating agent and sodium lauryl sulphate, cetyl trimethyl ammonium bromide or gelatin as collector was extensively investigated to establish the best conditions for caesium removal with each of the collectors under test. The investigated parameters include the collector dosage, the Cu 2+ /Fe(CN) 6 4- ratio, the caesium, potassium, sodium and calcium ion concentrations, the ageing time period of the Cu 2+ - Fe(CN) 6 4- - 134 Cs - water system and the bubbling time duration. The results indicate that copper ferrocyanide has a high affinity for caesium and can preferentially co-precipitate it in presence of relatively high amounts of other alkali or alkaline earth cations. For the alkali metals the affinity increases in the order Na < K < Cs. Under the optimal conditions removals higher than 99% could be achieved with any of the tested collectors. The results are discussed in terms of the ion exchange properties of copper ferrocyanide and collector behaviour. Advantages of the coflotation technique over other methods are enumerated. (Auth.)

Properties and reactivity of Fe-organic matter associations formed by coprecipitation versus adsorption: Clues from arsenate batch adsorption

Science.gov (United States)

Mikutta, Robert; Lorenz, Dennis; Guggenberger, Georg; Haumaier, Ludwig; Freund, Anja

2014-11-01

Ferric oxyhydroxides play an important role in controlling the bioavailability of oxyanions such as arsenate and phosphate in soil. Despite this, little is known about the properties and reactivity of Fe(III)-organic matter phases derived from adsorption (reaction of organic matter (OM) to post-synthesis Fe oxide) versus coprecipitation (formation of Fe oxides in presence of OM). Coprecipitates and adsorption complexes were synthesized at pH 4 using two natural organic matter (NOM) types extracted from forest floor layers (Oi and Oa horizon) of a Haplic Podzol. Iron(III) coprecipitates were formed at initial molar metal-to-carbon (M/C) ratios of 1.0 and 0.1 and an aluminum (Al)-to-Fe(III) ratio of 0.2. Sample properties were studied by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N2 gas adsorption, dynamic light scattering, and electrophoretic mobility measurements. Arsenic [As(V)] adsorption to Fe-OM phases was studied in batch experiments (168 h, pH 4, 100 μM As). The organic carbon (OC) contents of the coprecipitates (82-339 mg g-1) were higher than those of adsorption complexes (31 and 36 mg g-1), leading to pronounced variations in specific surface area (9-300 m2 g-1), average pore radii (1-9 nm), and total pore volumes (11-374 mm3 g-1) but being independent of the NOM type or the presence of Al. The occlusion of Fe solids by OM (XPS surface concentrations: 60-82 atom% C) caused comparable pHPZC (1.5-2) of adsorption complexes and coprecipitates. The synthesis conditions resulted in different Fe-OM association modes: Fe oxide particles in 'M/C 0.1' coprecipitates covered to a larger extent the outermost aggregate surfaces, for some 'M/C 1.0' coprecipitates OM effectively enveloped the Fe oxides, while OM in the adsorption complexes primarily covered the outer aggregate surfaces. Despite of their larger OC contents, adsorption of As(V) was fastest to coprecipitates formed at low Fe availability (M/C 0.1) and facilitated by desorption of weakly

Study and modelling of an innovative coprecipitation reactor for radioactive liquid wastes decontamination

International Nuclear Information System (INIS)

Flouret, Julie

2013-01-01

In order to decontaminate radioactive liquid wastes of low and intermediate levels, the coprecipitation is the process industrially used. The aim of this PhD work is to optimize the continuous process of coprecipitation. To do so, an innovative reactor is designed and modelled: the continuous reactor/classifier. Two model systems are studied: the coprecipitation of strontium by barium sulphate and the sorption of cesium by PPFeNi. The simulated effluent contains sodium nitrate in order to consider the high ionic strength of radioactive liquid wastes. First, each model system is studied on its own, and then a simultaneous treatment is performed. The kinetic laws of nucleation and crystal growth of barium sulphate are determined and incorporated into the coprecipitation model. Kinetic studies and sorption isotherms of cesium by PPFeNi are also performed in order to acquire the necessary data for process modelling. The modelling realised enables accurate prediction of the residual strontium and cesium concentrations according to the process used: it is a valuable tool for the optimization of existing units, but also the design of future units. The continuous reactor/classifier presents many advantages compared to the classical continuous process: the decontamination efficiency of strontium and cesium is highly improved while the volume of sludge generated by the process is reduced. A better liquid/solid separation is observed in the reactor/classifier and the global installation is significantly more compact. Thus, the radioactive liquid wastes treatment processes can be intensified by the continuous reactor/classifier, which represents a very promising technology for future industrial application. (author) [fr

Coprecipitation of cadmium with copper 8-hydroxyquinolate from homogeneous solution

International Nuclear Information System (INIS)

Takiyama, Kazuyoshi; Kozen, Terumi; Ueki, Yasuyo; Ishida, Hiromi

1976-01-01

The coprecipitation of copper and cadmium 8-hydroxyquinolates from homogeneous solution was conducted from the viewpoint of crystal and analytical chemistry. To the mixed solution containing copper and cadmium ions an 8-acetoxyquinoline solution was added by keeping the pH of the solution at 9 and the resulted solution was stirred at 25 0 C. The precipitate formed at each stage of the reaction was analyzed. The precipitates in an initial stage were composed of needle crystals which characterizes copper 8-hydroxyquinolate, and were associated with a slight amount of cadmium. The first half of the coprecipitation curve for the needle crystal formation resembles the logarithmic distribution curve of lambda equal to about 0.01. The precipitation of most of the copper ions was followed by the precipitation of cadmium 8-hydroxyquinolate crystal in the plate form. The needle crystals of copper 8-hydroxyquinolate started to dissolve and transformed to plate crystals. In the second half of the coprecipitation, both crystals, owing to the identical crystal structure, precipitated simultaneously and form a solid solution. When cadmium 8-hydroxyquinolate was precipitated by the PFHS method (precipitation from homogeneous solution) in the presence of the needle crystals of copper 8-hydroxyquinolate, the above mentioned phenomenon was observed. The precipitation of cadmium 8-hydroxyquinolate in the plate form is due to the seeding effect of the plate crystals of copper 8-hydroxyquinolate, which were scantily transformed from the needle crystals. The plate crystals of cadmium compound acts as a seed to transform the needle crystals of copper compound to plate crystals. (auth.)

Remanence properties of Co-precipitated cobalt ferrite

International Nuclear Information System (INIS)

Bueno-Baques, D.; Medina-Boudri, Angela; Matutes-Aquino, J.

2001-01-01

Isothermal remanent magnetization (IRM) and DC demagnetization (DCD) curves of a co-precipitated cobalt ferrite sample were obtained. From the IRM and DCD data, the Henkel plot was obtained and analyzed in the Preisach model framework. The Henkel plot data are below the Wohlfarth line that indicates a dominant local disorder (demagnetizing-like effect). Forward and reverse switching field distribution curves were obtained from differentiation of the IRM and DCD curves. The peak values of these switching field distributions differ by a factor of about 2.7

Coprecipitation of neptunium and plutonium with iron and zirconium dibutyl phosphates

International Nuclear Information System (INIS)

Sokhina, L.P.; Rovnyj, S.I.; Goncharuk, L.V.

1988-01-01

Neptunium and plutonium coprecipitation with precipitates of dibutyl phosphates of some elements significant for radiochemical technology is studied. By the ability to coprecipitation of actinides with precipitates of dibutyl phosphates the cations may be arranged in the series Fe > Al > La > ≥ Zr ≥ Th. The composition of neptunium and plutonium mixed precipitates on the basis of iron dibutyl phosphates corresponding to the formula (Me(NO 3 ) 2 Al 2 ) n x · FeA 3 , where Me-neptunium or plutonium, A-anion of dibutyl phosphoric acid, n=1-4, is determined. Solubility of mixed precipitations in nitric acid and carbonate solutions is studied. Mixed precipitations on the basis of iron dibutyl phosphates are found to have the least solubility, their solubility being lower than that of individual compounds of dibutyl phoshates. The mechanism of formation of mixed precipitates is suggested and discussed

Effect of preparation conditions on physicochemical, surface and catalytic properties of cobalt ferrite prepared by coprecipitation

Energy Technology Data Exchange (ETDEWEB)

El-Shobaky, G.A., E-mail: elshobaky@yahoo.co [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt); Turky, A.M.; Mostafa, N.Y.; Mohamed, S.K. [Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt)

2010-03-18

Cobalt ferrite nanoparticles were prepared via thermal treatment of cobalt-iron mixed hydroxides at 400-600 {sup o}C. The mixed hydroxides were coprecipitated from their nitrates solutions using NaOH as precipitating agent. The effects of pH and temperature of coprecipitation and calcination temperature on the physicochemical, surface and catalytic properties of the prepared ferrites were studied. The prepared systems were characterized using TG, DTG, DTA, chemical analysis, atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) as well as surface and texture properties based on nitrogen adsorption-desorption isotherms. The prepared cobalt ferrites were found to be mesoporous materials that have crystallite size ranges between 8 and 45 nm. The surface and catalytic properties of the produced ferrite phase were strongly dependent on coprecipitation conditions of the mixed hydroxides and on their calcination temperature.

Recovery of sludge from the treatment of liquid radioactive effluents by co-precipitation with calcium carbonate: laboratory study; Recuperation des boues de traitement des effluents radioactifs liquides par coprecipitation avec le carbonate de calcium: etude de laboratoire

Energy Technology Data Exchange (ETDEWEB)

Patti, F.; Gailledreau, C.; Cohen, P.

1961-02-24

As during the treatment by co-precipitation with calcium carbonate of liquid radioactive residues, a partial decontamination can be obtained by simply agitating an already formed radioactive sludge with the effluent to be processed, the authors study whether it would be possible to first perform a co-precipitation with a lower dose of calcium carbonate and then to complete decontamination by agitating with an adequate quantity of sludge stored during preceding operations. The authors report the study of the influence of reactant quantity on the chemical treatment efficiency, of the evolution of the activity of a radioactive residual solution in contact with a precipitate, of the cleaner element, of a precipitate reuse, of the technological and economic aspects, and of another possibility of reduction of the precipitate volume [French] Dans le traitement par coprecipitation avec le carbonate de calcium des residus radioactifs liquides, une decontamination partielle peut etre obtenue en agitant simplement une boue radioactive deja formee avec l'effluent a traiter. En consequence, il pourrait etre possible d'effectuer d'abord une coprecipitation avec une dose plus faible de carbonate de calcium et de completer ensuite la decontamination en agitant le liquide avec une quantite convenable de boue stockee a partir d'operations precedentes. (auteurs)

Determination of arsenic antimony and selenium in water by neutron activation and coprecipitation with bismuth sulfide

International Nuclear Information System (INIS)

Bertini, L.M.; Cohen, I.M.

1984-01-01

A method was developed for determination of arsenic, antimony and selenium in water samples, based on neutron activation and separation by coprecipitation with bismuth sulfide. Experiments performed with the aid of radioactive tracers proved that As(III), Sb(III) and Se, either as Se(IV) or Se(VI), were quantitatively coprecipitated in 1.2 N HCl, provided they were present in masses larger than 10 ng, 50 ng, and 20 ng, respectively; 24 Na and 82 Br were collected at minimum percentages (0.5 and 2) when using hold-back carriers, whereas no appreciable coprecipitation of 32 P was observed. Interferences by other trace elements were also investigated, finding that they were negligible in most of the cases. The method was applied to the analysis of underground water samples from the province of Cordoba (Republica Argentina). The characteristics of this method and the results are discussed. 12 references, 2 tables

Coprecipitation experiment with Sm hydroxide using a multitracer produced by nuclear spallation reaction: A tool for chemical studies with superheavy elements

International Nuclear Information System (INIS)

Kasamatsu, Yoshitaka; Yokokita, Takuya; Toyomura, Keigo; Shigekawa, Yudai; Haba, Hiromitsu; Kanaya, Jumpei; Huang, Minghui; Ezaki, Yutaka; Yoshimura, Takashi; Morita, Kosuke; Shinohara, Atsushi

2016-01-01

To establish a new methodology for superheavy element chemistry, the coprecipitation behaviors of 34 elements with samarium hydroxide were investigated using multitracer produced by a spallation of Ta. The chemical reactions were rapidly equilibrated within 10 s for many elements. In addition, these elements exhibited individual coprecipitation behaviors, and the behaviors were qualitatively related to their hydroxide precipitation behaviors. It was demonstrated that the ammine and hydroxide complex formations of superheavy elements could be investigated using the established method. - Highlights: • We established a new methodology for superheavy element (SHE) chemistry. • Coprecipitation behaviors of 34 elements with Sm hydroxide could be simultaneously investigated by using multitracer. • The complex formations were investigated from the coprecipitation behaviors. • The established method will lead to the study on various precipitates of SHEs.

[Studies on hydroxyapatite applicatied in coprecipitate of total salvianolic acids phospholipid complex].

Science.gov (United States)

Chen, Xiao-Yun; Zhang, Zhen-Hai; Liu, Dan; Sun, E; Jia, Xiao-Bin

2014-03-01

The purpose of this research was to prepare total salvianolic acids-phytosome-HA coprecipitate to improve drug dissolution and its micromeritic properties. Firstly, the coprecipitate was prepared by solvent method and in vitro dissolution of tripterine was performed with the salvianolic acid B and danshensu as criteria. At the same time, the micromeritic properties was characterizated, the structure of samples was characterized by TEM, DSC, XRD and FTIR. Results showed that when the ratio of drug to HA was 1:2, it had a better dissolution, the accumulative drug-release percent in vitro at 60 min was over 90%. At the same time, it has good liquidity and low moisture absorption. Its micromeritic properties have improved. It is proved that the drug still existed amorphously by microstructure analysis. The preparation process is simple and feasible, it has practical value.

Coprecipitation of gold(III) complex ions with manganese(II) hydroxide and their stoichiometric reduction to atomic gold (Au(0)): analysis by Mössbauer spectroscopy and XPS.

Science.gov (United States)

Yamashita, Mamiko; Ohashi, Hironori; Kobayashi, Yasuhiro; Okaue, Yoshihiro; Kurisaki, Tsutomu; Wakita, Hisanobu; Yokoyama, Takushi

2008-03-01

To elucidate the formation process of precursor of gold-supported manganese dioxide (MnO2), the coprecipitation behavior of [AuCl4-n(OH)n](-) (n=0-4) (Au(III)) complex ions with manganese(II) hydroxide (Mn(OH)2 and the change in their chemical state were examined. The Au(III) complex ions were rapidly and effectively coprecipitated with Mn(OH)(2) at pH 9. According to the Mössbauer spectra for gold (Au) coprecipitated with Mn(OH)2, below an Au content of 60 wt% in the coprecipitates, all of the coprecipitated Au existed in the atomic state (Au(0)), while, above an Au content of 65 wt%, part of the gold existed in the Au(III) state, and the proportion increased with increasing coprecipitated Au content. Based on the results of X-ray photoelectron spectroscopy, Mn(II) in Mn(OH)2 converted to Mn(IV) in conjunction with coprecipitation of Au(III) complex ions. These results indicate that the rapid stoichiometric reduction of Au(III) to Au(0) is caused by electron transfer from Mn(II) in Mn(OH)2 to the Au(III) complex ion through an Mn-O-Au bond.

228Ra and 226Ra measurement on a BaSO4 co-precipitation source

International Nuclear Information System (INIS)

Medley, Peter; Martin, Paul; Bollhöfer, Andreas; Parry, David

2015-01-01

One of the most commonly-used methods for determination of 226 Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO 4 , followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO 4 co-precipitation methods which enable determination of 228 Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for 226 Ra, and can be used for re-analysis of already existing sources prepared by BaSO 4 co-precipitation. The first adaptation uses detection of 228 Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As 228 Ac grows in quickly, taking less than 2 days to reach equilibrium with the 228 Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO 4 sources, allowing separation of thorium and subsequent determination of 228 Th activity. Although ingrowth periods for 228 Th can be lengthy, very low detection limits for 228 Ra can be achieved with this technique. - Highlights: • We developed two methods for 228 Ra measurement on Ba(Ra)SO 4 co-precipitation sources. • Measurement by gamma spectrometry using the daughter 228 Ac is rapid. • Detection limits are suitable for assessment of drinking water quality. • The second approach uses alpha spectrometry on a separated Th fraction. • This is more sensitive than gamma spectrometry after an ingrowth period greater than about 1 month

Study of the radioactive liquid waste treatment by coprecipitation: from modelling to design of new processes

International Nuclear Information System (INIS)

Pacary, V.

2008-01-01

To decontaminate liquid nuclear wastes, the coprecipitation process is the most commonly used in nuclear field because it can be applied to any type of aqueous effluents whatever their composition may be. This process deals with the in situ precipitation of solid particles to selectively remove one or more radioelements. The aim of this PhD work is to investigate phenomena which take place during the coprecipitation of a trace component. To reach this objective, we have proposed a new modelling of the coprecipitation mechanism. The originality of this new approach lies in the possibility to simulate the phenomenon in non equilibrium conditions and at the reactor scale. This modelling combined with the resolution of the population balance, enable to identify the influence of process parameters (flowrates, stirring speed...) on crystal size and ultimately on decontamination. To test this new modelling, simulations of the coprecipitation of strontium ions with barium sulphate have been performed in continuous and semibatch reactors. Thanks to these simulations, laws of the treatment efficiency variation as a function of several process parameters (mean residence time, stirring speed, BaSO 4 concentration) have been determined and experimentally verified. This study leads to the determination of optimal treatment conditions. Three apparatus (recycling apparatus, fluidized bed and reactor/settling tank) providing these optimal conditions have been successfully tested and offered significant outlooks for the reduction of the volume of sludge produced by the process. Two new processes are patent pending. (author) [fr

Optimisation of parameters for co-precipitation of uranium and plutonium - results of simulation studies

International Nuclear Information System (INIS)

Pandey, N.K.; Velvandan, P.V.; Murugesan, S.; Ahmed, M.K.; Koganti, S.B.

1999-01-01

Preparation of plutonium oxide from plutonium nitrate solution generally proceeds via oxalate precipitation route. In a nuclear fuel reprocessing scheme this step succeeds the partitioning step (separation of uranium and plutonium). Results of present studies confirm that it is possible to avoid partitioning step and recover plutonium and uranium as co-precipitated product. This also helps in minimising the risk of proliferation of fissile material. In this procedure, the solubility of uranium oxalate in nitric acid is effectively used. Co-precipitation parameters are optimised with simulated solutions of uranium nitrate and thorium nitrate (in place of plutonium). On the basis of obtained results a reconversion flow-sheet is designed and reported here. (author)

Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

International Nuclear Information System (INIS)

Gyergyek, Sašo; Drofenik, Miha; Makovec, Darko

2012-01-01

Highlights: ► Synthesis of oleic-acid-coated CoFe 2 O 4 nanoparticles from an aqueous solution. ► During the co-precipitation of Co 2+ /Fe 3+ single-phase spinel forms. ► During the co-precipitation of Co 2+ /Fe 2+ , feroxyhyte forms in addition to spinel. ► Oleic acid increases the spinel formation temperature and limits particle growth. ► Colloidal suspensions of ferrimagnetic CoFe 2 O 4 were prepared. - Abstract: Oleic-acid-coated CoFe 2 O 4 nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism

Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

Energy Technology Data Exchange (ETDEWEB)

Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal [Department of Chemistry, Karadeniz Technical University, Faculty of Arts and Sciences, 61080 Trabzon (Turkey); Soylak, Mustafa [Department of Chemistry, Erciyes University, Faculty of Arts and Sciences, 38039 Kayseri (Turkey)], E-mail: soylak@erciyes.edu.tr

2009-01-19

A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H{sub 2}SO{sub 4} and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N = 10) was found 0.7 {mu}g L{sup -1}. The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.

Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

International Nuclear Information System (INIS)

Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal; Soylak, Mustafa

2009-01-01

A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H 2 SO 4 and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N = 10) was found 0.7 μg L -1 . The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values

Studies on the promotion of nickel—alumina coprecipitated catalysts: I. Titanium oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Mercera, P.D.L.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

A series of TiO2-promoted nickel—alumina catalysts has been prepared and characterized. The promoter was added in various proportions to a calcined coprecipitated nickel—alumina material by adsorption of the acetylacetonate complex of titanium, followed by further calcination and reduction. The

Synthesis of layered double hydroxides containing Mg2+, Zn2+, Ca2+ and Al3+ layer cations by co-precipitation methods-A review

Science.gov (United States)

Theiss, Frederick L.; Ayoko, Godwin A.; Frost, Ray L.

2016-10-01

Co-precipitation is a common method for the preparation of layered double hydroxides (LDHs) and related materials. This review article is aimed at providing newcomers to the field with some examples of the types of co-precipitation reactions that have been reported previously and to briefly investigate some of the properties of the products of these reactions. Due to the sheer volume of literature on the subject, the authors have had to limit this article to the synthesis of Mg/Al, Zn/Al and Ca/Al LDHs by co-precipitation and directly related methods. LDHs have been synthesised from various reagents including metal salts, oxides and hydroxides. Co-precipitation is also useful for the direct synthesis of LDHs with a wide range of interlayer anions and various bases have been successfully employed to prepare LDHs. Examples of other synthesis techniques including the urea method, hydrothermal synthesis and various mechanochemical methods that are undoubtedly related to co-precipitation have also been included in this review. The effect of post synthesis hydrothermal has also been summarised.

Dehydration-rehydration behaviour of zirconium hydroxide and aluminium hydroxide coprecipitated hydrogel

International Nuclear Information System (INIS)

Mitra, N.K.; Guha, P.; Basumajumdar, A.

1989-01-01

Equilibrium dehydration loss experiments on zirconium and aluminium hydroxide coprecipitated hyrogels were carried out up to 600deg and the above heat treated samples were subjected to rehydration at various humidities in order to study the structural flexibilties of the above hydrogel with respect to orientation of water molecules. (author). 6 refs., 3 tabs

Gas sensing properties of magnesium ferrite prepared by co-precipitation method

International Nuclear Information System (INIS)

Hankare, P.P.; Jadhav, S.D.; Sankpal, U.B.; Patil, R.P.; Sasikala, R.; Mulla, I.S.

2009-01-01

Polycrystalline magnesium ferrite (MgFe 2 O 4 ) was prepared by the co-precipitation method. The synthesized compound was characterized for their phase and morphology by X-ray diffraction and scanning electron microscopy, respectively. Conductance responses of the (MgFe 2 O 4 ) were measured towards gases like hydrogen sulfide (H 2 S), liquefied petroleum gas (LPG), ethanol vapors (C 2 H 5 OH), SO x , H 2 , NO x , NH 3, methanol, acetone and petrol. The gas sensing characterstics were obtained by measuring the sensitivity as a function of various controlling factors like operating temperatures and concentrations of gases. It was found that the sensor exhibited various responses towards these gases at different operating temperatures. Furthermore; the MgFe 2 O 4 based sensor exhibited a fast response and a good recovery towards petrol at temperature 250 deg. C. The results of the response towards petrol reveal that (MgFe 2 O 4 ) synthesized by a simple co-precipitation method, would be a suitable material for the fabrication of the petrol sensor.

Laboratory study on coprecipitation of phosphate with ikaite in sea ice

Science.gov (United States)

Hu, Yu-Bin; Dieckmann, Gerhard S.; Wolf-Gladrow, Dieter A.; Nehrke, Gernot

2014-10-01

Ikaite (CaCO3·6H2O) has recently been discovered in sea ice, providing first direct evidence of CaCO3 precipitation in sea ice. However, the impact of ikaite precipitation on phosphate (PO4) concentration has not been considered so far. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105, temperatures from -4°C to 0°C, and PO4 concentrations from 5 to 50 µmol kg-1 in artificial sea ice brine so as to understand how ikaite precipitation affects the PO4 concentration in sea ice under different conditions. Our results show that PO4 is coprecipitated with ikaite under all experimental conditions. The amount of PO4 removed by ikaite precipitation increases with increasing pH. Changes in salinity (S ≥ 35) as well as temperature have little impact on PO4 removal by ikaite precipitation. The initial PO4 concentration affects the PO4 coprecipitation. These findings may shed some light on the observed variability of PO4 concentration in sea ice.

Coprecipitated nickel-alumina methanation catalysts

International Nuclear Information System (INIS)

Kruissink, E.C.

1981-01-01

In the last few years there has been a renewed interest in the methanation reaction CO+3H 2 =CH 4 +H 2 O. The investigations described in this thesis were performed in relation to the application of this reaction, within the framework of the so-called 'NFE' project, also called 'ADAM' and 'EVA' project. This project, which has been under investigation in West Germany for some years, aims at the investigation of the feasibility of transporting heat from a nuclear high temperature reactor by means of a chemical cycle. A promising possibility to realize such a cycle exists in applying the combination of the endothermic steam reforming of methane and the exothermic methanation reaction. This thesis describes the investigations into a certain type of methanation catalyst, viz. a coprecipitated nickel-alumina catalyst, with the aim to give more insight into the interrelationship between the preparation conditions on the one hand and catalyst properties such as activity and stability on the other hand. (Auth.)

Production of mixed oxide fuel for fast reactor irradiation test by co-precipitation

International Nuclear Information System (INIS)

Todokoro, Akio; Masuda, Sumio; Naruki, Kaoru; Kaya, Akira; Koizumi, Masumichi

1974-01-01

Studies were made on the production of homogeneous mixed oxide by co-precipitation. Experiments were made on the effects of the addition rate of ammonia water, precipitation temperature, aging time of co-precipitate, and pH value. Plutonium refined by anion exchange was mixed with solution of uranium. The concentration of free acid in the mixed solution was adjusted to 1.5-2.0 M, and the total volume of the solution was made 3.01. The weight of Pu and U in the solution was 100g. The solution was kept at a definite temperature while being stirred. Concentrated ammonia solution was added to the solution at a definite rate. The precipitate thus formed was filtrated after aging, then dried for 24 hours at 100 +- 2 0 C. Dried co-precipitate was calcinated for 1 hr at 550 0 C. The reduction for 4 hours at 800 0 C gave the mixed powder of PuO 2 and UO 2 . After pressing, the powder was sintered for 2 hours at 1700 0 C. The shrinkage ratio decreased as the activity and tap density of the original powder increased. The activity determined by specific surface area increased as the rate of ammonia water addition increased, and as the precipitation temperature rose. Tap density was independent of the rate of addition of ammonia water. The activity of the powder increased and the tap density decreased as the aging time of precipitate increased. (Fukutomi, T.)

Gadolinium-doped ceria nanopowders synthesized by urea-based homogeneous co-precipitation (UBHP)

Energy Technology Data Exchange (ETDEWEB)

Accardo, G., E-mail: d16605@kist.re.kr [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Spiridigliozzi, L. [Department of Civil and Mechanical Engineering, INSTM Research Unit, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR (Italy); Cioffi, R.; Ferone, C. [Department of Engineering, INSTM Research Unit, University Parthenope of Naples, Centro Direzionale, Is. C4, 80143 Napoli (Italy); Di Bartolomeo, E. [Department of Chemical Science and Technology, University of Rome “Tor Vergata”, Viale della Ricerca Scientifica, 00133 Rome (Italy); Yoon, Sung Pil [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Dell’Agli, G. [Department of Civil and Mechanical Engineering, INSTM Research Unit, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR (Italy)

2017-02-01

Gadolinium (10%)-doped ceria was successfully synthesized by using an urea-based co-precipitation method (UBHP). A single fluorite phase was obtained after a low temperature (400 °C) calcination treatment. The resulting powders showed grains of nanometric size with some agglomerations and an overall good sinterability. Pellets were sintered at 1300 and 1500 °C for 3 h. The ionic conductivity was measured by electrochemical impedance spectroscopy measurements and a correlation between electrical properties and microstructure was revealed. The promising conductivity values showed that the synthesized powders are suitable for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications. - Highlights: • Urea-based homogeneous co-precipitation is applied to synthesize nanocrystalline GDC. • Dense GDC samples at different sintering temperatures were characterized. • SEM and TEM revealed a well define microstructure and controlled composition. • Correlation between electrochemical properties by EIS and microstructure was discussed. • UBHP method can be used to prepare high performance GDC electrolytes.

Coprecipitation synthesis of zinc ferrit (FE 2 O 3 /ZNO) nanoparticles ...

African Journals Online (AJOL)

Zinc ferrite (Fe2O3/ZnO) nanocomposites were successfully synthesized by simple co-precipitation method via iron (III) nitrate 9-hydrate (Fe(NO3)3.9H2O) and zinc nitrate hexahydrate (Zn(NO3)2.6H2O) as precursor in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The samples were characterized by ...

An electroluminescence device for printable electronics using coprecipitated ZnS:Mn nanocrystal ink

International Nuclear Information System (INIS)

Toyama, T; Hama, T; Adachi, D; Nakashizu, Y; Okamoto, H

2009-01-01

Electroluminescence (EL) devices for printable electronics using coprecipitated ZnS:Mn nanocrystal (NC) ink are demonstrated. The EL properties of these devices were investigated along with the structural and optical properties of ZnS:Mn NCs with an emphasis on their dependence on crystal size. Transmission electron microscopy and x-ray diffraction studies revealed that the NCs, with a crystal size of 3-4 nm, are nearly monodisperse; the crystal size can be controlled by the Zn 2+ concentration in the starting solution for coprecipitation. The results of optical studies indicate the presence of quantum confinement effects; in addition, the NC surfaces are well passivated, regardless of the crystal size. Finally, an increase in the luminance of EL devices with a decrease in crystal size is observed, which suggests the excitation mechanism of ZnS:Mn NC EL devices.

Mechanisms of Se(IV) Co-precipitation with Ferrihydrite at Acidic and Alkaline Conditions and Its Behavior during Aging

DEFF Research Database (Denmark)

Francisco, Paul Clarence M.; Sato, Tsutomu; Otake, Tsubasa

2018-01-01

in nanopore and defect structures. These results demonstrate a potential long-term immobilization pathway for Se(IV) even after phase transformation. This work presents one of the first direct insights on Se(IV) co-precipitation and its behavior in response to iron phase transformations.......Understanding the form of Se(IV) co-precipitated with ferrihydrite and its subsequent behavior during phase transformation is critical to predicting its long-term fate in a range of natural and engineered settings. In this work, Se(IV)-ferrihydrite co-precipitates formed at different pH were......, Se(IV) was removed dominantly as a ferric selenite-like phase intimately associated with ferrihydrite, while at pH 10, it was mostly present as a surface species on ferrihydrite. Similarly, the behavior of Se(IV) and the extent of its retention during phase transformation varied with pH. At pH 5, Se...

Studies on the promotion of nickel—alumina coprecipitated catalysts: II. Lanthanum oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Paalman, R.P.A.M.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

Two series of lanthanum promoted nickel—alumina catalysts have been prepared by coprecipitation of the metal nitrates, using potassium carbonate. The molar ratio between nickel and the sum of aluminium and lanthanum was kept constant at 2.5 or 9.0 within each series. The calcination and reduction of

Coprecipitation of yttrium and aluminium hydroxide for preparation of yttrium aluminium garnet

NARCIS (Netherlands)

Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.

1990-01-01

Coprecipitation of yttrium and aluminium hydroxide for the preparation of pure yttrium aluminium garnet (YAG) powder with small grain size is the subject of this study. Starting materials are sulphates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3Al5O12), the pH during flocculation

Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater

Directory of Open Access Journals (Sweden)

Rodrigo Alarcón

2014-07-01

Full Text Available Sea level rise is able to change the geochemical conditions in coastal systems. In these environments, transport of contaminants can be controlled by the stability and adsorption capacity of iron oxides. The behavior of adsorbed and co-precipitated arsenic in jarosite, schwertmannite, ferrihydrite, and goethite in sea water (common secondary minerals in coastal tailings was investigated. The aim of the investigation was to establish As retention and transport under a marine flood scenario, which may occur due to climate change. Natural and synthetic minerals with co-precipitated and adsorbed As were contacted with seawater for 25 days. During this period As, Fe, Cl, SO4, and pH levels were constantly measured. The larger retention capability of samples with co-precipitated As, in relation with adsorbed As samples, reflects the different kinetics between diffusion, dissolution, and surface exchange processes. Ferrihydrite and schwertmannite showed good results in retaining arsenic, although schwertmannite holding capacity was enhanced due its buffering capacity, which prevented reductive dissolution throughout the experiment. Arsenic desorption from goethite could be understood in terms of ion exchange between oxides and electrolytes, due to the charge difference generated by a low point-of-zero-charge and the change in stability of surface complexes between synthesis conditions and natural media.

Co-precipitation synthesis of YAG:Dy nanophosphor and its thermometric properties

International Nuclear Information System (INIS)

Chong, Joo-Yun; Zhang, Yuelan; Wagner, Brent K.; Kang, Zhitao

2013-01-01

Highlights: •YAG:Dy nanophosphors were synthesized with particle size of about 50 nm. •Optimized doping concentration of 6%Dy was determined. •Thermometric photoluminescence properties were studied between 20 and 350 °C. •Temperature-sensitive change in peak ratio of 496/457 nm emissions was demonstrated. •Suitable for potential thermographic applications when dispersed in a liquid media. -- Abstract: Dy 3+ doped yttrium aluminum garnet (YAG) nanophosphors were synthesized by a co-precipitation method for potential thermographic applications in a liquid media dispersed with fluorescent nanoparticles. The doping concentration and annealing temperature on the structural and optical properties of YAG:Dy were investigated. Pure phase YAG:Dy nanophosphors were obtained by annealing the co-precipitated hydroxide products at above 900 °C. Maximum photoluminescence intensity was observed from 6%Dy doped YAG samples. The effect of measuring temperature between 20 and 350 °C on the photoluminescence spectra of nano YAG:Dy was investigated. A temperature-sensitive change in the peak intensity ratio of 496/457 nm emission lines was demonstrated for such nanophosphors for the first time, suggesting potential applications in temperature monitoring of fuel spray

Co-precipitation synthesis of YAG:Dy nanophosphor and its thermometric properties

Energy Technology Data Exchange (ETDEWEB)

Chong, Joo-Yun [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Zhang, Yuelan [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wagner, Brent K. [Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Kang, Zhitao, E-mail: zhitao.kang@gtri.gatech.edu [Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, GA 30332 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2013-12-25

Highlights: •YAG:Dy nanophosphors were synthesized with particle size of about 50 nm. •Optimized doping concentration of 6%Dy was determined. •Thermometric photoluminescence properties were studied between 20 and 350 °C. •Temperature-sensitive change in peak ratio of 496/457 nm emissions was demonstrated. •Suitable for potential thermographic applications when dispersed in a liquid media. -- Abstract: Dy{sup 3+} doped yttrium aluminum garnet (YAG) nanophosphors were synthesized by a co-precipitation method for potential thermographic applications in a liquid media dispersed with fluorescent nanoparticles. The doping concentration and annealing temperature on the structural and optical properties of YAG:Dy were investigated. Pure phase YAG:Dy nanophosphors were obtained by annealing the co-precipitated hydroxide products at above 900 °C. Maximum photoluminescence intensity was observed from 6%Dy doped YAG samples. The effect of measuring temperature between 20 and 350 °C on the photoluminescence spectra of nano YAG:Dy was investigated. A temperature-sensitive change in the peak intensity ratio of 496/457 nm emission lines was demonstrated for such nanophosphors for the first time, suggesting potential applications in temperature monitoring of fuel spray.

Aluminum Coprecipitates with Fe (hydr)oxides: Does Isomorphous Substitution of Al3plus for Fe3plus in Goethite Occur

Energy Technology Data Exchange (ETDEWEB)

E Bazilevskaya; D Archibald; M Aryanpour; J Kubicki; C Martinez

2011-12-31

Iron (hydr)oxides are common in natural environments and typically contain large amounts of impurities, presumably the result of coprecipitation processes. Coprecipitation of Al with Fe (hydr)oxides occurs, for example, during alternating reduction-oxidation cycles that promote dissolution of Fe from Fe-containing phases and its re-precipitation as Fe-Al (hydr)oxides. We used chemical and spectroscopic analyses to study the formation and transformation of Al coprecipitates with Fe (hydr)oxides. In addition, periodic density functional theory (DFT) computations were performed to assess the structural and energetic effects of isolated or clustered Al atoms at 8 and 25 mol% Al substitution in the goethite structure. Coprecipitates were synthesized by raising the pH of dilute homogeneous solutions containing a range of Fe and Al concentrations (100% Fe to 100% Al) to 5. The formation of ferrihydrite in initial suspensions with {<=}20 mol% Al, and of ferrihydrite and gibbsite in initial suspensions with {>=}25 mol% Al was confirmed by infrared spectroscopic and synchrotron-based X-ray diffraction analyses. While base titrations showed a buffer region that corresponded to the hydrolysis of Fe in initial solutions with {<=}25 mol% Al, all of the Al present in these solutions was retained by the solid phases at pH 5, thus indicating Al coprecipitation with the primary Fe hydroxide precipitate. In contrast, two buffer regions were observed in solutions with 30 mol% Al (at pH {approx}2.25 for Fe{sup 3+} and at pH {approx}4 for Al{sup 3+}), suggesting the formation of Fe and Al (hydr)oxides as two separate phases. The Al content of initial coprecipitates influenced the extent of ferrihydrite transformation and of its transformation products as indicated by the presence of goethite, hematite and/or ferrihydrite in aged suspensions. DFT experiments showed that: (i) optimized unit cell parameters for Al-substituted goethites (8 and 25 Mol% Al) in clustered arrangement (i.e., the

Purification of alkaline solutions and wastes from actinides and technetium by coprecipitation with some carriers using the method of appearing reagents: Final Report

International Nuclear Information System (INIS)

Peretrukhin, V.F.; Silin, V.I.; Kareta, A.V.; Gelis, A.V.; Shilov, V.P.; German, K.E.; Firsova, E.V.; Maslennikov, A.G.; Trushina, V.E.

1998-09-01

The coprecipitation of transuranium elements (TRU) and technetium from alkaline solutions and from simulants of Hanford Site tank wastes has been studied in reducing and oxidizing conditions on uranium(IV,VI) hydroxocompounds, tetraalkylammonium perrhenate and perchlorate, and on hydroxides of Fe(III), Co(III), Mn(II), and Cr(III) using the method of appearing reagents (MAR). Coprecipitations in alkaline solution have been shown to give high decontamination factors (DF) at low content of carrier and in the presence of high salt concentrations. Uranium(IV) hydroxide in concentrations higher than 3 x 10 -3 M coprecipitates Pu and Cm in any oxidation state from 0.2 to 4 M NaOH with DFs of 110 to 1000 and Np and Tc with DFs of 51 to 176. Technetium (VII) coprecipitates with (5 to 8) x 10 -4 M tetrabutylammonium (TBA) perrhenate in 0.01 to 0.02 M TBA hydroxide from 0.5 to 1.5 M NaOH to give DFs of 150 to 200. Coprecipitations of Np and Pu with Co(OH) 3 , Fe(OH) 3 , Cr(OH) 3 , and Mn(OH) 2 obtained by the MAR from precursors in the range from pH 10.5 to 0.4 M NaOH give DFs from 80 to 400

Low temperature synthesis of nanocrystalline lanthanum monoaluminate powders by chemical coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Kuo, C.-L. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, C.-L. [Department of Materials Science and Engineering, I-Shou University, 1 Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung 840, Taiwan (China); Chen, T.-Y. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Chen, G.-J. [Department of Materials Science and Engineering, I-Shou University, 1 Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung 840, Taiwan (China); Hung, I-M. [Department of Chemical Engineering and Materials Science, Yuan Ze University, 135 Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan (China); Shih, C.-J. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China)]. E-mail: CJShih@kmu.edu.tw; Fung, K.-Z. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China)

2007-08-16

Nanocrystalline lanthanum monoaluminate (LaAlO{sub 3}) powders were prepared by chemical coprecipitation using 25 vol.% of NH{sub 4}OH, 0.05 M La(NO{sub 3}){sub 3}.6H{sub 2}O and 0.05 M Al(NO{sub 3}){sub 3}.9H{sub 2}O aqueous solutions as the starting materials. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffraction (XRD), Raman spectrometry, specific surface area (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) were utilized to characterize the LaAlO{sub 3} powders prepared by chemical coprecipitation. The crystallization temperature of the LaAlO{sub 3} precursor gels precipitated at pH 9 is estimated as 810 deg. C by TG/DTA. The XRD pattern of the LaAlO{sub 3} precursor gels precipitated at pH 8-12 and calcined at 700 deg. C for 6 h shows a broad arciform continuum exist between 24{sup o} and 32{sup o} and sharp peaks of LaAlO{sub 3} except the precursor gels precipitated at pH 9. For the LaAlO{sub 3} precursor gels precipitated at pH 9 and calcined at 700 deg. C for 6 h, the formation of the perovskite LaAlO{sub 3} phase occurs and the presence of crystalline impurities is not found. The crystallite size of LaAlO{sub 3} slightly increases from 37.8 to 41.5 nm with calcination temperature increasing from 700 to 900 deg. C for 6 h. The LaAlO{sub 3} powders prepared by chemical coprecipitation have a considerably large specific surface of 30 m{sup 2}/g. The relative density greater than 97% is obtained when these nanocrystalline LaAlO{sub 3} powders are sintered at 1550 deg. C for 2 h.

Design and implementation of an intensified coprecipitation reactor for the treatment of liquid radioactive wastes

International Nuclear Information System (INIS)

Flouret, Julie; Barre, Yves; Muhr, Herve; Plasari, Edouard

2013-01-01

The coprecipitation is a robust and inexpensive process for the treatment of important volumes of low and intermediate radioactive level liquid wastes. Its major inconvenient is the huge volume of sludge generated. The purpose of this work is to optimize the industrial coprecipitation continuous process by achieving the following objectives: - maximize the decontamination efficiency; - minimize the volume of sludge generated by the process; - reduce the treatment cost decreasing the installation volume. An innovative reactor with an infinite recycling ratio was therefore designed. It is a multifunctional reactor composed of two zones: a perfectly mixed precipitation zone and a classifier to perform liquid-solid separation. The experiments are focused on the coprecipitation of strontium by barium sulphate. The effluent containing sulphate ions and the barium nitrate solution are injected in the reaction zone where strontium and barium co-precipitate as sulphates. The produced solid phase is returned into the reaction zone by the classifier and goes out slowly from the reactor bottom with a residence time much higher than the liquid phase. This creates both a high concentration of solid phase in the reaction zone and a high efficiency of decontamination. The experimental conditions simulate the industrial effluents. The total treatment flow rate is 17 L/h, with an effluent flow rate of 16 L/h and a reactive flow rate of 1 L/h, hence a mean residence time of 10 minutes. In these experimental conditions, the molar ratio sulphate/barium after mixing corresponds to 4.9. These conditions are used in the reprocessing plant of La Hague. The decontamination factor reached in these experimental conditions is excellent: DF = 1500. The decontamination factor obtained with the classical continuous process is only equal to 60. Different process parameters are studied in order to optimize the reactor/classifier: residence time, barium nitrate flow rate and racking flow rate. The

Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

International Nuclear Information System (INIS)

Krot, N.; Shilov, V.; Bessonov, A.; Budantseva, N.; Charushnikova, I.; Perminov, V.; Astafurova, L.

1996-06-01

Highly alkaline radioactive waste solutions originating from production of plutonium for military purposes are stored in underground tanks at the U.S. Department of Energy Hanford Site. The purification of alkaline solutions from neptunium and plutonium is important in the treatment and disposal of these wastes. This report describes scoping tests with sodium hydroxide solutions, where precipitation techniques were investigated to perform the separation. Hydroxides of iron (III), manganese (II), cobalt (II, III), and chromium (III); manganese (IV) oxide, and sodium uranate were investigated as carriers. The report describes the optimum conditions that were identified to precipitate these carriers homogeneously throughout the solution by reductive, hydrolytic, or catalytic decomposition of alkali-soluble precursor compounds by a technique called the Method of Appearing Reagents. The coprecipitation of pentavalent and hexavalent neptunium and plutonium was investigated for the candidate agents under optimum conditions and is described in this report along with the following results. Plutonium coprecipitated well with all tested materials except manganese (IV) oxide. Neptunium only coprecipitated well with uranate. The report presents a hypothesis to explain these behaviors. Further tests with more complex solution matrices must be performed

Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

Energy Technology Data Exchange (ETDEWEB)

Krot, N.; Shilov, V.; Bessonov, A.; Budantseva, N.; Charushnikova, I.; Perminov, V.; Astafurova, L. [Russian Academy of Science (Russian Federation). Inst. of Physical Chemistry

1996-06-06

Highly alkaline radioactive waste solutions originating from production of plutonium for military purposes are stored in underground tanks at the U.S. Department of Energy Hanford Site. The purification of alkaline solutions from neptunium and plutonium is important in the treatment and disposal of these wastes. This report describes scoping tests with sodium hydroxide solutions, where precipitation techniques were investigated to perform the separation. Hydroxides of iron (III), manganese (II), cobalt (II, III), and chromium (III); manganese (IV) oxide, and sodium uranate were investigated as carriers. The report describes the optimum conditions that were identified to precipitate these carriers homogeneously throughout the solution by reductive, hydrolytic, or catalytic decomposition of alkali-soluble precursor compounds by a technique called the Method of Appearing Reagents. The coprecipitation of pentavalent and hexavalent neptunium and plutonium was investigated for the candidate agents under optimum conditions and is described in this report along with the following results. Plutonium coprecipitated well with all tested materials except manganese (IV) oxide. Neptunium only coprecipitated well with uranate. The report presents a hypothesis to explain these behaviors. Further tests with more complex solution matrices must be performed.

Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

Science.gov (United States)

Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

2017-01-01

This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l -1 . Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L -1 . The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

Thorium coprecipitation method for spectrophotometric determination of arsenic (III) and arsenic (V) in groundwaters

International Nuclear Information System (INIS)

Tamari, Yuzo; Yamamoto, Nobuki; Tsuji, Haruo; Kusaka, Yuzuru

1989-01-01

A new coprecipitation method for the spectrophotometry of arsenic (III) and arsenic (V) in groundwater has been developed. Arsenic (III) and arsenic (V) were coprecipitated with thorium (IV) hydroxide from 1000ml of groundwater at pH9. The precipitate was centrifuged and then dissolved with hydrochloric acid. Arsenic (III) was spectrophotometrically determined by the usual silver diethylditiocarbamate (Ag-DDTC) method after generating the arsenic to arsine with sodium tetrahydroborate under masking the thorium with EDTA-NaF at pH6. From another portion of the same groundwater, both arsenic (III) and arsenic (V) were determined by the Ag-DDTC method after reducing all the arsenic to arsine with sodium tetrahydroborate at pH less than 1 in the presence of the EDTA-NaF. The concentration of arsenic (V) was obtained by subtracting that of arsenic (III) from the total for arsenic. (author)

On preparation of nanocrystalline chromites by co-precipitation and autocombustion methods

Energy Technology Data Exchange (ETDEWEB)

Matulkova, Irena [Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2 (Czech Republic); Department of Radiation and Chemical Physics, Institute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Holec, Petr [Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2 (Czech Republic); Department of Materials Chemistry, Institute of Inorganic Chemistry of the ASCR, v.v i., Husinec-Rez 1001, 250 68 Rez (Czech Republic); Pacakova, Barbara; Kubickova, Simona; Mantlikova, Alice [Department of Magnetic Nanosystems, Institute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Plocek, Jiri [Department of Materials Chemistry, Institute of Inorganic Chemistry of the ASCR, v.v i., Husinec-Rez 1001, 250 68 Rez (Czech Republic); Nemec, Ivan; Niznansky, Daniel [Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2 (Czech Republic); Vejpravova, Jana, E-mail: vejpravo@fzu.cz [Department of Magnetic Nanosystems, Institute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic)

2015-05-15

Highlights: • ACr{sub 2}O{sub 4} nanopowders, A = Cu, Fe, Ni, Mn and Mg were obtained in high yield. • Co-precipitation and autocombustion routes were optimized for single-phase product. • The nanopowders were examined by X-ray diffraction and vibrational spectroscopy. • Formation of cubic or tetragonal phase in Jahn–Teller NiCr{sub 2}O{sub 4} can be controlled. - Abstract: We present a comprehensive study on optimization of wet preparation routes yielding well-crystalline spinel chromite, ACr{sub 2}O{sub 4} nanoparticles (A = Cu, Fe, Ni, Mn and Mg). The auto-combustion and co-precipitation methods in the presence of nitrate or chloride ions and under different atmospheres, followed by annealing of final products at different temperatures were tested. All samples were characterized by powder X-ray diffraction (PXRD) and vibrational spectroscopy in order to evaluate their phase composition, particle size and micro-strain. Selected samples were subjected to investigation by transmission electron microscopy (TEM). The degree of the particle crystallinity was estimated by relating the apparent crystallite size obtained from the PXRD analysis to the physical grain size observed by the TEM. Optimal conditions leading to single-phase and highly-crystalline chromite nanoparticles are proposed.

The coprecipitation of strontium with hydroxyapatite

International Nuclear Information System (INIS)

Fujino, Osamu

1975-01-01

The distribution behavior of the strontium ion between hydroxyapatite and the parent solution was investigated. The hydroxyapatite was formed by the extremely slow addition of diammonium hydrogenphosphate to solutions of calcium and strontium nitrate buffered with ethylenediamine at 80 0 C. The precipitate yielded a typical X-ray diffraction pattern of hydroxyapatite and had a composition in which the Ca/P molar ratio was 1.67 at pH 6.80. The strontium ion was coprecipitated in the apatite, obeying the Doerner and Hoskins logarithnmic distribution law. The distribution coefficient was scarcely affected by the strontium concentration on the pH value in the parent solution, and had a value of 0.26+-0.02 at 80 0 C. On the other hand, the apparent distribution coefficient was a little affected by such organic anions as acetate, citrate, lactate, glycinate, and glutamate ions. The lattice constants of the precipitates prepared in the research were measured in order to confirm the formation of the solid solutions. (auth.)

Synthesis and characterization of laurate-intercalated Mg–Al layered double hydroxide prepared by coprecipitation

DEFF Research Database (Denmark)

Gerds, Nathalie Christiane; Katiyar, Vimal; Koch, Christian Bender

2012-01-01

Effective utilization of layered double hydroxides (LDH) for industrial applications requires the synthesis of pure and well-defined LDH phases. In the present study, dodecanoate (laurate) anions were intercalated into Mg–Al-layered double hydroxide (LDH-C12) by coprecipitation in the presence of...

Synthesis of [Zn-Al-CO 3] layered double hydroxides by a coprecipitation method under steady-state conditions

Science.gov (United States)

Chang, Z.; Evans, D. G.; Duan, X.; Vial, C.; Ghanbaja, J.; Prevot, V.; de Roy, M.; Forano, C.

2005-09-01

A continuous co-precipitation method under steady-state conditions has been investigated for the preparation of nanometer-size layered double hydroxide (LDH) particles using Zn 2Al(OH) 6(CO 3) 0.5·2H 2O as a prototype. The objective was to shorten the preparation time by working without an aging step, using a short and controlled residence time in order to maintain a constant supersaturation level in the reactor and constant particle properties in the exit stream over time. The effects of varying the operating conditions on the structural and textural properties of the LDHs have been studied, including total cation concentration, solvent, residence time, pH and intercalation anion. The products have been characterized using ICP, XRD, FTIR, BET, SEM and TEM. The LDHs prepared by the continuous coprecipitation method have a poorer crystallinity and lower crystallite sizes than those synthesized by the conventional batch method. The results have shown that increasing either cation concentration or the fraction of monoethylene glycol (MEG) in MEG/H 2O mixtures up to 80% (v/v) affect salt solubility and supersaturation, which gives rise to smaller crystallites, larger surface areas and more amorphous compounds. This increase is however limited by the precipitation of zinc and aluminum hydroxides occurring around a total cation concentration of 3.0×10 -1 M in pure water and 3.0×10 -2 M in H 2O/EtOH mixtures. Crystallite size increases with residence time, suggesting a precipitation process controlled by growth. Finally, the continuous coprecipitation method under steady-state conditions has been shown to be a promising alternative to the traditional coprecipitation technique in either pure water or mixed H 2O/MEG solvents.

Immobilization of Hg(II) by Coprecipitation in Sulfate-Cement Systems

Science.gov (United States)

2012-01-01

Uptake and molecular speciation of dissolved Hg during formation of Al- or Fe-ettringite-type and high-pH phases were investigated in coprecipitation and sorption experiments of sulfate-cement treatments used for soil and sediment remediation. Ettringite and minor gypsum were identified by XRD as primary phases in Al systems, whereas gypsum and ferrihydrite were the main products in Hg–Fe precipitates. Characterization of Hg–Al solids by bulk Hg EXAFS, electron microprobe, and microfocused-XRF mapping indicated coordination of Hg by Cl ligands, multiple Hg and Cl backscattering atoms, and concentration of Hg as small particles. Thermodynamic predictions agreed with experimental observations for bulk phases, but Hg speciation indicated lack of equilibration with the final solution. Results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt in ettringite as the primary immobilization mechanism. In Hg–Fe solids, structural characterization indicated Hg coordination by O atoms only and Fe backscattering atoms that is consistent with inner-sphere complexation of Hg(OH)20 coprecipitated with ferrihydrite. Precipitation of ferrihydrite removed Hg from solution, but the resulting solid was sufficiently hydrated to allow equilibration of sorbed Hg species with the aqueous solution. Electron microprobe XRF characterization of sorption samples with low Hg concentration reacted with cement and FeSO4 amendment indicated correlation of Hg and Fe, supporting the interpretation of Hg removal by precipitation of an Fe(III) oxide phase. PMID:22594782

Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

NARCIS (Netherlands)

Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

2008-01-01

Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

Synthesis, characterization, and Fischer–Tropsch performance of cobalt/zinc aluminate nanocomposites via a facile and corrosion-free coprecipitation route

International Nuclear Information System (INIS)

Liu, Zhenxin; Xing, Yu; Xue, Yingying; Wu, Depeng; Fang, Shaoming

2015-01-01

Literature about ZnAl 2 O 4 -supported cobalt Fischer–Tropsch synthesis (FTS) catalytic materials is sparse. A series of cobalt-containing nanocomposites, supported by nanosized ZnAl 2 O 4 spinel (i.e., a complex oxide of about 6.4 nm) or alumina (i.e., a simple oxide of about 6.2 nm), were prepared via urea-gelation, coprecipitation, or impregnation methods followed by stepwise reduction. These materials were examined by XRD, TGA, nitrogen sorption, FESEM, and EDS. Effects of corrosion and pore size distributions on materials preparation were also investigated. The “coprecipitation/stepwise reduction” route is facile and suitable to prepare nanosized ZnAl 2 O 4 -supported Co 0 nanocomposites. At similar CO conversions, the coprecipitated Co/ZnAl 2 O 4 exhibits significantly lower C 1 hydrocarbon distribution, slightly lower C 5+ hydrocarbon distribution, significantly higher C 2 –C 4 hydrocarbon distribution, and significantly higher olefin/paraffin ratio of C 2 –C 4 than Co/γ-Al 2 O 3

Coprecipitation of arsenate with metal oxides. 3. Nature, mineralogy, and reactivity of iron(III)-aluminum precipitates.

Science.gov (United States)

Violante, Antonio; Pigna, Massimo; Del Gaudio, Stefania; Cozzolino, Vincenza; Banerjee, Dipanjan

2009-03-01

Coprecipitation involving arsenic with aluminum or iron has been studied because this technique is considered particularly efficient for removal of this toxic element from polluted waters. Coprecipitation of arsenic with mixed iron-aluminum solutions has received scant attention. In this work we studied (i)the mineralogy, surface properties, and chemical composition of mixed iron-aluminum oxides formed at initial Fe/Al molar ratio of 1.0 in the absence or presence of arsenate [As/ Fe+Al molar ratio (R) of 0, 0.01, or 0.1] and at pH 4.0, 7.0, and 10.0 and aged for 30 and 210 days at 50 degrees C and (ii) the removal of arsenate from the coprecipitates after addition of phosphate. The amounts of short-range ordered precipitates (ferrihydrite, aluminous ferrihydrite and/or poorly crystalline boehmite) were greater than those found in iron and aluminum systems (studied in previous works), due to the capacity of both aluminum and arsenate to retard or inhibitthe transformation of the initially formed precipitates into well-crystallized oxides (gibbsite, bayerite, and hematite). As a consequence, the surface areas of the iron-aluminum oxides formed in the absence or presence of arsenate were usually much larger than those of aluminum or iron oxides formed under the same conditions. Arsenate was found to be associated mainly into short-range ordered materials. Chemical composition of all samples was affected by pH, initial R, and aging. Phosphate sorption was facilitated by the presence of short-range ordered materials, mainly those richer in aluminum, but was inhibited by arsenate present in the samples. The quantities of arsenate replaced by phosphate, expressed as percentages of its total amount present in the samples, were particularly low, ranging from 10% to 26%. A comparison of the desorption of arsenate by phosphate from aluminum-arsenate and iron-arsenate (studied in previous works) and iron-aluminum-arsenate coprecipitates evidenced that phosphate has a greater

Thermoluminescence and photoluminescence properties of NaCl:Mn, NaCL:Cu nano-particles produced using co-precipitation and sono-chemistry methods

Energy Technology Data Exchange (ETDEWEB)

Mehrabi, M. [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Zahedifar, M. [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Saeidi-Sogh, Z. [Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Ramazani-Moghaddam-Arani, A., E-mail: ramazmo@kashanu.ac.ir [Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Sadeghi, E. [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Harooni, S. [Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of)

2017-02-21

The NaCl: Cu and NaCl: Mn nanoparticles (NPs) were produced by co-precipitation and sono-chemistry methods and their thermoluminescence (TL) and photoluminescence (PL) properties were studied. By decreasing the particles size a considerable increase in sensitivity of the samples to high dose gamma radiation was observed. The NPs produced by sono-chemistry method have smaller size, homogeneous structure, more sensitivity to high gamma radiation and less fading than of those produced by co-precipitation method.

Electrochemical performance of multi-element doped α-nickel hydroxide prepared by supersonic co-precipitation method

International Nuclear Information System (INIS)

Zhang, Z.J.; Zhu, Y.J.; Bao, J.; Lin, X.R.; Zheng, H.Z.

2011-01-01

Highlights: → The α-nickel hydroxides doped with several elements were prepared by supersonic co-precipitation method. → Cyclic voltammetry and electrochemical impedance spectroscopy show sample C has the best electrochemical performance. → The charge/discharge tests show that the 0.5 C discharge capacity (346 mAh/g) of sample C is even larger than that (337 mAh/g) at 0.1 C rate, while the discharge capacity at 0.5 C rate is much lower than that at 0.1 C rate for samples A and B. - Abstract: The multi-element doped α-nickel hydroxides have been prepared by supersonic co-precipitation method. Three kinds of samples A, B, C were prepared by chemically coprecipitating Ni, Al, Co, Y, Zn. It was found that sample C produced better performance than the others. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements indicated that sample C has better electrochemical performance, such as better reaction reversibility, higher proton diffusion coefficient and lower charge-transfer resistance, than those of samples A and B. The charge-discharge tests showed that the discharge capacity (346 mA h/g) of sample C is even larger at 0.5 C rate than that (337mAh/g) at 0.1 C rate, while the discharge capacity at 0.5 C rate is much lower than that at 0.1 C rate for samples A and B. It indicates that all doped elements can produce the synergic effect and further improve the electrochemical properties of the active materials.

Hydrothermal treatment of coprecipitated YSZ powders

International Nuclear Information System (INIS)

Arakaki, Alexander Rodrigo; Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci

2009-01-01

Zirconia stabilized with 8.5 mol% yttria (YSZ) were synthesized by coprecipitation and resulting gels were hydrothermally treated at 200°C and 220 PSI for 4, 8 and 16 hours. Products were oven dried at 70°C for 24 hours, uniaxially pressed as pellets and sintered at 1500 °C for 1 hour. Powders were characterized for surface area with N 2 gas adsorption, X-ray diffraction, laser diffraction granulometric analysis and scanning and transmission electronic microscopy. Density of ceramics was measured by an immersion method based on the Archimedes principle. Results showed that powders dried at 70°C are amorphous and after treatment has tetragonal/cubic symmetry. Surface area of powders presented a significant reduction after hydrothermal treatment. Ceramics prepared from hydrothermally treated powders have higher green density but sintered pellets are less dense when compared to that made with powders calcined at 800°C for 1 hour due to the agglomerate state of powders. Solvothermal treatment is a promising procedure to enhance density. (author)

Measurement by liquid scintillation of 226 Ra coprecipitated in BaSO4

International Nuclear Information System (INIS)

Lopez del Rio, H.; Davila R, J.I.; Badillo A, V.E.; Mireles G, F.; Quirino T, L.; Lugo R, J.F.; Pinedo V, J.L.; Rios M, C.

2003-01-01

The 226 Ra is one of the more radio toxic nuclides since when entering to the organism it continues metabolically to the calcium, accumulating mainly in the bone tissue where it becomes in an internal radiation source. For the analysis of radium in water the methods of radon emanation are generally applied and coprecipitation with barium sulfate. This last is quick and efficient, and the radium in the precipitate can be measured by alpha or gamma spectrometry, or liquid scintillation dissolving the precipitate one with EDTA. In this work it is proposed a procedure for the radium measurement in water based on the coprecipitation with barium sulfate and in the detection by liquid scintillation. The precipitate of Ba(Ra)SO 4 it is carried with water and blended with the liquid scintillator OptiPhase Hi Safe 3, avoiding the dissolution with EDTA. A 92± 1.4% of radium it was recovered and it was reached a minimum activity detectable of 4.2 ± 0.9 mBq -1 . The procedure was essayed with natural mineral water with a knew activity in concentration of 226 Ra. The analytic result it coincided with the reported value with a relative error of 9%. (Author)

Mercury (II) reduction and co-precipitation of metallic mercury on hydrous ferric oxide in contaminated groundwater.

Science.gov (United States)

Richard, Jan-Helge; Bischoff, Cornelia; Ahrens, Christian G M; Biester, Harald

2016-01-01

Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer. Copyright © 2015 Elsevier B.V. All rights reserved.

Regularities of radium coprecipitation with barium sulfate from salt solutions

International Nuclear Information System (INIS)

Kudryavskij, Yu.P.; Rakhimova, O.V.

2007-01-01

Coprecipitation of radium with barium sulfate from highly concentrated NaCl solutions is studied, including the effects of the initial solution composition, alkaline reagent (CaO, NaOH), supporting electrolyte (NaCl) concentration, and pH. The process is promoted by high NaCl concentration in the initial solution, which is due to structural transformation and change in the sorption activity of the BaSO 4 precipitate in salt solutions. The results obtained were applied to recovery of radium from process solutions during the development and introduction of improved procedure for disinfection and decontamination of waste yielded by chlorination of loparite concentrates [ru

Investigation of neptunium (5), plutonium (5) and americium (5) complexing with some anions of inorganic acids by the method of coprecipitation

International Nuclear Information System (INIS)

Moskvin, A.I.; Poznyakov, A.N.; AN SSSR, Moscow. Inst. Geokhimii i Analiticheskoj Khimii)

1979-01-01

By using the method of coprecipitation with ferric hydroxide a study has been made of Np(5), Pu(5) and Am(5) ions complexing with the anions of inorganic acids SO 4 2- , SO 3 2- , HCO 3 - and HPO 4 2- . Consideration has been also given to how the process of coprecipitation is affected by such factors as collector mass, microcomponent concentration and solution pH. A composition and stability constants of actinide complexes appearing in the systems under study have been found

Synthesis of InGaZnO4 nanoparticles using low temperature multistep co-precipitation method

International Nuclear Information System (INIS)

Wu, Ming-Chung; Hsiao, Kai-Chi; Lu, Hsin-Chun

2015-01-01

Indium gallium zinc oxide (InGaZnO 4 , IGZO) has attracted explosive growth in investigations over the last decades as an important material in the thin-film transistor. In this study, the various nitrate precursors, including indium nitrate, gallium nitrate, and zinc nitrate, were prepared from the various metals dissolved in nitric acid. Then, we used these nitrate precursors to synthesize the IGZO precursor powder by the multistep co-precipitation method. The synthesis parameters of the co-precipitation method, such as reaction temperature, pH value and reaction time, were controlled precisely to prepare the high quality IGZO precursor powder. Finally, IGZO precursor powder was calcined at 900 °C. Then, the microstructure, the crystalline structure, the particle size distribution and specific surface area of calcined IGZO precursor powder were characterized by electron transmission microscopy, X-ray diffraction technique, dynamic light scattering method and the surface area and porosimetry analyzer, respectively. The relative density of IGZO tablet sintered at 1200 °C for 12 h is as high as 97.30%, and it showed highly InGaZnO 4 crystalline structure and the large grain size. The IGZO nanoparticles developed in our study has the potential for the high quality target materials used in the application of electronic devices. - Graphical abstract: Display Omitted - Highlights: • InGaZnO 4 (IGZO) nanoparticle was synthesized by multistep co-precipitation method. • The synthesis parameters were controlled precisely to prepare high quality powder. • The relative density of highly crystalline IGZO tablet is as high as 97.30%. • IGZO tablet exhibited highly crystalline structure and the large grain size

Coprecipitation of 137Cs and 85Sr microquantities with complex compound [M(18-crown-6)]BPH4 (M=Na+, Cs+) from neutral and alkaline solutions

International Nuclear Information System (INIS)

Konovalova, N.A.; Rumer, I.A.; Kulyukhin, S.A.

2009-01-01

The paper reports the possibility of joint separation of 137 Cs and 85 Sr from neutral and alkaline aqueous solutions by their coprecipitation with the solid phase of complex compounds [M(18-crown-6)]BPh 4 (M=Na + , Cs + ), as well as to study the coprecipitation of 137 Cs and 85 Sr with the solid phase CsBPh 4 . It is found that complex compounds [M(18-crown-6)]BPh 4 (M=Na + , Cs + ) increased the degree of 85 Sr separation from solutions virtually two- to threefold vs. CsBPh 4 . Chloride and nitrate were found to have hardly any impact on the coprecipitation of 137 Cs and 85 Sr with [M(18-crown-6)]BPh 4 (M = Na + , Cs + ). (orig.)

Fe-based soft magnetic composites coated with NiZn ferrite prepared by a co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Peng, Yuandong; Yi, Yi; Li, Liya; Ai, Hengyu; Wang, Xiaoxu [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chen, Lulu [Jiangsu Eagle-globe Group Co., Ltd., Nantong 226600 (China)

2017-04-15

Fe powder was coated with NiZn ferrite by a co-precipitation method using chlorate as the raw material. Soft magnetic composites were manufactured via compaction and heat treatment of the coated powder. The coated powder and heat treated powder were analysed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy. Their magnetic properties were determined using a Quantum Design-Vibrating Sample Magnetometer (QD-VSM). The composites were analysed with SEM and EDS. The permeability and magnetic loss of the composites were measured with a B-H curve analyzer. The results show that, using the co-precipitation method, the raw precipitate was successfully prepared and coated the pure Fe powder and turned into spinel NiZn ferrite treated at 600 ℃ for 1 h. After heat treatment at 500 ℃ under air, the insulation coating layer of soft magnetic composite (SMC) was not destroyed and containing Fe, Ni, Zn and oxygen. The permeabilities of the SMC are stable at edge of the 2–200 kHz frequency range and the total loss was lower. - Graphical abstract: Scanning electron microscopy (SEM) images of Fe/(NiZn)Fe{sub 2}O{sub 4} composite powder heated at 600 ℃ for 1 h. - Highlights: • Fe particles were coated with (NiZn)Fe{sub 2}O{sub 4} via a co-precipitation and calcined method. • Coating layers were uniform and dense. • The permeabilities of the SMC are stable at edge of the 2–200 kHz frequency range.

Co-precipitation of oppositely charged nanoparticles: the case of mixed ligand nanoparticles

International Nuclear Information System (INIS)

Moglianetti, Mauro; Ponomarev, Evgeniy; Szybowski, Maxime; Stellacci, Francesco; Reguera, Javier

2015-01-01

Colloid stability is of high importance in a multitude of fields ranging from food science to biotechnology. There is strong interest in studying the stability of small particles (of a size of a few nanometres) with complex surface structures, that make them resemble the complexity of proteins and other natural biomolecules, in the presence of oppositely charged nanoparticles. While for nanoparticles with homogeneously charged surfaces an abrupt precipitation has been observed at the neutrality of charges, data are missing about the stability of nanoparticles when they have more complex surface structures, like the presence of hydrophobic patches. To study the role of these hydrophobic patches in the stability of nanoparticles a series of negatively charged nanoparticles has been synthesized with different ratios of hydrophobic content and with control on the structural distribution of the hydrophobic moiety, and then titrated with positively charged nanoparticles. For nanoparticles with patchy nanodomains, the influence of hydrophobic content was observed together with the influence of the size of the nanoparticles. By contrast, for nanoparticles with a uniform distribution of hydrophobic ligands, size changes and hydrophobic content did not play any role in co-precipitation behaviour. A comparison of these two sets of nanoparticles suggests that nanodomains present at the surfaces of nanoparticles are playing an important role in stability against co-precipitation. (paper)

Effect of pH value on electromagnetic loss properties of Co–Zn ferrite prepared via coprecipitation method

International Nuclear Information System (INIS)

Huang, Xiaogu; Zhang, Jing; Wang, Wei; Sang, Tianyi; Song, Bo; Zhu, Hongli; Rao, Weifeng; Wong, Chingping

2016-01-01

In this paper, the cobalt zinc ferrite was prepared by coprecipitation method at different pH conditions. The influence of pH values on the coprecipitation reaction was theoretically analyzed at first. The calculated results showed that the pH values should be controlled in the range of 9–11 to form the stable precipitation. The XRD investigation was used to further confirm the formation of the composite on specific pH values. In addition, the morphological study revealed that the average particle size of the composite decreased from 40 nm to 30 nm when the pH value increased from 9–11. The variation of microstructure plays a critical role in controlling the electromagnetic properties. From the electromagnetic analysis, the dielectric loss factor was 0.02–0.07 and magnetic loss factor was 0.2–0.5 for the composite synthesized at pH of 9, which presents dramatically improved dielectric loss and magnetic loss properties than the samples prepared at pH of 10 and 11. The as-prepared cobalt zinc ferrite are highly promising to be used as microwave absorption materials. - Highlights: • Co–Zn ferrite was prepared by coprecipitation method with different pH values. • To obtain pure Co–Zn ferrite, the theoretical pH values were 9–11. • Microstructure and electromagnetic properties can be tuned by varying pH values. • Co–Zn ferrite prepared with pH=9 performed well electromagnetic loss properties.

Speciation analysis of 129I in seawater by carrier-free AgI-AgCl coprecipitation and accelerator mass spectrometric measurement

DEFF Research Database (Denmark)

Luo, Maoyi; Hou, Xiaolin; He, Chaohui

2013-01-01

A rapid and simple method was developed for speciation analysis of 129I in seawater by selective coprecipitation of carrier-free iodide and accelerator mass spectrometry (AMS) measurement of 129I. Iodide was separated from seawater and other species of iodine by coprecipitation of AgI with Ag2SO3......, AgCl, and AgBr by addition of only 100 mg/L Ag+ and 0.3 mmol/L NaHSO3 at pH 4.2-5.5. The separation efficiency of iodide was more than 95%, and crossover between 129IO3- and 129I- fractions is less than 3%. Iodate and total inorganic iodine were converted to iodide by use of NaHSO3 at pH 1......-2 and then separated by the same method as for iodide. Ag2SO3 in the coprecipitate was removed by washing with 3 mol/L HNO3 and the excess AgCl and AgBr was removed by use of diluted NH3, and finally a 1-3 mg precipitate was obtained for AMS measurement of 129I. The recovery of iodine species in the entire procedure...

Characterization of γ- Al2O3 nanopowders synthesized by Co-precipitation method

International Nuclear Information System (INIS)

Jbara, Ahmed S.; Othaman, Zulkafli; Ati, Ali A.; Saeed, M.A.

2017-01-01

Co-precipitation technique has been used to synthesize gamma-Al 2 O 3 (γ-Al 2 O 3 ) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m 2 /g. Morphology analysis indicates that γ-Al 2 O 3 nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al 2 O 3 may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al 2 O 3 nanopowders. • Pure gamma- Al 2 O 3 phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

Determination of total alpha index in samples of see water by coprecipitation method

International Nuclear Information System (INIS)

Suarez-Navarro, J.A.; Pujol, L.; Pozuelo, M.; Pablo, A. de

1998-01-01

An environmental radiological monitoring network in the Spanish sea waters was set up by CEDEX in 1993. Water radioactivity is determined quarterly in eleven sampling points along the Spanish coast. The gross alpha activity is one of the parameters to be determined. The usual method for monitoring the gross alpha activity includes sample evaporation to dryness on a disk and counting using ZnS(Ag) scintillation detector. Nevertheless, the gross alpha activity determination in saline waters, such as sea waters, is troublesome, because mass attenuation is high and a very small of water is needed (0.2 ml). The coprecipitation method allows to analyze 500 ml water samples, so the detection limit is reduced and sensitivity is improved. In this work, the coprecipitation method was used to determine the gross alpha activity in the radiological network of the Spanish coast sea waters during 1996 and 1997. Gross alpha activity was very homogenous. It averaged 0.0844±0.0086 Bq.1''1 and ranged from 0.062 to 0.102 Bq.1''1. In collaboration with CIEMAT a set of samples was analyzed, they averaged 0.0689±0.0074 Bq.1''1 and ranged from 0.056 to 0.082 Bq.1''1. (Author) 5 refs

The magnetic and colloidal properties of CoFe2O4 nanoparticles synthesized by co-precipitation.

Science.gov (United States)

Gyergyek, Sašo; Drofenik, Miha; Makovec, Darko

2014-01-01

Magnetic CoFe(2)O(4) nanoparticles were synthesized by co-precipitation at 80 °C. This co-precipitation was achieved by the rapid addition of a strong base to an aqueous solution of cations. The investigation of the samples that were quenched at different times after the addition of the base, using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) and X-ray powder diffractometry, revealed the formation of a Co-deficient amorphous phase and Co(OH)(2), which rapidly reacted to form small CoFe(2)O(4) nanoparticles. The nanoparticles grew with the time of aging at elevated temperature. The colloidal suspensions of the nanoparticles were prepared in both an aqueous medium and in a non-polar organic medium, with the adsorption of citric acid and ricinoleic acid on the nanoparticles, respectively. The measurements of the room-temperature magnetization revealed the ferrimagnetic state of the CoFe(2)O(4) nanoparticles, while their suspensions displayed superparamagnetic behaviour.

X-ray fluorescence analysis of strontium in environmental water by using barium carbonate coprecipitation method

International Nuclear Information System (INIS)

Nishioka, Hiroshi; Yoneda, Akio; Maeda, Yoshimichi; Azumi, Takatugu

1986-01-01

Determination of strontium in environmental water was studied by a coprecipitation method with barium carbonate and the subsequent X-ray fluorescence analysis. Fifty mg of barium ion and 1 g of sodium carbonate were added to sample water, which was then mixed for one hour by a magnetic stirrer. Precipitate was gathered onto a membrane filter paper to measure its XF intensity. The amount of strontium from 2 to 150 μg could be repeatedly determined by means of the calibration curve method, and the limit of detection was found to be 0.6 μg of strontium. A large amount of calcium and magnesium ions was found to interfere with the coprecipitation of strontium ion. However, this interference could be eliminated by using a small amount of sample water. Strontium in several environmental waters was determined by the above method. The results obtained from the calibration curve method and the standard addition method agreed with each other, and also agreed with those from the atomic absorption spectrometry. (author)

Simultaneous determination of Ra-226, Ra-228 and Pb-210 using a successive coprecipitations techniques

International Nuclear Information System (INIS)

Vilhena Schayer Sabino, C. de; Kastner, S.M.S.; Amaral, A.M.

1990-01-01

Several techniques for determination of Ra-226, Ra228 and Pb-210. were developed and used in routine at CDTN in the laboratories of radiochemistry. The matrixes were: water and industrial wastes. Some problems of these techniques were the time spent for analyses and chemical separations, interferents, among others. Now-a-days the method in routine developed here is the one of successive coprecipitations, followed α and β countings of the Ra-226 and Ra-228 daughters. This method is based on coprecipitation, purification of barium radium sulfate with EDTA in acetic solution. Lead is dissolved, radium remains precipitated and suffers a new purification and the time for growing of their daughters is waited to be performed the simultaneous α and β countings for Ra-226 and Ra-228 determination. Pb-210 is analyzed in the floating of the first purification with a carrier of bismuth, and the time for Bi-210 growing is waited. Then it is precipitated as hydroxid, purified as phosphate and the β counting of Bi-210 is done. (author) [pt

Co-precipitation and solubility studies of cesium, potassium and sodium tetraphenylborate

International Nuclear Information System (INIS)

Peterson, R.A.

2000-01-01

This report contains the results from a study requested by High Level Waste on the co-precipitation and solubility of cesium, potassium, and sodium tetraphenylborate. Co-precipitation of cesium (Cs), potassium (K), and sodium (Na) tetraphenylborate (TPB) helps determine the efficiency of reagent usage in the Small Tank Precipitation Process. This process uses NaTPB to remove cesium from waste by means of precipitation. Previous studies by McCabe suggested that if the sodium ion concentration [Na + ] increased the rate at which cesium tetraphenylborate (CsTPB) precipitates also increases. Serkiz also demonstrated that the precipitation of potassium tetraphenylborate (KTPB) in the presence of high [Na + ] (∼5M) appears to produce a mixed solid phase composed of NaTPB and KTPB together in the crystal lattice. In the crystallographic structure of these three tetraphenylborate salts (Cs,K,NaTPB), the tetraphenylborate ion dominates the size of the crystals. Also, note that the three crystals have nearly identical structures with the exception of two additional peaks in the cesium pattern. Given these similarities, TPB precipitation in the presence of Na + , Cs + and K + likely produces an impure isomorphic crystalline mixture of CsTPB, KTPB and NaTPB. The authors speculate that the primary crystalline structure resembles that of KTPB with NaTPB and CsTPB mixed throughout the crystal structure. The precipitation of NaTPB makes some of the anticipated excess tetraphenylborate relatively unavailable for precipitation of cesium. Thus, the amount of excess tetraphenylborate required to completely precipitate all of the potassium and cesium may increase significantly

Study of new U(VI) and Pu(VI) coprecipitation methods for the preparation of (U,Pu)O2

International Nuclear Information System (INIS)

Sanoit, J. de.

1990-01-01

Two U(VI) and Pu(VI) coprecipitation methods have been studied, for the definition of new processes to prepare (U,Pu)O 2 mixed oxides suitable for making MoX fuels or fast breeder reactor fuels. The first system is based on the coprecipitation of a new U(VI), Pu(VI) compound; ammonium uranoplutonate, where as a second system is related to the precipitation of uranyl plutonyl monocarbonate. Experimental conditions to optimize the precipitation and the filtration steps of these two systems have been determined. After calcination under reducing conditions, the mixed oxides obtained are characterized according to different techniques: granulometry, thermogravimetry, solubility in boiling HNO 3 solutions. The properties of such oxides are excellent. The possible processes for preparing (U, Pu)O 2 using these new routes are compared with those actually exploited [fr

Synthesis of InGaZnO{sub 4} nanoparticles using low temperature multistep co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Wu, Ming-Chung, E-mail: mingchungwu@mail.cgu.edu.tw; Hsiao, Kai-Chi; Lu, Hsin-Chun

2015-07-15

Indium gallium zinc oxide (InGaZnO{sub 4}, IGZO) has attracted explosive growth in investigations over the last decades as an important material in the thin-film transistor. In this study, the various nitrate precursors, including indium nitrate, gallium nitrate, and zinc nitrate, were prepared from the various metals dissolved in nitric acid. Then, we used these nitrate precursors to synthesize the IGZO precursor powder by the multistep co-precipitation method. The synthesis parameters of the co-precipitation method, such as reaction temperature, pH value and reaction time, were controlled precisely to prepare the high quality IGZO precursor powder. Finally, IGZO precursor powder was calcined at 900 °C. Then, the microstructure, the crystalline structure, the particle size distribution and specific surface area of calcined IGZO precursor powder were characterized by electron transmission microscopy, X-ray diffraction technique, dynamic light scattering method and the surface area and porosimetry analyzer, respectively. The relative density of IGZO tablet sintered at 1200 °C for 12 h is as high as 97.30%, and it showed highly InGaZnO{sub 4} crystalline structure and the large grain size. The IGZO nanoparticles developed in our study has the potential for the high quality target materials used in the application of electronic devices. - Graphical abstract: Display Omitted - Highlights: • InGaZnO{sub 4} (IGZO) nanoparticle was synthesized by multistep co-precipitation method. • The synthesis parameters were controlled precisely to prepare high quality powder. • The relative density of highly crystalline IGZO tablet is as high as 97.30%. • IGZO tablet exhibited highly crystalline structure and the large grain size.

Processing, structure and magnetic properties correlation in co-precipitated Ca-ferrite

Energy Technology Data Exchange (ETDEWEB)

Abasht, Behzad, E-mail: abasht@gmail.com [Space Thruster Research Institute, Iranian Space Research Center, Tabriz (Iran, Islamic Republic of); Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Beitollahi, Ali; Mirkazemi, Seyyed Mohammad [Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

2016-12-15

La-substituted hexagonal calcium ferrite, Ca{sub 1−X}La{sub X}Fe{sub 12}O{sub 19} (x varies from 0 to 0.6 with the step of 0.2), was synthesized by applying co-precipitation method, in which the molar ratio of Fe{sup 3+}/(Ca{sup 2+}+La{sup 2+}) was 11. The ferrite precursors were prepared from aqueous solution of calcium nitrate, ferric nitrate and lanthanum nitrate by co-precipitation of calcium, iron and lanthanum ions by using an aqueous base of sodium hydroxide (1.5 M) at the pH of 14 and at room temperature. These precursors were calcinated with different amount of La at different temperature of 700, 1100 and 1200 °C for constant calcination time of 1 h in a static air atmosphere. Some tests such as simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behavior, crystallographic properties, morphology and magnetic properties of the precursor powders which were calcinated at different temperatures. The powder XRD patterns of samples which consisted of La as dopant and were calcinated at 1200 °C for 1 h, indicates the formation of calcium hexaferrite and also α-Fe{sub 2}O{sub 3} besides Magnetoplumbite-phase (M-phase). However, the results showed that CaFe{sub 4}O{sub 7} and α-Fe{sub 2}O{sub 3} phases were formed in the sample with the same condition but without using any dopant. The results of SEM showed that the calcium hexaferrite particle were regular hexagonal platelets with the size range of 1–2 µm. The magnetic properties such as maximum magnetization (M{sub Max}), remanent magnetization (M{sub r}) and coercivity (H{sub c}) were measured from the hysteresis loops. Low values of coercive field (16.3 kA m{sup −1}) and maximum magnetization (50.6 A m{sup 2} kg{sup −1}) were obtained from calcium hexaferrite particle in optimum amount of La (X=0.4) which calcinated at the temperature of 1200 °C. - Highlights: • In this

Characterization of ZnS nanoparticles synthesized by co-precipitation method

International Nuclear Information System (INIS)

Iranmanesh Parvaneh; Nourzpoor Mohsen; Saeednia Samira

2015-01-01

ZnS nanoparticles are prepared by homogeneous chemical co-precipitation method using EDTA as a stabilizer and capping agent. The structural, morphological, and optical properties of as-synthesized nanoparticles are investigated using x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible (UV-Vis) absorption, and photoluminescence spectroscopy. The x-ray diffraction pattern exhibits a zinc-blended crystal structure at room temperature. The average particle size of the nanoparticles from the scanning electron microscopy image is about 50 nm. The ultraviolet absorption spectrum shows the blue shift in the band gap due to the quantum confinement effect. The photoluminescence spectrum of ZnS nanoparticles shows a blue visible spectrum. (paper)

Radiochemical investigation of the coprecipitation of microamounts of some hydrolyzable elements with metal hydroxides and metal oxides. Pt. 5

International Nuclear Information System (INIS)

Plotnikov, V.I.; Safonov, I.I.

1979-12-01

Investigation of the coprecipitation of various amounts of iron (III) (between 1 μg and 3.5 mg) with hydroxides of Sn(IV), Ga, Th, Sc, Be, Cd, and Mg as a function of the pH value of the solution. It is shown that the precipitation of the iron (III) with the precipitates of the hydroxides of Be, Cd, Ga, and Sc, which are of lower acidity compared with the microcomponent, is preceded by an acido-basic reaction of Fe(III) with the ions of the macrocomponent. The beginning of this reaction has been observed to coincide with the occurrence of its primary hydrolytical forms in the solution. It is furthermore intensified with decreasing difference in the acidic properties of iron (III) and the other element taking part in the reaction. The neutral hydroxide complex Fe(OH) 0 3 is shown to be the principal coprecipitated form of the iron (III). The coprecipitation of microquantities of iron (III) with tin (IV) hydroxide has been chosen as an example to illustrate the effect of additions of Th, Sc, and Be ions equimolar to the collector. The observed quantitative increase of the microcomponent in the solution is suggested to mainly result from the decrease of the hydrolytical degree of precipitation of tin (IV) due to the interaction of the latter with the ions of impurities. (orig.) 891 RSH/orig. 892 HIS [de

Coprecipitation-assisted hydrothermal synthesis of PLZT hollow nanospheres

International Nuclear Information System (INIS)

Zhu, Renqiang; Zhu, Kongjun; Qiu, Jinhao; Bai, Lin; Ji, Hongli

2010-01-01

Lanthanum-modified lead zirconate titanate Pb 1-x La x (Zr 1-y Ti y )O 3 (PLZT) hollow nanospheres have been successfully prepared via a template-free hydrothermal method using the well-mixed coprecipitated precursors and the KOH mineralizer. The structure, composition, and morphology of the PLZT hollow nanospheres were characterized by XRD (X-ray diffraction), ICP (inductive coupled plasma emission spectrometer), FTIR (Fourier transform infrared spectra), TG/DTA (thermogravimetric analysis and differential thermal analysis), TEM (transmission electron microscopy) and SEAD (selected area diffraction). The results show that the composition and the morphology control of the PLZT products are determined by the KOH concentration. The PLZT hollow nanospheres with uniform size of about 4 nm were synthesized in the presence of 5 M KOH. The crystalline nanoparticles can be prepared at dilute KOH, in contrast to the amorphous powders prepared at concentrated KOH. Formation mechanisms of the PLZT hollow nanospheres are also discussed.

An innovative carbonate coprecipitation process for the removal of zinc and manganese from mining impacted waters

Science.gov (United States)

Sibrell, P.L.; Chambers, M.A.; Deaguero, A.L.; Wildeman, T.R.; Reisman, D.J.

2007-01-01

Although mine drainage is usually thought of as acidic, there are many cases where the water is of neutral pH, but still contains metal species that can be harmful to human or aquatic animal health, such as manganese (Mn) and zinc (Zn). Typical treatment of mine drainage waters involves pH adjustment, but this often results in excessive sludge formation and removal of nontoxic species such as magnesium and calcium. Theoretical consideration of the stability of metal carbonate species suggests that the target metals could be removed from solution by coprecipitation with calcium carbonate. The U.S. Geological Survey has developed a limestone-based process for remediation of acid mine drainage that increases calcium carbonate saturation. This treatment could then be coupled with carbonate coprecipitation as an innovative method for removal of toxic metals from circumneutral mine drainage waters. The new process was termed the carbonate coprecipitation (CCP) process. The CCP process was tested at the laboratory scale using a synthetic mine water containing 50 mg/L each of Mn and Zn. Best results showed over 95% removal of both Mn and Zn in less than 2 h of contact in a limestone channel. The process was then tested on a sample of water from the Palmerton zinc superfund site, near Palmerton, Pennsylvania, containing over 300 mg/L Zn and 60 mg/L Mn. Treatment of this water resulted in removal of over 95% of the Zn and 40% of the Mn in the limestone channel configuration. Because of the potential economic advantages of the CCP process, further research is recommended for refinement of the process for the Palmerton water and for application to other mining impacted waters as well. ?? Mary Ann Liebert, Inc.

Helix-sense-selective co-precipitation for preparing optically active helical polymer nanoparticles/graphene oxide hybrid nanocomposites.

Science.gov (United States)

Huang, Huajun; Li, Weifei; Shi, Yan; Deng, Jianping

2017-05-25

Constructing optically active helical polymer based nanomaterials without using expensive and limited chirally helical polymers has become an extremely attractive research topic in both chemical and materials science. In this study, we prepared a series of optically active helical polymer nanoparticles/graphene oxide (OAHPNs/GO) hybrid nanocomposites through an unprecedented strategy-the co-precipitation of optically inactive helical polymers and chirally modified GO. This approach is named helix-sense-selective co-precipitation (HSSCP), in which the chirally modified GO acted as a chiral source for inducing and further stabilizing the predominantly one-handed helicity in the optically inactive helical polymers. SEM and TEM images show quite similar morphologies of all the obtained OAHPNs/GO nanocomposites; specifically, the chirally modified GO sheets were uniformly decorated with spherical polymer nanoparticles. Circular dichroism (CD) and UV-vis absorption spectra confirmed the preferentially induced helicity in the helical polymers and the optical activity of the nanocomposites. The established HSSCP strategy is thus proven to be widely applicable and is expected to produce numerous functional OAHPNs/GO nanocomposites and even the analogues.

Synthesis of Binary Magnesium-Transition Metal Oxides via Inverse Coprecipitation

Science.gov (United States)

Yagi, Shunsuke; Ichikawa, Yuya; Yamada, Ikuya; Doi, Takayuki; Ichitsubo, Tetsu; Matsubara, Eiichiro

2013-02-01

Synthesis of binary magnesium-transition metal oxides, MgM2O4 (M: Cr, Mn, Fe, Co) and MgNiO2, was performed by calcination at relatively low temperatures of 500 and 750 °C for 24 h through inverse coprecipitation of carbonate hydroxide precursors. The important roles of the precipitation agent, sodium carbonate, were clarified by considering equilibria in an aqueous solution. The structure parameters of the obtained binary magnesium-transition metal oxide powders, specifically the occupancy of atomic sites, were evaluated from synchrotron X-ray diffraction (XRD) profiles by Rietveld refinement in addition to the magnetic properties at room temperature. The present work provides general guidelines for low-cost and high-volume synthesis of complex oxides, which are easily decomposed at high temperatures.

Determination of radium isotopes by BaSO4 coprecipitation for the preparation of alpha-spectrometric sources

International Nuclear Information System (INIS)

Lozano, J.C.; Fernandez, F.; Gomez, J.M.G.

1997-01-01

A coprecipitation procedure for the preparation of α-spectrometric sources for radium, using BaSO 4 as carrier, has been applied to the determination of alpha radium isotopes in water samples. The use of 133 Ba as a suitable tracer for radium determination and possible losses of radon isotopes from the sources are studied and discussed. (author)

Speciation analysis of 129I in seawater using coprecipitation and accelerator mass spectrometry and its applications

DEFF Research Database (Denmark)

Xing, Shan; Hou, Xiaolin; Aldahan, Ala

2017-01-01

Speciation analysis of long-lived 129I in seawater can provide useful information on the source of water masses. This paper presents an improved method for speciation analysis of 129I based on coprecipitation of iodide as AgI with Ag2SO3 and AgCl. By adding a small amount of 127I carrier...

Revisiting Pocos de Caldas. Application of the co-precipitation approach to establish realistic solubility limits for performance assessment

International Nuclear Information System (INIS)

Bruno, J.; Duro, L.; Jordana, S.; Cera, E.

1996-02-01

Solubility limits constitute a critical parameter for the determination of the mobility of radionuclides in the near field and the geosphere, and consequently for the performance assessment of nuclear waste repositories. Mounting evidence from natural system studies indicate that trace elements, and consequently radionuclides, are associated to the dynamic cycling of major geochemical components. We have recently developed a thermodynamic approach to take into consideration the co-precipitation and co-dissolution processes that mainly control this linkage. The approach has been tested in various natural system studies with encouraging results. The Pocos de Caldas natural analogue was one of the sites where a full testing of our predictive geochemical modelling capabilities were done during the analogue project. We have revisited the Pocos de Caldas data and expanded the trace element solubility calculations by considering the documented trace metal/major ion interactions. This has been done by using the co-precipitation/co-dissolution approach. The outcome is as follows: A satisfactory modelling of the behaviour of U, Zn and REEs is achieved by assuming co-precipitation with ferrihydrite. Strontium concentrations are apparently controlled by its co-dissolution from Sr-rich fluorites. From the performance assessment point of view, the present work indicates that calculated solubility limits using the co-precipitation approach are in close agreement with the actual trace element concentrations. Furthermore, the calculated radionuclide concentrations are 2-4 orders of magnitude lower than conservative solubility limits calculated by assuming equilibrium with individual trace element phases. 34 refs, 18 figs, 13 tabs

Revisiting Pocos de Caldas. Application of the co-precipitation approach to establish realistic solubility limits for performance assessment

Energy Technology Data Exchange (ETDEWEB)

Bruno, J.; Duro, L.; Jordana, S.; Cera, E. [QuantiSci, Barcelona (Spain)

1996-02-01

Solubility limits constitute a critical parameter for the determination of the mobility of radionuclides in the near field and the geosphere, and consequently for the performance assessment of nuclear waste repositories. Mounting evidence from natural system studies indicate that trace elements, and consequently radionuclides, are associated to the dynamic cycling of major geochemical components. We have recently developed a thermodynamic approach to take into consideration the co-precipitation and co-dissolution processes that mainly control this linkage. The approach has been tested in various natural system studies with encouraging results. The Pocos de Caldas natural analogue was one of the sites where a full testing of our predictive geochemical modelling capabilities were done during the analogue project. We have revisited the Pocos de Caldas data and expanded the trace element solubility calculations by considering the documented trace metal/major ion interactions. This has been done by using the co-precipitation/co-dissolution approach. The outcome is as follows: A satisfactory modelling of the behaviour of U, Zn and REEs is achieved by assuming co-precipitation with ferrihydrite. Strontium concentrations are apparently controlled by its co-dissolution from Sr-rich fluorites. From the performance assessment point of view, the present work indicates that calculated solubility limits using the co-precipitation approach are in close agreement with the actual trace element concentrations. Furthermore, the calculated radionuclide concentrations are 2-4 orders of magnitude lower than conservative solubility limits calculated by assuming equilibrium with individual trace element phases. 34 refs, 18 figs, 13 tabs.

Synthesis of highly sinterable YAG nanopowders by a modified co-precipitation method

International Nuclear Information System (INIS)

Chen, Zhi-Hui; Yang, Yun; Hu, Zhang-Gui; Li, Jiang-Tao; He, Shu-Li

2007-01-01

A hydrate precursor of yttrium aluminum garnet (YAG) was synthesized by a modified co-precipitation method, in which n-butanol was employed as a low-cost recyclable dehydration solvent. A mixed solution of ethanol and ammonia were used as precipitant. Pure YAG phase appeared after the as-prepared precursors being calcined at 850 o C for 2 h. The nanocrystalline YAG particles calcined at 1100 o C were well dispersed with average diameter of about 40 nm, which can be densified to transparency under vacuum sintering at 1700 o C for 5 h with TEOS as sintering additive

The effect of Ni-Al ratio on the properties of coprecipitated nickel-alumina catalysts with high nickel contents

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Bosch, H.; van Ommen, J.G.; Ross, J.R.H.

1986-01-01

A series of nickel-alumina catalysts with a Ni/Al ratio between 3 and 20 has been prepared by coprecipitation. The calcination and reduction of these samples have been studied by thermogravimetry and their structures after calcination and reduction at different temperatures has been examined by

Selective separation, preconcentration and determination of Pd(II ions in environmental samples by coprecipitation with a 1,2,4-triazole derivative

Directory of Open Access Journals (Sweden)

D. Ozdes

2015-01-01

Full Text Available A simple, sensitive, facile and low cost methodology, combined with flame atomic absorption spectrometry (FAAS, was employed to evaluate the selective separation and preconcentration of Pd(II ions in environmental samples by using a triazole derivative as an organic coprecipitating agent without a carrier element. The developed method was systematically investigated in different set of experimental parameters that influence the quantitative recovery of Pd(II ions. The accuracy of the method was tested by analyzing certified reference material and spike tests. The developed coprecipitation procedure has been applied to road dust, anodic slime, industrial electronic waste materials and water samples to determine their Pd(II levels. DOI: http://dx.doi.org/10.4314/bcse.v29i1.1

Hexagonal ferrite powder synthesis using chemical coprecipitation

International Nuclear Information System (INIS)

Hsiang, H.-I; Yao, R.-Q.

2007-01-01

The formation mechanism of 3BaO.2CoO.12Fe 2 O 3 (Co 2 Z), 2BaO.2CoO.6Fe 2 O 3 (Co 2 Y) and BaO.6Fe 2 O 3 (BaM) powders were prepared using chemical coprecipitation methods in this study using X-ray diffraction (XRD), thermo-gravimetry (TG), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR). It was found that the BaM phase was formed directly through the reaction of the preceding ε-Fe 2 O 3 and amorphous BaCO 3 for BaM precursor. For the Co 2 Y precursor, the intermediate phase, BaM, was obtained through the reaction of the earlier formed BaFe 2 O 4 and α-Fe 2 O 3 . The Co 2 Y phase was obtained through a BaM and BaFe 2 O 4 reaction. However, for the Co 2 Z precursors, the BaM phase was obtained directly from the BaCO 3 and amorphous iron hydroxide reaction, with no α-Fe 2 O 3 and BaFe 2 O 4 formed as intermediates. Co 2 Z phase was obtained through the reaction of the two previous formed BaM and Co 2 Y phases

Nanoscale co-precipitation and mechanical properties of a high-strength low-carbon steel

International Nuclear Information System (INIS)

Mulholland, Michael D.; Seidman, David N.

2011-01-01

Nanoscale co-precipitation in a novel high-strength low-carbon steel is studied in detail after isothermal aging. Atom-probe tomography is utilized to quantify the co-precipitation of co-located Cu precipitates and M 2 C (M is any combination of Cr, Mo, Fe, or Ti) carbide strengthening precipitates. Coarsening of Cu precipitates is offset by the nucleation and growth of M 2 C carbide precipitate, resulting in the maintenance of a yield strength of 1047 ± 7 MPa (152 ± 1 ksi) for as long as 320 h of aging time at 450 deg. C. Impact energies of 153 J (113 ± 6 ft-lb) and 144 J (106 ± 2 ft-lb) are measured at -30 deg. C and -60 deg. C, respectively. The co-location of Cu and M 2 C carbide precipitates results in non-stationary-state coarsening of the Cu precipitates. Synchrotron-source X-ray diffraction studies reveal that the measured 33% increase in impact toughness after aging for 80 h at 450 deg. C is due to dissolution of cementite, Fe 3 C, which is the source of carbon for the nucleation and growth of M 2 C carbide precipitates. Less than 1 vol.% austenite is observed for aging treatments at temperatures less than 600 deg. C, suggesting that transformation-induced plasticity does not play a significant role in the toughness of specimens aged at temperatures less than 600 deg. C. Aging treatments at temperatures greater than 600 deg. C produce more austenite, in the range 2-7%, but at the expense of yield strength.

Red coloration by heat treatment of the coprecipitate of cadmium sulfide and mercury(II) sulfide prepared from the nitrates

International Nuclear Information System (INIS)

Nakahara, Fujiya

1979-01-01

The effects of starting salts on the color, particle size and crystal structure of mercury-cadmium-sulfide pigments were investigated. The coprecipitate (N-S) of cadmium sulfide and mercury (II) sulfide was prepared by adding sodium sulfide solution to a mixed cadmium-mercury (II) nitrate solution. The coprecipitate (C-S) of cadmium sulfide and mercury (II) sulfide was also prepared from the mixed solution of their chlorides by the same method as described above. The coprecipitated products were heat-treated (calcination or hydrothermal treatment) at 350 0 C for 2 hours and subsequent changes in powder properties of both products were compared from each other. The powder properties of N-S, C-S and their heat-treated products were investigated by spectral reflectance, electron microscopy, X-ray diffraction and specific surface area measurements. Sample (N-C) obtained by the calcination of N-S was brown, indicating no red coloration, but the calcined product (C-C) of C-S developed a red color. Cl - and hot water were found to be effective for the red color development of the pigment. The effectiveness was confirmed by calcining N-S in the presence of NaCl or by treating it hydrothermally. It was found that halides other than NaCl, (e.g., NH 4 Cl, KCl, KBr and KI), were also effective for the color development of the pigment. The red samples are solid solutions with a basically hexagonal CdS structure, and it appears that CdS takes up HgS without any apparent structural changes. The particle size of the red samples are larger than those of the non red samples. (author)

Characterization of γ- Al{sub 2}O{sub 3} nanopowders synthesized by Co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Jbara, Ahmed S., E-mail: ahmedsbhe@yahoo.com [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Physics Department, Science College, Al-Muthanna University, Samawah - 66001 (Iraq); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Othaman, Zulkafli [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Ati, Ali A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Saeed, M.A., E-mail: moalsd@gmail.com [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Division of Science and Technology, University of Education, Township, Lahore - 54770 (Pakistan)

2017-02-15

Co-precipitation technique has been used to synthesize gamma-Al{sub 2}O{sub 3} (γ-Al{sub 2}O{sub 3}) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m{sup 2}/g. Morphology analysis indicates that γ-Al{sub 2}O{sub 3} nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al{sub 2}O{sub 3} may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al{sub 2}O{sub 3} nanopowders. • Pure gamma- Al{sub 2}O{sub 3} phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

Synthesis and characterization of La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Fabian, F.A., E-mail: fernandafabianro@gmail.com [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Pedra, P.P.; Filho, J.L.S. [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Duque, J.G.S.; Meneses, C.T. [Universidade Federal de Sergipe, Campus Prof. Alberto Carvalho, Departamento de Física, 49500-000 Itabaiana, SE (Brazil)

2015-04-01

Magnetic and structural properties have been investigated in La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method. The X-ray diffraction measurements allied to Rietveld method confirm the formation of LaCrO{sub 3}, LaFeO{sub 3} and LaMnO{sub 3} nanoparticles with crystal structure orthorhombic (Pbnm), orthorhombic (Pnma) and rhombohedral (R-3c), respectively. We also verified an decreasing in the average crystallite size from 73 to 26 nm, depending of the transition metal. The magnetic measurements reveal an antiferromagnetic behavior for the LaCrO{sub 3} sample with T{sub N}~289 K, and a weak ferromagnetic ordering for the LaMnO{sub 3} sample with T{sub c}~200 K. - Highlights: • La(Cr,Fe,Mn)O{sub 3} nanoparticles were synthesized by coprecipitation method. • XRD results confirm the formation single phase in the compounds studied. • Magnetic property in the La(Fe,Cr,Mn)O{sub 3} nanoparticles dependent on the TM. • La(Cr,Fe)O{sub 3} nanoparticles presented behavior antiferromagnetic and LaMnO{sub 3} ferromagnetic.

Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis

Directory of Open Access Journals (Sweden)

Muhammad Faizan Shareef

2017-10-01

Full Text Available This paper presents the effect of a synthesis method for cobalt catalyst supported on hydrotalcite material for Fischer-Tropsch synthesis. The hydrotalcite supported cobalt (HT-Co catalysts were synthesized by co-precipitation and hydrothermal method. The prepared catalysts were characterized by using various techniques like BET (Brunauer–Emmett–Teller, SEM (Scanning Electron Microscopy, TGA (Thermal Gravimetric Analysis, XRD (X-ray diffraction spectroscopy, and FTIR (Fourier Transform Infrared Spectroscopy. Fixed bed micro reactor was used to test the catalytic activity of prepared catalysts. The catalytic testing results demonstrated the performance of hydrotalcite based cobalt catalyst in Fischer-Tropsch synthesis with high selectivity for liquid products. The effect of synthesis method on the activity and selectivity of catalyst was also discussed. Copyright © 2017 BCREC Group. All rights reserved Received: 3rd November 2016; Revised: 26th February 2017; Accepted: 9th March 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Sharif, M.S., Arslan, M., Iqbal, N., Ahmad, N., Noor, T. (2017. Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 357-363 (doi:10.9767/bcrec.12.3.762.357-363

Superior magnetic properties of Ni ferrite nanoparticles synthesized by capping agent-free one-step coprecipitation route at different pH values

Science.gov (United States)

Iranmanesh, P.; Tabatabai Yazdi, Sh.; Mehran, M.; Saeednia, S.

2018-03-01

In this work, well-dispersed nanoparticles of NiFe2O4 with diameters less than 10 nm and good crystallinity and excellent magnetic properties were synthesized via a simple one-step capping agent-free coprecipitation route from metal chlorides. The ammonia was used as the precipitating agent and also the solution basicity controller. The effect of pH value during the coprecipitation process was investigated by details through microstructural, optical and magnetic characterizations of the synthesized particles using X-ray diffraction, transmission electron microscopy, Fourier transform infrared and UV-vis spectroscopy, and vibrating sample magnetometer. The results showed that the particle size, departure from the inverse spinel structure, the band gap value and the magnetization of Ni ferrite samples increase with pH value from 9 to 11 indicating the more pronounced surface effects in the smaller nanoparticles.

Preparation and Heat-Treatment of DWPF Simulants With and Without Co-Precipitated Noble Metals

International Nuclear Information System (INIS)

Koopman, David C.:Eibling, Russel E

2005-01-01

The Savannah River National Laboratory is in the process of investigating factors suspected of impacting catalytic hydrogen generation in the Chemical Process Cell of the Defense Waste Processing Facility, DWPF. Noble metal catalyzed hydrogen generation in simulation work constrains the allowable acid addition operating window in DWPF. This constraint potentially impacts washing strategies during sludge batch preparation. It can also influence decisions related to the addition of secondary waste streams to a sludge batch. Noble metals have historically been added as trim chemicals to process simulations. The present study investigated the potential conservatism that might be present from adding the catalytic species as trim chemicals to the final sludge simulant versus co-precipitating the noble metals into the insoluble sludge solids matrix. Parallel preparations of two sludge simulants targeting the composition of Sludge Batch 3 were performed in order to evaluate the impact of the form of noble metals. Identical steps were used except that one simulant had dissolved palladium, rhodium, and ruthenium present during the precipitation of the insoluble solids. Noble metals were trimmed into the other stimulant prior to process tests. Portions of both sludge simulants were held at 97 C for about eight hours to qualitatively simulate the effects of long term storage on particle morphology and speciation. The simulants were used as feeds for Sludge Receipt and Adjustment Tank, SRAT, process simulations. The following conclusions were drawn from the simulant preparation work: (1) The first preparation of a waste slurry simulant with co-precipitated noble metals was successful, based on the data obtained. It appears that 99+% of the noble metals were retained in the simulant. (2) Better control of carbonate, hydroxide, and post-wash trim chemical additions is needed before the new method of simulant preparation will be as reproducible as the old method. (3) The two new

Synthesis, structure and magnetic properties of CoFe_2O_4 nanomaterial by coprecipitation method

International Nuclear Information System (INIS)

Nguyen Anh Tien; Hoang Thi Tuyet

2015-01-01

CoFe_2O_4 spinel nanomaterial has been synthesized by coprecipitation method through the hydrolysis of Co(II) and Fe(III) cations in boiling water. The results of DTA/TGA/DrTGA, XRD, TEM methods showed that CoFe_2O_4 crystals formed after a calcination at 700 °C exhibited structure of cubic with the particles size of 30-50 nm, H_c = 1526.89 Oe, M_s = 41.703 emu/g, M_r = 19.545 emu/g. (author)

[Inclusion of proteins into polyelectrolyte microcapsules by coprecipitation and adsorption].

Science.gov (United States)

Kochetkova, O Iu; Kazakova, L I; Moshkov, D A; Vinokurov, M G; Shabarchina, L I

2013-01-01

In present study microcapsules composed of synthetic (PSS and PAA) and biodegradable (DS and PAr) polyelectrolytes on calcium carbonate microparticles were obtained. The ultrastructural organization of biodegradable microcapsules was studied using transmission electron microscopy. The envelope of such capsules consisting of six polyelectrolyte layers is already well-formed, having the average thickness of 44 ± 3.0 nm, and their internal polyelectrolyte matrix is sparser compared to the synthetic microcapsules. Spectroscopy was employed to evaluate the efficiency of incorporation of FITC-labeled BSA into synthetic microcapsules by adsorption, depending on the number of polyelectrolyte layers. It was shown that the maximal amount of protein incorporated into the capsules with 6 or 7 polyelectrolyte layers (4 and 2 pg/capsule, correspondingly). As a result we conclude that, in comparison with co-precipitation, the use of adsorption allows to completely avoid the loss of protein upon encapsulation.

Investigation into complexing of pentavalent actinide forms with some anions of organic acids by the coprecipitation method

International Nuclear Information System (INIS)

Moskvin, A.I.; Poznyakov, A.N.; AN SSSR, Moscow. Inst. Geokhimii i Analiticheskoj Khimii)

1979-01-01

Complexing of pentavolent forms of Np, Pu, Am actinides with anions of acetic, oxalic acids and EDTA is studied using the method of coprecipitation with iron hydroxide. Composition and stability constants of the actinide complexes formed are determined. The acids anions are arranged in a row in the order of decrease of complexing tendency that is EDTA anion>C 2 O 4 2- >CH 3 COO -

Flame atomic absorption spectrometric determination of heavy metals in aqueous solution and surface water preceded by co-precipitation procedure with copper(II) 8-hydroxyquinoline

Science.gov (United States)

Ipeaiyeda, Ayodele Rotimi; Ayoade, Abisayo Ruth

2017-12-01

Co-precipitation procedure has widely been employed for preconcentration and separation of metal ions from the matrices of environmental samples. This is simply due to its simplicity, low consumption of separating solvent and short duration for analysis. Various organic ligands have been used for this purpose. However, there is dearth of information on the application of 8-hydroxyquinoline (8-HQ) as ligand and Cu(II) as carrier element. The use of Cu(II) is desirable because there is no contamination and background adsorption interference. Therefore, the objective of this study was to use 8-HQ in the presence of Cu(II) for coprecipitation of Cd(II), Co(II), Cr(III), Ni(II) and Pb(II) from standard solutions and surface water prior to their determinations by flame atomic absorption spectrometry (FAAS). The effects of pH, sample volume, amount of 8-HQ and Cu(II) and interfering ions on the recoveries of metal ions from standard solutions were monitored using FAAS. The water samples were treated with 8-HQ under the optimum experimental conditions and metal concentrations were determined by FAAS. The metal concentrations in water samples not treated with 8-HQ were also determined. The optimum recovery values for metal ions were higher than 85.0%. The concentrations (mg/L) of Co(II), Ni(II), Cr(III), and Pb(II) in water samples treated with 8-HQ were 0.014 ± 0.002, 0.03 ± 0.01, 0.04 ± 0.02 and 0.05 ± 0.02, respectively. These concentrations and those obtained without coprecipitation technique were significantly different. Coprecipitation procedure using 8-HQ as ligand and Cu(II) as carrier element enhanced the preconcentration and separation of metal ions from the matrix of water sample.

Application of Carrier Element-Free Co-precipitation Method for Ni(II), Cu(II) and Zn(II) Ions Determination in Water Samples Using Chrysin

International Nuclear Information System (INIS)

Layth Imad Abd Ali; Wan Aini Wan Ibrahim; Azli Sulaiman; Mohd Marsin Sanagi

2015-01-01

A co-precipitation method was developed to separate and pre-concentrate Ni(II), Cu(II) and Zn(II) ions using an organic co precipitant, chrysin without adding any carrier element termed as carrier element-free co-precipitation (CEFC). Analytes were determined using flame atomic absorption spectrometry (FAAS). The influence of analytical conditions, such as pH of the solution, quantity of co-precipitant, standing time, centrifugation rate and time, sample volume, and interference of concomitant ions were investigated over the recovery yields of the trace metals. The limit of detection, the limit of quantification and linearity range obtained from the FAAS measurements were found to be in the range of 0.64 to 0.86 μg L -1 , 2.13 to 2.86 μg L -1 and 0.9972 to 0.9989 for Ni(II), Cu(III) and Zn(II) ions, respectively. The precision of the method, evaluated as the relative standard deviation (RSD) obtained after analyzing a series of 10 replicates, was between 2.6 % to 3.9 % for the trace metal ions. The proposed procedure was applied and validated by analyzing river water reference material for trace metals (SLRS-5) and spiking trace metal ions in some water samples. The recoveries of the analyte metal ions were between 94.7-101.2 %. (author)

Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

Energy Technology Data Exchange (ETDEWEB)

Harzali, Hassen, E-mail: harzali@mines-albi.fr [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Saida, Fairouz; Marzouki, Arij; Megriche, Adel [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Baillon, Fabien; Espitalier, Fabienne [Université de Toulouse, Mines Albi, CNRS, Centre RAPSODEE, Campus Jarlard, F-81013 Albi CT cedex 09 (France); Mgaidi, Arbi [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Taibah University, Faculty of Sciences & art, Al Ula (Saudi Arabia)

2016-12-01

Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni–Cu–Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power P{sub diss}=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10–25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite. - Highlights: • Coprecipitation experiments were carried out with ultrasound. • The spinel ferrite NiCuZn was perfectly synthesized by ultrasound. • The saturation magnetization and crystals size are found to be correlated as the dissipated power was varied.

Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

International Nuclear Information System (INIS)

Harzali, Hassen; Saida, Fairouz; Marzouki, Arij; Megriche, Adel; Baillon, Fabien; Espitalier, Fabienne; Mgaidi, Arbi

2016-01-01

Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni–Cu–Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power P_d_i_s_s=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10–25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite. - Highlights: • Coprecipitation experiments were carried out with ultrasound. • The spinel ferrite NiCuZn was perfectly synthesized by ultrasound. • The saturation magnetization and crystals size are found to be correlated as the dissipated power was varied.

Comparison of structural and luminescence properties of Dy2O3 nanopowders synthesized by co-precipitation and green combustion routes

International Nuclear Information System (INIS)

Chandrasekhar, M.; Nagabhushana, H.; Sudheerkumar, K.H.; Dhananjaya, N.; Sharma, S.C.; Kavyashree, D.; Shivakumara, C.; Nagabhushana, B.M.

2014-01-01

Highlights: • Dy 2 O 3 nanopowders were prepared by co-precipitation and eco-friendly green combustion route using plant latex. • Both the products show excellent chromaticity coordinates in the white region, which were quite useful for white LED’s. • Thermoluminescence response of the Dy 2 O 3 product prepared by green synthesis was higher when compared to co-precipitation route. • Structural parameters of Dy 2 O 3 were estimated using Rietveld refinement. • The development of nanosize materials using eco-friendly resources was an attractive non-hazardous chemical route. - Abstract: Dysprosium oxide (Dy 2 O 3 ) nanopowders were prepared by co-precipitation (CP) and eco-friendly green combustion (GC) routes. SEM micrographs prepared by CP route show smooth rods with various lengths and diameters while, GC route show porous, agglomerated particles. The results were further confirmed by TEM. Thermoluminescence (TL) responses of the nanopowder prepared by both the routes were studied using γ-rays. A well resolved glow peak at 353 °C along with less intense peak at 183 °C was observed in GC route while, in CP a single glow peak at 364 °C was observed. The kinetic parameters were estimated using Chen’s glow peak route. Photoluminescence (PL) of Dy 2 O 3 shows peaks at 481, 577, 666 and 756 nm which were attributed to Dy 3+ transitions of 4 F 9/2 ⟶ 6 H 15/2 , 6 H 13/2 , 6 H 11/2 and 6 H 9/2 , respectively. Color co-ordinate values were located in the white region as a result the product may be useful for the fabrication of WLED’S

Advances on reverse strike co-precipitation method of uranium-plutonium mixed solutions

International Nuclear Information System (INIS)

Menghini, Jorge E.; Marchi, Daniel E.; Orosco, Edgardo H.; Greco, Luis

2000-01-01

The reverse strike coprecipitation of uranium-plutonium mixed solutions, is an alternative way to obtain MOX fuel pellets. Previous tests, carried out in the Alpha Laboratory, included a stabilization step for transforming 100 % of plutonium into Pu +4 . Therefore, the plutonium precipitated as Pu(OH) 4 . In this second step, the stabilization process was suppressed. In this way, besides Pu(OH) 4 , a part of the precipitated is composed of a mixed salt: AD(U,Pu). Then, a homogeneous solid solution is formed in the early steps of the process. The powders showed higher tap density, better performance during the pressing and lower sinterability than the powders obtained in previous tests. The advantageous and disadvantageous effects of the stabilization step are analyzed in this paper. (author)

TRANSPARENT CONDUCTING OXIDE SYNTHESIS OF ALUMINIUM DOPED ZINC OXIDES BY CHEMICAL COPRECIPITATION

Directory of Open Access Journals (Sweden)

Silvia Maioco

2013-03-01

Full Text Available Aluminium doped zinc oxides (AZO are promising replacements for tin doped indium oxides (ITO but thin films show a wide range of physical properties strongly dependent on deposition process conditions. Submicrometric 1% aluminum doped zinc oxide ceramics (AZO are examined, prepared by coprecipitation, from Zn(NO32 and Al(NO33 aqueous solutions, sintered at 1200°C and subsequently annealed in 10-16 atm controlled oxygen fugacity atmospheres, at 1000°C. Electrical resistivity diminishes by two orders of magnitude after two hours of annealing and the Seebeck coefficient gradually changes from -140 to -50 µV/K within 8 h. It is concluded that increased mobility is dominant over the increased carrier density, induced by changes in metal-oxygen stoichiometry

Zirconia-mullite obtained from co-precipitated zirconia-mullite composite powders by SPS

Energy Technology Data Exchange (ETDEWEB)

Li, H.Z.; Li, Z.J.; Luo, X.D. [Univ. of Science and Technology Liaoning, Anshan (China). School of High Temperature Materials and Magnesium Resource Engineering; Gui, J.Y.; Xie, Z.P. [Tsinghua Univ., Beijing (China). School of Materials Science and Engineering

2016-07-01

The co-precipitation method is used to fabricate precursor powder. This powder is densified by means of the spark plasma sintering (SPS) technique at 1500 C with a holding time of 7 min to prepare zirconia-mullite samples. Their density measures up to 97 % of the theoretical density, and the sintered mullite compacts exhibit better strength properties (289 ± 12 MPa) and H{sub v} (9.99 GPa). The mode of fracture is changed with the addition of ZrO{sub 2} and extensive fine cleavages are observed on the grain surface. These cleavages join together to form steps, which can absorb more energy. The flexural strength of the samples is almost double that of pure mullite, which is related to the formation of cleavages.

Gd doping induced weak ferromagnetic ordering in ZnS nanoparticles synthesized by low temperature co-precipitation technique

Energy Technology Data Exchange (ETDEWEB)

Kaur, Palvinder [Department of Physics, Punjabi University, Patiala, Punjab, 147002 (India); Kumar, Sanjeev, E-mail: sanjeev04101977@gmail.com [Applied Science Department, PEC University of Technology, Chandigarh, 160012 (India); Chen, Chi-Liang, E-mail: chen.cl@nsrrc.org.tw [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan (China); Yang, Kai-Siang [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan (China); Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Wei, Da-Hua [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Dong, Chung-Li [Department of Physics, Tamkang University, Tamsui, Taiwan (China); Srivastava, C. [Materials Engineering Department, Indian Institute of Science, Bangalore, 560012 (India); Rao, S.M. [Department of Physics, Punjabi University, Patiala, Punjab, 147002 (India); Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan (China)

2017-01-15

Zn{sub 1−x}Gd{sub x}S nanoparticles with Gd concentration x = 0.00, 0.02 and 0.04 were synthesized by the chemical co-precipitation technique using thioglycerol as capping agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, X-ray absorption near-edge structure (XANES) and vibrating sample magnetometer (VSM) were employed to characterize the as synthesized Gd doped ZnS nanoparticles. XRD and TEM studies show the formation of cubic ZnS nanoparticles with an average size in the range 5–10 nm. The doping did not alter the phase of the ZnS. The PL spectra of doped ZnS nanoparticles showed the presence of sulphur vacancies in the lattice. XANES of Gd doped ZnS nanoparticles depicts spectral changes may arise from charge transfer between host Zn and dopant Gd ions. A VSM study shows that the weak ferromagnetic behaviour increases with increase in Gd doping ZnS nanoparticles. - Highlights: • Gd doped ZnS nanoparticles synthesized using co-precipitation technique. • PL studies depict sulphur and zinc vacancies in Gd doped ZnS nanoparticles. • XANES studies depict the charge transfer between host Zn and dopant Gd ions. • Room temperature weak ferromagnetism is observed in Gd doped ZnS nanoparticles.

Experimental Investigation of the Coprecipitation Method: An Approach to Obtain Magnetite and Maghemite Nanoparticles with Improved Properties

Directory of Open Access Journals (Sweden)

Wilson Sacchi Peternele

2014-01-01

Full Text Available Iron oxides that exhibit magnetic properties have been widely studied not only from an academic standpoint, but also for numerous applications in different fields of knowledge, such as biomedical and technological research. In this work, magnetite and maghemite nanoparticles were synthesized by chemical coprecipitation of FeCl2·4H2O and FeCl3·6H2O (proportion of 1 : 2 in three different cases using two bases (sodium hydroxide and hydroxide ammonium as precipitants. The chemical coprecipitation method was selected for its simplicity, convenience, reproducibility, and low cost in the use of glassware. The nanostructured materials were characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD and magnetometry (VSM. The objective of this work is to study the variation in the morphological characteristics and physical properties of nanoparticles magnetic as a function of the different production processes. As observed by TEM, the materials obtained from the precipitating agent NH4OH are more uniform than those obtained with NaOH. From XRD pattern analysis, it appears that the obtained materials correspond to magnetite and maghemite and, from magnetometry VSM analysis, show high magnetization as a function of the magnetic field at room temperature, indicating that these materials are superparamagnetic.

Gd doping induced weak ferromagnetic ordering in ZnS nanoparticles synthesized by low temperature co-precipitation technique

International Nuclear Information System (INIS)

Kaur, Palvinder; Kumar, Sanjeev; Chen, Chi-Liang; Yang, Kai-Siang; Wei, Da-Hua; Dong, Chung-Li; Srivastava, C.; Rao, S.M.

2017-01-01

Zn_1_−_xGd_xS nanoparticles with Gd concentration x = 0.00, 0.02 and 0.04 were synthesized by the chemical co-precipitation technique using thioglycerol as capping agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, X-ray absorption near-edge structure (XANES) and vibrating sample magnetometer (VSM) were employed to characterize the as synthesized Gd doped ZnS nanoparticles. XRD and TEM studies show the formation of cubic ZnS nanoparticles with an average size in the range 5–10 nm. The doping did not alter the phase of the ZnS. The PL spectra of doped ZnS nanoparticles showed the presence of sulphur vacancies in the lattice. XANES of Gd doped ZnS nanoparticles depicts spectral changes may arise from charge transfer between host Zn and dopant Gd ions. A VSM study shows that the weak ferromagnetic behaviour increases with increase in Gd doping ZnS nanoparticles. - Highlights: • Gd doped ZnS nanoparticles synthesized using co-precipitation technique. • PL studies depict sulphur and zinc vacancies in Gd doped ZnS nanoparticles. • XANES studies depict the charge transfer between host Zn and dopant Gd ions. • Room temperature weak ferromagnetism is observed in Gd doped ZnS nanoparticles.

Synthesis and characterization of magnetite nanoparticles via the chemical co-precipitation method

International Nuclear Information System (INIS)

Petcharoen, K.; Sirivat, A.

2012-01-01

Highlights: ► Size-controlled magnetite nanoparticles were prepared via the chemical co-precipitation method in the range of 10–40 nm. ► The electrical conductivity of the smallest particle size is 1.3 × 10 −3 S/cm which belongs to the semiconductor material group. ► The surface modification of magnetite nanoparticles can provide the suspension stability over 1 week. - Abstract: Magnetite nanoparticles were synthesized via the chemical co-precipitation method using ammonium hydroxide as the precipitating agent. The size of the magnetite nanoparticles was carefully controlled by varying the reaction temperature and through the surface modification. Herein, the hexanoic acid and oleic acid were introduced as the coating agents during the initial crystallization phase of the magnetite. Their structure and morphology were characterized by the Fourier transform infrared spectroscopy (FTIR), the X-ray diffraction (XRD) and the field-emission scanning electron microscopy (FE-SEM). Moreover, the electrical and magnetic properties were studied by using a conductivity meter and a vibrating sample magnetometer (VSM), respectively. Both of the bare magnetite and the coated magnetite were of the cubic spinel structure and the spherical-shaped morphology. The reaction temperature and the surface modification critically affected the particle size, the electrical conductivity, and the magnetic properties of these particles. The particle size of the magnetite was increased through the surface modification and reaction temperature. In this study, the particle size of the magnetite nanoparticles was successfully controlled to be in the range of 10–40 nm, suitable for various biomedical applications. The electrical conductivity of the smallest particle size was 1.3 × 10 −3 S/cm, within the semi-conductive materials range, which was higher than that of the largest particle by about 5 times. All of the magnetite nanoparticles showed the superparamagnetic behavior with

Heavy metal immobilization via microbially induced carbonate precipitation and co-precipitation

Science.gov (United States)

Lauchnor, E. G.; Stoick, E.

2017-12-01

Microbially induced CaCO3 precipitation (MICP) has been successfully used in applications such as porous media consolidation and sealing of leakage pathways in the subsurface, and it has the potential to be used for remediation of metal and radionuclide contaminants in surface and groundwater. In this work, MICP is investigated for removal of dissolved heavy metals from contaminated mine discharge water via co-precipitation in CaCO3 or formation of other metal carbonates. The bacterially catalyzed hydrolysis of urea produces inorganic carbon and ammonium and increases pH and the saturation index of carbonate minerals to promote precipitation of CaCO3. Other heavy metal cations can be co-precipitated in CaCO3 as impurities or by replacing Ca2+ in the crystal lattice. We performed laboratory batch experiments of MICP in alkaline mine drainage sampled from an abandoned mine site in Montana and containing a mixture of heavy metals at near neutral pH. Both a model bacterium, Sporosarcina pasteurii, and a ureolytic bacterium isolated from sediments on the mine site were used to promote MICP. Removal of dissolved metals from the aqueous phase was determined via inductively coupled plasma mass spectrometry and resulting precipitates were analyzed via electron microscopy and energy dispersive x-ray spectroscopy (EDX). Both S. pasteurii and the native ureolytic isolate demonstrated ureolysis, increased the pH and promoted precipitation of CaCO3 in batch tests. MICP by the native bacterium reduced concentrations of the heavy metals zinc, copper, cadmium, nickel and manganese in the water. S. pasteurii was also able to promote MICP, but with less removal of dissolved metals. Analysis of precipitates revealed calcium carbonate and phosphate minerals were likely present. The native isolate is undergoing identification via 16S DNA sequencing. Ongoing work will evaluate biofilm formation and MICP by the isolate in continuous flow, gravel-filled laboratory columns. This research

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

Energy Technology Data Exchange (ETDEWEB)

Pušnik, Klementina; Goršak, Tanja [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, 1000 Ljubljana (Slovenia); Drofenik, Miha [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000 Maribor (Slovenia); Makovec, Darko [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, 1000 Ljubljana (Slovenia)

2016-09-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles’ formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe{sup 3+} ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH. - Highlights: • Co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions in the presence of aspartic amino acid (Asp). • Through analysis of nanoparticle formation mechanism. • Presence of Asp changes the mechanism of the nanoparticles’ formation. • Asp forms a coordination complex with the Fe{sup 3+} ions. • Asp impedes the formation of iron oxyhydroxide phase and suppresses the growth of iron-oxide nanoparticles. • The aspartic-acid-absorbed nanoparticles form stable aqueous suspensions.

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

International Nuclear Information System (INIS)

Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

2016-01-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe 3+ /Fe 2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles’ formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe 3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH. - Highlights: • Co-precipitation of Fe 3+ /Fe 2+ ions in the presence of aspartic amino acid (Asp). • Through analysis of nanoparticle formation mechanism. • Presence of Asp changes the mechanism of the nanoparticles’ formation. • Asp forms a coordination complex with the Fe 3+ ions. • Asp impedes the formation of iron oxyhydroxide phase and suppresses the growth of iron-oxide nanoparticles. • The aspartic-acid-absorbed nanoparticles form stable aqueous suspensions.

Determination of lanthanum and rare earth elements in bovine whole blood reference material by ICP-MS after coprecipitation preconcentration with heme-iron as coprecipitant

International Nuclear Information System (INIS)

Fujimori, Eiji; Hayashi, Tatsuya; Inagaki, Kazumi; Haraguchi, H.

1999-01-01

An analytical method for the determination of lanthanide elements in the bovine whole blood reference material (IAEA A-13) has been investigated by inductively coupled plasma mass spectrometry (ICP-MS). The bovine whole blood reference material was digested with HNO 3 and HClO 4 , and then the pH of the digested solution was adjusted to 12 with 3 M sodium hydroxide aqueous solution. In this experimental procedure, lanthanide elements in the blood sample were coprecipitated with iron mainly derived from heme-iron in blood itself. In order to minimize matrix effects due to iron, excess iron in the analysis solution was removed by solvent extraction using methyl isobutyl ketone (MIBK) prior to the determination of lanthanide elements by ICP-MS. The recoveries of all lanthanide elements were almost quantitative in the recovery test. In consequence, it has been found that all lanthanide elements in bovine whole blood reference material are at the wide concentration range of 0.90 pg/g for Tm ∝1880 pg/g for Ce. (orig.)

Structural characterization of FeVO{sub 4} synthesized by co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Bera, Ganesh; Sinha, Sourav; Rambabu, P.; Das, P.; Gupta, A. K.; Turpu, G. R., E-mail: dr.tgreddy@gmail.com [Department of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur 495 009 (India)

2016-05-06

A Low temperature method for synthesizing triclinic FeVO{sub 4} nanoparticles is manifested through co-precipitation method. Three precursor materials taken for the synthesis are Iron Nitrate, Ammonium Metavanadate and NaOH along with DI water. The attained precipitate was dried at 100°C for overnight and calcined at different temperatures ranging from 400°C - 650°C. The achieved powdered materials are studied through X-ray diffraction and found to be in pure single phase of P-1 space group symmetry. The crystallite size measured through Scherrer’s method is in found to be in the range of 40-60 nm. Raman spectroscopic studies were carried out at room temperature. Raman spectra is in agreement with the reported structural data of FeVO{sub 4}.

FTIR and structural properties of co-precipitated cobalt ferrite nano particles

International Nuclear Information System (INIS)

Hutamaningtyas, E.; Utari; Suharyana; Purnama, B.; Wijayanta, A. T.

2016-01-01

The FTIR and structural properties in co-precipitated cobalt ferrite (CoFe 2 O 4 ) nanoparticles are discussed in this paper. The synthesis was conducted at temperatures of 75°C and 95°C following post annealing at 1200°C for 5 hours. Other modification samples were synthesis at temperature of 95°C and then annealing at temperature of 1000°C and 1200°C for 5 hours. For both modification of synthesis and annealing temperature, FTIR result showed a metal oxide at a wave number of 590 cm -1 which indicated cobalt ferrite nanoparticles. The crystalline structure was confirmed using x-ray diffraction that the high purity of cobalt ferrite was realized. Calculation of the cation distribution by using comparison I 220 /I 222 and I 422 /I 222 show that the synthesis and annealing temperature succesfully modify cation occupy the site octahedral and tetrahedral. (paper)

Magnetic behavior of nickel ferrite nanoparticles prepared by co-precipitation route

International Nuclear Information System (INIS)

Maaz, K.; Mashiatullah, A.; Javed, T.; Ali, G.; Karim, S.

2008-01-01

Magnetic nanoparticles of nickel ferrite (NiFe/sub 2/O/sub 4/) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) analyses confirmed the formation of single phase nickel ferrite nanoparticles in the range 8-28 nm. The size of the particles was observed to be increasing linearly with increasing annealing temperature of the sample. Typical blocking effects were observed below -225 K for all the prepared samples. The superparamagnetic blocking temperature was found to be continuously increasing with increasing particle sizes that has been attributed to the increased effective anisotropy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins of these nanoparticles. (author)

Preparation and characterization of Ti-doped MgO nanopowders by a modified coprecipitation method

International Nuclear Information System (INIS)

Wang Wei; Qiao Xueliang; Chen Jianguo; Tan Fatang

2008-01-01

Ti-doped MgO nanopowders were prepared via a chemical coprecipitation method using acetic acid as a modifier in the presence of the surfactant polyethylene glycol (PEG 400). The as-obtained products were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The results show that titanium atoms have been successfully incorporated into the crystal lattice of MgO with periclase structure. The modifier, acetic acid, can significantly reduce the particle size, and improve size distribution and dispersion of nanoparticles. In addition, the effect of doped titanium on the structure and morphology of magnesium oxide was also investigated

Sintering behaviour of CeO2-Gd2O3 powders prepared by the oxalate coprecipitation method

International Nuclear Information System (INIS)

Duran, P.; Jurado, J.R.; Moure, C.

1993-01-01

The powder and compact characteristics as well as the sintering behaviour of two CeO 2 -Gd 2 O 3 compositions prepared by the oxalate coprecipitation method are studied as a function of the powder particle size and the pore-size distribution in the powder compacts. Shrinkage was measured at a constant heating rate and the results are compared with those obtained by isothermal sintering experiments. Grain growth and microstructural development on sintered samples were studied. (orig.)

Carrier element-free coprecipitation with 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one for separation/preconcentration of Cr(III), Fe(III), Pb(II) and Zn(II) from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Duran, Celal; Bulut, Volkan N.; Gundogdu, Ali; Ozdes, Duygu; Yildirim, Nuri [Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr [Department of Chemistry, Faculty of Arts and Sciences, Erciyes University, 38039 Kayseri (Turkey); Senturk, H. Basri [Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Elci, Latif [Pamukkale University, Faculty of Arts and Sciences, Department of Chemistry, 20020 Denizli (Turkey)

2009-08-15

A separation/preconcentration procedure, based on the coprecipitation of Cr{sup 3+}, Fe{sup 3+}, Pb{sup 2+} and Zn{sup 2+} ions using a new organic coprecipitant, 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one (POHBAT) without adding any carrier element has been developed. The method, thus, has been called carrier element-free coprecipitation (CEFC). The resultant concentrated elements were determined by flame atomic absorption spectrometric determinations. The influences of some analytical parameters including pH of the solution, amount of the coprecipitant, standing time, centrifugation rate and time, sample volume and diverse ions were investigated on the quantitative recoveries of analyte ions. The validation of the present preconcentration procedure was performed by the analysis of two certified reference materials. The recoveries of understudy analytes were found in the range of 93-98%, while the detection limits were calculated in the range of 0.3-2.0 {mu}g L{sup -1}. The precision of the method evaluated as relative standard deviation (R.S.D.), was in the range of 3-7% depend on the analytes. The proposed method was successfully applied to environmental samples for the determination of the analytes.

Carrier element-free coprecipitation with 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one for separation/preconcentration of Cr(III), Fe(III), Pb(II) and Zn(II) from aqueous solutions

International Nuclear Information System (INIS)

Duran, Celal; Bulut, Volkan N.; Gundogdu, Ali; Ozdes, Duygu; Yildirim, Nuri; Soylak, Mustafa; Senturk, H. Basri; Elci, Latif

2009-01-01

A separation/preconcentration procedure, based on the coprecipitation of Cr 3+ , Fe 3+ , Pb 2+ and Zn 2+ ions using a new organic coprecipitant, 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one (POHBAT) without adding any carrier element has been developed. The method, thus, has been called carrier element-free coprecipitation (CEFC). The resultant concentrated elements were determined by flame atomic absorption spectrometric determinations. The influences of some analytical parameters including pH of the solution, amount of the coprecipitant, standing time, centrifugation rate and time, sample volume and diverse ions were investigated on the quantitative recoveries of analyte ions. The validation of the present preconcentration procedure was performed by the analysis of two certified reference materials. The recoveries of understudy analytes were found in the range of 93-98%, while the detection limits were calculated in the range of 0.3-2.0 μg L -1 . The precision of the method evaluated as relative standard deviation (R.S.D.), was in the range of 3-7% depend on the analytes. The proposed method was successfully applied to environmental samples for the determination of the analytes.

Oxidation of aqueous EDTA and associated organics and coprecipitation of inorganics by ambient iron-mediated aeration.

Science.gov (United States)

Englehardt, James D; Meeroff, Daniel E; Echegoyen, Luis; Deng, Yang; Raymo, Françisco M; Shibata, Tomoyuki

2007-01-01

Cationic metal and radionuclide contaminants can be extracted from soils to groundwater with sequestering agents such as EDTA. However, EDTA must then be removed fromthe groundwater, by advanced oxidation or specialized biological treatment. In this work, aqueous individual metal-EDTA solutions were aerated with steel wool for 25 h, at ambient pH, temperature, and pressure. Removal of approximately 99% of EDTA (0.09-1.78 mM); glyoxylic acid (0.153 mM); chelated Cd2+ (0.94 and 0.0952 mM), Pb2+ (0.0502 mM), and Hg2+ (0.0419 mM); and free chromate and vanadate was shown. EDTA was oxidized to glyoxylic acid and formaldehyde, and metals/metalloids were coprecipitated together with iron oxyhydroxide floc. Free arsenite and arsenate were each removed at 99.97%. Free Sr2+, and chelated Ni2+ were removed at 92% and 63%, respectively. Similar removals were obtained from mixtures, including 99.996+/-0.004% removal of total arsenic (95% confidence). Traces of iminodiacetic acid, nitrilotriacetic acid, and ethylenediaminetriacetic acid were detected after 25 h. Results are consistent with first-order, solution-phase oxidation of EDTA and glyoxylic acid by ferryl ion and H202, respectively, with inhibition due to sludge accumulation, and equilibrium metal coprecipitation. This ambient process, to our knowledge previously unknown, agrees with recently reported findings and shows promise for remediation of metals, metalloids, and radionuclides in wastewater, soil, and sediment.

Phase pure synthesis of BiFeO3 nanopowders using diverse precursor via co-precipitation method

International Nuclear Information System (INIS)

Shami, M. Yasin; Awan, M.S.; Anis-ur-Rehman, M.

2011-01-01

Highlights: → Synthesized phase pure BiFeO 3 using diverse precursor by co-precipitation method. → Optimized synthesis and processing parameters. → Thermal behavior, structure and microstructure were analyzed. → Resistivity vs temperature and dielectric constant vs frequency were measured. → Multiferroicity at room temperature was confirmed by M-H and P-E loops. - Abstract: Amorphous powder of BiFeO 3 (BFO) was synthesized at low-temperature (80 deg. C) by co-precipitation method. Optimal synthesis conditions for phase pure BFO were obtained. Powders were calcined in the temperature range from 400 to 600 deg. C for 1 h. Iso-statically pressed powder was sintered at 500 deg. C for 2 h. Differential scanning calorimetric thermo-gram guided for phase transition, crystallization and melting temperatures. X-ray diffraction confirmed the amorphous nature of as synthesized powder and phase formation of calcined powders. Calcination at temperature ≥400 deg. C resulted in nano crystalline powders with perovskite structure. Average crystallite size increased with the increase in calcination temperature. Scanning electron microscopic studies revealed dense granular microstructure of the sintered samples. The sintered samples exhibited high dc resistivity at room temperature which decreased with the increase in temperature. Dielectric constant, dielectric loss tangent and ac conductivity measurements were carried out in the frequency range (10 Hz to 2 MHz). The samples responded weak electric and magnetic polarization at room temperature with unsaturated and hysteresis free loops, respectively.

Deproteinization assessment using isotopically enriched compounds to trace the coprecipitation of low-molecular-weight selenium species with proteins.

Science.gov (United States)

Godin, Simon; Bouzas-Ramos, Diego; Fontagné-Dicharry, Stéphanie; Bouyssière, Brice; Bueno, Maïté

2017-08-01

Studies have shown that information related to the presence of low-molecular-weight metabolites is frequently lost after deproteinization of complex matrices, such as blood and plasma, during sample preparation. Therefore, the effect of several deproteinization reagents on low-molecular-weight selenium species has been compared by species-specific isotope labeling. Two isotopically enriched selenium tracers were used to mimic models of small inorganic anionic ( 77 Se-selenite) and organic zwitterionic ( 76 Se-selenomethionine) species. The results presented here show that the use of a methanol-acetonitrile-acetone (1:1:1 v/v/v) mixture provided approximately two times less tracer loss from plasma samples in comparison with the classic procedure using acetonitrile, which may not be optimal as it leads to important losses of low-molecular-weight selenium species. In addition, the possible interactions between selenium tracers and proteins were investigated, revealing that both coprecipitation phenomena and association with proteins were potentially responsible for selenite tracer losses during protein precipitation in blood samples. However, coprecipitation phenomena were found to be fully responsible for losses of both tracers observed in plasma samples and of the selenomethionine tracer in blood samples. This successfully applied strategy is anticipated to be useful for more extensive future studies in selenometabolomics. Copyright © 2017 Elsevier Inc. All rights reserved.

Ubbelohde viscometer measurement of water-based Fe{sub 3}O{sub 4} magnetic fluid prepared by coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Gu, H. [School of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Tang, X. [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002 (China); Feng, W.G. [Suzhou Nanocomp Inc., Suzhou New District, Suzhou 215011 (China); Xie, H.D.; Chen, D.X. [Suzhou YouNuo Plastic Industry Co., Ltd., Suzhou 215021 (China); Badami, D. [Department of Chemical Engineering, University of Waterloo, Waterloo, Canada ON N2L 3G1 (Canada)

2013-12-15

Fe{sub 3}O{sub 4} nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid. - Highlights: • Fe{sub 3}O{sub 4} nanoparticles were prepared using co-precipitation and coated by sodium dodecyl benzene sulfonate to obtain water-based magnetic fluid. • The viscosity of different magnetic fluids was measured using an Ubbelohde viscometer. • The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity of magnetic fluids were studied.

Evaluation of Three Chitin Metal Silicate Co-Precipitates as a Potential Multifunctional Single Excipient in Tablet Formulations

Directory of Open Access Journals (Sweden)

Rana Al-Shaikh Hamid

2010-05-01

Full Text Available The performance of the novel chitin metal silicate (CMS co-precipitates as a single multifunctional excipient in tablet formulation using direct compression and wet granulation methods is evaluated. The neutral, acidic, and basic drugs Spironolactone (SPL, ibuprofen (IBU and metronidazole (MET, respectively, were used as model drugs. Commercial Aldactone®, Fleximex® and Dumazole® tablets containing SPL, IBU and MET, respectively, and tablets made using Avicel® 200, were used in the study for comparison purposes. Tablets of acceptable crushing strength (>40 N were obtained using CMS. The friability values for all tablets were well below the maximum 1% USP tolerance limit. CMS produced superdisintegrating tablets (disintegration time < 1 min with the three model drugs. Regarding the dissolution rate, the sequence was as follow: CMS > Fleximex® > Avicel® 200, CMS > Avicel® 200 > Dumazole® and Aldactone® > Avicel® 200 > CMS for IBU, MET and SPL, respectively. Compressional properties of formulations were analyzed using density measurements and the compression Kawakita equation as assessment parameters. On the basis of DSC results, CMS co precipitates were found to be compatible with the tested drugs. Conclusively, the CMS co-precipitates have the potential to be used as filler, binder, and superdisintegrant, all-in-one, in the design of tablets by the direct compression as well as wet granulation methods.

Quality-by-Design (QbD): An integrated process analytical technology (PAT) approach for a dynamic pharmaceutical co-precipitation process characterization and process design space development.

Science.gov (United States)

Wu, Huiquan; White, Maury; Khan, Mansoor A

2011-02-28

The aim of this work was to develop an integrated process analytical technology (PAT) approach for a dynamic pharmaceutical co-precipitation process characterization and design space development. A dynamic co-precipitation process by gradually introducing water to the ternary system of naproxen-Eudragit L100-alcohol was monitored at real-time in situ via Lasentec FBRM and PVM. 3D map of count-time-chord length revealed three distinguishable process stages: incubation, transition, and steady-state. The effects of high risk process variables (slurry temperature, stirring rate, and water addition rate) on both derived co-precipitation process rates and final chord-length-distribution were evaluated systematically using a 3(3) full factorial design. Critical process variables were identified via ANOVA for both transition and steady state. General linear models (GLM) were then used for parameter estimation for each critical variable. Clear trends about effects of each critical variable during transition and steady state were found by GLM and were interpreted using fundamental process principles and Nyvlt's transfer model. Neural network models were able to link process variables with response variables at transition and steady state with R(2) of 0.88-0.98. PVM images evidenced nucleation and crystal growth. Contour plots illustrated design space via critical process variables' ranges. It demonstrated the utility of integrated PAT approach for QbD development. Published by Elsevier B.V.

Synthesis of Zn{sub 0.95}Cr{sub 0.05}O DMS by co-precipitation and ceramic methods: Structural and magnetization studies

Energy Technology Data Exchange (ETDEWEB)

Paul Joseph, D. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Naveenkumar, S. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Sivakumar, N. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Venkateswaran, C. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India)]. E-mail: cvunom@hotmail.com

2006-05-10

Transitional metal ions-substituted ZnO are recently explored for SPINTRONICS applications. Synthesis of single-phase oxide 'diluted magnetic semiconductors' (DMS) is a must to explore the magnetic properties arising due to the strong sp-d exchange interaction. The synthesis route plays a vital role in this aspect. In this work, we have prepared Zn{sub 0.95}Cr{sub 0.05}O by using the co-precipitation method and also the standard ceramic method and optimized the conditions to obtain the single-phase compound. X-ray diffraction measurements were done on Zn{sub 0.95}Cr{sub 0.05}O annealed and sintered at various temperatures. Comparing these results, we conclude that the co-precipitation method is more convenient for obtaining single-phase compound by the relatively low temperature processing of the precipitated hydroxides. Pelleted sample examined for its magnetic property using a vibrating sample magnetometer (VSM) indicated ferromagnetic-like behavior at 300 K and a spin-glass state at 77 K.

Enhanced luminescent properties of long-persistent Sr{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} phosphor prepared by the co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Pan Wen [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Zhongshan Road 158-43, Dalian Liaoning 116012 (China); Ning Guiling [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Zhongshan Road 158-43, Dalian Liaoning 116012 (China)], E-mail: ninggl@dlut.edu.cn; Zhang Xu; Wang Jing; Lin Yuan; Ye Junwei [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Zhongshan Road 158-43, Dalian Liaoning 116012 (China)

2008-12-15

Sr{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} phosphors were prepared by the (aminopropyl)-triethoxysilane (APTES) co-precipitation method. Effects of synthesis temperature on the crystal characteristics, luminescent properties and afterglow performance of Sr{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} phosphors have been discussed in detail and compared with the corresponding commercial product. The experimental results indicated that the sample could be synthesized at a relatively lower temperature and had better performance on the above-mentioned properties using the co-precipitation method.

Cerium doped hydroxyapatite nanoparticles synthesized by coprecipitation method

Directory of Open Access Journals (Sweden)

Ciobanu Carmen Steluta

2016-01-01

Full Text Available The present work reports a simple coprecipitation adapted method for the synthesis of stable Ce substituted to Ca hydroxyapatite (HAp nanoparticles. The structural and morphological properties of Ce doped hydroxyapatite (Ce:HAp were characterized by X-ray diffraction (XRD, Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM and Energy Dispersive X-ray analysis (EDAX. The optical properties of Ce doped hydroxyapatite were also investigated using Fourier Transform Infrared (FTIR spectroscopy, FT Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a- and c-axes with increasing of Ce concentrations. In the FTIR studies of Ce:HAp powders a similar structure to hydroxyapatite was observed. IR and Raman wavenumbers and the peak strength of the bands associated to the P-O and O-H bonds decreases progressively with the increase of Ce concentration. All the emission maxima could be attributed to the 5d-4f transitions of Ce ions. The displacement of maximum emission bands with the increase of Cerium in the samples is in agreement with the results obtained by XRD studies. The Ce:HAp samples with xCe =0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus ATCC 6538 and E. coli 714 bacterial strains compared to Ce:HAp samples with xCe =0 (pure HAp and 0.01.

Green and red luminescence in co-precipitation synthesized Pr:LuAG nanophosphor

Energy Technology Data Exchange (ETDEWEB)

Kumar, S. Arun; Kumar, K. Ashok; Gunaseelan, M.; Senthilselvan, J., E-mail: jsselvan@hotmail.com [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai–600 025, Tamil Nadu (India); Asokan, K. [Materials Science Group, Inter University Accelerator Centre, New Delhi-110067 (India)

2016-05-06

Pr:LuAG nanophosphor is an effective candidate in magnetic resonance imaging coupled positron emission tomography (MRI-PET) for medical imaging and scintillator applications. LuAG:Pr (0.05, 0.15 mol%) nanoscale ceramic powders were synthesized by co-precipitation method using urea as precipitant. Effect of antisite defect on structure and luminescence behavior was investigated. Pr:LuAG nanoceramic powders are found crystallized in cubic structure by high temperature calcination at 1400 °C and it shows antisite defect. HR-SEM analysis revealed spherically shaped Pr:LuAG nanoceramic particulate powders with ∼100 nm size. By the excitation at 450 nm, Pr:LuAG nanophosphor exhibit green to red luminescence in the wavelength range of 520 to 680 nm, which is originated from multiplet transition of Pr{sup 3+} ions.

Tunable Properties of Exfoliated Polyvinylalcohol Nanocomposites by In Situ Coprecipitation of Layered Double Hydroxides

Science.gov (United States)

Liu, Jiajia; Yuen, Richard K. K.; Hu, Yuan

2017-10-01

Poly(vinyl alcohol) (PVA) nanocomposites were prepared by a “one step” method based on the coprecipitation of layered double hydroxide (LDH) nanosheets in the polymer aqueous solution. The morphology, fire resistance properties, mechanical and optical properties of the PVA/LDH nanocomposites were studied. The LDH nanosheets were homogeneously dispersed in the PVA matrix as indicated by X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) characterization. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) were decreased by 58% and 28%, respectively. Storage modulus at 30 °C was increased, and the transmittance of more than 90% at the visible region was obtained upon addition of 5 wt% LDH.

Bulk tungsten with uniformly dispersed La2O3 nanoparticles sintered from co-precipitated La2O3/W nanoparticles

International Nuclear Information System (INIS)

Xia, Min; Yan, Qingzhi; Xu, Lei; Guo, Hongyan; Zhu, Lingxu; Ge, Changchun

2013-01-01

Graphical abstract: La 2 O 3 doped La 2 O 3 /W nanoparticles with high-purity and uniform diameters have been fabricated by a co-precipitation process. The as-prepared nanoparticles demonstrate the potential of this method for fabricating uniformly structured bulk tungsten materials. -- Abstract: We report the preparation of 1 wt% La 2 O 3 doped La 2 O 3 /W nanoparticles by a co-precipitation process, using ammonium metatungstate (AMT) and lanthanum nitrate as raw materials. The as-synthesized nanoparticles were characterized by X-ray diffraction, Filed-emission scanning electron microscopy, Transmission electron microscopy (TEM), energy dispersive spectroscopy. Our results reveal that the as-synthesized particles possess uniform diameters of about 70 nm, and are of high purity. The TEM and the corresponding fast Fourier transform images demonstrated that La 2 O 3 precipitates were homogeneously doped into the nano-sized tungsten particles. When the as-synthesized nanoparticles were sintered by spark plasma sintering, the electron backscatter diffraction images of the bulk material reveal that La 2 O 3 nanoparticles were homogenously distributed in both the tungsten grains and the grain boundaries, and the sample exhibit a narrow micro-hardness distribution

Co-precipitation of phosphate and iron limits mitochondrial phosphate availability in Saccharomyces cerevisiae lacking the yeast frataxin homologue (YFH1).

Science.gov (United States)

Seguin, Alexandra; Santos, Renata; Pain, Debkumar; Dancis, Andrew; Camadro, Jean-Michel; Lesuisse, Emmanuel

2011-02-25

Saccharomyces cerevisiae cells lacking the yeast frataxin homologue (Δyfh1) accumulate iron in the mitochondria in the form of nanoparticles of ferric phosphate. The phosphate content of Δyfh1 mitochondria was higher than that of wild-type mitochondria, but the proportion of mitochondrial phosphate that was soluble was much lower in Δyfh1 cells. The rates of phosphate and iron uptake in vitro by isolated mitochondria were higher for Δyfh1 than wild-type mitochondria, and a significant proportion of the phosphate and iron rapidly became insoluble in the mitochondrial matrix, suggesting co-precipitation of these species after oxidation of iron by oxygen. Increasing the amount of phosphate in the medium decreased the amount of iron accumulated by Δyfh1 cells and improved their growth in an iron-dependent manner, and this effect was mostly transcriptional. Overexpressing the major mitochondrial phosphate carrier, MIR1, slightly increased the concentration of soluble mitochondrial phosphate and significantly improved various mitochondrial functions (cytochromes, [Fe-S] clusters, and respiration) in Δyfh1 cells. We conclude that in Δyfh1 cells, soluble phosphate is limiting, due to its co-precipitation with iron.

Uranium (III)-Plutonium (III) co-precipitation in molten chloride

Science.gov (United States)

Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

2018-02-01

Co-management of the actinides in an integrated closed fuel cycle by a pyrochemical process is studied at the laboratory scale in France in the CEA-ATALANTE facility. In this context the co-precipitation of U(III) and Pu(III) by wet argon sparging in LiCl-CaCl2 (30-70 mol%) molten salt at 705 °C is studied. Pu(III) is prepared in situ in the molten salt by carbochlorination of PuO2 and U(III) is then introduced as UCl3 after chlorine purge by argon to avoid any oxidation of uranium up to U(VI) by Cl2. The oxide conversion yield through wet argon sparging is quantitative. However, the preferential oxidation of U(III) in comparison to Pu(III) is responsible for a successive conversion of the two actinides, giving a mixture of UO2 and PuO2 oxides. Surprisingly, the conversion of sole Pu(III) in the same conditions leads to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation of Pu(III) to Pu(IV). This is in contrast with coconversion of U(III)-Pu(III) mixtures but in agreement with the conversion of Ce(III).

Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

International Nuclear Information System (INIS)

Shih, C.J.; Chen, Y.J.; Hon, M.H.

2010-01-01

Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol -1 .

Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

Energy Technology Data Exchange (ETDEWEB)

Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Chen, Y.J. [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hon, M.H. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

2010-05-15

Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol{sup -1}.

PEG capped CaS nanoparticles synthesized by wet chemical co-precipitation method

Science.gov (United States)

Rekha, S.; Anila, E. I.

2018-04-01

Calcium sulfide (CaS) nanoparticles capped with polyethyleneglycol (PEG) were synthesized using wet chemical co-precipitation method. The structural and optical properties of the prepared sample were studied by X-ray diffractogram (XRD), transmission electron microscopy (TEM), diffuse reflectance spectrum (DRS) and photoluminescence (PL) spectrum. The structure of CaS nanoparticles is cubic as demonstrated by the X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) analysis. TEMimage revealed the spherical morphology of the particles with diameter in the range 15-20 nm. The optical band gap of the prepared sample was determined from the DRS and its value was found to be 4.1 eV. The PL studies showed that the relative intensity of the PEG capped CaS nanoparticles was higher than that of uncapped CaS nanoparticles. The presence of various functional groups in the capped samples were examined by Fourier Transform Infrared (FTIR) spectroscopy.

Preparation of (U, Gd)O2 by inverse co-precipitation in nitric solutions. Study of homogeneity and process optimization

International Nuclear Information System (INIS)

Marchi, Daniel E.; Menghini, Jorge E.; Trimarco, Viviana G.

1999-01-01

The inverse co-precipitation method has been used at the laboratory level to produce uranium - gadolinium mixed oxides. The formation of a mixed phase in the precipitates has been determined as well as the occurrence of only one phase in the sintered pellets, corresponding to a gadolinium - uranium solution. Moreover, a modification in the calcination-reduction stage was introduced that allows the elimination of the fissures previously detected in the sintered pellets

Method for Determination of Neptunium in Large-Sized Urine Samples Using Manganese Dioxide Coprecipitation and ²⁴²Pu as Yield Tracer

DEFF Research Database (Denmark)

Qiao, Jixin; Hou, Xiaolin; Roos, Per

2013-01-01

A novel method for bioassay of large volumes of human urine samples using manganese dioxide coprecipitation for preconcentration was developed for rapid determination of 237Np. 242Pu was utilized as a nonisotopic tracer to monitor the chemical yield of 237Np. A sequential injection extraction chr...... and rapid analysis of neptunium contamination level for emergency preparedness....

Y-TZP ceramic processing from coprecipitated powders: a comparative study with three commercial dental ceramics.

Science.gov (United States)

Lazar, Dolores R R; Bottino, Marco C; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H A

2008-12-01

(1) To synthesize 3mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. A coprecipitation route was used to synthesize a 3mol% yttria-stabilized zirconia ceramic processed by uniaxial compaction and pressureless sintering. Commercially available alumina or alumina/zirconia ceramics, namely Procera AllCeram (PA), In-Ceram Zirconia Block (CAZ) and In-Ceram Zirconia (IZ) were chosen for comparison. All specimens (6mmx5mmx5mm) were polished and ultrasonically cleaned. Qualitative phase analysis was performed by XRD and apparent densities were measured on the basis of Archimedes principle. Ceramics were also characterized using SEM, TEM and EDS. The hardness measurements were made employing Vickers hardness test. Fracture toughness (K(IC)) was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (alpha=0.05). ANOVA revealed that the Vickers hardness (pceramic materials composition. It was confirmed that the PA ceramic was constituted of a rhombohedral alumina matrix, so-called alpha-alumina. Both CAZ and IZ ceramics presented tetragonal zirconia and alpha-alumina mixture of phases. The SEM/EDS analysis confirmed the presence of aluminum in PA ceramic. In the IZ and CAZ ceramics aluminum, zirconium and cerium in grains involved by a second phase containing aluminum, silicon and lanthanum were identified. PA showed significantly higher mean Vickers hardness values (H(V)) (18.4+/-0.5GPa) compared to vitreous CAZ (10.3+/-0.2GPa) and IZ (10.6+/-0.4GPa) ceramics. Experimental Y-TZP showed significantly lower results than that of the other monophased ceramic (PA) (pceramics (pceramic processing conditions led to ceramics with mechanical properties comparable to commercially available reinforced ceramic materials.

Study of UO2-10WT%Gd2O3 fuel pellets obtained by seeding method using AUC co-precipitation and mechanical mixing processes

International Nuclear Information System (INIS)

Lima, M.M.F.; Ferraz, W.B.A.; Santos, M.M. dos; Pinto, L.C.M.; Santos, A.

2008-01-01

The use of gadolinium and uranium mixed oxide as a nuclear fuel aims to obtain a fuel with a performance better than that of UO 2 fuel. In this work, seeding method was used to improve ionic diffusivity during sintering to produce high density pellets containing coarse grains by co-precipitation and mechanical mixing processes. Sintered UO 2 -10 wt% Gd 2 O 3 pellets were obtained using the reference processes with 2 wt% and 5 wt% UO 2 seeds with two granulometries, less than 20 μm and between 20 and 38 μm. Characterisation was carried out by chemical analysis, surface area, X-ray diffraction, SEM, WDS, image analysis, and densitometry. The seeding method using mechanical mixing process was more effective than the co-precipitation method. Furthermore, mechanical mixing process resulted in an increase in density of UO 2 -10wt% Gd 2 O 3 with seeds in relation to that of UO 2 -10wt% Gd 2 O 3 without seeds. (author)

Structural variation study of cobalt nanoparticles synthesized by co-precipitation method using 59Co NMR

Science.gov (United States)

Manjunatha, M.; Kumar, Rajeev; B. M., Siddesh; Sahoo, Balaram; Damle, R.; Ramesh, K. P.

2018-04-01

We have synthesized cobalt nanoparticles using co-precipitation method. Further, the two phases of the cobalt is monitored by varying the synthesis parameters. 59Co NMR and XRD are used as characterization tools to study the phase variation in the cobalt samples. XRD and NMR results show a remarkable correlation in the two samples (Co-1 and Co-2). Co-2 has predominant fcc and hcp phases, whereas, Co-1 has fcc phase with lower amount of hcp. Both the samples show same saturation magnetization (Ms) but there is a remarkable difference in the phase composition. Thus, 59Co NMR appears to be a good tool to identify the phase purity of the ferromagnetic cobalt samples.

Removal of nickel and strontium from simulated radioactive wastewater via a pellet coprecipitation-microfiltration process

International Nuclear Information System (INIS)

Xiangdan Jin; Ping Gu; Guanghui Zhang; Xuan Shang; Li'an Hou

2014-01-01

In order to increase the decontamination factor (DF) and concentration factor (CF) for the treatment of radioactive wastewater, a pellet coprecipitation microfiltration process which aimed at removing the neutron activation product 63 Ni and fission product 90 Sr was studied. In this study average DFs were (4.60 ± 0.42) × 10 3 for nickel and 559 ± 24 for strontium, respectively. When about 1.8 m 3 wastewater was treated, the sludge volume was significantly minimised after 24 h settling and CF reached over 1 × 10 3 . DFs and CF values were improved by 1-2 orders of magnitude in this study compared with those achieved by conventional methods. (author)

Neptunium sorption and co-precipitation of strontium in simulated DWPF salt solution

International Nuclear Information System (INIS)

McIntyre, P.F.; Orebaugh, E.G.; King, C.M.

1988-01-01

Batch experiments performed using crushed slag saltstone (∼40 mesh) removed >80% of 237 Np from simulated Defense Waste Processing Facility (DWPF) salt solution. The concentration of 237 Np (110 pCi/ml) used was 1000x greater than levels in actual DWPF solutions. Neptunium-239 was used as a tracer and was formed by neutron activation of uranyl nitrate. Results showed that small amounts of crushed saltstone (as little as 0.05 grams), removed >80% of neptunium from 15 ml of simulated DWPF solution after several hours equilibration. The neptunium is sorbed on insoluble carbonates formed in and on the saltstone matrix. Further testing showed that addition of 0.01 and 0.10 ml of 1 molar Ca +2 (ie. Ca (NO 3 ) 2 , CaCl 2 ) into 15 ml of simulated DWPF solution yielded a white carbonate precipitate which also removed >80% of the neptunium after 1 hour equilibration. Further experiments were performed to determine the effectiveness of this procedure to co-precipitate strontium

Effect of preparation conditions on Nickel Zinc Ferrite nanoparticles: A comparison between sol–gel auto combustion and co-precipitation methods

Directory of Open Access Journals (Sweden)

Manju Kurian

2016-09-01

Full Text Available The experimental conditions used in the preparation of nano crystalline mixed ferrite materials play an important role in the particle size of the product. In the present work a comparison is made on sol–gel auto combustion methods and co-precipitation methods by preparing Nickel Zinc Ferrite (Ni0.5Zn0.5Fe2O4 nano particles. The prepared ferrite samples were calcined at different temperatures and characterized by using standard methods. X-ray diffraction analysis indicated the formation of single phase ferrite nanoparticles for samples calcined at 500 °C. The lattice parameter range of 8.32–8.49 Å confirmed the cubic spinel structure. Average crystallite size estimated from X-ray diffractogram was found to be between 17 and 40 nm. The IR spectra showed two main absorption bands, the high frequency band ν1 around 600 cm−1 and the low frequency band ν2 around 400 cm−1 arising from tetrahedral (A and octahedral (B interstitial sites in the spinel lattice. TEM pictures showed particles in the nanometric range confirming the XRD data. The studies revealed that the sol–gel auto combustion method was superior to the co-precipitation method for producing single phase nano particles with smaller crystallite size.

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

Science.gov (United States)

Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

2016-09-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

Properties of Er{sub 2}O{sub 3} nanoparticles synthesized by a modified co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Castaneda C, J.; Maranon R, V. F.; Perez Ladron de G, H.; Rodriguez R, R. A.; Chiu Z, R. [Universidad de Guadalajara, Centro Universitario de los Lagos, Av. Enrique Diaz de Leon s/n, Lagos de Moreno 47460, Jalisco (Mexico); Meneses N, M. A., E-mail: jcc050769@yahoo.com.mx [Centro de Investigaciones en Optica, A. C., Apdo. Postal 1-948, Leon, Guanajuato (Mexico)

2015-07-01

Er{sub 2}O{sub 3} nanoparticles were synthesized by co-precipitation with the addition of ascorbate as stabilizing agent. The nanoparticles had spherical shapes with a mean diameter of 32 nm and were allocated in clusters, as determined by X-ray diffraction, atomic force microscopy and optical microscopy. Characteristic green and red emissions from Er{sup 3+} were recorded by pumping the nanoparticles at 525 nm, 805 nm and 975 nm. However, the luminescence spectra show an enhancement of red emission for Nir pump wavelengths. We proposed this behavior was due to phonon-assisted depopulation mechanisms and energy transfer processes related to the different excitation schemes. (Author)

Facile synthesis of radial-like macroporous superparamagnetic chitosan spheres with in-situ co-precipitation and gelation of ferro-gels.

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Chih-Hui Yang

Full Text Available Macroporous chitosan spheres encapsulating superparamagnetic iron oxide nanoparticles were synthesized by a facile and effective one-step fabrication process. Ferro-gels containing ferrous cations, ferric cations and chitosan were dropped into a sodium hydroxide solution through a syringe pump. In addition, a sodium hydroxide solution was employed for both gelation (chitosan and co-precipitation (ferrous cations and ferric cations of the ferro-gels. The results showed that the in-situ co-precipitation of ferro-ions gave rise to a radial morphology with non-spheroid macro pores (large cavities inside the chitosan spheres. The particle size of iron oxide can be adjusted from 2.5 nm to 5.4 nm by tuning the concentration of the sodium hydroxide solution. Using Fourier Transform Infrared Spectroscopy and X-ray diffraction spectra, the synthesized nanoparticles were illustrated as Fe(3O(4 nanoparticles. In addition, the prepared macroporous chitosan spheres presented a super-paramagnetic behaviour at room temperature with a saturation magnetization value as high as ca. 18 emu/g. The cytotoxicity was estimated using cell viability by incubating doses (0∼1000 µg/mL of the macroporous chitosan spheres. The result showed good viability (above 80% with alginate chitosan particles below 1000 µg/mL, indicating that macroporous chitosan spheres were potentially useful for biomedical applications in the future.

Structure and electrochemical properties of Mg2SnO4 nanoparticles synthesized by a facile co-precipitation method

International Nuclear Information System (INIS)

Tang, Hao; Cheng, Cuixia; Yu, Gaige; Liu, Haowen; Chen, Weiqing

2015-01-01

Nanosized Mg 2 SnO 4 has been synthesized by a facile co-precipitation method. The structure and morphology of the as-prepared samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), fourier Transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that Mg 2 SnO 4 sample is very sensitive to the aging time of the precursor. The single phase Mg 2 SnO 4 nanoparticles with ∼23 nm can be obtained at 900 °C using the aging 35 min percusor as source. The electrochemical properties of the powder obtained at 900 °C are investigated by galvanostatic discharge-charge tests and cyclic voltammograms (CVs). The initial specific discharge capacity reaches as high as 927.7 mAh g −1 at 0.2 mA cm −2 in 0.05–3.0 V, which indicates that Mg 2 SnO 4 nanoparticles could be a promising candidate of anode material for Li-ion batteries. - Highlights: • Nanosized Mg 2 SnO 4 has been synthesized by a facile co-precipitation method. • We find that Mg 2 SnO 4 sample is very sensitive to the ageing time of the precursor. • The single phase Mg 2 SnO 4 nanoparticles with about 23 nm can be obtained by calcining the ageing 35 min percusor at 900 °C. • The obtained powders show a better electrochemical performance

Synthesis, Characterization, and Atenolol Delivery Application of Functionalized Mesoporous Hydroxyapatite Nanoparticles Prepared by Microwave-Assisted Co-precipitation Method.

Science.gov (United States)

Mortazavi-Derazkola, Sobhan; Naimi-Jamal, Mohammad Reza; Ghoreishi, Seyedeh Masoumeh

2016-01-01

Atenolol has been used to treat angina and hypertension, either alone or with other antihypertensives. Despite its usefulness, it shows some side effects such as diarrhea and nausea in some patients. A method for slow release of atenolol in intestine is helpful to prevent such side effects. A facile co-precipitation microwave-assisted method was used to fabricate mesoporous hydroxyapatite nanoparticles (mHAp). It was then functionalized to have SO3H groups. The synthesized material was used for storage/slow release study of atenolol. Atenolol loaded mHAp shows immediate release of atenolol in pH 8, whileafter functionalizing shows up to ca. 30% release at the beginning. In pH 1, 50% of drug was released after 10 h from AT@mHAp and after 18h the drug was almost completely released.The drug release profiles of functionalized HAp at pH value 1 and 8reveals the complete release of atenolol in intestine pH, while no complete release is observed in stomach environment. The aims of this work were synthesis and characterization of mesoporous HAp through the microwave-assisted co-precipitation method and elucidate the underlying drug release capability of mesoporous HAp nanoparticles. The SO3H group was incorporated into the mesoporous HAp and then used as drug delivery carriers using atenolol as a model drug to investigate their drug storage/release properties in simulated body fluid (SBF). Increasing pH value to 8 causes increase in the drug release.

Lithium recycling and cathode material regeneration from acid leach liquor of spent lithium-ion battery via facile co-extraction and co-precipitation processes.

Science.gov (United States)

Yang, Yue; Xu, Shengming; He, Yinghe

2017-06-01

A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li 2 CO 3 with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5M H 2 SO 4 , and the cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 is miro spherical morphology without any impurities, which can meet with LiNi 1/3 Co 1/3 Mn 1/3 O 2 production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of pH on the Structural and Magnetic Properties of Magnetite Nanoparticles Synthesised by Co-Precipitation

International Nuclear Information System (INIS)

Ramadan, W.; Kareem, M.; Hannoyer, B.; Saha, Sh.

2011-01-01

Magnetite, Fe3O4, nanoparticles were synthesized using co-precipitation aqueous method at room temperature and at different pH, from 8 to 12.5. The pH value was found to influence greatly the resulting phases and has no significant effect on the particle size. In all cases, magnetite was found to be the main phase but the contribution of Goethite phase was identified clearly with the increase in pH. Significant reduction in saturation magnetization was evident. Structural and magnetic properties of the nanoparticles were examined using; XRD, TEM, Raman Spectroscopy and SQUID. (author)

Co-precipitation of radium with barium and strontium sulfate and its impact on the fate of radium during treatment of produced water from unconventional gas extraction.

Science.gov (United States)

Zhang, Tieyuan; Gregory, Kelvin; Hammack, Richard W; Vidic, Radisav D

2014-04-15

Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far

Superparamagnetic behavior of nanosized Co{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} synthesized by a flow rate controlled chemical coprecipitation method

Energy Technology Data Exchange (ETDEWEB)

Dey, S. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Dey, S.K. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Department of Physics, NITMAS, 24 Pargana(s) 743368 (India); Majumder, S. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Poddar, A.; Dasgupta, P.; Banerjee, S. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Kumar, S., E-mail: kumars@phys.jdvu.ac.in [Department of Physics, Jadavpur University, Kolkata 700032 (India)

2014-09-01

We have studied the structural, microstructural and magnetic properties of nanosized (∼20 nm) Co{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} synthesized by a flow rate controlled coprecipitation method. The phase purity and crystallinity of the sample have been confirmed by powder X-ray diffraction and high resolution transmission electron microscopic studies. According to the results of dc magnetic measurements the sample exhibits superparamagnetic behavior above 70 K due to its nanometric size. This has been corroborated by Mössbauer spectroscopic study at 300 K. The infield Mössbauer spectroscopic study indicates that the sample behaves ferrimagnetically at 10 K and it possesses equilibrium cation distribution. The saturation magnetization of the sample (M{sub SAT}∼32 emu g{sup −1} at 300 K) is substantially lower than its bulk counterpart (M{sub SAT}=80 emu g{sup −1}) but higher than those having same composition synthesized by the conventional coprecipitation method. This has been attributed to finite size and spin canting effects as well as good crystalline character and bulk like equilibrium cation distribution of the sample. We have shown that the flow rate controlled coprecipitation method can produce nanosized ferrites with very good crystalline order and equilibrium cation distribution but they exhibit reduction of magnetization, magnetic order and ordering temperature compared to their bulk counterparts due to spin canting effect and finite size effect.

Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

2016-07-01

An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

Determination of uranium and thorium isotopes in soil samples by coprecipitation

International Nuclear Information System (INIS)

Ngo Quang Huy; Trinh Thi Bich; Nguyen Van Suc

2012-01-01

The paper presents a procedure to prepare soil samples for U and Th isotope measurement by alpha-spectrometry after coprecipitation with LaF 3 . In this procedure the reduction of U(VI) to U(IV) was performed by Zn metal in 4M HCl solution. The recoveries of chemical separation equal to ε U-chemistry = 78±4% for uranium and ε Th-chemistry = 82±4% for thorium. Canberra alpha-spectrometer was used with PIPS detectors of A-1200-37-AM Model of 1200 mm 2 active area. The counting efficiency of the measuring system equals to ε counting = 18% and the total efficiencies were ε U = ε counting - ε U-chemistry = 14.0 ± 0.7% for uranium and ε Th = ε counting - ε Th-chemistry = 14.7 ± 0.7% for thorium. The recoveries of chemical separation were rather high (about 80%), that leads to the use of a small weight of soil sample (about 0.5 g). The efficiencies were also stable, that allows analyzing the soil sample without using radiotracers. They are advantages of the sample preparation procedure of this work. (author)

Characteristics of Barium Hexaferrite Nanoparticles Prepared by Temperature-Controlled Chemical Coprecipitation

International Nuclear Information System (INIS)

Kwak, Jun Young; Lee, Choong Sub; Kim, Don; Kim, Yeong Il

2012-01-01

Ba-ferrite (BaFe 12 O 19 ) nanoparticles were synthesized by chemical coprecipitation method in an aqueous solution. The particle size and the crystallization temperature of the Ba-ferrite nanoparticles were controlled varying the precipitation temperature. The precipitate that was prepared at 0 .deg. C showed the crystal structure of Ba-ferrite in X-ray diffraction when it was calcined at the temperature above 580 .deg. C, whereas what was prepared at 50 .deg. C showed the crystallinity when it was calcined at the temperature higher than about 700 .deg. C. The particle sizes of the synthesized Ba-ferrite were in a range of about 20-30 nm when it was prepared by being precipitated at 0 .deg. C and calcined at 650 .deg. C. When the precipitation temperature increased, the particle size also increased even at the same calcination temperature. The magnetic properties of the Ba-ferrite nanoparticles were also controlled by the synthetic condition of precipitation and calcination temperature. The coercive force could be appreciably lowered without a loss of saturation magnetization when the Ba-ferrite nanoparticles were prepared by precipitation and calcination both at low temperatures

Influence of coprecipitation and mechanical mixture methods on the characteristics of nickel oxide-alumina composites; Influencia dos metodos de coprecipitacao e mistura mecanica nas caracteristicas de compositos oxido de niquel-alumina

Energy Technology Data Exchange (ETDEWEB)

Cordeiro, G.L.; Yoshito, W.K.; Ussui, V.; Lima, N.B. de; Lazar, D.R.R., E-mail: gcordeiro@usp.br [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

2014-07-01

Alumina-supported nickel catalysts are currently used in the reforming process due to low cost and high activity for hydrogen production from alcohols. In this work, the effect of preparation methods on nickel oxide-alumina based materials has been investigated. Nickel content was fixed at 15 wt%. Ceramic powders were obtained by coprecipitation in ammonia medium and mechanical mixture. Coprecipitated materials were calcined in air at 750 deg C to obtain the corresponding oxides. Materials obtained by mechanical mixture were prepared by wet milling of nickel oxide and alumina powders, both synthesized by precipitation and calcination in air at 450 and 750 deg C, respectively. Powders were characterized by X-ray diffraction, nitrogen gas sorption by applying the BET method, laser diffraction, scanning electron microscopy, electrophoretic mobility measurements for zeta potential determination and infrared spectroscopy. The results showed that coprecipitation method allowed the production of mixed oxides with high surface area (232,7 ± 3,2 m{sup 2}.g{sup -1}) and normal granulometric distribution while mechanical mixture led to the formation of materials constituted by gamma alumina and nickel oxide phases, with low surface area (136,2 ± 0,5 m{sup 2}.g{sup -1}) and bimodal granulometric distribution. (author)

A study on the coprecipitation of arsenite and arsenate into calcite coupled with the determination of oxidation states of arsenic both in calcite and water

International Nuclear Information System (INIS)

Yokoyama, Yuka; Takahashi, Yoshio; Mitsunobu, Satoshi; Tanaka, Kazuya; Itai, Takaaki

2009-01-01

It was found that the amount of arsenite incorporated into calcite is much less than that of arsenate. The result suggests that the sequestration of arsenic by coprecipitation with calcite cannot be an important chemical process under reducing conditions such as in groundwater where arsenite is the dominant arsenic species. (author)

Superior sinterability of nano-crystalline gadolinium doped ceria powders synthesized by co-precipitation method

International Nuclear Information System (INIS)

Hari Prasad, D.; Kim, H.-R.; Park, J.-S.; Son, J.-W.; Kim, B.-K.; Lee, H.-W.; Lee, J.-H.

2010-01-01

Reduced sintering temperature of doped ceria can greatly simplify the fabrication process of solid oxide fuel cells (SOFCs) by utilizing the co-firing of all cell components with a single step. In the present study, nano-crystalline gadolinium doped ceria (GDC) powders of high sinterability at lower sintering temperature has been synthesized by co-precipitation at room temperature. The successful synthesis of nano-crystalline GDC was confirmed by XRD, TEM and Raman spectroscopy analysis. Dilatometry studies showed that GDC prepared by this method can be fully densified (97% relative density) at a sintering temperature of 950 o C which is fairly lower than ever before. It has also been found that the sintered samples have a higher ionic conductivity of 1.64 x 10 -2 S cm -1 at 600 o C which is suitable for the intermediate temperature SOFC application.

Synthesis of nickel oxide - zirconia composites by coprecipitation route followed by hydrothermal treatment

International Nuclear Information System (INIS)

Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci; Paschoal, Jose Octavio Armani

2009-01-01

Nickel oxide-yttria stabilized zirconia (NiO-YSZ) for use as solid oxide fuel cell anode were synthesized by coprecipitation to obtain amorphous zirconia and crystallized β-nickel gels of the corresponding metal hydroxides. Hydrothermal treatment at 200°C and 220 psi from 2 up to 16 hours, under stirring, was performed to produce nanocrystalline powder. The as-synthesized powders were uniaxially pressed and sintered in air. Powders were characterized by X-ray diffraction, laser scattering, scanning and transmission electron microscopy (SEM/TEM), gas adsorption technique (BET) and TGDTA thermal analysis. Ceramic samples were characterized by dilatometric analysis and density measurements by Archimedes method. The characteristics of hydrothermally synthesized powders and compacts were compared to those produced without temperature and pressure application. Crystalline powders were obtained after hydrothermal process, excluding the calcination step from this route. The specific surface area of powders decreases with increasing time of hydrothermal treatment while the agglomerate mean size is not affected by this parameter. (author)

Suitability of Sr{sub 0.5}Ba{sub 0.5-x}Ce{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} co-precipitated nanomaterials for inductor applications

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.co [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Farooq, Saima [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2010-03-18

The present investigation deals with the synthesis and characterization of Ce-Ni ions substituted nanocrystalline strontium-barium hexaferrites (Sr{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19}) by the chemical co-precipitation method, with focus on the optimization of annealing temperature for the hexagonal phase development. The synthesis involves co-precipitation of aqueous solutions of water-soluble salts of strontium, barium and iron, at pH 9 using an ammonium hydroxide solution as a precipitating agent. The optimum temperature of annealing, necessary for the hexagonal phase development, is determined on the basis of thermo-gravimetric analysis (TGA). The co-precipitate is annealed at a temperature of 1323 K for 6 h, to produce a single magnetoplumbite phase of Sr-Ba hexaferrites, with the corresponding average crystallite size ranging from 36 to 48 nm. Observed changes in the lattice structure determined by the powder X-ray diffraction (XRD) studies are not in contradiction with the results of TGA. DC-electrical resistivity increases from 1.8 x 10{sup 10} to 12.5 x 10{sup 10} {Omega} cm, whereas the drift mobility, dielectric constant and dielectric loss tangent decrease with increasing the Ce-Ni content of the samples. Material of above-mentioned characteristics is considered to be suitable for applications in the microwave and surface mount devices (SMD) for fabricating the multilayer chip inductors (MLCI).

Size-controlled Synthesis and Characterization of Fe3O4 Nanoparticles by Chemical Coprecipitation Method

International Nuclear Information System (INIS)

Chia Chin Hua; Sarani Zakaria; Farahiyan, R.; Liew Tze Khong; Mustaffa Abdullah; Sahrim Ahmad; Nguyen, K.L.

2008-01-01

Magnetite (Fe 3 O 4 ) nanoparticles have been synthesized using the chemical coprecipitation method. The Fe 3 O 4 nanoparticles were likely formed via dissolution-recrystallization process. During the precipitation process, ferrihydrite and Fe(OH) 2 particles formed aggregates and followed by the formation of spherical Fe 3 O 4 particles. The synthesized Fe 3 O 4 nanoparticles exhibited superparamagnetic behavior and in single crystal form. The synthesis temperature and the degree of agitation during the precipitation were found to be decisive in controlling the crystallite and particle size of the produced Fe 3 O 4 nanoparticles. Lower temperature and higher degree of agitation were the favorable conditions for producing smaller particle. The magnetic properties (saturation magnetization and coercivity) of the Fe 3 O 4 nanoparticles increased with the particle size. (author)

Ultratrace analysis of actinides via coprecipitation/laser-induced fluorescence spectroscopy

International Nuclear Information System (INIS)

Miller, S.M.

1982-01-01

Actinides were selectively preconcentrated by coprecipitating each out of solution with a fluoride matrix and calcining each sample at 800 0 C. The fluorescence spectrum of each sample was recorded by illuminating the sample with laser light and detecting fluorescence with either a fluorescence/Raman spectrometer, an infrared spectrometer or in certain cases a filter fluorimeter. Three previously unobserved actinide spectra were recorded. Narrow lines at 546.9 nm, 564.6 nm, and 569.6 nm were found for CaF 2 :PuO 2++ at 10K. CaF 2 :Am + 3 displayed two broadband fluorescent peaks at 625 nm and 746 nm at room temperature and CaF 2 :Pu + 3 possessed a fluorescent peak at 1.22 microns at 10K. Energy transfer was observed in the form of Tb fluorescence quenching in TbF 3 :Pu + 3 when Pu was present in quantities of 10 ppM or more and in the form of Tb fluorescence enhancement in TbF 3 :Am + 3 when 1 ppM or more of Am was present. Careful sample preparation and the use of temporal as well as a spectral discrimination system extended the detection limit of U from 1 ml samples to the subfemtogram level. The fluorescence detection limits for Pu and Am were extended to 0.48 and 0.032 pg/ml. 39 figures, 9 tables

Synthesis of cerium oxide (CeO{sub 2}) nanoparticles using simple CO-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Farahmandjou, M.; Zarinkamar, M.; Firoozabadi, T. P., E-mail: farahamndjou@iauvaramin.ac.ir [Islamis Azad University, Varamin-Phisva Branch, Department of Physics, Varamin (Iran, Islamic Republic of)

2016-11-01

Synthesis of cerium oxide (CeO{sub 2}) nanoparticles was studied by new and simple co-precipitation method. The cerium oxide nanoparticles were synthesized using cerium nitrate and potassium carbonate precursors. Their physicochemical properties were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (Sem), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (Ftir) and UV-Vis spectrophotometer. XRD pattern showed the cubic structure of the cerium oxide nanoparticles. The average particle size of CeO{sub 2} was around 20 nm as estimated by XRD technique and direct HRTEM observations. The surface morphological studies from Sem and Tem depicted spherical particles with formation of clusters. The sharp peaks in Ftir spectrum determined the existence of CeO{sub 2} stretching mode and the absorbance peak of UV-Vis spectrum showed the bandgap energy of 3.26 eV. (Author)

Separation of valent forms of chromium (3) and chromium (6) by coprecipitation with iron (3) hydroxide

International Nuclear Information System (INIS)

Nazirmadov, B.; Khamidov, B.O.; Egorova, L.A.

1988-01-01

Soption 9.62x10 -5 mol/l of 51 Cr radioactive isotope in oxidation states 3 and 6 by iron(3) hydroxide in 1 mol/l of KNO 3 and KCl depending on pH medium is investigated. The region of practically total concentration of Cr(3) and Cr(6 + ) (pH=3-6.5) is determined. The results of spectrophotometric investigations, calculational data on distribution of hydroxocation forms of chromium (3) and of chromium (6) anions and sorption by iron (3) hydroxide permit to characterize sorption of chromium forms in different stages of oxidation. The methods of chromium (3) and chromium (6) separation by coprecipitation of iron (3) hydroxide and their precipitation from it is developed on the above foundation

Study of magnetic and electrical properties of La doped Mn-Zn nanoferrites synthesized by co-precipitation technique

International Nuclear Information System (INIS)

Panwar, Neena; Thakur, Atul; Thakur, Preeti

2013-01-01

Lanthanum manganese zinc ferrite powder of the composition Mn 0.4 Zn 0.6 La 0.4 Fe 1.6 O 4 were synthesized via co-precipitation technique. Metallic chlorides of manganese, zinc and iron in which Lanthanum is doped were taken. Sodium hydroxide (NaOH) base was used as precipitant agent. The calcinations (presintering) were performed at 700℃ for 3h and sintering at different temperatures 900℃, 850℃, 800℃ also for 3h. The structural investigation of the prepared sample was performed with X-ray diffraction (XRD) and scanning electron microscope (SEM). For studying magnetic properties vibrating sample magnetometer (VSM) are used. Electrical properties were studied by DC resistivity set up. (author)

Upconversion emission study of Er3+/Yb3+ doped barium titanate phosphor prepared by co-precipitation method

International Nuclear Information System (INIS)

Mahata, M.K.; Dey, R.; Kumar, K.; Rai, V.K.; Rai, S.B.

2012-01-01

In the present work we have successfully synthesized the Er 3+ , Yb 3+ doped barium titanate phosphor via co-precipitation synthesis method. Under 980 nm excitation, tri-color upconversion fluorescence has been observed. The Fourier Transform Infrared measurement was done to check the presence of organic impurities. In order to find out how many photons are involved in each emission band, the variation of UC emission intensity of the codoped phosphor is studied with increase in excitation power. Upconversion emission spectra show that as the annealing temperature of the powder is increased, intensity of red emission decreases and intensity of green emission increases due to the decrease in maximum phonon frequency of the host material. (author)

Filterless pre-concentration by co-precipitation by formation of crystalline precipitate in the analysis of barium by FIA-FAES

DEFF Research Database (Denmark)

Plamboeck, C.; Westtoft, H.C.; Pedersen, S.A.

2003-01-01

A novel method based on flow injection analysis (FIA) and flame atomic emission spectrometry (FAES) is presented. It was developed for direct determination of barium in drinking water, in natural water, in digested samples of bone and liver, in saline water and in a standard reference material...... (NIST SRM 1640). It was found that digestion of bone by an incineration procedure was required, in order to extract most of the barium. In the FIA manifold, barium was pre-concentrated by co-precipitation with lead chromate leading to a crystalline deposit that adhered well to the inner walls of a nylon...

Synthesis of Sr- and Mg- doped lanthanum gallate by carbonate co-precipitation

International Nuclear Information System (INIS)

Sunitha, Y.; Narasimham, K.V.N.S.V.P.L.; Raju, V.S.; Kumar, Sanjiv

2010-01-01

Sr- and Mg- doped lanthanum gallate (LSGM) are promising electrolytes for low temperature solid oxide fuel cells (SOFCs) in view of their high ionic conductivity and stability over a wide range of oxygen partial pressures. LSGM powders are usually prepared by solid-state reactions. However high sintering temperature (∼ 1500 deg C) required for densification and the formation of secondary phases are the major drawbacks of the method. Wet-chemical method is a suitable alternative to solid-state synthesis with the prospect of the realisation of phase pure material with good sinterability at comparatively lower temperatures. In this paper we present the results of our investigation on the synthesis of LaGaO 3 and LSGM by a wet-chemical method through carbonate co-precipitation using ammonium carbonate and ammonium bicarbonate as precipitants. Phase and microstructural evolution of the material have been studied by XRD and SEM respectively, while compositional analysis has been performed by ion beam analysis (IBA) techniques. In addition we have also investigated the incorporation of Sr and Mg in the lattice of LaGaO 3 by (a) solid-state reaction route and (b) wet-chemical approach

Fuel-pellet-fabrication experience using direct-denitration-recycle-PuO2-coprecipitated mixed oxide

International Nuclear Information System (INIS)

Rasmussen, D.E.; Schaus, P.S.

1980-01-01

The fuel pellet fabrication experience described in this paper involved three different feed powders: coprecipitated PuO 2 -UO 2 which was flash calcined in a fluidized bed; co-direct denitrated PuO 2 -UO 2 ; and direct denitrated LWR recycle PuO 2 which was mechanically blended with natural UO 2 . The objectives of this paper are twofold; first, to demonstrate that acceptable quality fuel pellets were fabricated using feed powders manufactured by processes other than the conventional oxalate process; and second, to highlight some pellet fabrication difficulties experienced with the direct denitration LWR recycle PuO 2 feed material, which did not produce acceptable pellets. The direct denitration LWR recycle PuO 2 was available as a by-product and was not specifically produced for use in fuel pellet fabrication. Nevertheless, its characteristics and pellet fabrication behavior serve to re-emphasize the importance of continued process development involving both powder suppliers and fuel fabricators to close the fuel cycle in the future

Conductivity and dielectric behaviour of indium substituted zinc ferrites prepared by coprecipitation method

International Nuclear Information System (INIS)

Cvejić, Željka; Rakić, Srđan; Jankov, Stevan; Skuban, Sonja; Rapajić, Sanja; Srdić, Vladimir V

2015-01-01

This paper presents the results concerning dielectric behavior and conductivity of the nanosized Zn 1−x In x Fe 2 O 4 powders (x = 0, 0.15, 0.2, and 0.3), obtained by coprecipitation method. The frequency dependence of dielectric permittivity and conductivity of the samples is determined in the frequency range of 1–10 5 Hz, at temperatures from 300–350 K, while the temperature dependence of conductivity was recorded at 100 Hz, 10 kHz and 100 kHz. The ac conductivity was found to follow universal dielectric response, which is typical for charge transport by hopping or tunneling processes. Analyzing the variation of the parameter n (as a measure of the degree of correlation between conductivity and frequency), with the temperatures we discuss the possible conduction mechanism in investigated samples. Qualitatively, non-overlapping small polarons (NSPT) are usually associated with increase in n with increasing temperature, while correlated barrier hopping (CBH) shows a decrease in n with increasing T. (paper)

Facile Synthesis and Characterization of ZrO₂ Nanoparticles via Modified Co-Precipitation Method.

Science.gov (United States)

Ramachandran, M; Subadevi, R; Liu, Wei-Ren; Sivakumar, M

2018-01-01

The crystalline Zirconium oxide (ZrO2) nano particles were synthesized using optimized content of Zirconium nitrate (Zr(NO3)2·3H2O) with varying KOH concentration (0.5, 1 and 1.5 M) by co-precipitation method. The thermal history of the precursor was carefully analyzed through Thermogravimetric (TG/DTA) measurement. The as prepared samples were characterized to ensure structural, functional, morphological, compositional, chemical composition and band gap by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Laser Raman, scanning electron microscopy (SEM), High resolution Transverse Electron Microscopy (HR-TEM), X-ray photo electron spectroscopy (XPS), EDX, Photo luminescence spectroscopy (PL). The monoclinic structure with space group P21/c has been confirmed from XRD (JCPDS 89-9066). The Zr-O stretching vibration and Zr-O2-Zr bending vibrations were confirmed through FTIR analysis. The well dispersed particles with spherical morphology were confirmed through SEM and TEM analysis. The oxidation states of Zr, O and C were confirmed through XPS analysis. The oxygen vacancies and band gap of the particles were investigated through PL analysis.

Multielement determination of trace elements in seawater by inductively coupled plasma mass spectrometry after tandem preconcentration with cooperation of chelating resin adsorption and lanthanum coprecipitation

International Nuclear Information System (INIS)

Yabutani, Tomoki; Chiba, Koichi; Haraguchi, Hiroki

2001-01-01

A tandem preconcentration method, in which chelating resin adsorption and La coprecipitation were cooperatively employed for preconcentration, was developed as a pretreatment method for simultaneous multielement determination of trace elements in seawater by ICP-MS. First, the seawater sample (250 ml) was treated with a chelating resin for preconcentration of trace elements, and then trace elements with good recoveries were determined by ICP-MS. Trace elements with the chemical properties of oxoanion- and hydride-formation, which were poorly recovered in the chelating resin preconcentration, were further subjected to preconcentration by La coprecipitation. As a result, more than 30 elements could be determined in the concentration range from 9.6 μg L -1 for Mo to 0.00018 μg L -1 for Tm, when the present tandem method was applied to the analysis of open seawater standard reference material (NASS-4). Furthermore, the analytical results for open seawater reference materials were compared with those for coastal seawater reference material as well as for coastal seawater collected in the Ise Bay. It was found that the multielement data for trace elements in these seawater samples clearly showed different elemental distributions, reflecting the different marine environments. (author)

Superior Photocatalytic Performance of CeO₂ Nanoparticles and Reduced Graphene Oxide Nanocomposite Prepared by Low Cost Co-Precipitation Method.

Science.gov (United States)

Jayanthi, Mani; Lavanya, Thirugnanam; Saradha, Nagarajan Anbil; Satheesh, Kaveri; Chenthamarai, SriRangarajan; Jayavel, Ramasamy

2018-05-01

In this article, cerium oxide nanoparticles (CeO2 NPs) and reduced graphene oxide nanocomposite have been fabricated through simple, easy and cost effective co-precipitation method. The structural, optical and morphological characterization provides the evidence of successful synthesis of CeO2 NPs and nanocomposite. X-ray photoelectron spectroscopic characterization provides useful information about the concentrations and proportions of Ce3+ and Ce4+ ions in nanoparticles as well as in nanocomposite. These studies provide an insight to understand enhanced photocatalytic activity of nanocomposite. The nanocomposite produces 81% photocatalytic degradation of methyl orange compared to only 45% degradation by CeO2 NPs alone.

Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

OpenAIRE

Otter, Philipp; Malakar, Pradyut; Jana, Bana Bihari; Grischek, Thomas; Benz, Florian; Goldmaier, Alexander; Feistel, Ulrike; Jana, Joydev; Lahiri, Susmita; Alvarez, Juan Antonio

2017-01-01

Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the finding...

Formation and stability of aluminosilicate colloids by coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Putri, Kirana Yuniati

2011-02-15

Colloids are ubiquitous in natural waters. Colloid-facilitated migration is of importance in safety assessment of a nuclear waste disposal. Aluminosilicate colloids are considered to be the kernel of aquatic colloids. Their stability is affected by a number of geochemical parameters. This work aims to study qualitatively and quantitatively the stability of aluminosilicate colloids formed by coprecipitation under various geochemical conditions, i.e. pH, concentration of Al and Si metal ions, ionic strength, and omnipresent cations (Na{sup +}, Ca{sup 2+}, and Mg{sup 2+}). The work is performed by colorimetric method and laser-induced breakdown detection (LIBD). Two consecutive phase separations at 450 nm and 1 kDa are applied to separate the precipitates and colloids from the ionic species. By means of colorimetry, Si and Al can be detected down to 5.8 x10{sup -8} M and 7.4x10{sup -7} M, respectively. On the other hand, LIBD is able to quantify the colloidal size and its number density down to several ppt. Depending on the concentration of Al and Si metal ions, the formation trend of aluminosilicate colloid changes following its solubility curve. The lower the concentration, the higher the pH range in which the colloids start to emerge. Furthermore, the colloids are stable at higher Al and Si concentration and at low ionic strength. In the low pH range, cations provide different effects at low and high ionic strengths. At high ionic strength, the colloids are stable in the presence of a larger cation, while all cations exhibit similar effects at low ionic strength. However, in the high pH range, valence seems to have a stronger effect than ionic radius; colloids are more stable in the presence of monovalent cations than divalent ones. Meanwhile, XRD shows non- and/or poor crystalline structure of the aluminosilicate species. Nevertheless, results from XPS may suggest that the chemical composition (Si/Al ∼ 0.6) of the aluminosilicate precipitates is sillimanite or

Study of morphological and luminescent properties (TL and OSL) of ZnO nanocrystals synthetized by coprecipitation method

Energy Technology Data Exchange (ETDEWEB)

Soares, A.F., E-mail: alvarodefarias@hotmail.com; Tatumi, S.H., E-mail: sonia.tatumi@gmail.com; Mazzo, T.M.; Rocca, R.R.; Courrol, L.C.

2017-06-15

In this work, ZnO nanocrystalline phosphorus were synthesized using the method of coprecipitation, subsequently different heat treatments at 900 and 1000 °C for 2 h and 1000 °C for 4 h were performed. Afterward, Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) emissions were verified after exposure to β-radiation. Photoluminescence results showed UV and VIS emissions. Morphological studies with X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) confirmed the crystallinity of the samples, with their well-shaped wurtzite hexagonal structures in nanoscale. ZnO calcinated at 900 °C – 2 h emitted a broad TL peak located between the 362–372 °C; for ZnO calcinated at 1000 °C – 2 h, two intense peaks were observed at 144 and 308 °C, this TL emission curve was investigated with more details using Computerized Glow Curve Deconvolution and six individual TL peaks were obtained, for sample irradiated with 40.6 Gy, corroborating with the T{sub m}-T{sub stop} results. A study of Minimum Detectable Dose (MDD) was made and a dose of (492±40) μGy was determined. CW-OSL and LM-OSL analysis were made for ZnO calcinated at 1000 °C – 2 h, allowed to verify the behaviour, and the curve existing components (fast and medium, depending on dose). As well as the calculation of the Minimum Detectable Dose for CW-OSL. - Highlights: •ZnO nanocrystals were successfully produced by the method of coprecipitation. •Grains sizes by Scherrer Equation were between 26.9–40.6 nm, corroborating with SEM. •Study of the TL emission: Computerized Glow Curve Deconvolution (CGCD) and Tm-Tstop. •TL emission of ZnO calcinated supplied the minimum detectable dose of (492±40) μGy. •Study of CW-OSL and LM-OSL with CGCD. MDD for CW-OSL evaluation of ZnO calcinated.

Development, evaluation and optimization of superparamagnetite nanoparticles prepared by co-precipitation method.

Science.gov (United States)

Montaseri, Hashem; Alipour, Shohreh; Vakilinezhad, Molood Alsadat

2017-08-01

Magnetic nanoparticles (MNPs) are of high interest due to their application in medical fields, in particular for theranostics. Specific properties required for such particles include high magnetization, appropriate size and stability. Biocompatible magnetically soft magnetite particles (Fe 3 O 4 ) have been investigated for biological purposes. The intrinsic instability of these nanoparticles and their susceptibility to the oxidization in air, are limitations for their applications. Various methods have been described for synthesis of these nanoparticles among which co-precipitation method is widely experimented. In order to illustrate the synthesis of MNPs elaborately, the effect of different factors on particle formation were studied. The particles morphology, stability, paramagnetic effect, chemical structure and cytotoxicity were evaluated. Particles of 58 and 60 nm obtained by oleic acid coated (OMNPs) and citric acid coated (CMNPs) magnetite nanoparticles respectively. Transmission electron microscopy images exhibited the real sizes are 15 and 13 nm. Magnetic saturations of these nanoparticles were 72 and 68 emu/g which is suitable for medical applications. Both OMNPs and CMNPs were non-toxic to the SK-Br-3 and MCF-7 cells in the concentrations of <2.5 μg/mL. Since these particles exhibit relatively high magnetic saturation, low dose of such material would be required; therefore, these NPs seem to be suitable for theranostics.

High coercivity Gd-substituted Ba hexaferrites, prepared by chemical coprecipitation

Science.gov (United States)

Litsardakis, G.; Manolakis, I.; Serletis, C.; Efthimiadis, K. G.

2008-04-01

A series of Gd-substituted Ba hexaferrites with nominal formula (Ba1-xGdx)Oṡ5.25 Fe2O3 (x=0-0.30) were prepared by the chemical coprecipitation method from nitrate precursors and heating at T =800-1200°C for 2h. The samples have been examined by x-ray diffraction, vibrating-sample magnetometer, and scanning electron microscopy methods. Gd substituted samples form single phase materials with the M-type hexaferrite structure at all heating temperatures, in the range of x ⩽0.10-0.20. The saturation magnetization (at 1.8T) varies slightly with x in most cases and, for x =0.05-0.10, it increases up to 66.7Am2/kg, exceeding the value of the unsubstituted hexaferrite. A strong enhancement of the coercivity is observed for all substituted samples, with maximum values Hc=457kA/m for the single-phase x =0.10 sample annealed at 1000°C and Hc=477kA/m for the x =0.25 sample annealed at 1100°C which contains Fe2O3 and GdFeO3 impurities. As the variation of coercivity with either substitution rate (x ) or annealing temperature is not monotonic, three different factors may account for the high coercivities that are obtained: (a) an inhibition of grain growth due to the presence of Gd, (b) a possible inherent effect on magnetocrystalline anisotropy, especially for single phase samples, and (c) a microstructural effect of secondary phases.

Method for determination of Fe, Co, Ni, Cu, Zn and Pb in sea water using X-ray fluorescence analysis, after concentration step of these elements by coprecipitation with APDC

International Nuclear Information System (INIS)

Lam, P.; Estevez Alvarez, J.R.; Pupo Gonzalez, I.; Ramirez, M.; Rivera, N.

1998-01-01

In this work an analytical procedure has been applied to the to the determination of Fe, Co, Ni, Cu, Zn y Pb in seawater, that includes a coprecipitation step applied of these metals with APDC. The final analysis is carried out by X-Ray Fluorescence Analysis thin layer absolute method

Co-precipitation synthesis and photoluminescence properties of K2GdZr (PO4)3:Eu3+—a deep red luminomagnetic nanophosphor

International Nuclear Information System (INIS)

Chawla, Santa; Ravishanker,; Rajkumar,; Khan, A.F.; Kotnala, R.K.

2013-01-01

Nanoparticles of Eu 3+ activated K 2 GdZr(PO 4 ) 3 has been successfully synthesized by controlled inclusive co-precipitation method in high alkaline environment to enable complex crystalline phase formation. Much enhanced deep red luminescence, broadened emission bands with unusually prominent 5 D 0 – 7 F 4 transition at 699 nm are defining characteristics of the nanoparticles compared to bulk counterpart synthesized by solid state reaction route. Among various excitation pathways such as charge transfer from O 2− –Eu 3+ , Gd 3+ –Eu 3+ , the direct excitation of Eu 3+ at 394 nm is the most effective as revealed by photoluminescence and time resolved studies. Occurrence and variation of superparamagnetism in undoped and Eu 3+ doped nanoparticles indicate the role of unpaired 4f electron spin of Gd 3+ in making the nanoparticles superparamagnetic. A room temperature cost effective synthesis process of Eu 3+ doped multimetallic complex phosphate supermagnetic nanophosphor can pave way for applications requiring such functionality. -- Highlights: ► Eu 3+ doped K 2 GdZr(PO 4 ) 3 nanocrystals have been synthesized successfully by coprecipitation. ► K 2 GdZr(PO 4 ) 3 :Eu 3+ emit intense deep red fluorescence. ► Red emitting K 2 GdZr(PO 4 ) 3 :Eu 3+ nanocrystals show superparamagnetism due to Gd 3+ . ► Luminomagnetic KGP:Eu 3+ have application potential in biology, lighting and display

Synthesis and magnetic characterization of nickel ferrite nanoparticles prepared by co-precipitation route

Science.gov (United States)

Maaz, K.; Karim, S.; Mumtaz, A.; Hasanain, S. K.; Liu, J.; Duan, J. L.

2009-06-01

Magnetic nanoparticles of nickel ferrite (NiFe 2O 4) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses confirmed the formation of single-phase nickel ferrite nanoparticles in the range 8-28 nm depending upon the annealing temperature of the samples during the synthesis. The size of the particles ( d) was observed to be increasing linearly with annealing temperature of the sample while the coercivity with particle size goes through a maximum, peaking at ˜11 nm and then decreases for larger particles. Typical blocking effects were observed below ˜225 K for all the prepared samples. The superparamagnetic blocking temperature ( T B) was found to be increasing with increasing particle size that has been attributed to the increased effective anisotropy energy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins or dead/inert layer in these nanoparticles.

Triethylamine-assisted Mg(OH)2 coprecipitation/preconcentration for determination of trace metals and rare earth elements in seawater by inductively coupled plasma mass spectrometry (ICP-MS).

Science.gov (United States)

Arslan, Zikri; Oymak, Tulay; White, Jeremy

2018-05-30

In this paper, we report an improved magnesium hydroxide, Mg(OH) 2 , coprecipitation method for the determination of 16 trace elements (Al, V, Cr, Mn, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sb, Sn and Pb) and 18 rare earth elements (REEs), including Sc, Y, U and Th in seawater and estuarine water samples. The procedure involves coprecipitation of the trace elements and REEs on Mg(OH) 2 upon addition of a small volume of triethylamine (TEA) followed by analysis of the dissolved pellet solutions by inductively coupled plasma mass spectrometry (ICP-MS). Three-step sequential coprecipitation was carried out on 10 mL aliquots of seawater to eliminate the matrix ions and to preconcentrate the analytes of interest into a 1 mL final volume. Spike recoveries varied from 85% (Th) to 105% (Y). Calcium (Ca), sodium (Na) and potassium (K) matrices were virtually eliminated from the analysis solutions. Collision reaction interface (CRI) technology utilizing H 2 and He gases was employed to determine its effectiveness in removing the spectral interferences originating from the residual Mg matrix, TEA and plasma gases. H 2 was more effective than He in reducing spectral interferences from TEA and plasma gases. Limits of detection (LODs) ranged from 0.01 ng L -1 (Ho) to 72 ng L -1  (Al). The method was validated by using certified seawater (CASS-4) and estuarine water (SLEW-3) reference materials. Precision for five (n = 5) replicate measurements were between 1.2% (Pr) and 18% (Lu). Fe, Pb, Sn, and Zn impurities in TEA were significant in comparison to the levels in CASS-4 and SLEW-3, while relatively high background signals impacted determinations of low levels of Sc and Th. The effects of these hurdles on precision and accuracy were alleviated by measuring these elements in spiked CASS-4 and SLEW-3. Copyright © 2018 Elsevier B.V. All rights reserved.

Towards deriving Ni-rich cathode and oxide-based anode materials from hydroxides by sharing a facile co-precipitation method.

Science.gov (United States)

Qiu, Haifa; Du, Tengfei; Wu, Junfeng; Wang, Yonglong; Liu, Jian; Ye, Shihai; Liu, Sheng

2018-05-22

Although intensive studies have been conducted on layered transition metal oxide(TMO)-based cathode materials and metal oxide-based anode materials for Li-ion batteries, their precursors generally follow different or even complex synthesis routes. To share one route for preparing precursors of the cathode and anode materials, herein, we demonstrate a facile co-precipitation method to fabricate Ni-rich hydroxide precursors of Ni0.8Co0.1Mn0.1(OH)2. Ni-rich layered oxide of LiNi0.8Co0.1Mn0.1O2 is obtained by lithiation of the precursor in air. An NiO-based anode material is prepared by calcining the precursor or multi-walled carbon nanotubes (MWCNTs) incorporated precursors. The pre-addition of ammonia solution can simplify the co-precipitation procedures and the use of an air atmosphere can also make the heat treatment facile. LiNi0.8Co0.1Mn0.1O2 as the cathode material delivers a reversible capacity of 194 mA h g-1 at 40 mA g-1 and a notable cycling retention of 88.8% after 100 cycles at 200 mA g-1. This noticeable performance of the cathode arises from a decent particle morphology and high crystallinity of the layered oxides. As the anode material, the MWCNTs-incorporated oxides deliver a much higher reversible capacity of 811.1 mA h g-1 after 200 cycles compared to the pristine oxides without MWCNTs. The improvement on electrochemical performance can be attributed to synergistic effects from MWCNTs incorporation, including reinforced electronic conductivity, rich meso-pores and an alleviated volume effect. This facile and sharing method may offer an integrated and economical approach for commercial production of Ni-rich electrode materials for Li-ion batteries.

Fe(II)–Al(III) layered double hydroxides prepared by ultrasound-assisted co-precipitation method for the reduction of bromate

International Nuclear Information System (INIS)

Zhong, Yu; Yang, Qi; Luo, Kun; Wu, Xiuqiong; Li, Xiaoming; Liu, Yang; Tang, Wangwang; Zeng, Guangming; Peng, Bo

2013-01-01

Highlights: ► Fe(II)–Al(III) LDHs were synthesized by ultrasound-assisted co-precipitation method. ► The Fe–Al (30 min) exhibited highly reduction reactivity on bromate. ► Pseudo-first-order model described the experimental data well. ► The mechanisms of bromate removal were proposed. -- Abstract: Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this paper, Fe(II)–Al(III) layered double hydroxides (Fe–Al LDHs) prepared by the ultrasound-assisted co-precipitation method were used for the reduction of bromate in solution. The Fe–Al LDHs particles were characterized by X-ray diffractometer, scanning electron microscopy and thermogravimetry–differential scanning calorimetry. It was found that ultrasound irradiation assistance promoted the formation of the hydrotalcite-like phase and then improved the removal efficiency of bromate. In addition, the effects of solid-to-solution ratio, contact time, initial bromate concentration, initial pH, coexisting anions on the bromate removal were investigated. The results showed the bromate with an initial concentration of 1.56 μmol/L could be completely removed from solution by Fe–Al LDHs within 120 min. When the initial bromate concentration was 7.81 μmol/L, the Fe–Al LDHs with irradiation time of 30 min exhibited the optimum removal efficiency and the bromate removal capacity (q e ) was 6.80 μmol/g. In addition, the appearance of sulfate and production of bromide were observed simultaneously in this process, which suggested that ion-exchange between sulfate and bromate, and the reduction of bromate to bromide by Fe 2+ were the main mechanisms responsible for the bromate removal by Fe–Al LDHs

BaFe{sub 12}O{sub 19} powder with high magnetization prepared by acetone-aided coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Yu, Hsuan-Fu, E-mail: hfyu@mail.tku.edu.tw

2013-09-15

BaFe{sub 12}O{sub 19} particles with high magnetization were produced using an acetone-aided coprecipitation process. An aqueous solution of iron and barium nitrates, in an Fe{sup 3+}/Ba{sup 2+} molar ratio of 12, was added in a stirred precipitation liquid medium composed of H{sub 2}O, CH{sub 3}(CO)CH{sub 3} and NH{sub 4}OH. After reacting metallic ions with ammonia, the precipitates were formed, centrifugally filtered, freeze dried and calcined. Effects of amount of the acetone in the precipitation liquid medium on the formation of crystalline BaFe{sub 12}O{sub 19} were investigated. The presence of acetone in the precipitation liquid medium can greatly promote formation of the crystalline BaFe{sub 12}O{sub 19} at temperature as low as 650 °C and can enhance magnetization of the derived particles. On the other hand, raising the calcination temperature can effectively accelerate development of crystallite morphology and magnetic characters of the barium hexaferrites. While the barium hexaferrite powder obtained without acetone additions and calcined at 1000 °C had magnetization (measured at 50 kOe; M(50 kOe)) of 63.5 emu/g, remanence magnetization (Mr) of 31.3 emu/g and coercivity (Hc) of 4.7 kOe, the single magnetic domain size BaFe{sub 12}O{sub 19} powder with M(50 kOe) of 70.6 emu/g, Mr of 34.4 emu/g and Hc of 3.7 kOe was produced at 1000 °C, using a precipitation liquid medium of 64 vol% acetone. - Highlights: • BaFe{sub 12}O{sub 19} with high magnetic characters was produced by an acetone-aided coprecipitation. • The effects of acetone addition in the precipitation on the formation of BaFe{sub 12}O{sub 19} were studied. • Acetone presence in the precipitation liquid medium promoted BaFe{sub 12}O{sub 19} formation at ≥650 °C. • BaFe{sub 12}O{sub 19} with M(50 kOe) of 70.6 emu/g, Mr of 34.4 emu/g and Hc of 3.7 kOe was obtained.

Structural and optical studies of Mg doped nanoparticles of chromium oxide (Cr2O3) synthesized by co-precipitation method

Science.gov (United States)

Singh, Jarnail; Verma, Vikram; Kumar, Ravi

2018-04-01

We present here the synthesization, structural and optical studies of Mg doped nanoparticles of Chromium oxide (Cr2O3) prepared using co-precipitation method. These samples were characterized using powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Raman spectroscopy and UV-Vis spectroscopy techniques. We have demonstrated that there is negligible change in optical band gap with the Mg doping. The prepared Cr2O3 nanoparticles are spherical in shape, but they are transformed into platelets when doped with Mg. The XRD studies reveal that the Mg doping in Cr2O3 doesn't affect the structure of Chromium oxide (Cr2O3).

Synthesis and magnetic properties of bacterial cellulose—ferrite (MFe2O4, M  =  Mn, Co, Ni, Cu) nanocomposites prepared by co-precipitation method

Science.gov (United States)

Sriplai, Nipaporn; Mongkolthanaruk, Wiyada; Pinitsoontorn, Supree

2017-09-01

The magnetic nanocomposites based on bacterial cellulose (BC) matrix and ferrite (MFe2O4, M  =  Mn, Co, Ni and Cu) nanoparticles (NPs) were fabricated. The never-dried and freeze-dried BC nanofibrils were used as templates and a co-precipitation method was applied for NPs synthesis. The nanocomposites were either freeze-dried or annealed before subjected to characterization. The x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy showed that only MnFe2O4 and CoFe2O4 NPs could be successfully incorporated in the BC nanostructures. The results also indicated that the BC template should be freeze-dried prior to the co-precipitation process. The magnetic measurement by a vibrating sample magnetometer (VSM) showed that the strongest ferromagnetic signal was found for BC-CoFe2O4 nanocomposites. The morphological investigation by a scanning electron microscope (SEM) showed the largest volume fraction of NPs in the BC-CoFe2O4 sample which was complimentary to the magnetic property measurement. Annealing resulted in the collapse of the opened nanostructure of the BC composites. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

Determination of tellurium in coal samples by means of graphite furnace atomic absorption spectrometry after coprecipitation with iron(III) hydroxide

Energy Technology Data Exchange (ETDEWEB)

Oda, S.; Arikawa, Y. [Japan Womens University, Tokyo (Japan)

2005-11-01

A simple and accurate method for the determination of tellurium in coal samples was investigated by the combustion of samples under a high pressure of oxygen and coprecipitation with Fe(OH){sub 3}, followed by a measurement by graphite furnace atomic absorption spectrometry (GF-AAS). About 0.5 g of an accurately weighed ground coal sample and 0.5 g of starch were combusted in an oxygen combustion bomb filled with oxygen to 3 MPa and added with 3 ml of water as an absorbing solution. The formed tellurium trioxide TeOs dissolved in water as TeO{sub 4}{sup 2-}, which was in turn reduced to TeO{sub 3}{sup 2-} by heating. After diluting the above-mentioned solution up to about 50 ml with water, Fe(OH){sub 3} is formed upon adding Fe(NO{sub 3}){sub 3} and sodium hydroxide solutions at pH 8-9 and left standing overnight. After dissolving the precipitate by HCl, the solution was diluted to 10 ml with water and the concentration of tellurium was measured by GF-AAS at a wavelength of 214.3 nm. The standard addition method was employed for the determination of tellurium in real coal samples, because those processes for the formation of tellurium(VI) oxide and coprecipitation with Fe(OH)3 were interfered by matrices. For NIST SRM 1632c, the standard coal sample tellurium content of 0.057 {+-} 0.004 mg kg{sup -1} was in good agreement with the information value of 0.05 mg kg{sup -1} with 7% of RSD in five replicate analyses. The tellurium contents in 20 real coal samples given by Center for Coal Utilization, Japan were also determined. The tellurium contents in these samples were scattered over the narrow range between 0.032 and 0.100 mg kg{sup -1}.

Separation of valence forms of chromium(III) and chromium(VI) by coprecipitation with iron(III) hydroxide

International Nuclear Information System (INIS)

Nazirmadov, B.; Khamidov, B.O.; Egorova, L.A.

1989-01-01

The sorption of 9.62·10 -5 M of Cr (III) and Cr (VI) with iron hydroxide in 1 M potassium nitrate and potassium chloride was investigated in relation to the pH of the medium. Experimental data on the sorption of chromium(III) and chromium(VI) with iron(III) hydroxide made it possible to determine the region of practically complete concentration of Cr (III) and Cr (VI) (pH = 3-6.5). The results from spectrophotometric investigations, calculated data on the distribution of the hydroxocationic forms of chromium(III) and the anions of chromium(IV), and their sorption by iron-(III) hydroxide made it possible to characterize the sorbability of the cationic and anionic forms of chromium in various degrees of oxidation. On this basis a method was developed for the separation of chromium(III) and chromium(VI) by coprecipitation on iron(III) hydroxide and their separation from the iron(III) hydroxide support

Synthesis, Optical and Electrochemical Properties of Y2O3 Nanoparticles Prepared by Co-Precipitation Method.

Science.gov (United States)

Saravanan, Thulasingam; Raj, Srinivasan Gokul; Chandar, Nagamuthu Raja Krishna; Jayavel, Ramasamy

2015-06-01

Y2O3 nanoparticles were synthesized by co-precipitation route using yttrium nitrate hexahydrate and ammonium hydroxide as precursors. The prepared sample was calcined at 500 degrees C and subjected to various characterization studies like thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible (UV-Vis) and photoluminescence (PL) spectroscopy. The XRD pattern showed the cubic fluorite structure of Y2O3 without any impurity peaks, revealing high purity of the prepared sample. TEM images revealed that the calcined Y2O3 nanoparticles consist of spherical-like morphology with an average particle size of 12 nm. The absorption spectrum of calcined samples shows blue-shift compared to the as-prepared sample, which was further confirmed by PL studies. The possible formation mechanism of Y2O3 nanoparticles has been discussed based on the experimental results. Electrochemical behavior of Y2O3 nanoparticles was studied by cyclic voltammetry to assess their suitability for supercapacitor applications.

Structural Characterization of Polymer-Clay Nanocomposites Prepared by Co-Precipitation Using EPR Techniques

Directory of Open Access Journals (Sweden)

Udo Kielmann

2014-02-01

Full Text Available Polymer-clay nanocomposites (PCNCs containing either a rubber or an acrylate polymer were prepared by drying or co-precipitating polymer latex and nanolayered clay (synthetic and natural suspensions. The interface between the polymer and the clay nanoparticles was studied by electron paramagnetic resonance (EPR techniques by selectively addressing spin probes either to the surfactant layer (labeled stearic acid or the clay surface (labeled catamine. Continuous-wave (CW EPR studies of the surfactant dynamics allow to define a transition temperature T* which was tentatively assigned to the order-disorder transition of the surfactant layer. CW EPR studies of PCNC showed that completely exfoliated nanoparticles coexist with agglomerates. HYSCORE spectroscopy in PCNCs showed couplings within the probe −assigned with DFT computations− and couplings with nuclei of the environment, 1H and 23Na for the surfactant layer probe, and 29Si, 7Li, 19F and 23Na for the clay surface probe. Analysis of these couplings indicates that the integrity of the surfactant layer is conserved and that there are sizeable ionic regions containing sodium ions directly beyond the surfactant layer. Simulations of the very weak couplings demonstrated that the HYSCORE spectra are sensitive to the composition of the clay and whether or not clay platelets stack.

Effect of Calcination at Synthesis of Mg-Al Hydrotalcite Using co-Precipitation Method

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Niar Kurnia Julianti

2017-01-01

Full Text Available The use of hydrotalcite in catalysis has wide attention in academic research and industrial parties. Based on its utilization, hydrotalcite can be active catalyst or support. This research is focused on the investigation of characteristic like spesific surface area of Mg-Al hydrotalcite which is prepared with different temperature of calcination. Synthesis of Mg-Al hydrotalcites with Mg/Al molar ratio 3:1 were prepared by co-precipitation method. Mg(NO33.6H2O and Al(NO33.9H2O as precursors of Mg-Al hydrotalcite. Na2CO3 was used as precipitant agent and NaOH was used as buffer solution. The solution was mixed and aging for 5 hours at 650oC. The dried precipitate was calcined at 2500oC, 3500oC, 4500oC, 5500oC and 6500oC. The characterization of functional group was determined by Fourier Transform Infra Red (FT-IR. The Identical peaks diffractogram were analyzed by X-Ray Diffraction (XRD. The spesific surface area was determined by adsorption-desorption of nitrogen. The largest surface area that obtained from the calcination temperature of 650oC is 156.252 m2/g.

Synthesis of mono and multidomain YIG particles by chemical coprecipitation or ceramic procedure

International Nuclear Information System (INIS)

Fernandez-Garcia, L.; Suarez, M.; Menendez, J.L.

2010-01-01

Yttrium iron garnet powders have been synthesized by chemical coprecipitation using two different precursors, nitrates and chlorides, and by an oxides mixture route. It is shown that depending on the precursors and synthesis conditions used pure yttrium iron garnet powders can be obtained with a mono or multidomain magnetic behaviour. The yttrium iron garnet crystalline structure, as studied by Raman spectroscopy, was already formed after calcination at temperatures as low as 800 o C when the nitrate precursors were used. However, calcination temperatures of up to 1100 o C were required to obtain yttrium iron garnet powders when the precursors were chlorides or when the oxides mixture route was chosen. The saturation magnetization of the powders correlates well with the structural characterization: when nitrate precursors were used, the saturation magnetization was already close to the bulk value, 26.8 emu/cm 3 , after calcination at 800 o C. However, the saturation magnetization of the powders obtained by the chlorides and oxides mixture routes was close to zero up to calcination temperatures of 1100 o C. Finally, both the chlorides and the oxides mixture routes yield multidomain micron sized yttrium iron garnet powders, whereas the nitrates route led to monodomain submicron sized powders.

The effect of hydrothermal treatment on samaria and gadolinia doped ceria powders synthesized by coprecipitation

International Nuclear Information System (INIS)

Arakaki, Alexander Rodrigo; Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci

2009-01-01

One of the main applications of ceria-based (CeO 2 ) ceramics is the manufacturing of Intermediate Temperature Solid Oxide Fuel Cells electrolytes. In order to improve ionic conductivity and densification of these materials various powder synthesis routes have been studied. In this work powders with composition Ce 0.8 (SmGd) 0.2 O 1.9h ave been synthesized by coprecipitation and hydrothermal treatment. A concentrate of rare earths containing 90wt% of CeO 2 and other containing 51% of Sm 2 O 3 and 30% of Gd 2 O 3 , both prepared from monazite processing, were used as precursor materials. The powders were characterized by X-ray diffraction, scanning and transmission electron microscopy, agglomerate size distribution by laser scattering and specific surface area by gas adsorption. Ceramic sinterability was evaluated by dilatometry and density measurements by Archimedes method. High specific surface area powders (~100m 2 /g) and cubic fluorite structure were obtained after hydrothermal treatment around 200 deg C. Ceramic densification was improved when compared to the one prepared from powders calcined at 800 deg C. (author)

Structural, Optical, Morphological and Microbial Studies on SnO₂ Nanoparticles Prepared by Co-Precipitation Method.

Science.gov (United States)

Arularasu, M V; Anbarasu, M; Poovaragan, S; Sundaram, R; Kanimozhi, K; Magdalane, C Maria; Kaviyarasu, K; Thema, F T; Letsholathebe, D; Mola, Genene T; Maaza, M

2018-05-01

Nanoparticles of tin oxide (SnO2) powders were prepared by co-precipitation method at 500 °C, 700 °C and 900 °C temperature. The sintered SnO2 nanoparticles, structural, optical, magnetic, morphological properties and microbial activity have been studied. XRD studies reveals that sintered powder which exhibits tetragonal crystal structure and both crystallinity as well as crystal size increase with increase in temperature. The morphological studies reveal randomly arranged grains with compact nature grain size increases with sintering temperature. The compositional analyses of SnO2 nanoparticles have been studied using X-ray photoelectron spectroscopy analysis. The optical band gap values of SnO2 nanoparticles were calculated to be about 4.3 eV in the temperature 500 °C, comparing with that of the bulk SnO2 3.78 eV, by optical absorption measurement. Room temperature M-H curve for pure SnO2 nanoparticles exhibits ferromagnetic behaviour. The tin oxide nanoparticles are acted as potential candidate material for bacterial and fungal activity.

Fabrication of Tb3Al5O12 transparent ceramics using co-precipitated nanopowders

Science.gov (United States)

Dai, Jiawei; Pan, Yubai; Wang, Wei; Luo, Wei; Xie, Tengfei; Kou, Huamin; Li, Jiang

2017-11-01

Terbium aluminum garnet (TAG) precursor was synthesized by a co-precipitation method from a mixed solution of terbium and aluminum nitrates using ammonium hydrogen carbonate (AHC) as the precipitant. The powders calcined at different temperatures were investigated by XRD, FTIR and FESEM in order to choose the optimal calcination temperature. Fine and low-agglomerated TAG powders with average particle size of 88 nm were obtained by calcining the precursor at 1100 °C for 4 h. Using this powder as starting material, TAG transparent ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) sintering. For the sample pre-sintered at 1700 °C for 20 h with HIP post-treated at 1700 °C for 3 h, the average grain size is about 3.9 μm and the in-line transmittance is beyond 55% in the region of 500-1600 nm, reaching a maximum transmittance of 64.2% at the wavelength of 1450 nm. The Verdet constant at 633 nm is measured to be -178.9 rad T-1 m-1, which is 33% larger than that of the commercial TGG single crystal (-134 rad T-1 m-1).

Room Temperature Co-Precipitation Synthesis of Magnetite Nanoparticles in a Large pH Window with Different Bases.

Science.gov (United States)

Mascolo, Maria Cristina; Pei, Yongbing; Ring, Terry A

2013-11-28

Magnetite nanoparticles (Fe₃O₄) represent the most promising materials in medical applications. To favor high-drug or enzyme loading on the nanoparticles, they are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation. The direct synthesis of mesoporous structures appears to be of interest. To this end, magnetite nanoparticles have been synthesized using a one pot co-precipitation reaction at room temperature in the presence of different bases, such as NaOH, KOH or (C₂H₅)₄NOH. Magnetite shows characteristics of superparamagnetism at room temperature and a saturation magnetization (Ms) value depending on both the crystal size and the degree of agglomeration of individual nanoparticles. Such agglomeration appears to be responsible for the formation of mesoporous structures, which are affected by the pH, the nature of alkali, the slow or fast addition of alkaline solution and the drying modality of synthesized powders.

Structure, morphology, and cathode performance of Li{sub 1-x}[Ni{sub 0.5}Mn{sub 1.5}]O{sub 4} prepared by coprecipitation with oxalic acid

Energy Technology Data Exchange (ETDEWEB)

Liu, Dongqiang; Han, Jiantao; Goodenough, John B. [Texas Materials Institute, ETC 9.184, University of Texas at Austin, 1 University Station, C2200, Austin, TX 78712 (United States)

2010-05-01

The cathode materials Li{sub 1-x}[Ni{sub 0.5}Mn{sub 1.5}]O{sub 4} prepared by coprecipitation from acetate solution by oxalic acid and annealing at 900 C in air had the preferred disordered Ni and Mn on the 16d octahedral sites of a spinel Fd anti 3m structure. The coprecipitation method provides better crystallinity than the Fd anti 3m phase previously obtained by quenching from the melt. Polycrystalline octahedral-shaped particles with smooth surfaces contained trace amounts of a Li{sub y}Ni{sub 1-y}O impurity that introduced some Mn(III) into the spinel phase. Half-cells cycled at 0.2 C rate between 3.5 and 4.8 V versus Li exhibited a flat voltage V {approx} 4.7 V with a small step at x {approx} 0.5 and a capacity at room temperature of 130 mAh g{sup -1} that showed no fade after 50 cycles. A small capacity fade was initiated with a cut-off voltage {>=}4.9 V; a significant capacity loss between 2 and 5 C cycling rates was reversible to 134 mAh g{sup -1} on returning to 0.1 C after 50 cycles at 10 C between 3.5 and 5.0 V. (author)

Preparation of Au/Y2O3 and Au/NiO catalysts by co-precipitation and their oxidation activities

International Nuclear Information System (INIS)

Sreethawong, Thammanoon; Sitthiwechvijit, Norsit; Rattanachatchai, Apiwat; Ouraipryvan, Piya; Schwank, Johannes W.; Chavadej, Sumaeth

2011-01-01

Research highlights: → The catalytic activity of Au catalysts supported on Y 2 O 3 and NiO prepared by co-precipitation was investigated for CO and methanol oxidation. → The phase transformation of yttrium support greatly affected the CO oxidation activity. → The Au/Y 2 O 3 exhibited the same activity as Au/NiO for the methanol oxidation while the Au/NiO gave higher activity for CO oxidation. - Abstract: The objective of this work was to investigate the catalytic activity of gold catalysts supported on two metal oxides, yttrium oxide and nickel oxide, prepared by co-precipitation for CO and methanol oxidation reactions. The TGA and XRD results confirmed that yttrium hydroxide (Y(OH) 3 ) was formed at calcination temperature below 300 deg. C. When it was calcined at 400 deg. C, the Y(OH) 3 was transformed to yttrium oxide hydroxide (YOOH). Finally, when calcination temperature was raised to 600 deg. C, the YOOH was completely transformed to yttrium oxide (Y 2 O 3 ). Interestingly, the gold loaded on YOOH calcined at 400 deg. C and gold loaded on Y 2 O 3 calcined at 500 deg. C comparatively showed the highest catalytic activity for complete CO oxidation at a reaction temperature of 300 deg. C. The 0.12% Au/Y 2 O 3 catalyst calcined at 500 deg. C was employed for both CO and methanol oxidation studies. For complete CO oxidation, the reaction temperatures of Au/Y 2 O 3 and Au/NiO catalysts were 325 deg. C and 250 deg. C, respectively. The light-off temperatures of Au/Y 2 O 3 and Au/NiO catalysts for methanol oxidation were 210 deg. C and 205 deg. C, respectively. Conclusively, the Au/Y 2 O 3 clearly exhibited the same activity as that of Au/NiO for methanol oxidation while the Au/NiO gave higher activity for CO oxidation.

Structural, dielectric and magnetic properties of Bi{sub 1−x}Y{sub x}FeO{sub 3} (0⩽x⩽0.2) obtained by acid–base co-precipitation

Energy Technology Data Exchange (ETDEWEB)

Medina, Leila María Saleh [Instituto de Química Física de Materiales, Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Jorge, Guillermo A. [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Martín Negri, R., E-mail: rmn@qi.fcen.uba.ar [Instituto de Química Física de Materiales, Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

2014-04-01

Highlights: • Yttrium-substituted bismuth-iron oxides were prepared by co-precipitation synthesis. • Single-phase materials with absence of other bismuth-oxides were obtained. • Strong dependence of magnetic and electrical properties with yttrium percentage at RT. • Magnetic and electric properties are related to particle size and structural changes. - Abstract: Bismuth–iron oxides with partial substitution of bismuth by yttrium, referred as (Bi{sub 1−x}Y{sub x})FeO{sub 3}, were synthesized by simple-low cost acid–base co-precipitation method, which constitutes a difference with the currently used synthetic methods for obtaining BiFeO{sub 3}-doped compounds (e.g. polymer assisted sol–gel, solid state, microwave, etc.) Samples were characterized by XRD, EDS, SEM, TEM, DSC and FTIR. The influence of yttrium (Y) substitution on magnetization curves of (Bi{sub 1−x}Y{sub x})FeO{sub 3} powders were studied at room temperature by VSM. The particle size systematically decreases with the Y percentage. Ferromagnetic curves were obtained at room temperature for Y-percentage lower than 20% with relatively large values of the coercive field, H{sub c}, which increases with Y-substitution, while for 20% yttrium a superparamagnetic behavior is observed. The electrical impedance of compressed disks were investigated also by impedance analysis in the range 1Hz–1MHz and the results were successfully fitted by a simple parallel R–C model. The dc-leakage currents are lower than previously reported for (Bi{sub 1−x}Y{sub x})FeO{sub 3} compounds and for most of the doped-BiFeO{sub 3} ceramics. As a difference with the influence on the magnetic behavior, the doping with yttrium does not seem to have a large influence on the dielectrical properties. These results suggest that magnetization can be systematically modified by the relatively simple co-precipitation synthesis while keeping invariable the dielectrical properties.

A feasibility study of the preparation of (U,Gd)3O8 solid solutions by thermal decomposition of co-precipitated carbonate mixtures

International Nuclear Information System (INIS)

Ravindran, P.V.; Rajagopalan, K.V.; Mathur, K.P.

1998-01-01

Co-precipitation from equimolar nitrate solutions of uranium (VI) and gadolinium has been used to obtain a mixture of (NH 4 ) 4 UO 2 (CO 3 ) 3 and Gd 2 (CO 3 ) 3 .3H 2 O at a pre-determined composition. Simultaneous measurements by TG, DTA and evolved gas analysis (EGA) showed that a calcination temperature of 700 C was necessary to decompose the carbonate completely to oxides. X-ray diffraction data indicated that a solid solution of Gd 2 O 3 in U 3 O 8 cannot be obtained by heating the carbonate mixtures up to 800 C in inert atmospheres. (orig.)

Synthesis of LiNi0.8Co0.1Mn0.1O2 cathode material by chloride co-precipitation method

Institute of Scientific and Technical Information of China (English)

李灵均; 李新海; 王志兴; 伍凌; 郑俊超; 李金辉

2010-01-01

LiNi0.8Co0.1Mn0.1O2 was prepared by a chloride co-precipitation method and characterized by thermogravimetric analysis, X-ray diffractometry with Rietveld refinement,electron scanning microscopy and electrochemical measurements.Effects of lithium ion content and sintering temperature on physical and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 were also investigated. The results show that the sample synthesized at 750℃with 105%lithium content has fine particle sizes around 200 nm and homogenous sizes distribution.The initial discharge capacity for the powder is 184 mA·h/g between 2.7 and 4.3 V at 0.1C and room temperature.

Magnetic properties of co-precipitated hexaferrite powders with Sm-Co substitutions optimized with the molten flux method

Science.gov (United States)

Serletis, C.; Litsardakis, G.; Pavlidou, E.; Efthimiadis, K. G.

2017-11-01

In this work, using the chemical coprecipitation method, Sr1-xSmxFe12-xCoxO19 (x = 0, 0.1, 0.2) hexaferrite powders were prepared. Major magnetization loops were recorded at room temperature in order to determine the correct calcination temperature for optimum hard magnetic properties. It is found that a small degree of substitution increases substantially the coercive field. Also, the use of the molten flux calcination method increases the remanent magnetization. SEM/EDXS and XRD measurements were performed at the calcined powders: the results show that a single hexaferrite phase is formed and that the substituted powders consist of an assembly of grains with a mean diameter of 40 nm. Measurements of minor magnetization loops and of the temperature and time dependence of the magnetization confirm that the powders consist of a non-oriented single domain magnetic particles assembly. The results indicate that Sm could be a viable replacement for La in the manufacturing of hexaferrites with a high-energy product.

Room Temperature Co-Precipitation Synthesis of Magnetite Nanoparticles in a Large pH Window with Different Bases

Directory of Open Access Journals (Sweden)

Maria Cristina Mascolo

2013-11-01

Full Text Available Magnetite nanoparticles (Fe3O4 represent the most promising materials in medical applications. To favor high-drug or enzyme loading on the nanoparticles, they are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation. The direct synthesis of mesoporous structures appears to be of interest. To this end, magnetite nanoparticles have been synthesized using a one pot co-precipitation reaction at room temperature in the presence of different bases, such as NaOH, KOH or (C2H54NOH. Magnetite shows characteristics of superparamagnetism at room temperature and a saturation magnetization (Ms value depending on both the crystal size and the degree of agglomeration of individual nanoparticles. Such agglomeration appears to be responsible for the formation of mesoporous structures, which are affected by the pH, the nature of alkali, the slow or fast addition of alkaline solution and the drying modality of synthesized powders.

Measurement by liquid scintillation of {sup 226} Ra coprecipitated in BaSO{sub 4}; Medicion por centelleo liquido de {sup 226} Ra coprecipitado en BaSO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Lopez del Rio, H.; Davila R, J.I.; Badillo A, V.E.; Mireles G, F.; Quirino T, L.; Lugo R, J.F.; Pinedo V, J.L.; Rios M, C. [UAEN-UAZ, A.P. 579C, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)]. e-mail: idavila@cantera.reduaz.mx

2003-07-01

The {sup 226} Ra is one of the more radio toxic nuclides since when entering to the organism it continues metabolically to the calcium, accumulating mainly in the bone tissue where it becomes in an internal radiation source. For the analysis of radium in water the methods of radon emanation are generally applied and coprecipitation with barium sulfate. This last is quick and efficient, and the radium in the precipitate can be measured by alpha or gamma spectrometry, or liquid scintillation dissolving the precipitate one with EDTA. In this work it is proposed a procedure for the radium measurement in water based on the coprecipitation with barium sulfate and in the detection by liquid scintillation. The precipitate of Ba(Ra)SO{sub 4} it is carried with water and blended with the liquid scintillator OptiPhase Hi Safe 3, avoiding the dissolution with EDTA. A 92{+-} 1.4% of radium it was recovered and it was reached a minimum activity detectable of 4.2 {+-} 0.9 mBq{sup -1}. The procedure was essayed with natural mineral water with a knew activity in concentration of {sup 226} Ra. The analytic result it coincided with the reported value with a relative error of 9%. (Author)

Preparation of La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} fine powders by carbonate coprecipitation for solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Ha, Sang Bu; Cho, Pyeong-Seok; Cho, Yoon Ho; Lee, Dokyol; Lee, Jong-Heun [Department of Materials Science and Engineering, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713 (Korea)

2010-01-01

A range of La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} (LSCM) powders is prepared by the carbonate coprecipitation method for use as anodes in solid oxide fuel cells. The supersaturation ratio (R = [(NH{sub 4}){sub 2}CO{sub 3}]/([La{sup 3+}] + [Sr{sup 2+}] + [Cr{sup 3+}] + [Mn{sup 2+}])) during the coprecipitation determines the relative compositions of La, Sr, Cr, and Mn. The composition of the precursor approaches the stoichiometric one at the supersaturation range of 4 {<=} R {<=} 12.5, whereas Sr and Mn components are deficient at R < 4 and excessive at R = 25. The fine and phase-pure LSCM powders are prepared by heat treatment at very low temperature (1000 C) at R = 7.5 and 12.5. By contrast, the solid-state reaction requires a higher heat-treatment temperature (1400 C). The catalytic activity of the LSCM electrodes is enhanced by using carbonate-derived powders to manipulate the electrode microstructures. (author)

Investigating the effect of Mn-doped CeO2 nanoparticles by co-precipitation method

International Nuclear Information System (INIS)

Prabaharan, D.D.M.; Sadaiyandi, K.; Mahendran, M.; Sagadevan, Suresh

2018-01-01

The paper exhibits a detailed study about the synthesis and characterization in analysis of structural, morphological, optical and electrical investigations of pure and Mn-doped Cerium oxide (CeO 2 ) nanoparticles which were synthesized by co-precipitation technique. Phase formation of the prepared sample was analyzed with powder X-ray diffraction (PXRD) examines, scanning electron microscopy (SEM) examination. The PXRD comes about affirmed partial crystallinity having cubic phases and the crystallite sizes of the pure and Mn-doped Cerium oxide (CeO 2 ) were estimated by utilizing Debye-Scherrer's formula and they were calculated to be 12 and 14 nm individually. SEM pictures revealed that the particles were profoundly accumulated and were of permeable nature. The optical properties of pure and Mn-doped CeO 2 were ascertained by using UV-visible absorption spectrum. The estimated band gap values for the pure and the Mn-doped CeO 2 nanoparticles were observed to be 2.7 and 2.6 eV, respectively, utilizing UV-Vis spectroscopy. At different frequencies and temperatures the dielectric properties of the Mn-doped Cerium oxide (CeO 2 ) nanoparticles, for example, the dielectric consistent, the dielectric loss and the AC conductivity, were studied. (orig.)

Effect of synthesis conditions on the preparation of YIG powders via co-precipitation method

International Nuclear Information System (INIS)

Rashad, M.M.; Hessien, M.M.; El-Midany, A.; Ibrahim, I.A.

2009-01-01

Yttrium iron garnet (YIG) (Y 3 Fe 5 O 12 ) powders have been synthesized through a co-precipitation method in the presence of sodium bis(2-ethylhexylsulfosuccinate), AOT as an anionic surfactant. The garnet precursors produced were obtained from aqueous iron and yttrium nitrates mixtures using 5 M sodium hydroxide at pH 10. A statistical Box-Behnken experimental design was used to investigate the effect of the main parameters (i.e. AOT surfactant concentration, annealing time and temperature) on YIG powder formation, crystallite size, morphology and magnetic properties. YIG particles were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer. XRD revealed that the formation of single cubic phase of YIG was temperature dependent and increased by increasing the annealing temperature from 800 to 1200 o C. SEM micrographs showed that the addition of AOT surfactant promoted the microstructure of YIG in crystalline cubic-like structure. The magnetic properties were sensitive to the synthesis variables of annealing temperature, time and AOT surfactant concentration. The maximum saturation magnetization (28.13 emu/g), remanence magnetization (21.57 emu/g) and coercive force (703 Oe) were achieved at an annealing temperature of 1200 o C, time 2 h and 500 ppm of AOT surfactant concentration.

Effectiveness of Arsenic Co-Precipitation with Fe-Al Hydroxides for Treatment of Contaminated Water

Directory of Open Access Journals (Sweden)

Jaime Wilson Vargas de Mello

2018-03-01

Full Text Available ABSTRACT Wastewater treatment is a challenging problem faced by the mining industry, especially when mine effluents include acid mine drainage with elevated arsenic levels. Iron (hydroxides are known to be effective in removal of As from wastewater, and although the resulting compounds are relatively unstable, the presence of structural Al enhances their stability, particularly under reducing conditions. The purpose of this study was to assess the effectiveness of Al-Fe (hydroxide co-precipitates for the removal of As from wastewater and to assess the chemical stability of the products. Different Al-Fe (hydroxides were synthesized at room temperature from ferrous and aluminum salts using three different Fe:Al molar ratios (1:0.0, 1:0.3, and 1:0.7 and aged for 90 days (sulfate experiments or 120 days (chloride experiments in the presence of arsenic. At the end of the aging periods, the precipitated sludges were dried and characterized in order to evaluate their stability and therefore potential As mobility. All treatments were effective in reducing As levels in the water to below 10 µg L-1, but the presence of Al impaired the effectiveness of the treatment. Aluminum decreased the chemical stability of the precipitated sludge and hence its ability to retain As under natural environmental conditions.

Magnetic and electrical properties of the La doped Mn-Zn ferrite nanoparticles synthesized by the co-precipitation method

International Nuclear Information System (INIS)

Chandel, Vipin; Vijeta; Thakur, Atul; Thakur, Preeti

2013-01-01

In the present study, nano crystalline Mn-Zn-La ferrite with chemical formula Mn 0.4 Zn 0.6 La 0.3 Fe 1.7 O 4 was successfully synthesized by a co-precipitation method. The prepared powders were presintered at 700℃. The pallets formed were finally sintered at 700℃, 800℃ and 900℃ for 3h reach. The structural and morphological behavior was investigated by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD confirms the formation of the expected spinel structure. Scanning Electron Microscopy (SEM) was used to characterize the microstructure of the ferrite samples i.e. grain morphology, grain size, grain size distribution and shape. Fourier transform infrared spectroscopy (FTIR) confirms the peaks of different molecules in the given sample. Electrical and magnetic properties were studied by using dc resistivity set up and vibrating sample magnetometer (VSM). (author)

Preparation of palladium nanoparticles on alumina surface by chemical co-precipitation method and catalytic applications

Energy Technology Data Exchange (ETDEWEB)

Kumar, Avvaru Praveen; Kumar, B. Prem; Kumar, A.B.V. Kiran; Huy, Bui The [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Yong-Ill, E-mail: yilee@changwon.ac.kr [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Facile synthesis of palladium nanoparticles on alumina surface. Black-Right-Pointing-Pointer The surface morphology and properties of the nanocrystalline powders were characterized. Black-Right-Pointing-Pointer The catalytic activities of palladium nanoparticles were investigated. - Abstract: The present work reports a chemical co-precipitation process to synthesize palladium (Pd) nanoparticles using alumina as a supporting material. The optimized temperature for the formation of nanocrystalline palladium was found to be 600 Degree-Sign C. The X-ray diffraction (XRD) and Raman spectroscopy were used to study the chemical nature of the Pd in alumina matrix. The surface morphology and properties of the nanocrystalline powders were examined using thermogravimetric analysis (TG-DTA), XRD, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The calcinations in different atmospheres including in the inert medium forms the pure nano Pd{sup 0} while in the atmospheric air indicates the existence pure Pd{sup 0} along with PdO nanoparticles. The catalytic activities of the as-synthesized nanocrystalline Pd nanoparticles in the alumina matrix were investigated in Suzuki coupling, Hiyama cross-coupling, alkene and alkyne hydrogenation, and aerobic oxidation reactions.

Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

Science.gov (United States)

Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

2016-04-01

Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+.

Determination of Ultra-trace Amounts of Arsenic(III) by Flow Injection Hydride Generation Atomic Absorption Spectrometry with On-line Preconcentration by Coprecipitation with Lanthanum Hydroxide or Hafnium Hydroxide

DEFF Research Database (Denmark)

Nielsen, Steffen; Sloth, Jens Jørgen; Hansen, Elo Harald

1996-01-01

-dissolution in a filterless knotted Microline reactor. The sample and coprecipitating agent are mixed on-line and merged with an ammonium buffer solution, which promotes a controllable and quantitative collection of the generated hydroxide on the inner walls of the knotted reactor incorporated into the FI-HG-AAS system....../h. The limit of detection (3s) was 0.003 µg/l and the precision (relative standard deviation) was 1.0% (n = 11)at the 0.1 µg/l level....

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

Science.gov (United States)

Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Yang, Qiuhong; Zhou, Chunlin; Zhang, Pande; Mao, Xiaojian; Zhang, Long

2015-01-01

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders. PMID:28793510

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

Directory of Open Access Journals (Sweden)

Liangjie Pan

2015-08-01

Full Text Available The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h with high terminal pH value (>7.80 resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.

Structural characterization, formation mechanism and stability of curcumin in zein-lecithin composite nanoparticles fabricated by antisolvent co-precipitation.

Science.gov (United States)

Dai, Lei; Sun, Cuixia; Li, Ruirui; Mao, Like; Liu, Fuguo; Gao, Yanxiang

2017-12-15

Curcumin (Cur) exhibits a range of bioactive properties, but its application is restrained due to its poor water solubility and sensitivity to environmental stresses. In this study, zein-lecithin composite nanoparticles were fabricated by antisolvent co-precipitation technique for delivery of Cur. The result showed that the encapsulation efficiency of Cur was significantly enhanced from 42.03% in zein nanoparticles to 99.83% in zein-lecithin composite nanoparticles. The Cur entrapped in the nanoparticles was in an amorphous state confirmed by differential scanning calorimetry and X-ray diffraction. Fourier transform infrared analysis revealed that hydrogen bonding, electrostatic interaction and hydrophobic attraction were the main interactions among zein, lecithin, and Cur. Compared with single zein and lecithin nanoparticles, zein-lecithin composite nanoparticles significantly improved the stability of Cur against thermal treatment, UV irradiation and high ionic strength. Therefore, zein-lecithin composite nanoparticles could be a potential delivery system for water-insoluble bioactive compounds with enhanced encapsulation efficiency and chemical stability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Continuous precipitation of mineral products: influence of mixing conditions on the co-precipitation of cerium-zirconium mixed oxides

International Nuclear Information System (INIS)

Di Patrizio, Nicolas

2015-01-01

An automated experimental set-up with rapid mixers is used to study the influence of mixing conditions on the co-precipitation of cerium-zirconium mixed oxides. The intensity of mixing is controlled by the inlet flow rates of the reacting solutions. An engulfment model is used to estimate a mixing time from the measurement of a segregation index by the Villermaux-Dushman reaction system. Three geometries of Hartridge Roughton mixers are compared. Mixing performance is better when a separate mixing chamber upstream of a narrower outlet pipe is present. A better mixing decreases the maximal reducibility temperature of the material and increases the crystal strains of the particles calcined at 1100 C. This is probably due to a better homogenization of the particles content. The important incorporation of nitrates in the particle at the outlet of the mixers shows precipitation occurs while the mixing process is not finished. This experimental result was confirmed by numerical simulation and an estimation of sur-saturations during the mixing process. (author)

Ultrasound assisted co-precipitation of nanostructured CuO-ZnO-Al2O3 over HZSM-5: effect of precursor and irradiation power on nanocatalyst properties and catalytic performance for direct syngas to DME.

Science.gov (United States)

Allahyari, Somaiyeh; Haghighi, Mohammad; Ebadi, Amanollah; Hosseinzadeh, Shahin

2014-03-01

Nanostructured CuO-ZnO-Al2O3/HZSM-5 was synthesized from nitrate and acetate precursors using ultrasound assisted co-precipitation method under different irradiation powers. The CuO-ZnO-Al2O3/HZSM-5 nanocatalysts were characterized using XRD, FESEM, BET, FTIR and EDX Dot-mapping analyses. The results indicated precursor type and irradiation power have significant influences on phase structure, morphology, surface area and functional groups. It was observed that the acetate formulated CuO-ZnO-Al2O3/HZSM-5 nanocatalyst have smaller CuO crystals with better dispersion and stronger interaction between components in comparison to nitrate based nanocatalysts. Ultrasound assisted co-precipitation synthesis method resulted in nanocatalyst with more uniform morphology compared to conventional method and increasing irradiation power yields smaller particles with better dispersion and higher surface area. Additionally the crystallinity of CuO is lower at high irradiation powers leading to stronger interaction between metal oxides. The nanocatalysts performance were tested at 200-300 °C, 10-40 bar and space velocity of 18,000-36,000 cm(3)/g h with the inlet gas composition of H2/CO = 2/1 in a stainless steel autoclave reactor. The acetate based nanocatalysts irradiated with higher levels of power exhibited better reactivity in terms of CO conversion and DME yield. While there is an optimal temperature for CO conversion and DME yield in direct synthesis of DME, CO conversion and DME yield both increase with the pressure increase. Furthermore ultrasound assisted co-precipitation method yields more stable CuO-ZnO-Al2O3/HZSM-5 nanocatalyst while conventional precipitated nanocatalyst lost their activity ca. 18% and 58% in terms of CO conversion and DME yield respectively in 24 h time on stream test.

Synthesis of YAG nanopowder by the co-precipitation method: Influence of pH and study of the reaction mechanisms

Science.gov (United States)

Marlot, Caroline; Barraud, Elodie; Le Gallet, Sophie; Eichhorn, Marc; Bernard, Frédéric

2012-07-01

YAG nanopowders with an average grain size of 30 nm have been successfully synthesized by the co-precipitation method using nitrates with precipitant of ammonium hydrogen carbonate. The influence of precipitation conditions such as pH, aging time and calcination temperature on the formation of secondary phases has been studied. The accurate control of pH value at every stage of precipitation process is crucial to avoid the presence of YAM (Yttrium Aluminium Monoclinic, Y4Al2O9) and yttrium oxide (Y2O3) after calcination. The reaction mechanisms have been investigated using different techniques such as infrared spectroscopy, x-ray diffraction and thermal analyses. The YAG phase is formed around 1050 °C passing through an intermediate phase called YAP (Yttrium Aluminium Perovskite, YAlO3). Local chemical heterogeneities are responsible for the deviation of the Y:Al ratio and the formation of YAP during heat treatment.

One-step synthesis and characterizations of cerium oxide nanoparticles in an ambient temperature via Co-precipitation method

Science.gov (United States)

Pujar, Malatesh S.; Hunagund, Shirajahammad M.; Desai, Vani R.; Patil, Shivaprasadgouda; Sidarai, Ashok H.

2018-04-01

We report the simple Co-precipitation method for the synthesis of Cerium oxide (CeO2) nanoparticles (NPs) in an ambient temperature. We have taken the Cerium (III) nitrate hexahydrate (Ce(NO3)3.6H2O) and Sodium hydroxide (NaOH) as the precursors. The obtained NPs were analyzed using the UV-Vis spectrophotometer, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The obtained results signify that UV-Vis spectrum exhibited a well-defined absorption peak at 274 nm and the estimated energy gap (Eg) is 4.05 eV. The FT-IR analysis provides the supporting evidence for the presence of bonding of O-H, nitrates, alcohols and O-Ce-O vibrations. The XRD result reveals that the synthesized CeO2 NPs was crystallite with cubic phase structure and the estimated average crystallite size of CeO2 NPs using Scherer's and W-H method was significantly different due to their assumptions. Further, it is purposed to study their photocatalytic biological activities.

Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

Science.gov (United States)

Malakar, Pradyut; Jana, Bana Bihari; Benz, Florian; Goldmaier, Alexander; Feistel, Ulrike; Jana, Joydev; Lahiri, Susmita; Alvarez, Juan Antonio

2017-01-01

Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V) occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L), iron (5.5 ± 0.8 mg/L), manganese (1.5 ± 0.4 mg/L), phosphate (2.4 ± 1.3 mg/L) and ammonium (1.4 ± 0.5 mg/L) concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L), >99% for iron (0.03 ± 0.03 mg/L), 96% for manganese (0.06 ± 0.05 mg/L), 72% for phosphate (0.7 ± 0.3 mg/L) and 84% for ammonium (0.18 ± 0.12 mg/L) were achieved—without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas. PMID:28974053

Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration-A Long Term Field Test Conducted in West Bengal.

Science.gov (United States)

Otter, Philipp; Malakar, Pradyut; Jana, Bana Bihari; Grischek, Thomas; Benz, Florian; Goldmaier, Alexander; Feistel, Ulrike; Jana, Joydev; Lahiri, Susmita; Alvarez, Juan Antonio

2017-10-02

Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V) occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus ® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L), iron (5.5 ± 0.8 mg/L), manganese (1.5 ± 0.4 mg/L), phosphate (2.4 ± 1.3 mg/L) and ammonium (1.4 ± 0.5 mg/L) concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L), >99% for iron (0.03 ± 0.03 mg/L), 96% for manganese (0.06 ± 0.05 mg/L), 72% for phosphate (0.7 ± 0.3 mg/L) and 84% for ammonium (0.18 ± 0.12 mg/L) were achieved-without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas.

Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

Directory of Open Access Journals (Sweden)

Philipp Otter

2017-10-01

Full Text Available Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L, iron (5.5 ± 0.8 mg/L, manganese (1.5 ± 0.4 mg/L, phosphate (2.4 ± 1.3 mg/L and ammonium (1.4 ± 0.5 mg/L concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L, >99% for iron (0.03 ± 0.03 mg/L, 96% for manganese (0.06 ± 0.05 mg/L, 72% for phosphate (0.7 ± 0.3 mg/L and 84% for ammonium (0.18 ± 0.12 mg/L were achieved—without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas.

Preparation of catalysts based on Ce-Mn mixed oxide by coprecipitation for combustion of n-hexane

International Nuclear Information System (INIS)

Picasso, Gino; Zavala, Cesar; Cruz, Romulo; Sun Kou, Rosario; Lopez, Alcides

2013-01-01

Catalysts based on Ce-Mn mixed with different Ce/Mn molar ratios ranging from 0,5 to 2 have been prepared by coprecipitation at pH constant with ageing times of 4, 18 and 24 h for combustion of n-hexane. XRD patterns of the mixed oxides showed the majority presence of fluorite phase. Specific BET surface areas of mixed oxides were always higher than their single counterparts and their adsorption isotherm depicted a mesoporous surface of Type IV. TPR thermograms confirmed the presence of mixed oxide phase, whose profile shifted to smaller temperatures with increasing content of ceria. Catalytic tests were performed with 2000 ppm of n-hexane and WHSV of 80 h -1 in a fixed-bed reactor. For all samples, only CO 2 and water were observed at total conversion and no partial combustion products were obtained. Ce-Mn mixed oxides were more active than simple oxide samples no matter the aging time. Mixed samples presented thermal stability in contrast with simple ones. Mixed sample with Ce/Mn molar ratio of 2 depicted the highest activity probably due to higher surface area and better reducibility ability of mixed phase. (author)

Photodegradation of Acid Black 1 and Removing Heavy Metals from the Water by an Inorganic Nanocomposite Synthesized via Simple Co-Precipitation Method

Directory of Open Access Journals (Sweden)

Marziyeh Mohammadi

2016-07-01

Full Text Available In this experimental work, PbS/ZnS/ZnO nanocomposite was synthesized via a simple co-precipitation method. The effect of Zn2+/Pb2+ mole ratio was investigated on the product size and morphology. The products were characterized via scanning electron microscopy to obtain product size and morphology. The optical properties of the nanocomposites were studied by ultra violet-visible spectroscopy. Photocatalytic activity of the product was examine by decomposition of acid black 1 as dye. To investigation of the effect of as synthesized nanocomposite on the water treatment, the influences of the nanocomposite to remove heavy ions was studied by atomic absorption spectroscopy. The results showed that the synthesized nanocomposite has well optical properties, photocatalytic and water treatment activities.

Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders prepared by the co-precipitation process

Energy Technology Data Exchange (ETDEWEB)

Chen, Jian-Chih [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Chen, Wen-Cheng [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Tien, Yin-Chun [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Shih, Chi-Jen, E-mail: cjshih@kmu.edu.t [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan1st Road, Kaohsiung 80708, Taiwan (China)

2010-04-30

Cerium oxide nanocrystallites were synthesized by a co-precipitation process at a relatively low temperature, using cerium (III) nitrate as the starting material in a water solution with pH in the range of 8-9. The effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K, by XRD analysis. When calcined at temperatures from 473 to 1273 K, face-centered cubic phase crystallization was observed by XRD. The crystallite size of the cerium oxide increased from 12.0 to 48 nm as the calcining temperature increased from 473 to 1273 K, in the pH range 8-9. The activation energy for the growth of cerium oxide nanoparticles was found to have very low values of 17.5 kJ/mol for pH = 8 and 16.0 kJ/mol for pH = 9.

Highly transparent Tb3Al5O12 magneto-optical ceramics sintered from co-precipitated powders with sintering aids

Science.gov (United States)

Dai, Jiawei; Pan, Yubai; Xie, Tengfei; Kou, Huamin; Li, Jiang

2018-04-01

Highly transparent terbium aluminum garnet (Tb3Al5O12, TAG) magneto-optical ceramics were fabricated from co-precipitated nanopowders with tetraethoxysilane (TEOS) as sintering aid by vacuum sintering combined with hot isostatic pressing (HIP) post-treatment. The ball milled TAG powder shows better dispersity than the as-synthesized powder, and its average particle size is about 80 nm. For the ceramic sample pre-sintered at 1720 °C for 20 h with HIP post-treated at 1700 °C for 3 h, the in-line transmittance exceeds 76% in the region of 400-1580nm (except the absorption band), reaching a maximum value of 81.8% at the wavelength of 1390 nm. The microstructure of the TAG ceramic is homogeneous and its average grain size is approximately 19.7 μm. The Verdet constant of the sample is calculated to be -182.7 rad·T-1·m-1 at room temperature.

Sequestration of uranium on fabricated aluminum co-precipitated with goethite (Al-FeOOH)

Energy Technology Data Exchange (ETDEWEB)

Sun, Yubing; Yang, Shubin; Wang, Qi; Wang, Xiangke [Chinese Academy of Science, Hefei (China). Key Laboratory of Novel Thin Film Solar Cells; Alsaedi, Ahmad [King Abdulaziz Univ., Jeddah (Saudi Arabia). Nonlinear Analysis and Applied Mathematics (NAAM) Research Group

2014-11-01

Aluminum co-precipitated with goethites (Al-FeOOHs) are ubiquitous within (sub)-surface environments, which are considered one of the most important sinks for radionuclide pollution management. Accordingly, various mole ratios Al-FeOOH were synthesized and characterized by XRD, FT-IR, TEM, specific surface area and potentiometric acid-base titration. According to XRD and TEM images, the morphology of Al-FeOOH was transformed from acicular-like goethite to cotton-like gibbsite with increasing Al content. The adsorption and sequential desorption of U(VI) on Al-FeOOHs were conducted by batch techniques under N{sub 2} conditions. The batch adsorption results showed that the adsorption of U(VI) on Al-FeOOHs slightly increased at pH < 4.0, then the significant increase of U(VI) adsorption was observed at pH from 4.0 to 7.0, whereas the suppressed adsorption at pH > 8.0 was due to the electrostatic repulsion between negative charge surface and negative carbonato-complexes. The adsorption of U(VI) on Al-FeOOHs was independent of ionic strength at pH > 5.0, indicating that the inner-sphere surface complexation predominated their adsorption behaviors, whereas U(VI) adsorption on Al-FeOOH could be the outer-sphere surface/cation exchange reaction. The sequential extraction texts showed that the desorption of U(VI) from Al-FeOOHs decreased with increasing Al content. These findings highlighted the effect of Al content on the sequestration and immobilization of U(VI) onto Al-FeOOHs from (sub)-surface environments in pollution management.

Magnetite nanoparticles prepared by co-precipitation method in different conditions

Energy Technology Data Exchange (ETDEWEB)

Aphesteguy, J.C., E-mail: caphestegu@fi.uba.ar [LAFMACEL-INTECIN, Facultad de Ingeniería, UBA, Paseo Colón 850, C1063EHA Buenos Aires (Argentina); Kurlyandskaya, G.V. [Universidad del País Vasco UPV-EHU, Dept. Electricidad y Electronica, 48940 Leioa (Spain); Ural Federal University, Dept. Magnetism and Magnetic Nanomaterials, 620000 Ekaterinburg (Russian Federation); Celis, J.P. de [National Technology University (UTN), Facultad Regional Avellaneda, Department of Chemistry (Argentina); Safronov, A.P. [Ural Federal University, Dept. Magnetism and Magnetic Nanomaterials, 620000 Ekaterinburg (Russian Federation); Institute of Electrophysics UD RAS, Ekaterinburg 620016 (Russian Federation); Schegoleva, N.N. [Institute of Metal Physics UD RAS, Ekaterinburg 620044 (Russian Federation)

2015-07-01

Magnetic nanoparticles (MNPs) of pure magnetite (Fe{sub 3}O{sub 4}) were prepared in an aqueous solution (sample M−I) and in a water-ethyl alcohol mixture (sample M−II) by the co-precipitation method. The structure and magnetic properties of both samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic (M−H) and microwave measurements (FMR). The mean average particle diameter and particle size distribution was evaluated by the Dynamic Light Scattering (DLS) and Brunauer- Emmett-Teller techniques (BET). The Quantitative chemical analysis of iron was performed by Inductively Coupled Plasma (ICP)- Atomic Emission Spectroscopy (AES) technique. The MNPs prepared in aqueous solution show a higher grain than those prepared in the water-ethyl alcohol mixture. The type of phase structure in both cases can be defined as “defective spinel”. The shape of the majority of M−I MNPs is octahedral. The shape of the majority of M−II MNPs is cubic. The specific surface area of MNPs was as high as 14.4 m{sup 2}/g for M−I sample and 77.8 m{sup 2}/g for sample M–II. The obtained saturation magnetization values of 75 emu/g (M−I) and 68 emu/g (M−II) are consistent with expected values for magnetite MNPs of observed sizes. Ferromagnetic resonance (FMR) measurements confirmed that MNPs of both types are magnetically homogeneous materials. FMR lines' position and line widths can be understood by invoking the local dipolar fields, deviations from sphericity, magnetocrystalline anisotropy and stresses. M−I sample shows sizeable zero field microwave absorption which is absent in the M−II case. The differences in microwave behaviour of M−I and M−II MNPs can be used in the design of microwave radiation absorbing multilayers. - Highlights: • Magnetite nanoparticles were prepared in two different conditions. • Specific surface area of sample prepared in water- ethanol mix is

Structural and magnetic properties Co_3O_4 obtained by the coprecipitation

International Nuclear Information System (INIS)

Junior, M.E.; Junior, F.A.; Hernandez, E.P.; Barbosa, F.C.G.; Paulo, V.I.M.; Junior, J.N.A.; Almeida, J.C.

2016-01-01

Full text: The study shows a structural and magnetic properties of cobalt oxide Co3O4 doped with Cr as a function of the parameters adopted during the synthesis by chemical co-precipitation were flowing neutralizing NaOH and calcination temperature to 800 °C and 1000 °C. First, a series of samples of this oxide in which the flow was changed neutralization of the NaOH solution was generated. Thermal treatments were carried out at 800 °C and 1000 °C in anticipation of changing voltages on the network, average crystal size, etc. XRD observed in this case that the major phase and Co3O4 was found that the change of flow, the average crystallite size of network parameters and changes suffered distorted. In magnetic measurements MxT for samples to 800 °C and 1000 °C we observed behavioral evidence of a ferri / ferromagnetic-paramagnetic transition. On the other hand, the Curie-Weiss parameter was found negative for all samples associated with the major phase Co3O4 antiferromagnetic. Thus, we could correlate these phenomena the possible presence of phase clusters / nanoclusters amorphous ferri / ferromagnetic with CoCr2O4 / CrO2 generated with the incorporation of Cr under different NaOH flows. These coupling steps leading to the observed behavior. Have the MXH measures to 1000 °C in 50K presented a characteristic hysteresis loop system ferri / ferromagnetic well pronounced and could associate this, beyond the coupling phase, the fact that higher temperatures increase the grain size decreasing the surface anisotropy and favoring phases ferri / ferromagnetic. We are convinced that the results of our research is an important contribution to the field. (author)

Photocatalytic properties of BiVO4 prepared by the co-precipitation method: Degradation of rhodamine B and possible reaction mechanisms under visible irradiation

International Nuclear Information System (INIS)

Martinez-de la Cruz, A.; Perez, U.M. Garcia

2010-01-01

Bismuth vanadate (BiVO 4 ) was synthesized by the co-precipitation method at 200 o C. The photocatalytic activity of the oxide was tested for the photodegradation of rhodamine B under visible light irradiation. The analysis of the total organic carbon showed that the mineralization of rhodamine B over a BiVO 4 photocatalyst (∼40% after 100 h of irradiation) is feasible. In the same way, a gas chromatography analysis coupled with mass spectroscopy revealed the existence of organic intermediates during the photodegradation process such as ethylbenzene, o-xylene, m-xylene, and phthalic anhydride. The modification of variables such as dispersion pH, amount of dissolved O 2 , and irradiation source was studied in order to know the details about the photodegradation mechanism.

Coprecipitation of trace amounts of 137Cs and 85Sr with [Na(18-Crown-6]BPh4 from neutral and alkaline solutions

International Nuclear Information System (INIS)

Kulyukhin, S.A.; Konovalova, N.A.; Rumer, I.A.; Kamenskaya, A.N.; Mikheev, N.B.

2005-01-01

Coprecipitation of 137 Cs and 85 Sr with [Na(18-crown-6]BPh 4 solid phase from aqueous, aqueous-ethanolic, and alkaline solutions is studied. 137 C s and 85 Sr co-crystallize with [Na(18-crown-6]BPh 4 from aqueous and aqueous-ethanolic solutions. The cocrystallization coefficients D of 137 Cs and 85 Sr from aqueous solutions are 2.6 ± 0.5 and 3.3 ± 0.3, respectively. For aqueous-ethanolic solutions, the corresponding values are 4.4 ± 0.5 and 3.4 ± 0.4. In the alkaline solutions (0.1 and 1 M NaOH), 54-74% of 137 Cs and 37-51% of 85 Sr pass into the [Na(18-crown-6)]BPh 4 solid phase, depending on the crown ether concentration in the system [ru

Evaluation of the structure and microstructure of NixMg1-xO oxides obtained by co-precipitation

International Nuclear Information System (INIS)

Martinez L, G.; Kryshtab, T.; Hesiquio G, M.; Kryvko, A.

2013-01-01

Ni x Mg 1-x O oxides were prepared by thermal treatment at temperatures of 400, 600 and 800 C from a hydrotalcite-like precursor obtained by co-precipitation at constant ph. The oxides obtained were characterized by X-ray diffraction methods. From the obtained results we concluded that the oxides calcined at temperatures of 400, and 600 C are unstable that means that there exists the effect of memory and with a time they return to the precursor. Presence of Ni in Mg oxide provides stability of the compounds thermally treated at 800 C. In order to analyze the structure and microstructure, the reflections 111, 200 and 220 were used. The positions of the maxima of the diffraction peaks are shifted with respect to the simulated ones for Mg O and Ni O. This result reveals that in solid solutions studied compressive strains or vacation are present. The parameters of the microstructure (coherent domain size and micro deformations) were evaluated. The coherent domain size was found to be in the range of 8 - 10 nm and the presence of residual strains of micro deformation can be associated with the existence of extended defects. (Author)

Thermogravimetric and magneticproperties of Ni1-X Zn xFe2O4 nanoparticles synthesized by coprecipitation

Directory of Open Access Journals (Sweden)

Kandasamy Velmurugan

2009-01-01

Full Text Available Ni1-xZn xFe2O4 (x = 0 to 1 nanoparticles of size less than 9 nm were prepared by a chemical coprecipitation method which could be used for ferrofluid preparation. XRD, VSM and DTA-TG (STA were used to study the effect of variation in Zn substitution and its influence on particle size, magnetic properties such as M S, H C and Curie temperature, as well as on the water content. ICP was used to estimate Ni, Zn and Fe concentrations. The average crystallite size (DaveXR of the particles was found to decrease from 8.95 to 6.92 nm with increasing zinc substitution. The lattice constant (a o increased with increasing zinc substitution. The specific saturation magnetization (M S of the particles was measured at room temperature. Magnetic parameters such as M S, Hc, and Mr were found to decrease with increasing zinc substitution. Estimation of the water content, which varies the Zn concentration, plays a vital role for the correct determination of cation contents. The Curie temperature was found to decrease with increasing zinc substitution.

Effect of irradiation power and time on ultrasound assisted co-precipitation of nanostructured CuO–ZnO–Al2O3 over HZSM-5 used for direct conversion of syngas to DME as a green fuel

International Nuclear Information System (INIS)

Allahyari, Somaiyeh; Haghighi, Mohammad; Ebadi, Amanollah; Hosseinzadeh, Shahin

2014-01-01

Graphical abstract: Nanostructured CuO–ZnO–Al 2 O 3 /HZSM-5 catalyst has been prepared by an ultrasound-assisted co-precipitation hybrid method. Effect of power and irradiation time have been studied by changing the time (30–45–60 min) and power of sonication (50–100–150 W) during the synthesis which lead to different physiochemical properties of the catalyst. The XRD, FESEM, EDX, FTIR and BET analyses exhibited smaller particles with higher surface area and less population of particle aggregates at longer and highly irradiated catalysts. Study on the performance of investigated catalysts in direct synthesis of DME from syngas showed ultrasound-assisted co-precipitated synthesized catalysts have superior reactivity and stability compared with non-sonicated catalyst. Among sonicated catalysts, with increasing power and time of irradiation, the catalyst represents higher activity and DME selectivity. - Highlights: • Synthesis of CuO–ZnO–Al 2 O 3 /HZSM-5 by ultrasound assisted co-precipitation method. • Significant changes in morphology and surface area after ultrasound irradiations. • Smaller dispersed particle aggregates in longer and more intense irradiated catalysts. • Improvement in reactivity and stability of the longer and more intense ultrasound irradiated CZAZ catalyst. - Abstract: Nanostructured CuO–ZnO–Al 2 O 3 /HZSM-5 catalyst has been prepared by an ultrasound-assisted co-precipitation hybrid method. The effect of irradiation power and irradiation time have been studied by changing time (30, 45, 60 min) and power of the sonication (50, 100, 150 W) during the synthesis which led to different physiochemical properties of the nanocatalyst. The XRD, FESEM, EDX, FTIR and BET analyses exhibited smaller particles with higher surface area and less population of particle aggregates at longer and highly irradiated nanocatalysts. The nanocatalyst irradiated at 150 W for 60 min (the longest irradiation time and the most intense power

Preparation and characterization of a carbon-based magnetic nanostructure via co-precipitation method: Peroxidase-like activity assay with 3,3ʹ,5,5ʹ-tetramethylbenzidine

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Navvabeh Salarizadeh

2017-09-01

Full Text Available Objective(S: Natural and artificial enzymes have shown important roles in biotechnological processes. Recently, design and synthesis of artificial enzymes especially peroxidase mimics has been interested by many researchers. Due to disadvantages of natural peroxidases, there is a desirable reason of current research interest in artificial peroxidase mimics. Methods: In this study, magnetic multiwall carbon nanotubes with a structure of Fe3O4/MWCNTs as enzyme mimetic were fabricated using in situ co-precipitation method. The structure, composition, and morphology of Fe3O4/MWCNTs nanocomposite were characterized using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, and transmission electron microscopy (TEM. The magnetic properties were investigated by the vibrating sample magnetometer (VSM. Peroxidase-like catalytic activity of nanocomposite was investigated using colorimetric and electrochemical tests with 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB substrate. Results: The obtained data proved the synthesis of Fe3O4/MWCNTs nanocomposite. The average crystallite size of nanostructures was estimated about 12 nm by Debye–Scherer equation. It was found that Fe3O4/MWCNTs nanocomposite exhibit peroxidase-like activity. Colorimetric and electrochemical data demonstrated that prepared nanocomplex has higher catalytic activity toward H2O2 than pure MWCNT nanocatalyst. From electrochemical tests concluded that the Fe3O4/MWCNTs electrode exhibited the better redox response to H2O2, which is ~ 2 times larger than that of the MWCNTs. Conclusions: The synthesis of Fe3O4nanoparticles on MWCNTs was successfully performed by in situ co-precipitation process. Fe3O4/MWCNTs nanocatalyst exhibited a good peroxidase-like activity. These biomimetic catalysts have some advantages such as simplicity, stability and cost effectiveness that can be used in the design of enzyme-based devices for various applied fields.

Synthesis and Characterization of Cu- and Co-Doped Bi4V2O11 for Intermediate-Temperature Solid Oxide Fuel Cell Electrolytes by Carbonate Coprecipitation

Science.gov (United States)

Lee, Jin Goo; Yoon, Hyon Hee

2011-01-01

Bi2MexV1-xO5.5-3x/2 (Me = Cu; 0≤x≤0.2) powders were prepared by the ammonium carbonate coprecipitation method. The starting salts were bismuth nitrate, copper nitrate, cobalt nitrate, and vanadium sulphate. The thermal decomposition of Bi2MexV1-xO5.5-3x/2 precursors was completed at about 500 °C. The crystallite structure, surface morphology, and ionic conductivity of the prepared powders and pellets were examined using X-ray diffractometry, field emission scanning electron microscopy, and an impedance analyzer, respectively. The average particle sizes of the Bi2Cu0.1V0.9O5.35 and Bi2Co0.1V0.9O5.35 powders were 10-50 nm. The tetragonal structure (γ-phase) appeared at sintering temperatures higher than 700 °C and the peak intensity increased at higher sintering temperatures. The ionic conductivities of the Bi2Cu0.1V0.9O5.35 and Bi2Co0.1V0.9O5.35 pellets sintered at 800 °C showed the highest values of 6.8×10-2 S cm-1 at 700 °C and 9.1×10-2 S cm-1 at 700 °C, respectively. The optimum concentration of the Cu and Co dopants in Bi2MexV1-xO5.5-3x/2 was determined to be 0.1. The results of this study demonstrated that the ammonium carbonate coprecipitation process could be used as an economical method for the preparation of Bi2MexV1-xO5.5-3x/2 electrolytes for intermediate-temperature solid oxide fuel cells.

Detailed crystallization study of co-precipitated Y1.47 Gd1.53 Fe5 O12 and relevant magnetic properties

International Nuclear Information System (INIS)

Serra, Rogerio Arving; Ogasawara, Tsuneharu; Ogasawara, Angelica Soares

2007-01-01

The crystallization process of co-precipitated Y 1.5 Gd 1.5 Fe 5 O 12 powder heated up to 1000 deg C at rate of 5 deg C min -1 was investigated. Above 810 deg C crystalline Y 1.47 Gd 1.53 Fe 5 O 12 was obtained with a lattice parameter of 12.41 A and a theoretical density of 5.84 g cm -3 . Dry pressed rings were sintered at 1270 and 1320 deg C, increasing the grain-size from 3.1 to 6.5 μm, the theoretical density by 87.6 to 95.3% and decreasing H c from 2.9725 to 1.4005 Oe. Additionally, Hc increased when the frequency of the hysteresis graph varied from 60 Hz to 10 kHz, the curie temperature was 282.4 deg C and Ms equalled 9.25 emu g -1 (0.17 kG) agreeing well with the B s -value of the hysteresis graph and literature values. (author)

Preparation of ZnO-SnO2 ceramic materials by a coprecipitation method

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Caballero, A. C.

2006-06-01

Full Text Available Tin (IV-doped zinc oxide ceramics find its main application as specific gas sensor devices. The sensor ability of the mixture and its particular affinity for a particular gas (selectivity depends both on the crystalline phases in the microstructure of the sintered semiconductor and on the degree of tin incorporation into ZnO lattice. By means of a highly reactive coprecipitation method it is revealed that the range of solid solution of tin in zinc oxide stays below 0.1 mol % of SnO2 since higher concentrations lead to segregation of a secondary Zn2SnO4 spinel type-phase.Los materiales cerámicos basados en óxido de cinc dopado con estaño (IV encuentran su principal aplicación como dispositivos sensores específicos de gases. La capacidad sensora de la mezcla de óxidos y su particular afinidad por un determinado gas específico (selectividad es función directa de cuáles sean las fases cristalinas presentes en la microestructura del semiconductor sinterizado, así como del grado de incorporación del estaño en la red del ZnO. La obtención del polvo cerámico de partida por un método de coprecipitación altamente reactivo revela que el rango de solución sólida del estaño en el óxido de cinc se encuentra por debajo del 0.1 % en moles de SnO2; concentraciones superiores llevan a la segregación de una fase secundaria, Zn2SnO4, con estructura de tipo espinela.

Structural, electric and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics obtained by co-precipitation route

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Mohamed Afqir

2018-03-01

Full Text Available This paper presents a study of the structure and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics prepared by co-precipitation route and sintered at 850 °C. The materials were examined using XRD and FTIR methods. XRD data indicated the formation of well crystallized structure of the pure and doped SrBi2Nb2O9, without the presence of undesirable phases. FTIR spectra do not bring a significant shift in the band positions. Moreover, the AC conductivity, dielectric constant and dielectric loss of the ceramics were determined through the frequency range [50 kHz–1 MHz]. In particular, the dielectric constant (ε′ and dielectric losses (tan δ of the SrBi2Nb2O9 and SrBi1.6Eu0.4Nb2O9 ceramics were measured as a function of temperature at various frequencies.

Preparation of magnetic albumin nanoparticles via a simple and one-pot desolvation and co-precipitation method for medical and pharmaceutical applications.

Science.gov (United States)

Nosrati, Hamed; Salehiabar, Marziyeh; Manjili, Hamidreza Kheiri; Danafar, Hossein; Davaran, Soodabeh

2018-03-01

In this study, iron oxide magnetic bovine serum albumin core-shell nanoparticles (BSA coated IONPs) with narrow particle size distribution were synthesized under one-pot reaction via the desolvation and chemical co-precipitation method. Functionalized IONPs were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) techniques. Furthermore, vibrating sample magnetometer (VSM) analysis show these nanoparticles (NPs) have an excellent magnetic properties. Cellular toxicity of IONPs was also investigated on HFF2 cell lines. Additionally, a hemolysis test of as prepared core-shell NPs were performed. The presence of albumin as a biomolecule coating on the surface of IONPs showed an improving effect to reduce the cytotoxicity. The properties of the designed NPs propose the BSA coated IONPs as a promising candidate for multifunctional biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis, microstructure and EPR of CaMnO3 and EuxCa1-xMnO3 manganite, obtained by coprecipitation

International Nuclear Information System (INIS)

Santiago T, M.; Hernandez C, L.; Legorreta G, F.; Montiel S, H.; Alvarez L, G.; Flores G, M. A.

2011-01-01

The synthesis of CaMnO 3 and Eu x Ca 1-x MnO 3 obtained by coprecipitation method is showed. The synthesized samples were characterized by X-ray diffraction and scanning electronic microscopy, the powders showed orthorhombic structure and pnma space group. When it was doped with Europium, their morphology tendency was spherical. Measurements were carried out on electron paramagnetic resonance (EPR) with constant frequency = 9.4 GHz (band X) and dc magnetic field (H dc) 0-0.8 T, measurements were at 300 K and 77 K. EPR spectra showed significant differences between both samples, indicating that the substitution of divalent alkaline earth cations by trivalent rare earth ions, allowing the formation of a mixed valence state of manganese, Mn 3+ and Mn 4+ . A 77 K, the manganite of concentration x = 0.30 had a magnetic ordering, noted by the presence of hysteresis. (Author)

Effect of pH variation on the stability and structural properties of In(OH){sub 3} nanoparticles synthesized by co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Goh, Kian Wei; Wong, Yew Hoong [University of Malaya, Department of Mechanical Engineering, Faculty of Engineering, Kuala Lumpur (Malaysia); Johan, Mohd Rafie [University of Malaya, Department of Mechanical Engineering, Faculty of Engineering, Kuala Lumpur (Malaysia); University of Malaya, Nanotechnology and Catalysis Research Centre, Kuala Lumpur (Malaysia)

2016-10-15

Indium hydroxide (In(OH){sub 3}) nanoparticles were synthesized at various pH values (8-11) by co-precipitation method. Its properties were characterized by X-ray diffractometer, Fourier transform infrared spectroscopy, Raman spectroscopy and transmission electron microscope. The electrostatic stability of nanoparticles is carried out through zeta potential measurement. The crystallite size of nanoparticles calculated by Scherrer equation has similar trend with the values obtained from William-Hall plot. TEM images show that the particles size is within the range of 11.76-20.76 nm. The maximum zeta potential is 3.68 mV associated with the smallest particle size distribution of 92.6 nm occurred at pH 10. Our work clearly confirms the crystallite size, stability and the morphology of In(OH){sub 3} NPs are strongly depending on the pH of precursor solution. (orig.)

PTFE Additive and Re-annealing Effect on Thermoluminescence Response of CaSO4:Dy Derived from Co-precipitation Method

Science.gov (United States)

Nuraeni, Nunung; Dwi Septianto, Ricky; Iskandar, Ferry; Haryanto, Freddy; Waris, Abdul; Hiswara, Eri

2017-07-01

Effect of re-annealing treatment in thermoluminescence response of thermoluminescent dosimeter (TLD) CaSO4:Dy and CaSO4:Dy with PTFE (Polytetrafluoroethylene) addition was investigated. CaSO4:Dy was prepared by a co-precipitation method. The PTFE was added before re-annealing treatment which the mass ratio of CaSO4:Dy and PTFE was fixed to 2:3. The re-annealing treatments of the samples were done at temperature 700 °C for 1 hr. The obtained samples were characterized using a Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) to observe the molecule bonding in sample and crystal properties, respectively. From the experimental results, it was observed that the thermoluminescence intensity of CaSO4:Dy, CaSO4:Dy re-annealed at 700 °C, and CaSO4:Dy + PTFE re-annealed at 700 °C are 57.03, 75.15, and 1191.11 nC, respectively. The intensity of 700 °C-re-annealed CaSO4:Dy increased significantly after PTFE addition.

Co-precipitation synthesis and luminescence behavior of Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor: The effect of precipitant

International Nuclear Information System (INIS)

Zhang Kai; Liu Hezhou; Wu Yating; Hu Wenbin

2008-01-01

YAG:Ce precursors were co-precipitated using ammonia water and ammonium hydrogen carbonate as precipitants, respectively. Phase transition of the precursors during sintering was compared between the two precipitants. The precursors synthesized with ammonia water transformed to YAG at about 1000 deg. C via YAlO 3 phase. The precursors synthesized with ammonium hydrogen carbonate directly converted to pure YAG at about 900 deg. C. Comparing the powders produced with the two precipitants, the powders produced with ammonia hydrogen carbonate showed good dispersity. When sintered at 1600 deg. C, aggregation of the powders synthesized with the two precipitants both became severe. With increase the sintering temperature, the maximum wavelength of excitation and emission spectra of the phosphors synthesized with ammonium water hardly varied. While the maximum wavelength of excitation spectra of the phosphors synthesized with ammonium hydrogen carbonate unchanged, and the emission spectra showed red shift. Because of size effect and higher loss of cerium content, the emission intensity of phosphors prepared with ammonium hydrogen carbonate was lower than the phosphors prepared with ammonium water, when sintered at the same temperature

Modification the Oxalic Co-precipitation Method on a Novel Catalyst Cu/Zn/Al2O3/Cr2O3 for Autothermal Reforming Reaction of Methanol

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Cheng- Hsin Kuo

2013-12-01

Full Text Available This study addresses the catalytic performance of Cu/ZnO/Al2O3/Cr2O3 in low-temperature of autothermal reforming (ATR reaction. Various operating conditions were used to decide the optimum reaction conditions: type of promoter (ZrO2, CeO2, and Cr2O3, precipitation temperature, precipitation pH, operation temperature, molar ratio of O2/CH3OH (O/C, and weight hourly space velocity (WHSV. The catalysts were prepared using the oxalic coprecipitation method. Characterization of the catalyst was conducted using a porosity analyzer, XRD, and SEM. The methanol conversion and volumetric percentage of hydrogen using the best catalyst (Cu/ZnO/Al2O3/Cr2O3 exceeded 93% and 43%, respectively. A catalyst prepared by precipitation at -5 oC and at pH of 1 converted methanol to 40% H2 and less than 3000 ppm CO at reaction temperature of 200 oC. The size and dispersion of copper and the degradation rate and turnover frequency of the catalyst was also calculated. Deactivation of the Cu catalyst at a reaction temperature of 200 oC occurred after 30 h. © 2013 BCREC UNDIP. All rights reservedReceived: 8th May 2013; Revised: 10th August 2013; Accepted: 18th August 2013[How to Cite: Cheng, H.K., Lesmana, D., Wu, H.S. (2013. Modification the Oxalic Co-precipitation Method on a Novel Catalyst Cu/Zn/Al2O3/Cr2O3 for Autothermal Reforming Reaction of Methanol. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (2: 110-124. (doi:10.9767/bcrec.8.2.4844.110-124][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.2.4844.110-124

Modeling and optimization of effective parameters on the size of synthesized Fe{sub 3}O{sub 4} superparamagnetic nanoparticles by coprecipitation technique using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Ghazanfari, Mohammad Reza, E-mail: Ghazanfari.mr@gmail.com [Department of Materials Science and Engineering, Ferdowsi University of Mashhad, 9177948974 Mashhad (Iran, Islamic Republic of); Kashefi, Mehrdad, E-mail: m-kashefi@um.ac.ir [Department of Materials Science and Engineering, Ferdowsi University of Mashhad, 9177948974 Mashhad (Iran, Islamic Republic of); Jaafari, Mahmoud Reza [Biotechnology Research Center, Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

2016-05-01

Generally, the statistical methods are defined as appropriate techniques to study the processes trends. In current research, the Fe{sub 3}O{sub 4} superparamagnetic nanoparticles were synthesized by coprecipitation method. In order to investigate the size properties of synthesized particles, the experimental design was done using central composite method (CCD) of response surface methodology (RSM) while the temperature, pH, and cation ratio of reaction were selected as influential factors. After particles synthesis based on designed runs, the different responses such as hydrodynamic size of particles (both freeze dried and air dried), size distribution, crystallite size, magnetic size, and zeta potential were evaluated by different techniques i.e. dynamic light scattering (DLS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Based on these results, the quadratic polynomial model was fitted for each response that could predict the response amounts. In following, the study of factors effects was carried out that showed the temperature, pH, and their interactions had higher effectiveness. Finally, by optimizing, it was clear that the minimum amounts of particle size (10.15 nm) and size distribution (13.01 nm) were reached in the minimum temperature (70 °C) and cation ratio (0.5) amounts and maximum pH amount (10.5). Moreover, the characterizations showed the particles size was about 10 nm while the amounts of M{sub s}, H{sub c}, and M{sub r} were equal to 60 (emu/g), 0.2 (Oe) and 0.22 (emu/g), respectively. - Highlights: • The Fe{sub 3}O{sub 4} nanoparticles were successfully synthesized by coprecipitation method. • By RSM technique, some predicted models were presented for particles size. • Temperature, pH and their interactions had most effectiveness on the particles size. • The drying techniques can effect on the size properties.

Photoluminescence and magnetic properties of Fe-doped ZnS nano-particles synthesized by chemical co-precipitation

Energy Technology Data Exchange (ETDEWEB)

Nie Eryong; Liu Donglai; Zhang Yunsen; Bai Xue; Yi Liang; Jin Yong; Jiao Zhifeng [School of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Sun Xiaosong, E-mail: sunxs@scu.edu.cn [School of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China)

2011-08-15

This paper is focusing on the synthesis of Zn{sub 1-x}Fe{sub x}S nano-particles with x = 0, 0.1 and 0.2 by chemical co-precipitation method, the prepared of which are characterized by XRD, EDS, TEM, PL, magnetization versus field behavior and M-T curve. In the XRD patterns, Zn{sub 1-x}Fe{sub x}S nano-particles are shown of cubic zinc blende structure, and the broadening diffraction peaks consistent with the small-size characteristic of nano-materials. The diameter of nano-particles is between 3.3 and 5.5 nm according to the HR-TEM images. The EDS data confirm the existence of Fe ions in Fe-doped ZnS nanoparticles. There we found that Fe-doping did not import new energy bands or defect states, but reduced the intensity of PL peaks. The magnetization versus field behaviors were illustrated by the M-H curves at both 5 K and 300 K, respectively, where no remanence or coercive force was observed. This phenomenon indicates that the Zn{sub 1-x}Fe{sub x}S (x = 0.1) nano-particles are superparamagnetic. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves further reveal that the blocking temperature (T{sub B}) of the superparamagnetic behavior might be below 5 K.

Parametric study on co-precipitation of U/Th in MOX fuel of AHWR

International Nuclear Information System (INIS)

Tiwari, S.K.; Swaroopa Lakshmi, Y.; Nath, Baidurjya; Setty, D.S.; Kalyana Krishnan, G.; Saibaba, N.

2015-01-01

During manufacturing of Mixed Oxide Fuel (MOX) pellets for Advance Heavy Water Reactor (AHWR-LEU), around 30% rejected MOX pellets are generated in every cycle. These rejected MOX pellets are dissolved in nitric acid for recovery of U/Th. The recovered U/Th is recycled for production of MOX pellets. MOX pellets of varying compositions are used in AHWR fuel. Dissolution of MOX pellets in nitric acid is a challenging task because of its low surface area and longer dissolution times. High normal nitric acid is used in order to increase rate of dissolution, which in turn results in generation of high free acidity solution which influences the precipitation characteristics of Uranium (VI) by oxalic acid. Oxalic acid precipitation helps in generation of nitric acid which can be used for dissolution there by effectively facilitating nil effluent generation. Precipitation by oxalic acid unlike ammonia has advantage of zero liquid effluent discharge by complete recycle of oxalate filtrate to dissolution section. In the present work, the effect of various parameters like free acidity, residence time, concentration of oxalic acid, initial concentration of uranium and thorium etc. on the precipitation of U(VI) and Th(IV) in nitrate media by oxalic acid was carried out. The precipitated powder was subjected to various morphological evaluations like particle size etc. Study of various parameters on the co-precipitation of uranium and thorium by oxalic acid was carried out. It was observed that complete precipitation (> 99.9%) of thorium as oxalate does not depend on free acidity range (1- 6 N). Excess oxalic acid is not required for complete precipitation of thorium oxalate. The precipitation of uranyl oxalate varies with initial free acidity of solution. Uranyl oxalate precipitation does not take place at and above 5 N of free acidity

Effect of calcination temperature on the photocatalytic activity of TiO2 powders prepared by co-precipitation of TiCl3

International Nuclear Information System (INIS)

Yudoyono, Gatut; Ichzan, Nur; Zharvan, Vicran; Daniyati, Rizqa; Santoso, Hadi; Indarto, Bachtera; Pramono, Yono Hadi; Zainuri, Mochamad; Darminto

2016-01-01

The adsorption of basic dye methylene blue (MB) onto titanium dioxide (titania) powder that were prepared by coprecipitation method of TiCl 3 and NH 4 OH as iniatial material with different calcination temperature was studied to examine the photocatalytic activity. Synthesis process carried out by the solution pH was adjusted to be 8. Effect of calcination temperature on the titania powder were characterized with Differential Scanning Calorimetry/Thermogravimetry (DSC/TG), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The result of TG and XRD showed that the NH 4 Cl decomposed between 235-372°C. The XRD result showed that the anatase TiO 2 only contained a single phase when the calcination temperature of the precursor at 800°C, and over which it began to grow rutile phase. The influence of synthesis condition on the photocatalytic activity of TiO 2 powder was determined by the photodegradation of MB dye under UV light.

Synthesis and characterization of polyethylene glycol (PEG) coated Fe3O4 nanoparticles by chemical co-precipitation method for biomedical applications.

Science.gov (United States)

Anbarasu, M; Anandan, M; Chinnasamy, E; Gopinath, V; Balamurugan, K

2015-01-25

Polyethylene glycol (PEG) coated Fe3O4 nanoparticles were synthesized by chemical co-precipitation method. With polyethylene glycol (PEG) as a stabilizer and dispersant. The X-ray diffraction and selected area electron diffraction (SAED) results show that the cubic inverse spinel structure of pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and field emission transmission electron microscopy (FE-TEM) results exhibited that the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FT-IR) results suggested that PEG indicated with Fe3O4 via its carbonyl groups. Results of vibrating sample magnetometer (VSM) indicated that the prepared Fe3O4 nanoparticles exhibit superparamagnetic behavior and high saturation magnetization at room temperature. Such Fe3O4 nanoparticles with favorable size and tunable magnetic properties are promising biomedical applications. Copyright © 2014. Published by Elsevier B.V.

Modified structural and magnetic properties of nanocrystalline MnFe{sub 2}O{sub 4} by pH in capping agent free co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Iranmanesh, P., E-mail: p.iranmanesh@vru.ac.ir [Department of Physics, Vali-e-Asr University of Rafsanjan, 77139-36417 Rafsanjan (Iran, Islamic Republic of); Saeednia, S. [Department of Chemistry, Vali-e-Asr University of Rafsanjan, 77139-36417 Rafsanjan (Iran, Islamic Republic of); Mehran, M.; Dafeh, S. Rashidi [Department of Physics, Vali-e-Asr University of Rafsanjan, 77139-36417 Rafsanjan (Iran, Islamic Republic of)

2017-03-01

Nano-sized manganese ferrite (MnFe{sub 2}O{sub 4}) particles were prepared using co-precipitation method in two different pH (9 and 11). The structural, morphological, optical and magnetic properties of as-synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis absorption and vibrating sample magnetometer (VSM). The FTIR spectra revealed two strong peaks at about 600 and 400 cm{sup −1} that can be attributed to the vibration mode of octahedral and tetrahedral sites of spinel structure of MnFe{sub 2}O{sub 4}, respectively. The XRD results showed that the nanocrystalline MnFe{sub 2}O{sub 4} has pure cubic spinel crystal structure with average crystallite size of 11 nm. The cation distribution of these nanoparticles was estimated by X-ray analysis data. The blue shift was observed in the band gap when compared with bulk sample which is due to the quantum size effect. The absence of hysteresis for MnFe{sub 2}O{sub 4} nanoparticles indicated the superparamagnetic behaviour, as expected for single domain nanoparticles. The obtained value for saturation magnetization being less than its value of bulk ones and larger pH is due to surface effects. The calculated magnetic particle size was smaller than crystallite size estimated from the XRD results; which indicate the presence of dead layer on particle surface. - Highlights: • We study effect of pH on the size and magnetic properties of MnFe{sub 2}O{sub 4} nanoparticles. • MnFe{sub 2}O{sub 4} were synthesized by co-precipitation method without any capping agent. • The physical properties are affected by cation contribution and surface effects. • The smaller nanoparticles with larger pH show a red shift in the band gap energy. • The M{sub s} is less than its value of bulk ones due to surface effects.

Photocatalytic properties of BiVO{sub 4} prepared by the co-precipitation method: Degradation of rhodamine B and possible reaction mechanisms under visible irradiation

Energy Technology Data Exchange (ETDEWEB)

Martinez-de la Cruz, A., E-mail: azael70@yahoo.com.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Ciudad Universitaria, C.P. 66451, San Nicolas de los Garza, N.L. (Mexico); Perez, U.M. Garcia [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Ciudad Universitaria, C.P. 66451, San Nicolas de los Garza, N.L. (Mexico)

2010-02-15

Bismuth vanadate (BiVO{sub 4}) was synthesized by the co-precipitation method at 200 {sup o}C. The photocatalytic activity of the oxide was tested for the photodegradation of rhodamine B under visible light irradiation. The analysis of the total organic carbon showed that the mineralization of rhodamine B over a BiVO{sub 4} photocatalyst ({approx}40% after 100 h of irradiation) is feasible. In the same way, a gas chromatography analysis coupled with mass spectroscopy revealed the existence of organic intermediates during the photodegradation process such as ethylbenzene, o-xylene, m-xylene, and phthalic anhydride. The modification of variables such as dispersion pH, amount of dissolved O{sub 2}, and irradiation source was studied in order to know the details about the photodegradation mechanism.

Speciation of Mn(II), Mn(VII) and total manganese in water and food samples by coprecipitation-atomic absorption spectrometry combination

International Nuclear Information System (INIS)

Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

2010-01-01

A speciation procedure based on the coprecipitation of manganese(II) with zirconium(IV) hydroxide has been developed for the investigation of levels of manganese species. The determination of manganese levels was performed by flame atomic absorption spectrometry (FAAS). Total manganese was determined after the reduction of Mn(VII) to Mn(II) by ascorbic acid. The analytical parameters including pH, amount of zirconium(IV), sample volume, etc., were investigated for the quantitative recoveries of manganese(II). The effects of matrix ions were also examined. The recoveries for manganese(II) were in the range of 95-98%. Preconcentration factor was calculated as 50. The detection limit for the analyte ions based on 3 sigma (n = 21) was 0.75 μg L -1 for Mn(II). The relative standard deviation was found to be lower than 7%. The validation of the presented procedure was performed by analysis of certified reference material having different matrices, NIST SRM 1515 (Apple Leaves) and NIST SRM 1568a (Rice Flour). The procedure was successfully applied to natural waters and food samples.

Structural and magnetic properties of cobalt ferrite nanoparticles synthesized by co-precipitation at increasing temperatures

Science.gov (United States)

Stein, C. R.; Bezerra, M. T. S.; Holanda, G. H. A.; André-Filho, J.; Morais, P. C.

2018-05-01

This study reports on the synthesis and characterization of cobalt ferrite (CoFe2O4) nanoparticles (NPs) synthesized by chemical co-precipitation in alkaline medium at increasing temperatures in the range of 27 °C to 100 °C. High-quality samples in the size range of 5 to 10 nm were produced using very low stirring speed (250 rpm) and moderate alkaline aqueous solution concentration (4.8 mol/L). Three samples were synthesized and characterized by x-ray diffraction (XRD) and room-temperature (RT) magnetization measurements. All samples present superparamagnetic (SPM) behavior at RT and Rietveld refinements confirm the inverse cubic spinel structure (space group Fd-3m (227)) with minor detectable impurity phase. As the synthesis temperature increases, structural parameters such as lattice constant and grain size change monotonically from 8.385 to 8.383 Å and from 5.8 to 7.4 nm, respectively. Likewise, as the synthesis temperature increases the NPs' magnetic moment and saturation magnetization increases monotonically from 2.6 ×103 to 16×103 μB and from 37 to 66 emu/g, respectively. The RT magnetization (M) versus applied field (H) curves were analyzed by the first-order Langevin function averaged out by a lognormal distribution function of magnetic moments. The excellent curve-fitting of the M versus H data is credited to a reduced particle-particle interaction due to both the SPM behavior and the existence of a surface amorphous shell layer (dead layer), the latter reducing systematically as the synthesis temperature increases.

Controlling the size and magnetic properties of nano CoFe2O4 by microwave assisted co-precipitation method

Science.gov (United States)

Prabhakaran, T.; Mangalaraja, R. V.; Denardin, Juliano C.

2018-02-01

In this report, cobalt ferrite nanoparticles synthesized using microwave assisted co-precipitation method was reported. Efforts have been made to control the particles size, distribution, morphology and magnetic properties of cobalt ferrite nanoparticles by varying the concentration of NaOH solution and microwave irradiation time. It was observed that the rate of nucleation and crystal growth was influenced by the tuning parameters. In that way, the average crystallite size of single phase cobalt ferrite nanoparticles was controlled within 9-11 and 10-12 nm with an increase of base concentration and microwave irradiation time, respectively. A narrow size distribution of nearly spherical nanoparticles was achieved through the present procedure. A soft ferromagnetism at room temperature with the considerable saturation magnetization of 58.4 emu g-1 and coercivity of 262.7 Oe was obtained for the cobalt ferrites synthesized with 2.25 M of NaOH solution for 3 and 7 min of microwave irradiation time, respectively. The cobalt ferrite nanoparticles synthesized with a shorter reaction time of 3-7 min was found to be advantageous over other methods that involved conventional heating procedures and longer reaction time to achieve the better magnetic properties for the technological applications.

Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

Energy Technology Data Exchange (ETDEWEB)

Barahuie, Farahnaz [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Hussein, Mohd Zobir, E-mail: mzobir@putra.upm.edu.my [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Arulselvan, Palanisamy [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Fakurazi, Sharida [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zainal, Zulkarnain [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

2014-09-15

A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro. - Highlights: • We intercalated chlorogenic into Zn/Al-layered double hydroxide by ion-exchange and coprecipitation methods. • The two methods gave nanocomposites

Determination of Pb in river water samples by inductively coupled plasma optical emission spectrometry after ultrasound-assisted co-precipitation with manganese dioxide

International Nuclear Information System (INIS)

Sousa Bispo, Marcia; Santos da Boa Morte, Elane; Korn das Gracas Andrade, Maria; Sena Gomes Teixeira, Leonardo; Korn, Mauro; Costa, Antonio Celso Spinola

2005-01-01

A simple and efficient procedure for separation and pre-concentration using ultrasound-assisted co-precipitation with manganese dioxide was developed for Pb determination by inductively coupled plasma optical emission spectrometry (ICP OES). The optimization process was carried out using a two-level factorial design and a Doehlert matrix. Three variables (i.e. concentration of oxidizing solution-KMnO 4 , concentration of MnSO 4 solution and time of ultrasonic irradiation) were used as factors in the optimization. The recoveries, based on the analysis of spiked samples, were between 90% and 105%, and the precision was ≤ 5%. The detection limit and quantification limit for Pb determination were 3.2 and 10.7 μg L -1 , respectively. The proposed method was applied for the determination of Pb in water samples from a river heavily polluted by industrial effluents. The recovery measured by analyte addition technique showed that the proposed pre-concentration method had good accuracy

Irregular distribution of metal ions in ferrites prepared by co-precipitation technique structure analysis of Mn-Zn ferrite using extended X-ray absorption fine structure

International Nuclear Information System (INIS)

Jeyadevan, B.; Tohji, K.; Nakatsuka, K.; Narayanasamy, A.

2000-01-01

The tetrahedral/octahedral site occupancy of non-magnetic zinc ion, added to maximize the net magnetic moment of mixed ferrites has been found to depend on the method of preparation. In this paper, we qualitatively analyze the metal ion distribution in Mn-Zn ferrite particles prepared by co-precipitation and ceramic methods using extended X-ray absorption fine structure (EXAFS) technique. The results suggest that the differences observed in the magnetic properties of the samples prepared by different methods are not only due to the difference in particle size but also due to the difference in cation distribution. The difference in cation distributions between ferrites of similar composition prepared differently has been found to depend on the crystal field stability energies of the metal ion of interest and associated cations

Room Temperature Gas Sensing Properties of Sn-Substituted Nickel Ferrite (NiFe2O4) Thin Film Sensors Prepared by Chemical Co-Precipitation Method

Science.gov (United States)

Manikandan, V.; Li, Xiaogan; Mane, R. S.; Chandrasekaran, J.

2018-04-01

Tin (Sn) substituted nickel ferrite (NiFe2O4) thin film sensors were prepared by a simple chemical co-precipitation method, which initially characterized their structure and surface morphology with the help of x-ray diffraction and scanning electron microscopy. Surface morphology of the sensing films reveals particles stick together with nearer particles and this formation leads to a large specific area as a large specific area is very useful for easy adsorption of gas molecules. Transmission electron microscopy and selected area electron diffraction pattern images confirm particle size and nanocrystallnity as due to formation of circular rings. Fourier transform infrared analysis has supported the presence of functional groups. The 3.69 eV optical band gap of the film was found which enabled better gas sensing. Gas sensors demonstrate better response and recovery characteristics, and the maximum response was 68.43%.

Structure and magnetic properties of Mg0.35Cu0.2Zn0.45Fe2O4 ferrite synthesized by co-precipitation method

Directory of Open Access Journals (Sweden)

Bo Yang

2017-05-01

Full Text Available Mg0.35Cu0.2Zn0.45Fe2O4 nanosize particles have been synthesized by chemical co-precipitation method and characterized by X-ray diffraction (XRD and vibrating sample magnetometry (VSM. The XRD patterns confirmed the single phase spinel structure of the synthesized powder. The average crystallite size of the powder varied from 14 to 55 nm by changing annealing temperature. The activation energy for crystal growth was estimated as about 18.61KJ/mol. With the annealing temperature increasing, saturation magnetization (MS was successively increased while the coercivity (HC was first increased, passed through a maximum and then declined. The sintering temperature has significant influence on bulk density, initial permeability and Curie temperature of Mg0.35Cu0.2Zn0.45Fe2O4 ferrite.

Magnetic and structural properties of Cu0.85Fe0.15O system synthesized by co-precipitation

International Nuclear Information System (INIS)

Colorado, H. D.; Pérez Alcázar, G. A.

2011-01-01

Cu 0.94 Fe 0.06 O and Cu 0.85 Fe 0.15 O samples were synthesized by using the co-precipitation chemical method. Starting from aqueous solutions of copper nitrate, CuO (NO 3 ) 2 3H 2 O, iron nitrate, Fe (NO 3 ) 3 9H 2 O and sodium hydroxide as precipitating agent, NaOH. The precipitate of three samples for Cu 0.94 Fe 0.06 O and five for Cu 0.85 Fe 0.15 O of fine powder were calcined for 5 h at different temperatures. The obtained X rays diffraction patterns refined by the Rietveld method show the CuO characteristic pattern, showing that the Fe atoms enter to replace Cu atoms. Furthermore, it was obtained that the crystallite size decreases with calcination temperatures for Cu 0.94 Fe 0.06 O. The transmission Mössbauer spectroscopy showed that the samples present a disordered paramagnetic behavior due to the big value of the half-width of line of the quadrupolar splitting. Vibrating sample magnetometry confirms the paramagnetic character. The XRD results indicate that the material is nanostructured, due that the crystallite sizes are of the order of 10 nm for Cu 0.94 Fe 0.06 O and 40 nm for Cu 0.85 Fe 0.15 O.

Preparation and characterization of polyol assisted ultrafine Cu–Ni–Mg–Ca mixed ferrite via co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Boobalan, T. [Park College of Engineering and Technology, Coimbatore (India); Pavithradevi, S. [Department of Physics, Government College of Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: nsuri22@gmail.com [Department of Physics, PSG Polytechnic College, Coimbatore (India); Manivel Raja, M. [Defence Metallurgical Research Laboratory, Ministry of Defence, Govt. of India, Hyderabad (India); Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Dr. NGP Institute of Technology, Coimbatore (India)

2017-04-15

Nanocrystalline spinel ferrite of composition Cu{sub 0.2}Ni{sub 0.2}Mg{sub 0.2}Ca{sub 0.4}Fe{sub 2}O{sub 4} is synthesized by wet hydroxyl co-precipitation method in ethylene glycol as chelating agent and sodium hydroxide as precipitator at pH 8. Ethylene glycol is utilized as the medium which serves as the dissolvable and in addition a complexing specialist. The synthesized particles are annealed at various temperatures. Thermogravimetric investigation affirms that at 280 °C ethylene glycol is dissipated totally and stable phase arrangement happens over 680 °C. FTIR spectra of as synthesized and annealed at 1050 °C recorded between 400 cm{sup −1} and 4000 cm{sup −1}. Structural characterizations of all the samples are carried out by X-ray diffraction (XRD) technique. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) affirm that the particles are spherical and cubic shape with the crystallite size of 12 nm to 32 nm. Magnetic measurements are performed utilizing vibrating sample magnetometer at room temperature. - Highlights: • Polyol improves purity of the spinel ferrite. • TG curves confirm the single phase ferrite is obtained above 680 °C. • Super paramagnetic behavior is seen at lower annealing temperature. • Soft ferromagnetic behavior is obtained at 1050 °C.

Optimizing and modeling of effective parameters on the structural and magnetic properties of Fe{sub 3}O{sub 4} nanoparticles synthesized by coprecipitation technique using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Ghazanfari, Mohammad Reza [Department of Materials Science and Engineering, Ferdowsi University of Mashhad, 9177948974 Mashhad (Iran, Islamic Republic of); Kashefi, Mehrdad, E-mail: m-kashefi@um.ac.ir [Department of Materials Science and Engineering, Ferdowsi University of Mashhad, 9177948974 Mashhad (Iran, Islamic Republic of); Jaafari, Mahmoud Reza [Biotechnology Research Center, Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

2016-07-01

In present work, the Fe{sub 3}O{sub 4} magnetic nanoparticles were successfully synthesized by coprecipitation method. In order to study the effects of influential factors on the structural and magnetic properties of particles, the experimental runs were designed using response surface methodology (RSM) based on central composite design (CCD), while the reaction temperature, Fe{sup 2+}/Fe{sup 3+} cation ratio, and pH of reaction were defined as effective factors on the two responses include the amounts of crystallinity degree and saturation magnetization (M{sub s}). The investigation of structural, magnetic, and microstructural properties of particles were carried out by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. As a result, the predictive quadratic models were fitted on the both responses while the R{sup 2} values were more than 0.97 for both models. The highest amounts of both responses (crystallinity degree: 88.07% and M{sub s}: 65.801 emu/g) are presented when the reaction temperature, cation ratio, and pH amounts are equal to 90 °C, 0.60, and 10.5, respectively. Finally, the TEM results show the particles with size of about 10 nm and narrow size distribution. - Highlights: • The Fe{sub 3}O{sub 4} nanoparticles were successfully synthesized by coprecipitation method. • By RSM technique, the predictive models were presented for crystallinity degree. • By RSM technique, the predictive models were presented for amounts of M{sub s}. • Temperature, pH and their interactions had most effectiveness on the amounts of M{sub s}. • Temperature, cation ratio and their interactions had most effectiveness on the crystallinity degree.

Influence of Yb{sup 3+} on the structural, dielectric and magnetic properties of Mg{sub 0.7}Co{sub 0.3}Fe{sub 2}O{sub 4} nanocrystallites synthesized via co-precipitation route

Energy Technology Data Exchange (ETDEWEB)

Ejaz, Muhammad [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Mahmood, Azhar [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Hussain, Altaf [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Sultan, Amber [Quaid-e-Azam Medical College, Bahawalpur 63100 (Pakistan); Mahmood, Asif [College of Engineering, Department of Chemical Engineering, King Saud University, Riyadh (Saudi Arabia); Chughtai, Adeel Hussain; Ashiq, Muhammad Naeem [Institute of Chemical Sciences, Bahauddin Zakaryia University, Multan 60800 (Pakistan); Warsi, Muhammad Farooq, E-mail: farooq.warsi@iub.edu.pk [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) center, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia)

2016-04-15

A series of nanostructured ferrites having chemical composition Mg{sub 0.7}Co{sub 0.3}Yb{sub x}Fe{sub 2−x}O{sub 4} (x=0.0–0.08) was prepared by the chemical co-precipitation route. The synthesized samples were characterized by X-ray diffraction (XRD), Thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), vibrating sample magnetometer (VSM) and impedance analyzer. The analysis of XRD patterns confirmed the spinel structure and the crystallite size calculated by Scherer's formula was found in the range of 18–43 nm. The crystallite size was small enough to obtain considerable signal to noise ratio in the recording media. The lattice constant was increased from 8.362 Ǻ to 8.383 Ǻ as the Yb contents were increased in the magnesium-cobalt ferrites. The TGA and DTA were carried out for prepared sample to investigate the thermal decomposition process. Magnetization results obtained from VSM measurements elucidate that the substitution of rare earth ytterbium decreased the saturation magnetization and retentivity. The dielectric properties of the samples were studied at room temperature in the frequency range of 1 MHz to 3 GHz and the samples exhibited the dispersion in high frequency region. The dielectric constant (ε) and dielectric loss (tan δ) were decreased with the increased frequency and ytterbium doping. The dielectric parameters were explained on the basis of space charge distribution. The dielectric and magnetic parameters suggested that these nano-materials are potential candidates for switching and recording media applications. - Graphical abstract: Mg{sub 0.7}Co{sub 0.3}Yb{sub x}Fe{sub 2−x}O{sub 4} nanostructured spinel ferrites were prepared by chemical co-precipitation technique. The crystallite size was found in the range 18–43 nm. The substitutions of rare earth ytterbium decrease the saturation magnetization and retentivity. The dielectric parameters were explained on the basis of space charge distribution. The

Structural and magnetic properties Co{sub 3}O{sub 4} obtained by the coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Junior, M.E.; Junior, F.A.; Hernandez, E.P.; Barbosa, F.C.G.; Paulo, V.I.M.; Junior, J.N.A.; Almeida, J.C. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

2016-07-01

Full text: The study shows a structural and magnetic properties of cobalt oxide Co3O4 doped with Cr as a function of the parameters adopted during the synthesis by chemical co-precipitation were flowing neutralizing NaOH and calcination temperature to 800 °C and 1000 °C. First, a series of samples of this oxide in which the flow was changed neutralization of the NaOH solution was generated. Thermal treatments were carried out at 800 °C and 1000 °C in anticipation of changing voltages on the network, average crystal size, etc. XRD observed in this case that the major phase and Co3O4 was found that the change of flow, the average crystallite size of network parameters and changes suffered distorted. In magnetic measurements MxT for samples to 800 °C and 1000 °C we observed behavioral evidence of a ferri / ferromagnetic-paramagnetic transition. On the other hand, the Curie-Weiss parameter was found negative for all samples associated with the major phase Co3O4 antiferromagnetic. Thus, we could correlate these phenomena the possible presence of phase clusters / nanoclusters amorphous ferri / ferromagnetic with CoCr2O4 / CrO2 generated with the incorporation of Cr under different NaOH flows. These coupling steps leading to the observed behavior. Have the MXH measures to 1000 °C in 50K presented a characteristic hysteresis loop system ferri / ferromagnetic well pronounced and could associate this, beyond the coupling phase, the fact that higher temperatures increase the grain size decreasing the surface anisotropy and favoring phases ferri / ferromagnetic. We are convinced that the results of our research is an important contribution to the field. (author)

Preparation of nano-porous LiNi0.5Mn1.5O4 with high electrochemical performances by a co-precipitation method for 5 V lithium-ion batteries

Science.gov (United States)

Cui, Xiaoling; Li, Hongliang; Li, Shiyou

2017-10-01

Porous LiNi0.5Mn1.5O4 is prepared by co-precipitation method. The results of scanning electron microscopy show that the sample has a nano-porous structure. Charge-discharge tests show that the synthesized product exhibits excellent electrochemical performance with a high initial discharge capacity of 129.1 mAh g-1 at 0.5 C and a preferably capacity retention of 96.5% after 200 cycles. The superior performance of the synthesized product is attributed to its nano-porous structure. The nanoparticle reduces the path of Li+ diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge-discharge.

Synthesis of well-dispersed magnetic CoFe2O4 nanoparticles in cellulose aerogels via a facile oxidative co-precipitation method.

Science.gov (United States)

Wan, Caichao; Li, Jian

2015-12-10

With the increasing emphasis on green chemistry, it is becoming more important to develop environmentally friendly matrix materials for the synthesis of nanocomposites. Cellulose aerogels with hierarchical micro/nano-scale three-dimensional network beneficial to control and guide the growth of nanoparticles, are suitable as a class of ideal green nanoparticles hosts to fabricate multifunctional nanocomposites. Herein, a facile oxidative co-precipitation method was carried out to disperse CoFe2O4 nanoparticles in the cellulose aerogels matrixes, and the cellulose aerogels were prepared from the native wheat straw based on a green NaOH/polyethylene glycol solution. The mean diameter of the well-dispersed CoFe2O4 nanoparticles in the hybrid aerogels is 98.5 nm. Besides, the hybrid aerogels exhibit strong magnetic responsiveness, which could be flexibly actuated by a small magnet. And this feature also makes this class of magnetic aerogels possibly useful as recyclable adsorbents and some magnetic devices. Meanwhile, the mild green preparation method could also be extended to fabricate other miscellaneous cellulose-based nanocomposites. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of solution concentration and capping agents on the properties of potassium titanyl phosphate noparticles synthesized using a co-precipitation method

Science.gov (United States)

Gharibshahian, E.; Jafar Tafershi, M.; Fazli, M.

2018-05-01

In this study, KTiOPO4 (KTP) nanoparticles were synthesized using a co-precipitation method. The effects of the solution concentration (M) and capping agents, such as PVA, oxalic acid, glycine, triethanolamine, and L-alanine, on the structural, microstructural, and optical properties of the products were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Decreasing the solution concentration decreased the crystallite size from 53.07 nm (for M = 2) to 39.42 nm (for M = 0.5). After applying different capping agents to the sample at the optimum concentration (M = 0.5), the crystallite size decreased again and grains as small as 10.61 nm were obtained. XRD and FTIR analyses indicated the formation of KTP nanoparticles with an orthorhombic structure in all of the samples. The optical band gap increased as the crystallite size decreased. Different morphological patterns such as spherical, needle shaped, polyhedron, and tablet forms were observed in the nanoparticles, which were correlated with the effects of the capping agents employed.

Structural, magnetic and optical characterization of Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} nano particles prepared by co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Kannan, Y.B., E-mail: ybkans@gmail.com [Department of Physics, Arumugam Pillai Seethai Ammal College, Tiruppattur 630211 (India); Saravanan, R. [Research Centre & PG Department of Physics, The Madura College, Madurai 625011 (India); Srinivasan, N. [Research Centre & PG Department of Physics, Thiagarajar College, Madurai 625009 (India); Praveena, K. [School of Physics, Univeristy of Hyderabad, Hyderabad 500046 (India); Sadhana, K. [Material Research Center, Indian Institute of Science, Bangalore 560012 (India)

2016-12-01

Bond strength values, between tetrahedral sites and octahedral sites atoms in the unit cell, are evaluated using maximum entropy method (MEM) for the Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} nano ferrite particles, prepared by co-precipitation method and sintered at 900 °C. The spinel structure is confirmed from the XRD analysis done using the Rietveld method. Substitution of zinc ion causes increase in lattice parameter value. Thermal behavior, morphology, magnetic properties and optical band gap energy values of the sample are determined by using thermogravimetric analysis and differential thermal analysis, scanning electron microscope, vibrating sample magnetometer and UV–VIS–NIR techniques respectively. Low value of saturation magnetization is attributed to the disorder in cation distribution.

A pre-concentration procedure using coprecipitation for determination of lead and iron in several samples using flame atomic absorption spectrometry

International Nuclear Information System (INIS)

Saracoglu, S.; Soylak, M.; Peker, D.S. Kacar; Elci, L.; Santos, W.N.L. dos; Lemos, V.A.; Ferreira, S.L.C.

2006-01-01

The present paper proposes a pre-concentration procedure for determination of lead and iron in several samples by flame atomic absorption spectrometry. In it, lead(II) and iron(III) ions are coprecipitated using the violuric acid-copper(II) system as collector. Afterwards, the precipitate is dissolved with 1 M HNO 3 solution and the metal ions are determined. The optimization step was performed using factorial design involving the variables: pH, violuric acid mass (VA) and copper concentration (Cu). Using the optimized experimental conditions, the proposed procedure allows the determination these metals with detection limits of 0.18 μg L -1 for iron and 0.16 μg L -1 for lead. The effects of foreign ions on the pre-concentration procedure were also evaluated and the results demonstrated that this method could be applied for determination of iron and lead in several real samples. The proposed method was successfully applied to the analysis of seawater, urine, mineral water, soil and physiological solution samples. The concentrations of lead and iron achieved in these samples agree well with others data reported in the literature

Enhanced electrochemical performance of nano-sized LiFePO4/C synthesized by an ultrasonic-assisted co-precipitation method

International Nuclear Information System (INIS)

Liu Youyong; Cao Chuanbao

2010-01-01

A simple and effective method, the ultrasonic-assisted co-precipitation method, was employed to synthesize nano-sized LiFePO 4 /C. A glucose solution was used as the carbon source to produce in situ carbon to improve the conductivity of LiFePO 4 . Ultrasonic irradiation was adopted to control the size and homogenize the LiFePO 4 /C particles. The sample was characterized by X-ray powder diffraction, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). FE-SEM and TEM show that the as-prepared sample has a reduced particle size with a uniform size distribution, which is around 50 nm. A uniform amorphous carbon layer with a thickness of about 4-6 nm on the particle surface was observed, as shown in the HRTEM image. The electrochemical performance was demonstrated by the charge-discharge test and electrochemical impedance spectra measurements. The results indicate that the nano-sized LiFePO 4 /C presents enhanced discharge capacities (159, 147 and 135 mAh g -1 at 0.1, 0.5 and 2 C-rate, respectively) and stable cycling performance. This study offers a simple method to design and synthesis nano-sized cathode materials for lithium-ion batteries.

Preparation of Fe3O4/Bentonite Nanocomposite from Natural Iron Sand by Co-precipitation Method for Adsorbents Materials

Science.gov (United States)

Sebayang, Perdamean; Kurniawan, Candra; Aryanto, Didik; Arief Setiadi, Eko; Tamba, Konni; Djuhana; Sudiro, Toto

2018-03-01

An adsorption method is one of the effective ways to filter the heavy metals wastes in aqueous system. In this paper, the Fe3O4/bentonite nanocomposites were successfully prepared from natural iron sand by co-precipitation method. The chemical process was carried out by dissolving and hot stirring the milled iron sand and bentonite in acid solution and precipitating it by NH4OH. The sediment was then washed using distilled water to neutralize pH and dried at 100 °C for 5 hours to produce Fe3O4/bentonite powders. The samples were characterized by XRD, FTIR, BET, TEM, VSM and AAS. All samples were composed by Fe3O4 single phase with a spinnel structure and lattice parameter of 8.373 Å. The transmittance peak of FTIR curve proved that the Fe3O4 particles and bentonite had a molecular bonding. The addition of bentonite to Fe3O4 nanoparticles generally reduced the magnetic properties of Fe3O4/bentonite nanocomposites. The optimum condition of 30 wt% bentonite resulted 105.9 m2/g in surface area, 14 nm in an average particle size and 3.2 nm in pore size. It can be used as Cu and Pb adsorbent materials.

Research on a pellet co-precipitation micro-filtration process for the treatment of liquid waste containing strontium

International Nuclear Information System (INIS)

Xin Luo; North China Institute of Science and Technology, Beijing; Guanghui Zhang; Xue Wang; Ping Gu

2013-01-01

The chemical precipitation method for radioactive wastewater treatment has the advantages of being simple and cost-effective. However, difficulties with the solid–liquid separation and sludge concentration restrict the application of this method. In this paper, a pellet co-precipitation micro-filtration (PCM) process was studied for treating strontium-containing wastewater on a laboratory scale. The seed was prepared by CaCO 3 powders. Sr 2+ and CO 3 2- were constantly crystallised on the seed surface, with Na 2 CO 3 as the precipitating agent in the pellet reactor. The following membrane separator with the addition of FeCl 3 enhanced the treatment effect. The average strontium concentrations in the raw water and in the effluent were 12.0 and 0.0220 mg/L, respectively. The strontium decontamination factor (DF) increased with the operation time, with an average value of 577. The precipitate particles formed gradually grew larger, with good sedimentation properties. When the experiment was complete, the formed precipitate was separated easily from the liquid phase and directly discharged. The concentration factor (CF) was 1,958. In the PCM process, crystallisation was the main mechanism for strontium removal, with the influent strontium level playing an important role. Membrane pore blockage and cake layer formation could help to further intercept the strontium crystallites. Furthermore, ferric chloride coagulation in the membrane separator also contributed to strontium removal. The PCM process has potential for wider application in the removal of strontium from wastewater. (author)

Removal of arsenic from synthetic acid mine drainage by electrochemical pH adjustment and coprecipitation with iron hydroxide.

Science.gov (United States)

Wang, Jenny Weijun; Bejan, Dorin; Bunce, Nigel J

2003-10-01

Acid mine drainage (AMD), which is caused by the biological oxidation of sulfidic materials, frequently contains arsenic in the form of arsenite, As(III), and/or arsenate, As(V), along with much higher concentrations of dissolved iron. The present work is directed toward the removal of arsenic from synthetic AMD by raising the pH of the solution by electrochemical reduction of H+ to elemental hydrogen and coprecipitation of arsenic with iron(III) hydroxide, following aeration of the catholyte. Electrolysis was carried out at constant current using two-compartment cells separated with a cation exchange membrane. Four different AMD model systems were studied: Fe(III)/As(V), Fe(III)/As(III), Fe(II)/As(V), and Fe(II)/As(III) with the initial concentrations for Fe(III) 260 mg/L, Fe(II) 300 mg/L, As(V), and As(III) 8 mg/L. Essentially quantitative removal of arsenic and iron was achieved in all four systems, and the results were independent of whether the pH was adjusted electrochemically or by the addition of NaOH. Current efficiencies were approximately 85% when the pH of the effluent was 4-7. Residual concentrations of arsenic were close to the drinking water standard proposed by the World Health Organization (10 microg/L), far below the mine waste effluent standard (500 microg/L).

Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc iron layered double hydroxides by one-step coprecipitation route

Science.gov (United States)

Zhang, Hui; Wen, Xing; Wang, Yingxia

2007-05-01

Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Mössbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO 42--containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO 42--containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn 0.435·Fe II0.094·Fe III0.470·(OH) 2]·(SO 42-) 0.235·1.0H 2O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO 42--containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS.

Synthesis and Characterization of Perovskite Type La1-xSrxAlO3-sigma(0<=X<=0.3) by Co-Precipitation Method

International Nuclear Information System (INIS)

Mahmoud, O.; Abderezak, G.

2015-01-01

This work shows the electrochemical activity of O/sub 2/ evolution reaction in KOH of perovskite type- aluminate oxide (La/sub 1-x/Sr/sub x/AlO/sub 3-sigma/ with x = 0, 0.1, 0.2, 0.3). La/sub 1-x/Sr/sub x/AlO/sub 3-sigma/ (0co-precipitation method. The white precipitates were then washed in distilled water by centrifugation, and calcined at 1000/degree C/ for 6h, the pure phase was characterized by X-ray diffraction (XRD), thermal gravimetric analysis and differential thermal (TG/DSC), Fourier transform infrared spectroscopy (FTIR), specific surface area (BET). The MEB micrographs are shown of the spherical grains and uniform agglomeration of the grains. The oxide powders were used as the films to form a support on Ni/oxides. Oxygen evolution on each oxide catalyst was signed in the cyclic voltammetry with +- 15 V range and the electrochemical impedance in the equivalent of 100 kHz. The results point out the electrode activity and stability of the x = 0.3 composition. (author)

A novel pharmaceutical excipient: Coprecipitation of calcium and magnesium silicate using brine-seawater in date palm cellulose as an absorbing host

Directory of Open Access Journals (Sweden)

Mohammad Hamaidi

2017-09-01

Full Text Available This research aims to produce a cost competitive and innovative pharmaceutical additive with multi-purpose use in the pharmaceutical industry from Saudi Arabia natural resources and bio-wastes. The waste substance, brine, and the naturally occurring compound, sodium silica, were reacted together to produce water insoluble calcium and magnesium silicate salts [WISS]. The purity index WISS was compared with synthetic Mg silicae.The produced particle size was 1.994 µm. Date palm cellulose [DPC] with a high purity index [0.99] was produced from the biomass waste of date palm tree. DPC was used as a host for coprecipitation of synthetic calcium magnesium silicate within its intimate structures. The interaction between the cellulose polymer and silicates is physical in nature. WISS-DPC was more flowable than DPC. In SEM, the particles of DPC were fibrous and irregular in shape, while WISS-DPC showed more regular shape than DPC. Tablets prepared from WISS-DPC were harder and had lower disintegration time at all compression forces compared to those made from DPC. The produced excipient had excellent compaction and disintegration properties and could be used as a superdisintegrant and tablet binder in pharmaceutical industries.

Simple simultaneous determination of soluble and insoluble trace metal components in sea salts by a combined coprecipitation/X-ray fluorescence method

International Nuclear Information System (INIS)

Iwatsuki, Masaaki; Ali, Muhammad; Kyotani, Tomohiro; Fukasawa, Tsutomu

1996-01-01

An X-ray fluorescence method using the coprecipitation-preconcentration technique has been developed for simple determination of both acid-soluble and insoluble trace metal components, such as manganese, iron, nickel, copper and zinc in sea salts. A salt sample is dissolved in a nitric acid solution, and the residue is filtered off onto a membrane filter. After the pH is adjusted to 7-8, the filtrate is boiled, followed by addition of aluminum carrier, oxine and thionalide solutions. The solution is re-adjusted to pH 9, and kept at 80-85degC for 60 min. The precipitates are filtered off onto another membrane filter. X-Ray fluorescence intensities from two filters loaded with the residue and precipitates are measured and the concentrations of the elements are determined simultaneously using the calibration curves. Detection limits were 0.01 μg g -1 for manganese and copper, 0.04 μg g -1 for nickel and zinc, and 0.05 μg g -1 for iron, regardless of the soluble and the insoluble components. The present method was successfully applied to the analysis of sea salt samples. (author)

Synthesized of PEG-6000 coated MgFe2O4 nanoparticles based on natural iron sand by co-precipitation method

Science.gov (United States)

Setiadi, E. A.; Simbolon, S.; Saputra, A. S. P.; Marlianto, E.; Djuhana; Kurniawan, C.; Yunus, M.; Sebayang, P.

2018-02-01

The polymer coated Magnesium Ferrite nanoparticles (MgFe2O4) based on natural iron sand, Mg(CH3COO)2.4H2O, and PEG-6000 have been successfully prepared by co-precipitation method. The mass variation of PEG-6000 content was from 0 to 12 gram. It was prepared at synthesize temperature of 70°C. The PEG coating reduced the effect of agglomeration, so the coercivity value can be closed to soft magnets. The nanoparticle of synthesized has MgFe2O4 single phase and cubic spinel structure. The bonding of MgFe2O4 and PEG-6000 as a coating material was confirmed by FTIR curve. The MgFe2O4 density decreased with the increasing of PEG 6000 content. On the other hand, the coercivity value was slightly reduced as the addition of PEG-6000, with the lowest value was obtained on 8 gram PEG content. The optimum condition is obtained at addition of 8 gram PEG 6000 to MgFe2O4, with coercivity, saturation, and remanence are 198.41 Oe, 52.53 emu/g, and 8.51 emu/g, respectively. So that, the sample is widely used as absorbance material of heavy metal.

Determination of Ultra-Trace Amounts of Selenium(IV) by Flow Injection Hydride Generation Atomic Absorption Spectrometry with On-line Preconcentration by Co-precipitation with Lanthanium Hydroxide. Part II. On-line Addition of Coprecipating Agent

DEFF Research Database (Denmark)

Nielsen, Steffen; Sloth, Jens Jørgen; Hansen, Elo Harald

1996-01-01

-line and merged with an ammonium buffer solution of pH 9.1, which promotes precipitation and quantitative collection on the inner walls of an incorporated knotted Microline reactor. The Se(IV) preconcentrated by coprecipitation with the generated lanthanum hydroxide precipitate is subsequently eluted...... with hydrochloric acid, allowing an ensuing determination via hydride generation. At different sample flow rates, i.e., 4.8, 6.4 and 8.8 ml/min, enrichment factors of 30, 40 and 46, respectively, were obtained at a sampling frequency of 33 samples/h. The detection limit (3s) was 0.005 µg/l at a sample flow rate...

Synthesis and magnetic properties of (Eu–Ni) substituted Y-type hexaferrite by surfactant assisted co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Ali, Irshad, E-mail: irshadalibzu@gmail.com [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Islam, M.U. [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Sadiq, Imran [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Centre of Excellence in Solid State Physics, University of The Punjab, Lahore (Pakistan); Karamat, Nazia [Institute of Chemical Science, Bahauddin Zakariya University, Multan 60800 (Pakistan); Iftikhar, Aisha [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Khan, M. Azhar [Department of Physics, Islamia University of Bahawalpur, 63100 Pakistan (Pakistan); Shah, Afzal [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Athar, Muhammad [Institute of Chemical Science, Bahauddin Zakariya University, Multan 60800 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) Center, College of Engineering, King Saud University (Saudi Arabia); Ashiq, Muhammad Naeem, E-mail: naeemashiqqau@yahoo.com [Institute of Chemical Science, Bahauddin Zakariya University, Multan 60800 (Pakistan)

2015-07-01

A series of (Eu–Ni) substituted Y-type hexaferrite with composition Sr{sub 2}Co{sub (2−x)}Ni{sub x}Eu{sub y}Fe{sub (12−y)}O{sub 22} (x=0.0–1, Y=0.0–0.1) were prepared by the surfactant assisted co-precipitation method. The present samples were sintered at 1050 °C for 8 h. The shape of the particles is plate-like which is very advantageous for various applications and the grain size varies from 73 to 269 nm. The values of saturation magnetization (M{sub s}), remanent magnetization (M{sub r}) and magnetic moment (n{sub B}) were found to decrease which are attributed to the weakening of super exchange interactions. The values of in-plane Squareness ratios (M{sub r}/M{sub s}) ranging from 0.41 to 0.65 whereas in case of out of plane measurement it varies from 0.30 to 0.62.The investigated samples can be used in perpendicular recording media (PRM) due to high value of coercivity 2300 Oe which is analogous to the those of M-type and W-type hard magnetic. - Highlights: • The present samples sintered at 1050 °C for 8 h. • The grain size varies from 73 to 269 nm. • The magnetic moment varies from 15.27 to 6.07. • The shape of grains is plate like for microwave devices. • The present samples can be used in PRM due to high value of coercivity i.e. 2300 Oe.

Characterization of FeCo particles synthesized via co-precipitation, particle growth using flux treatment and reduction in hydrogen gas

Energy Technology Data Exchange (ETDEWEB)

Kishimoto, Mikio, E-mail: kishimoto.mikio.gb@u.tsukuba.ac.jp; Latiff, Hawa; Kita, Eiji; Yanagihara, Hideto

2017-06-15

The possibility of high coercive force in FeCo particles was examined focusing on distortion introduced in the particles. The particles were synthesized via co-precipitation of Fe and Co ions, heat-treatment in potassium bromide flux for particle growth, and reduction using hydrogen gas. The particle shape was spherical or a slightly elongated with the size of approximately 30–200 nm, and the composition with approximately Fe{sub 60}Co{sub 40} was determined from the D-spacing of (110) peak. The coercive force of approximately 90 kA/m was obtained in particles with the saturation magnetization of approximately 150 Am{sup 2}/kg. The coercive force was higher than those in reported FeCo particles with same level of saturation magnetization. As one of the reason of high coercive force, we expected the possibility of occurrence of magnetic anisotropy based on the anisotropic distortion generated between FeCo alloy and surface oxides in a slightly elongated particles. - Highlights: • FeCo particles synthesized via Fe/Co:1/1, flux treated, and reduction. • Spherical or slightly elongated shape with size of approximately 30–200 nm. • Composition with Fe{sub 60}Co{sub 40} determined from D-spacing of (110) peak. • Coercive force of 90 kA/m and saturation magnetization of 150 Am{sup 2}/kg.

Novel Synthesis of Ultra-Small Dextran Coated Maghemite Nanoparticles for MRI and CT Contrast Agents via a Low Temperature Co-Precipitation Reaction.

Science.gov (United States)

Rabias, Ioannis; Fardis, Michael; Kehagias, Thomas; Kletsas, Dimitris; Pratsinis, Harris; Tsitrouli, Danai; Maris, Thomas G; Papavassiliou, George

2015-01-01

Ultra-small dextran coated maghemite nanoparticles are synthesized via a low temperature modified co-precipitation method. A monoethylene glycol/water solution of 1:1 molar ratios and a fixed apparatus is used at a constant temperature of 5-10 degrees C. The growth of nanoparticles is prohibited due to low temperature synthesis and differs from usual thermal decomposition methods via Ostwald ripening. Strict temperature control and reaction timing of less than 20 minutes are essential to maintain narrow distribution in particle size. These nanoparticles are water-dispersible and biocompatible by capping with polyethylene glycol ligands. The aqueous suspensions are tested for cytotoxic activity on normal human skin fibroblasts. There is no reduction of the cells' viability at any concentration tested, the highest being 1% v/v of the suspension in culture medium, corresponding to the highest concentrations to be administered in vivo. Initial comparison with a T1 MRI contrast agent in sale shows that maghemite nanoparticles exhibit high r1 and r2 relaxivities in MRI tomography and strong contrast in computed tomography, demonstrating that these nanoparticles can be efficient T1, T2 and CT contrast agents.

Synthesis of composite nanoparticles using co-precipitation of a magnetic iron-oxide shell onto core nanoparticles

International Nuclear Information System (INIS)

Primc, Darinka; Belec, Blaž; Makovec, Darko

2016-01-01

Composite nanoparticles can be synthesized by coating a shell made of one material onto core nanoparticles made of another material. Here we report on a novel method for coating a magnetic iron oxide onto the surface of core nanoparticles in an aqueous suspension. The method is based on the heterogeneous nucleation of an initial product of Fe"3"+/Fe"2"+ co-precipitation on the core nanoparticles. The close control of the supersaturation of the precipitating species required for an exclusively heterogeneous nucleation and the growth of the shell were achieved by immobilizing the reactive Fe"3"+ ions in a nitrate complex with urea ([Fe((CO(NH_2)_2)_6](NO_3)_3) and by using solid Mg(OH)_2 as the precipitating reagent. The slow thermal decomposition of the complex at 60 °C homogeneously releases the reactive Fe"3"+ ions into the suspension of the core nanoparticles. The key stage of the process is the thermal hydrolysis of the released Fe"3"+ ions prior to the addition of Mg(OH)_2. The thermal hydrolysis results in the formation of γ-FeOOH, exclusively at the surfaces of the core nanoparticles. After the addition of the solid hydroxide Mg(OH)_2, the pH increases and at pH ~ 5.7 the Fe"2"+ precipitates and reacts with the γ-FeOOH to form magnetic iron oxide with a spinel structure (spinel ferrite) at the surfaces of the core nanoparticles. The proposed low-temperature method for the synthesis of composite nanoparticles is capable of forming well-defined interfaces between the two components, important for the coupling of the different properties. The procedure is environmentally friendly, inexpensive, and appropriate for scaling up to mass production.Graphical abstract

Detailed crystallization study of co-precipitated Y{sub 1.47} Gd{sub 1.53} Fe{sub 5} O{sub 12} and relevant magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Serra, Rogerio Arving [Instituto de Criminalistica Carlos Eboli (ICCE), Rio de Janeiro, RJ (Brazil); Ogasawara, Tsuneharu; Ogasawara, Angelica Soares [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Dept. de Engenharia Metalurgica e de Materiais]. E-mail: ogasawat@metalmat.ufrj.br

2007-07-01

The crystallization process of co-precipitated Y{sub 1.5}Gd{sub 1.5}Fe{sub 5}O{sub 12} powder heated up to 1000 deg C at rate of 5 deg C min{sup -1} was investigated. Above 810 deg C crystalline Y{sub 1.47}Gd{sub 1.53}Fe{sub 5}O{sub 12} was obtained with a lattice parameter of 12.41 A and a theoretical density of 5.84 g cm{sup -3}. Dry pressed rings were sintered at 1270 and 1320 deg C, increasing the grain-size from 3.1 to 6.5 {mu}m, the theoretical density by 87.6 to 95.3% and decreasing H{sub c} from 2.9725 to 1.4005 Oe. Additionally, Hc increased when the frequency of the hysteresis graph varied from 60 Hz to 10 kHz, the curie temperature was 282.4 deg C and Ms equalled 9.25 emu g{sup -1} (0.17 kG) agreeing well with the B{sub s}-value of the hysteresis graph and literature values. (author)

Synthesis, microstructure and EPR of CaMnO{sub 3} and Eu{sub x}Ca{sub 1-x}MnO{sub 3} manganite, obtained by coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Santiago T, M.; Hernandez C, L.; Legorreta G, F. [Universidad Autonoma del Estado de Hidalgo, AACTyM, Carretera Pachuca-Tulancingo Km 4.5, 42074 Pachuca, Hidalgo (Mexico); Montiel S, H. [UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Departamento de Tecnociencias, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Alvarez L, G. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, U. P. Adolfo Lopez Mateos, Edif. 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Flores G, M. A., E-mail: mar200878@hotmail.com [Universidad Politecnica de Pachuca, Laboratorio de Nanotecnologia y Bioelectromagnetismo Aplicado, Carretera Pachuca-Cd. Sahagun Km 20, Ex-Hacienda de Santa Barbara, 43830 Zempoala, Hidalgo (Mexico)

2011-07-01

The synthesis of CaMnO{sub 3} and Eu{sub x}Ca{sub 1-x}MnO{sub 3} obtained by coprecipitation method is showed. The synthesized samples were characterized by X-ray diffraction and scanning electronic microscopy, the powders showed orthorhombic structure and pnma space group. When it was doped with Europium, their morphology tendency was spherical. Measurements were carried out on electron paramagnetic resonance (EPR) with constant frequency = 9.4 GHz (band X) and dc magnetic field (H dc) 0-0.8 T, measurements were at 300 K and 77 K. EPR spectra showed significant differences between both samples, indicating that the substitution of divalent alkaline earth cations by trivalent rare earth ions, allowing the formation of a mixed valence state of manganese, Mn{sup 3+} and Mn{sup 4+}. A 77 K, the manganite of concentration x = 0.30 had a magnetic ordering, noted by the presence of hysteresis. (Author)

Co-precipitation synthesis and characterization of tin-doped α-Fe2O3 nanoparticles with enhanced photocatalytic activities

Science.gov (United States)

Mansour, Houda; Bargougui, Radhouane; Autret-Lambert, Cécile; Gadri, Abdellatif; Ammar, Salah

2018-03-01

In this study, Sn-doped hematite (α-Fe2O3) nanoparticles with various dopant concentrations ranging from 1 to 6 mol% were prepared successfully using a simple co-precipitation technique. The effects of Sn doping on the structural, morphological, optical, and magnetic properties were determined using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy, and a superconducting quantum interference device. XRD analysis showed that all of the samples had a typical hematite-type hexagonal structure of Fe2O3 without any additional peaks due to spurious phases. The cell parameters a and c decreased monotonically as the Sn content increased, thereby indicating that Sn ions were substituted into the α-Fe2O3 lattice. These results and the TEM analyses showed that the size of the nanoparticles decreased to 10 nm as the Sn doping concentration increased. UV-visible absorption measurements showed that the decrease in particle size was accompanied by a decrease in the band gap value from 2.07 eV for α-Fe2O3 to 1.87 eV with 6 mol% Sn doping. Furthermore, the magnetic properties demonstrated that all of the samples exhibited ferromagnetic behavior at room temperature. The photocatalytic activities of the samples were studied based on the degradation of methylene blue as a model compound, where the results showed that an appropriate amount of Sn dopant could greatly increase the amount of hydroxyl radicals generated by α-Fe2O3 nanoparticles, which were responsible for the obvious increase in the photocatalytic activity.

Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Nikumbh, A.K., E-mail: aknik@chem.unipune.ac.in; Pawar, R.A.; Nighot, D.V.; Gugale, G.S.; Sangale, M.D.; Khanvilkar, M.B.; Nagawade, A.V.

2014-04-15

Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRE{sub x}Fe{sub 2−x}O{sub 4} (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like M{sub S}, H{sub C} and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x≤0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe{sub 2}O{sub 4} exhibit the particle size 36.1 to 67.8 nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio M{sub R}/M{sub S} and magnetic moments may be due to dilution of the magnetic interaction.

Influence of Co{sup 2+} on the structural and magnetic properties of substituted magnetites obtained by the coprecipitation method

Energy Technology Data Exchange (ETDEWEB)

Velásquez, A. A., E-mail: avelas26@eafit.edu.edu.co [Universidad EAFIT, Grupo de Electromagnetismo Aplicado (Colombia); Urquijo, J. P. [Universidad de Antioquia, Grupo de Estado Sólido, Instituto de Física (Colombia)

2015-06-15

In this paper we report the effect of divalent cobalt on the structural and magnetic properties of substituted magnetites, Fe {sub 3−x}Co {sub x}O{sub 4}, with γ=Co {sup 2+}/Fe = 0, 5, 10, 15, 20 and 30 % wt, synthesized by the coprecipitation method. The samples were characterized by Atomic Absorption Spectroscopy, X-ray Diffraction, room temperature Mössbauer Spectroscopy and Vibrating Sample Magnetometry. The effect of Co {sup 2+} was found to depend strongly of the concentration employed in the synthesis process. For γ≤15 % the Co {sup 2+} promotes the formation of particles more crystalline and with higher saturation magnetization, remanence and coercivity than those obtained in absence of this cation. A sequential increasing of the lattice parameter is observed, as well as a reduction in the hyperfine magnetic field of the Fe {sup 2.5+}sub spectrum, while the hyperfine magnetic field of the Fe {sup 3+}sub spectrum keeps almost constant. For γ=20 % and 30 % the crystallinity of the samples decreases, particle size distribution effects are evidenced and the saturation magnetization decreases drastically. The results suggest that for low Co {sup 2+} contents the substitution of Fe {sup 3+}by Co {sup 2+} at octahedral sites of the inverse spinel system is the dominant effect, while for the highest concentrations used the substitution of Fe {sup 2+} by Co {sup 2+} and the increasing of the particle size distribution are the dominant effects.

Magnetic and structural properties of Cu{sub 0.85}Fe{sub 0.15}O system synthesized by co-precipitation

Energy Technology Data Exchange (ETDEWEB)

Colorado, H. D., E-mail: herdacom@gmail.com; Perez Alcazar, G. A. [Universidad del Valle, Departamento de Fisica (Colombia)

2011-11-15

Cu{sub 0.94}Fe{sub 0.06}O and Cu{sub 0.85}Fe{sub 0.15}O samples were synthesized by using the co-precipitation chemical method. Starting from aqueous solutions of copper nitrate, CuO (NO{sub 3}){sub 2} 3H{sub 2}O, iron nitrate, Fe (NO{sub 3}){sub 3} 9H{sub 2}O and sodium hydroxide as precipitating agent, NaOH. The precipitate of three samples for Cu{sub 0.94}Fe{sub 0.06}O and five for Cu{sub 0.85}Fe{sub 0.15}O of fine powder were calcined for 5 h at different temperatures. The obtained X rays diffraction patterns refined by the Rietveld method show the CuO characteristic pattern, showing that the Fe atoms enter to replace Cu atoms. Furthermore, it was obtained that the crystallite size decreases with calcination temperatures for Cu{sub 0.94}Fe{sub 0.06}O. The transmission Moessbauer spectroscopy showed that the samples present a disordered paramagnetic behavior due to the big value of the half-width of line of the quadrupolar splitting. Vibrating sample magnetometry confirms the paramagnetic character. The XRD results indicate that the material is nanostructured, due that the crystallite sizes are of the order of 10 nm for Cu{sub 0.94}Fe{sub 0.06}O and 40 nm for Cu{sub 0.85}Fe{sub 0.15}O.

Sintering study of NiO-YSZ composite obtained by coprecipitation route; Estudo de sinterabilidade do composito de NiO-YSZ obtido pela rota de coprecipitacao

Energy Technology Data Exchange (ETDEWEB)

Yoshito, W K; Resitivo, T A.G.; Ussui, V; Lazar, D R.R.; Paschoal, J O.A., [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

2009-07-01

NiO-YSZ composite is a widely used anode material for solid oxide fuel cell. The main purpose of the present work was the evaluation of the appropriate conditions of ceramic processing, by sintering behavior study of NiO-YSZ pressed powders, synthesized by hydroxide coprecipitation route. Using the empirical rate equation developed by Makipirtti-Meng, it was analyzed shrinkage rate in the temperature ranges of 900-1400 deg C as function of time. The powders were characterized by X-ray diffraction, scanning electron microscopy, gas adsorption, laser diffraction and helium picnometry. The microstructural characterization of the samples was evaluated by X-ray diffraction, scanning electron microscopy and relative density by the Archimedes method. It was found that activation energy value is 48,3 kJ.mol{sup -1} in the temperature range of 900-950 deg C and 604,83 kJ.mol{sup -1} for 1000-1200 deg C. These values correspond to the change that occurs in the microstructure during the heat treatment process. The sintering process was evaluated by the dilatometry date treatment. (author)

High solar-light photocatalytic activity of using Cu3Se2/rGO nanocomposites synthesized by a green co-precipitation method

Science.gov (United States)

Nouri, Morteza; Saray, Abdolali Moghaddam; Azimi, H. R.; Yousefi, Ramin

2017-11-01

Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu2Se3 with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu2Se3/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.

Nitrate conversion and supercritical fluid extraction of UO2-CeO2 solid solution prepared by an electrolytic reduction-coprecipitation method

International Nuclear Information System (INIS)

Zhu, L.Y.; Duan, W.H.; Wen, M.F.; Xu, J.M.; Zhu, Y.J.

2014-01-01

A low-waste technology for the reprocessing of spent nuclear fuel (SNF) has been developed recently, which involves the conversion of actinide and lanthanide oxides with liquid N 2 O 4 into their nitrates followed by supercritical fluid extraction of the nitrates. The possibility of the reprocessing of SNF from high-temperature gas-cooled reactors (HTGRs) with nitrate conversion and supercritical fluid extraction is a current area of research in China. Here, a UO 2 -CeO 2 solid solution was prepared as a surrogate for a UO 2 -PuO 2 solid solution, and the recovery of U and Ce from the UO 2 -CeO 2 solid solution with liquid N 2 O 4 and supercritical CO 2 containing tri-n-butyl phosphate (TBP) was investigated. The UO 2 -CeO 2 solid solution prepared by electrolytic reduction-coprecipitation method had square plate microstructures. The solid solution after heat treatment was completely converted into nitrates with liquid N 2 O 4 . The XRD pattern of the nitrates was similar to that of UO 2 (NO 3 ) 2 . 3H 2 O. After 120 min of online extraction at 25 MPa and 50 , 99.98% of the U and 98.74% of the Ce were recovered from the nitrates with supercritical CO 2 containing TBP. The results suggest a promising potential technology for the reprocessing of SNF from HTGRs. (orig.)

Photocatalytic properties of TiO{sub 2} prepared by coprecipitation and by hydrothermal synthesis and study of the effect of doping Gd{sup 3+}; Fotokatalyticke vlastnosti TiO{sub 2} pripraveneho koprecipitaciou a hydrotermalnou syntezou a studium vplyvu dopovania Gd{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Sipos, M [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia)

2012-04-25

In this paper we described a synthesis of TiO{sub 2} nanopowders by coprecipitation and by hydrothermal method. We examined the effect of sample preparation procedure, of annealing temperature and doping by Gd{sup 3+} ions on the photocatalytic properties of TiO{sub 2}. We did not observe a correlation between primary micro-crystallites largeness and their photocatalytic activity. Sulfation and samples doping by G{sup d}3{sup +} ions enhances their photodegradation properties. Effect of doping is significantly larger at hydrothermally prepared samples. (authors)

Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc-iron layered double hydroxides by one-step coprecipitation route

International Nuclear Information System (INIS)

Zhang Hui; Wen Xing; Wang Yingxia

2007-01-01

Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Moessbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO 4 2- -containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO 4 2- -containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn 0.435 .Fe II 0.094 .Fe III 0.470 .(OH) 2 ].(SO 4 2- ) 0.235 .1.0H 2 O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO 4 2- -containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS. - Graphical abstract: For Zn 2+ -Fe 2+ -Fe 3+ GR2(SO 4 2- ), according to the derived chemical formula, Fe 3+ was arranged at 1a (0, 0, 0) position, while all Zn 2+ were in 2d position with the occupancy 0.645, and the left part of 2d positions were taken by Fe 2+ /Fe 3+

Fate of nickel ion in (II-III hydroxysulphate green rust synthesized by precipitation and coprecipitation Adsorção de íon níquel em (II-III green rust hidroxisulfato sintetizado por precipitação e co-precipitação

Directory of Open Access Journals (Sweden)

Lucia Helena Garófalo Chaves

2007-08-01

Full Text Available In order to investigate the efficiency of sulfate green rust (GR2 to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II and Fe(III sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II, Fe(II and Fe(III sulfate salts, i.e., in the presence of Ni. In another sample, Ni(II sulfate salt was added to pre-formed GR2. After an initial X-ray diffraction (XRD characterization all samples were exposed to ambient air in order to understand the role of Ni in the transformation of the GR2 samples. XRD was repeated after 45 days. The results showed that Nious GR2 prepared by coprecipitation is isomorphous to Ni-free GR2, i.e. Ni is incorporated into the crystalline structure. Fe(II was not replaced by Ni(II in the crystalline structure of GR2 formed prior to exposure to solution-phase Ni. This suggests Ni was adsorbed to the GR2 surface. Sulfate green rust is more efficient in removing Ni from the environment by coprecipitation.Com objetivo de investigar a eficiência do "sulfate green rust" (GR2 na remoção de Ni da solução, amostras de GR2 foram sintetizadas em laboratório sob condições controladas. Algumas amostras de GR2 foram sintetizadas pela precipitação de sais de Fe(II e de Fe(III; outras amostras, pela co-precipitação de sais de Ni(II, Fe(II e de Fe(III; e em outras amostras, o sulfato de Ni(II foi adicionado às amostras GR2 pré-formadas. Após caracterização inicial, por difração de raios X, todas as amostras ficaram expostas ao ar atmosférico durante 45 dias, a fim de se avaliar o papel do Ni na transformação delas. Após esse período, a difração de raios X das amostras foi repetida. Os resultados mostraram que Ni-GR2 preparado por co-precipitação é isomórfico do GR2, estando o íon Ni na estrutura cristalina deste. Fe(II não foi substituído por Ni(II na estrutura cristalina de GR2 formado a priori

Synthesis of mesoporous TiO(2-x)N(x) spheres by template free homogeneous co-precipitation method and their photo-catalytic activity under visible light illumination.

Science.gov (United States)

Parida, K M; Naik, Brundabana

2009-05-01

The article presents preparation, characterization and catalytic activity evaluation of an efficient nitrogen doped mesoporous titania sphere photo-catalyst for degradation of methylene blue (MB) and methyl orange (MO) under visible light illumination. Nitrogen doped titania was prepared by soft chemical route i.e. template free, slow and controlled homogeneous co-precipitation from titanium oxysulfate sulfuric acid complex hydrate, urea, ethanol and water. The molar composition of TiOSO(4) to urea was varied to prepare different atomic % nitrogen doped titania. Mesoporous anatase TiO(2-x)N(x) spheres with average crystallite size of 10 nm and formation of titanium oxynitride center were confirmed from HRTEM, XRD and XPS study. UV-vis DRS showed a strong absorption in the range of 400-500 nm which supports its use in visible spectrum of light. Nitrogen adsorption-desorption study supports the porous nature of the doped material. All the TiO(2-x)N(x) samples showed higher photo-catalytic activity than Degussa P(25) and undoped mesoporous titania. Sample containing around one atomic % nitrogen showed highest activity among the TiO(2-x)N(x) samples.

Structural and magnetic characterization of co-precipitated Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Srinivas, Ch., E-mail: srinivas.chintoju75@gmail.com [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Tirupanyam, B.V. [Department of Physics, Government College (Autonomous), Rajamahendravaram 533103 (India); Meena, S.S.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Babu, Ch. Seshu [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Ramakrishna, K.S. [Department of Physics, Srinivasa Institute of Engineering and Technology, Amalapuram 533222 (India); Potukuchi, D.M. [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University, Kakinada 533003 (India); Sastry, D.L., E-mail: dl_sastry@rediffmail.com [Department of Physics, Andhra University, Visakhapatnam 530003 (India)

2016-06-01

A series of Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni{sup 2+} ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core–shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe{sup 3+} ions and absence of Fe{sup 2+} ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core–shell interactions. - Highlights: • Thermodynamic solubility of Ni{sup 2+} in zinc ferrite influences the crystallite sizes. • At room temperature the ferrite systems exhibit superparamagnetism. • Core–shell model was exactly suited to explain magnetic behavior. • Core–shell interactions decrease with increase in Ni{sup 2+} ion concentration.

Microwave-Assisted Coprecipitation Synthesis of LaCoO3 Nanoparticles and Their Catalytic Activity for Syngas Production by Partial Oxidation of Methane

Directory of Open Access Journals (Sweden)

Consuelo Alvarez-Galvan

2018-04-01

Full Text Available LaCoO3 perovskite-type oxides were prepared by microwave-assisted coprecipitation route and investigated in the catalytic partial oxidation of methane (CPOM to syngas. This preparation method aims to achieve higher specific surface areas (ssa than soft-chemical methods commonly used in the preparation of engineered materials. In an attempt to accomplish the creation of mesostructured porous LaCoO3, an ionic template such as cetyl trimethyl ammonium bromide has been used as endotemplate in some samples. The influence of pH and the type of precipitating agent has been studied. The materials have been characterized at different levels: morphology has been studied by scanning electron microscopy, textural properties by nitrogen adsorption–desorption at −196°C, structural analysis by X-ray diffraction, surface composition by X-ray photoelectron spectroscopy, thermal stability by thermogravimetric analysis, and carbon formation in spent catalysts by Raman spectroscopy. Structure-activity correlations point out that the precipitating agent has a key role on the morphology and porosity of the resultant oxide, as well as on the average crystalline domain of lanthanum perovskite (catalyst precursor. Thus, the use of ammonium hydroxide as precipitant leads to materials with a higher surface area and a greater ssa of cobalt (per unit mass, improving their catalytic performance for the CPOM reaction. The best catalytic performance was found for the catalyst prepared using ammonium hydroxide as precipitant (pH 9 and without adding CTAB as endotemplate.

Study of structural phase transformation and hysteresis behavior of inverse-spinel α-ferrite nanoparticles synthesized by co-precipitation method

Science.gov (United States)

Dabagh, Shadab; Chaudhary, Kashif; Haider, Zuhaib; Ali, Jalil

2018-03-01

Substitution of cobalt (Co2+) ions in cobalt ferrite (CoFe2O4) with copper (Cu2+) and aluminum (Al3+) ions allows variations in their electric and magnetic properties which can be optimized for specific applications. In this article, synthesis of inverse-spinel Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nanoparticles by substituting Cu2+ and Al3+ ions in CoFe2O4 via co-precipitation method is reported. By controlling copper and aluminum (Cu-Al) substituent ratio, the magnetic moment and coercivity of synthesized cobalt ferrite nanoparticles is optimized. The role of substituents on the structure, particle size, morphology, and magnetic properties of nano-crystalline ferrite is investigated. The Co1-xCuxFe2-xAlxO4 (0.0 ≤ x≤ 0.8) nanoparticles with crystallite size in the range of 23.1-26.5 nm are observed, 26.5 nm for x = 0.0-23.1 nm for x = 0.8. The inverse-spinel structure of synthesized Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nano-particles is confirmed by characteristic vibrational bands at tetrahedral and octahedral sites using Fourier transform infrared spectroscopy. A decreases in coercive field and magnetic moment is observed as Cu-Al contents are increased (x = 0.0-0.8). The positive anisotropy of synthesized particles Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) is obtained in the range 1.96 × 105 J/m3 for x = 0.0 to 0.29 × 105 J/m3 for x = 0.8.

In situ co-precipitation preparation of a superparamagnetic graphene oxide/Fe3O4 nanocomposite as an adsorbent for wastewater purification: synthesis, characterization, kinetics, and isotherm studies.

Science.gov (United States)

Pu, Shengyan; Xue, Shengyang; Yang, Zeng; Hou, Yaqi; Zhu, Rongxin; Chu, Wei

2018-04-13

A superparamagnetic graphene oxide (GO)/Fe 3 O 4 nanocomposite (MGO) was prepared by a facile in situ co-precipitation strategy, resulting in a prospective material for the application of graphene oxide in wastewater treatment. MGO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The prepared adsorbent showed a high adsorption efficiency relevant to the purification of dye-contaminated wastewater and could be readily magnetically separated. The maximum adsorption capacity was ca. 546.45 mg g -1 for the common cationic dye methylene blue (MB) and ca. 628.93 mg g -1 for the anionic dye Congo red (CR). The adsorption processes fit the pseudo-second-order kinetic model well, which revealed that these processes may involve the chemical interaction between adsorbate and adsorbent. The thermodynamic parameters indicated that the adsorption reaction was an endothermic and spontaneous process. Furthermore, the prepared magnetic adsorbent had a wide effective pH range from 5 to 11 and showed good stability after five reuse cycles. The synthetic MGO showed great potential as a promising adsorbent for organic contaminant removal in wastewater treatment.

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

Energy Technology Data Exchange (ETDEWEB)

Hsu, Yu-Wei [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yang, Ko-Ho, E-mail: yangkoho@cc.kuas.edu.tw [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Dental Materials Research Center, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yeh, Sung-Wei [Metal Industries Research and Development Centre, 1001 Kaohsiung Highway, Kaohsiung 811, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100, Shihchuan 1st Road, Kaohsiung 80728, Taiwan (China)

2011-06-16

Highlights: > The thermal behavior of 3Y-TZP precursor powders had been investigated. > The crystallization behavior of 3Y-TZP nanopowders had been investigated. > The activation energy for crystallization of tetragonal ZrO{sub 2} was obtained. > The growth morphology parameter n is approximated as 2.0. > The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO{sub 2} crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 {+-} 21.9 kJ mol{sup -1}, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO{sub 2} was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

International Nuclear Information System (INIS)

Hsu, Yu-Wei; Yang, Ko-Ho; Chang, Kuo-Ming; Yeh, Sung-Wei; Wang, Moo-Chin

2011-01-01

Highlights: → The thermal behavior of 3Y-TZP precursor powders had been investigated. → The crystallization behavior of 3Y-TZP nanopowders had been investigated. → The activation energy for crystallization of tetragonal ZrO 2 was obtained. → The growth morphology parameter n is approximated as 2.0. → The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO 2 crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 ± 21.9 kJ mol -1 , was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO 2 was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Dosimetric sensing and optical properties of ZnO–SnO2 nanocomposites synthesized by co-precipitation method

International Nuclear Information System (INIS)

Baitha, Pankaj Kr.; Pal, Partha P.; Manam, J.

2014-01-01

In this study an effort has been made to investigate the dosimetric sensing and optical properties of ZnO–SnO 2 nanocomposites at different pH values. The nanocomposites samples are irradiated by X-ray and then thermoluminescence (TL) analysis is carried out to investigate the response. The structural details of nanocomposites are characterized by Scanning Electron microscope, X-Ray Powder Diffraction and Fourier Transform Infrared Spectroscopy. Similarly, optical properties were characterized by UV–vis spectroscopy and Photoluminescence spectroscopy. The XRD studies revealed good crystallnity of samples with presence of both phases, ZnO as well as SnO 2 simultaneously. The SEM image revealed nanoflakes and nanoflower shape of ZnO–SnO 2 nanocomposite for sample synthesized at pH 7. Also, nanocube and nanosphere can be seen at higher pH value of 9. The room temperature photoluminescence spectra of ZnO–SnO 2 nanocomposite contain multi peaks at 398 nm, 410 nm, 451 nm, 469 nm, 484 nm, 493 nm and 545 nm at an excitation wavelength of 225 nm, which arises mainly due to oxygen and zinc related defects. The TL glow curve shows intense glow peaks at 346°, 261°, 209° and 153° for the samples synthesized at pH 3, pH 5, pH 7 and pH 9 respectively. The peaks are found to be increased with higher pH values. The peaks are found to be shifted towards lower temperature with higher pH values. The study shows that the ZnO–SnO 2 nano-composite is more developed material than singly ZnO compound or SnO 2 with enhanced opto-electronic and thermal properties and great applications in thermal dosimetry. - Highlights: • ZnO–CNT nanocomposites prepared by coprecipitation method at different pH values. • Sample at different pH show different nanostructures as revealed by SEM. • PL spectra indicate intense peaks related to O 2 and Zn defects for all samples. • TL spectra show peak shift with increasing pH values of samples. • ZnO–CNTs are very effective for both

Determination of trace amounts of indium in some sediments by means of coprecipitation with zirconium hydroxide and differential pulse anodic stripping voltammetry

International Nuclear Information System (INIS)

Yoshimura, Wataru; Uzawa, Atushi; Hong Luxin.

1994-01-01

Indium in some sediments was determined by means of coprecipitation and differential pulse anodic stripping voltammetry. The analytical procedure was as follows. Fifty milliliters of distilled water is added to 10 ml of sample solution containing 0.04 g of sediment. Then, constant amounts of indium standard solution and 1 ml of zirconium oxychloride solution are added and the pH adjusted to 8.8 with ammonia water (1:2). The precipitate is separated by filtration and then dissolved in 25 ml of 4 M hydrochloric acid. After 1 ml of 5% KCNS solution is added, this solution is diluted to 50 ml with distilled water. A portion of this solution is employed for the determination of indium. After bubbling nitrogen gas through the sample solution for 100 s it was pre-electrolyzed for 100 s. The potential was scanned from -0.9 V to -0.3 Vυs. SCE for dissolution of indium ion. Indium ion was determined from the peak current of the voltammogram. The results are as follows: (1) Zirconium hydroxide was the most effective collector of indium when the pH was adjusted to 8.8 with ammonia water (1:2). (2) Iron (III) and cadmium ions were found to interfere with the determination of indium. (3) The analytical procedure took about 90 min and 0.01 ppm of indium in sample solution could be determined. (4) This method is applicable to the determination of indium in river bottom and sea floor sediment. (author)

Fabrication of In-rich AgInS{sub 2} nanoplates and nanotubes by a facile low-temperature co-precipitation strategy and their excellent visible-light photocatalytic mineralization performance

Energy Technology Data Exchange (ETDEWEB)

Deng, Fang; Zhong, Fei [Nanchang Hangkong University, Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, College of Environmental and Chemical Engineering (China); Hu, Peng [Jiaozuo University, College of Chemical Industry and Environment Engineering (China); Pei, Xule; Luo, Xubiao, E-mail: luoxubiao@126.com; Luo, Shenglian, E-mail: sllou@hnu.edu.cn [Nanchang Hangkong University, Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, College of Environmental and Chemical Engineering (China)

2017-01-15

Visible-light-driven In-rich AgInS{sub 2} nanoplates and nanotubes were successfully prepared by a convenient co-precipitation strategy at low temperature. The effect of different In/Ag molar ratio in the raw materials on the physicochemical properties and photocatalytic activity of AgInS{sub 2} was investigated. The In/Ag molar ratio has an obvious effect on the morphology of AgInS{sub 2}, and the physicochemical properties and photocatalytic activity of AgInS{sub 2} are also dependent on the In/Ag molar ratio. When the molar ratio of In/Ag is 9, the photoluminescence intensity of AgInS{sub 2} reaches a minimum value, while its photocurrent density is maximum (0.011 mA/cm{sup 2}), indicating the most efficient separation of electron-hole pairs. The AgInS{sub 2} with the In/Ag molar ratio of 9 exhibits the highest visible-light photocatalytic activities with almost complete degradation of 2-nitrophenol, which is attributed to the narrowest band gap and the most efficient separation of electron-hole pairs. Moreover, In-rich AgInS{sub 2} exhibits excellent regeneration ability.

Lithium-Rich Nanoscale Li _1.2 Mn _0.54 Ni _0.13 Co _0.13 O ₂ Cathode Material Prepared by Co-Precipitation Combined Freeze Drying (CP-FD) for Lithium-Ion Batteries

Energy Technology Data Exchange (ETDEWEB)

Bai, Ying; Li, Yu; Wu, Chuan; Lu, Jun; Li, Hui; Liu, Zhaolin; Zhong, Yunxia; Chen, Shi; Zhang, Cunzhong; Amine, Khalil; Wu, Feng

2015-07-14

Nanoscale Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 material is synthesized by a co-precipitation combined freeze drying (CP-FD) method, and compared with a conventional co-precipitation method combined vacuum drying (CP-VD). With the combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM), it is found that the sample from CP-FD method consists of a pure phase with good crystallinity and small, homogenous particles (100-300 nm) with uniform particle size distribution. Inductively coupled plasma spectroscopy (ICP) shows that the sample has a stoichiometric ratio of n((Li)): n((Mn)): n((Ni)): n((Co))=9: 4: 1: 1; and its Brunauer-Emmett-Teller (BET) specific surface area is 5.749 m(2)g(-1). This sample achieves excellent electrochemical properties: its initial discharge capacities are 298.9 mAhg(-1) at 0.1C (20 mAg(-1)), 246.1 mAhg(-1) at 0.5C, 215.8 mAhg(-1) at 1C, and 154.2 mAhg(-1) at 5C (5C charge and 5C discharge), as well as good cycling performance. In addition, the Li+ chemical diffusion coefficient of Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by the CP-FD method is 4.59 x 10(-11) cm(2) s(-1), which is higher than that of the Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by CP-VD. This phenomenon illustrates the potential for Li1.2Mn0.54Ni0.13Co0.13O2 with good rate performance synthesized by CP-FD method.

Fixation of Radionuclides in Titanium Dioxide and Titanates via co-Precipitation; Fixation de Radioelements dans le Bioxyde de Titane et dans les Titanates par Coprecipitation; 0424 0418 041a 0421 0410 0426 0418 042f 0420 0410 0414 0418 041e 0418 0417 041e 0422 041e 041f 041e 0412 0412 0414 0412 0423 041e 041a 0418 0421 0418 0422 0418 0422 0410 041d 0410 0418 1 0418 0422 0410 041d 0410 0422 0410 0425 041c 0415 0422 041e 0414 041e 041c 0421 041e 041e 0421 0410 0416 0414 0415 041d 0418 042f ; Fijacion de Radionuclidos en Dioxido de Titanio y Titanatos por Coprecipitacion

Energy Technology Data Exchange (ETDEWEB)

Levi, H. W. [Hahn-Meitner Institut fuer Kernforschung, Berlin-Wannsee, Federal Republic of Germany (Germany)

1963-02-15

Calcination and adsorption on clay minerals are the most frequently studied ways of radionuclide fixation. A third way - fixation via co-precipitation - has not attracted much interest up to now. The characteristic for all three methods is high-temperature treatment of a pre-product containing the radioactivity, but they differ in introducing the activity into this pre-product. The disadvantages of co-precipitation are the difficult separation of the highly active sludge from solution and its bad qualification for caesium removal. Its advantages are the suitability for head-end processes, the less restricted volume capacity compared with clay mineral adsorption, and the avoidance of evaporation operations. Therefore it seemed worth while to look more closely into the chemistry of proper co-precipitation systems. The first system chosen was TiO{sub 2} * aq because of the good fixation qualities of TiO{sub 2} and titanates. The co-precipitation properties of TiO{sub 2} * aq were studied under different experimental conditions. For some radionuclides the distribution coefficient was found to be as good as or better than that for other oxide hydrates. High concentration of the radionuclide ion or similar ions causes decreasing distribution coefficient. This could be avoided by simultaneously precipitating carbonates or oxalates which remove the bulk oi the ions. The influence of high aluminium content was studied as well. An investigation of the formation of anatas and rutil from pure TiO{sub 2} * aq precipitates and of titanates from TiO{sub 2} * aq + carbonate or oxalate precipitates during high-temperature treatment was started. (author) [French] La calcination et l'adsorption par les mineraux argileux sont les modes de fixation des radioelements les plus frequemment etudies. Une troisieme methode, la fixation par coprecipitation, n'a guere suscite d'interet jusqu'a present. Ces trois methodes ont un point commun: le traitement a haute temperature des matieres

Development of a calcium phosphate co-precipitate/poly(lactide-co-glycolide) DNA delivery system: release kinetics and cellular transfection studies.

Science.gov (United States)

Kofron, Michelle D; Laurencin, Cato T

2004-06-01

One of the most common non-viral methods for the introduction of foreign deoxyribonucleic acid (DNA) into cultured cells is calcium phosphate co-precipitate transfection. This technique involves the encapsulation of DNA within a calcium phosphate co-precipitate, particulate addition to in vitro cell culture, endocytosis of the co-precipitate, and exogenous DNA expression by the transfected cell. In this study, we fabricated a novel non-viral gene transfer system by adsorbing DNA, encapsulated in calcium phosphate (DNA/Ca-P) co-precipitates, to biodegradable two- and three-dimensional poly(lactide-co-glycolide) matrices (2D-DNA/Ca-P/PLAGA, 3D-DNA/Ca-P/PLAGA). Co-precipitate release studies demonstrated an initial burst release over the first 48 h. By day 7, approximately 96% of the initially adsorbed DNA/Ca-P co-precipitate had been released. This was followed by low levels of co-precipitate release for 42 days. Polymerase chain reaction was used to demonstrate the ability of the released DNA containing co-precipitates to transfect SaOS-2 cells cultured in vitro on the 3D-DNA/Ca-P/PLAGA matrix and maintenance of the structural integrity of the exogenous DNA. In summary, a promising system for the incorporation and controlled delivery of exogenous genes encapsulated within a calcium phosphate co-precipitate from biodegradable polymeric matrices has been developed and may have applicability to the delivery of therapeutic genes and the transfection of other cell types.

Radionuclide co-precipitation

International Nuclear Information System (INIS)

Bruno, J.; Sandino, A.

1987-12-01

The thermodynamic and kinetic behaviour of the minor components of the spent fuel matrix has been theoretically and experimentally investigated. Two different situations have been studied: Part I, the near field scenario, where the release and migration of the minor components is dependent on the solubility behaviour of UO 2 (s); Part II, the far field, where the solubility and transport of the radionuclides is related to the major geochemical processes occurring. (orig.)

Nitrate conversion and supercritical fluid extraction of UO{sub 2}-CeO{sub 2} solid solution prepared by an electrolytic reduction-coprecipitation method

Energy Technology Data Exchange (ETDEWEB)

Zhu, L.Y. [Tsinghua Univ., Beijing (China). Inst. of Nuclear and New Energy Technology; China Institute of Atomic Energy, Beijing (China); Duan, W.H.; Wen, M.F.; Xu, J.M.; Zhu, Y.J. [Tsinghua Univ., Beijing (China). Inst. of Nuclear and New Energy Technology

2014-04-01

A low-waste technology for the reprocessing of spent nuclear fuel (SNF) has been developed recently, which involves the conversion of actinide and lanthanide oxides with liquid N{sub 2}O{sub 4} into their nitrates followed by supercritical fluid extraction of the nitrates. The possibility of the reprocessing of SNF from high-temperature gas-cooled reactors (HTGRs) with nitrate conversion and supercritical fluid extraction is a current area of research in China. Here, a UO{sub 2}-CeO{sub 2} solid solution was prepared as a surrogate for a UO{sub 2}-PuO{sub 2} solid solution, and the recovery of U and Ce from the UO{sub 2}-CeO{sub 2} solid solution with liquid N{sub 2}O{sub 4} and supercritical CO{sub 2} containing tri-n-butyl phosphate (TBP) was investigated. The UO{sub 2}-CeO{sub 2} solid solution prepared by electrolytic reduction-coprecipitation method had square plate microstructures. The solid solution after heat treatment was completely converted into nitrates with liquid N{sub 2}O{sub 4}. The XRD pattern of the nitrates was similar to that of UO{sub 2}(NO{sub 3}){sub 2} . 3H{sub 2}O. After 120 min of online extraction at 25 MPa and 50 , 99.98% of the U and 98.74% of the Ce were recovered from the nitrates with supercritical CO{sub 2} containing TBP. The results suggest a promising potential technology for the reprocessing of SNF from HTGRs. (orig.)

Effect of Ca and Li additions on densification and electrical conductivity of 10 mol% gadolinia-doped ceria prepared by the coprecipitation technique; Efeito de adicoes de litio e calcio na densificacao e na condutividade eletrica da ceria-10% mol gadolinia preparada pela tecnica de co-precipitacao

Energy Technology Data Exchange (ETDEWEB)

Porfirio, T.C.

2010-07-01

Ceria containing rare-earth ceramics are potential candidates for application in intermediate-temperature solid oxide fuel cells. One of the main problems related to these ceramic materials is their relatively low sinterability. In this work, the effects of Ca and Li additions on densification and electrical conductivity of 10 mol% gadolinia-doped ceria was investigated. Ceramic compositions containing 1.5 mol% Ca or Li were prepared by the oxalate coprecipitation technique. Results of sintered density and electrical conductivity were compared to those of ceramic samples obtained by solid state reactions showing the effects of the synthesis method on densification and total electrical conductivity of the sintered materials. (author)

Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

Science.gov (United States)

Rajendran, V.; Deepa, B.

2018-03-01

Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

Synthesis of Nano-Structured La0.6Sr0.4Co0.2Fe0.8O3 Perovskite by Co-Precipitation Method

Directory of Open Access Journals (Sweden)

Ebrahim Mostafavi

2015-06-01

Full Text Available Nano-structured lanthanum strontium cobalt ferrite, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF, was successfully synthesized via co-precipitation method using metal nitrates as starting materials. Effects of precipitating agent and calcination temperature on the phase composition and morphology of synthesized powders were systematically studied using X-ray diffraction (XRD and field emission scanning electron microscopy (FESEM, respectively. XRD analysis revealed that a single phase La0.6Sr0.4Co0.2Fe0.8O3 perovskite was obtained in the processed sample using ammonium carbonate as precipitating agent with a NH4+/NO3-molar ratio of 2 after calcination at 1000C for 1 h. The phase composition of products was also affected by changing pH values. Moreover, using sodium hydroxide as a precipitant resulted in a mixture of La0.6Sr0.4Co0.2Fe0.8O3 and cobalt ferrite (CoFe2O4 phases. Careless washing of the precursors can also led to the formation of mixed phase after calcination of final powders. Mean crystallite size of the obtained powders was not noticeably affected by varying calcination temperature from 900 to 1050C and remained almost the same at 10 nm, however increasing calcination temperature to 1100C resulted in sharp structural coarsening. FESEM studies demonstrate that relatively uniform particles with mean particle size of 90 nm were obtained in the sample processed with a NH4+/NO3- molar ratio of 2 after calcination at 1000C for 1 h.

Determination of radionuclides {sup 90}Sr, {sup 239,240} Pu, {sup 238}Pu and {sup 241}Am in soil using methods of extraction chromatography and coprecipitation; Stanovenie radionuklidov {sup 90}Sr, {sup 239,240}Pu, : 2{sup 38}Pu a {sup 241}Am v pode vyuzivajuce metody extrakcnej chromatografie a spoluzrazania

Energy Technology Data Exchange (ETDEWEB)

Gardonova, V.; Dulanska, S.; Bilohuscin, J. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra jadrovej chemie, 84215 Bratislava (Slovakia)

2013-04-16

Ecosystems, which include soil and sediments, contain not only natural radionuclides but also radionuclides from deposits, mainly {sup 137}Cs, {sup 90}Sr and {alpha}-emitting radionuclides such as {sup 239,240}Pu, {sup 238}Pu and {sup 241}Am, that originate from global fallout and nuclear facilities leaks worldwide. The goal of the work was optimization of separation and determination of {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu and {sup 241}Am in soil from Slovak Republic. The newest methods were applied for separation of selected radionuclides based on coprecipitation with oxalic salts and extraction chromatography using selective commercial sorbents. (authors)

Structural and luminescence properties of CaTiO{sub 3}:Eu{sup 3+} phosphor synthesized by chemical co-precipitation method for the application of solid state lighting devices

Energy Technology Data Exchange (ETDEWEB)

Singh, Dhananjay Kumar, E-mail: dksism89@gmail.com; Manam, J., E-mail: jairam.manam@gmail.com [Department of Applied Physics, Indian School of Mines, Dhanbad-826004 (India)

2016-05-06

The present work report a series of trivalent Europium (Eu{sup 3+}) doped well crystallized perovskite CaTiO{sub 3} phosphors successfully synthesized by chemical co-precipitation method. The crystal structure was confirmed by X-ray diffraction (XRD) which is in good agreement with pure orthorhombic phase with space group Pbnm, and it also indicated that the incorporation of the dopant did not affect the crystal structure. The impact of doping on the photoluminescence performances of the sample has been investigated by emission, excitation, and diffuse reflectance spectra at the room temperature. Photoluminescence spectra of Eu{sup 3+} doped CaTiO{sub 3} nanophosphor revealed the characteristic emission peak around wavelength 618 nm in the visible region upon the excitation of near-UV light at wavelength 397 nm due to {sup 5}D{sub 0} → {sup 7}F{sub 2} transition in Eu{sup 3+}. It was further proved that the dipole– dipole interactions results in the concentration quenching of Eu{sup 3+} in CaTiO{sub 3}:Eu{sup 3+} nanophosphors. The elemental composition of sample carried out by energy dispersive spectroscopy (EDS). EDS analysis reveals that the Eu{sup 3+} doped successfully into host CaTiO{sub 3}. The experimental result reveals that prepared nanophosphor can be used in the application of solid state lighting devices.

Effect of electron irradiation exposure on phase formation, microstructure and mechanical strength of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} superconductor prepared via co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Mohiju, Zaahidah ' Atiqah; Hamid, Nasri A., E-mail: Nasri@uniten.edu.my; Kannan, V. [Center for Nuclear Energy, College of Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, 43000 Kajang, Selangor (Malaysia); Abdullah, Yusof [Materials Technology Group, Industrial Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

2015-04-29

In this work the effect of electron irradiation on the mechanical properties of Bi2Sr2CaCu2O8 (Bi-2212) superconductor was studied by exposing the Bi-2212 superconductor with different doses of electron irradiation. Bi-2212 samples were prepared by using co-precipitation method. Irradiation was performed with irradiation dose of 100 kGray and 200 kGray, respectively. Characterization of the samples was performed by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Instron Universal Testing machine was used to measure the strength of the samples. The XRD patterns for the non-irradiated and irradiated samples show well-defined peaks of which could be indexed on the basis of a Bi-2212 phase structure. XRD patterns also indicate that electron irradiation did not affect the Bi-2212 superconducting phase. SEM micrographs show disorientation in the texture of the microstructure for irradiated samples. Sample exposed to 200 kGray electron irradiation dose shows enhancement of grain size. Their grain growth and texture improved slightly compared to other sample. The results also show that enlargement of grain size resulted in higher mechanical strength.

Nanocrystalline composites of transition metal molybdate (Ni1-xCoxMoO4; x = 0, 0.3, 0.5, 0.7, 1) synthesized by a co-precipitation method as humidity sensors and their photoluminescence properties

Science.gov (United States)

Jeseentharani, V.; Dayalan, A.; Nagaraja, K. S.

2018-04-01

In this study, nanocrystalline transition metal nickel-cobalt molybdate (Ni1-xCoxMoO4, NiCM; x = 0, 0.3, 0.5, 0.7, 1) composites were prepared using a simple co-precipitation method. The composites were characterized by thermogravimetric/differential thermal analysis, Fourier transform-infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The NiCM composites were studied to determine their possible use as humidity sensors, and photoluminescence (PL) measurements were obtained. The sensing study was performed in environments with different relative humidity levels (5-98%). The maximum sensitivity of 18624 ± 168 was observed with the Ni0.7Co0.3MoO4 composite where the humidity could be calculated according to the relationship: Sf = R5%/R98%, where R5% and R98% are the dc resistances at 5 and 98% RH, respectively. The photoluminescence measurements acquired at room temperature for the NiCMs included green and red emission peaks when excited at a wavelength (λex) of 520 nm.

Soil Organic Matter Stabilization via Mineral Interactions in Forest Soils with Varying Saturation Frequency

Science.gov (United States)

Possinger, A. R.; Inagaki, T.; Bailey, S. W.; Kogel-Knabner, I.; Lehmann, J.

2017-12-01

Soil carbon (C) interaction with minerals and metals through surface adsorption and co-precipitation processes is important for soil organic C (SOC) stabilization. Co-precipitation (i.e., the incorporation of C as an "impurity" in metal precipitates as they form) may increase the potential quantity of mineral-associated C per unit mineral surface compared to surface adsorption: a potentially important and as yet unaccounted for mechanism of C stabilization in soil. However, chemical, physical, and biological characterization of co-precipitated SOM as such in natural soils is limited, and the relative persistence of co-precipitated C is unknown, particularly under dynamic environmental conditions. To better understand the relationships between SOM stabilization via organometallic co-precipitation and environmental variables, this study compares mineral-SOM characteristics across a forest soil (Spodosol) hydrological gradient with expected differences in co-precipitation of SOM with iron (Fe) and aluminum (Al) due to variable saturation frequency. Soils were collected from a steep, well-drained forest soil transect with low, medium, and high frequency of water table intrusion into surface soils (Hubbard Brook Experimental Forest, Woodstock, NH). Lower saturation frequency soils generally had higher C content, C/Fe, C/Al, and other indicators of co-precipitation interactions resulting from SOM complexation, transport, and precipitation, an important process of Spodosol formation. Preliminary Fe X-ray Absorption Spectroscopic (XAS) characterization of SOM and metal chemistry in low frequency profiles suggest co-precipitation of SOM in the fine fraction (soils showed greater SOC mineralization per unit soil C for low saturation frequency (i.e., higher co-precipitation) soils; however, increased mineralization may be attributed to non-mineral associated fractions of SOM. Further work to identify the component of SOM contributing to rapid mineralization using 13C

Growth mechanisms for spherical mixed hydroxide agglomerates prepared by co-precipitation method: A case of Ni1/3Co1/3Mn1/3(OH)2

International Nuclear Information System (INIS)

Yang, Yue; Xu, Shengming; Xie, Ming; He, Yinghe; Huang, Guoyong; Yang, Youcai

2015-01-01

Highlights: • Anisotropic growth of Ni 1/3 Co 1/3 Mn 1/3 (OH) 2 along the [0 0 1] direction was revealed. • DFT calculation results show crystal surface energies of (0 0 1) plane is highest. • A new model was proposed to explain the formation of spherical agglomerates. - Abstract: Spherical Ni 1/3 Co 1/3 Mn 1/3 (OH) 2 agglomerates were synthesized by the co-precipitation method in the presence of ammonia. The results show that the growth mechanism of spherical agglomerates follows three-stages, i.e. nucleation and anisotropic growth of single crystals; agglomeration of polycrystalline crystallites agglomerated by single crystal grains as primary particles to form embryonic agglomerates; formation, growth and consolidation of spherical agglomerates or particles by agglomeration of embryonic agglomerates, continued growth of individual crystals in the agglomerates and further attachment of primary particles. The first two stages are very fast while the last stage takes almost the entire process to complete. The main reason for the anisotropic growth of Ni 1/3 Co 1/3 Mn 1/3 (OH) 2 crystal is that crystal surface energy of E (001) , E (100) , E (101) and E (102) is different with E (001) being the highest. The morphology of the final spherical agglomerates is explained by partial re-crystallization of contacting primary particles. The growth process of spherical agglomerates was examined by X-ray diffraction, scanning electron microscope, transmission electron microscope and calculation of crystal surface energy using density function theory

Investigation on orientation, epitaxial growth and microstructure of a-axis-, c-axis-, (103)/(110)- and (113)-oriented YBa2Cu3O7-δ films prepared on (001), (110) and (111) SrTiO3 single crystal substrates by spray atomizing and coprecipitating laser chemical vapor deposition

Science.gov (United States)

Zhao, Pei; Wang, Ying; Huang, Zhi liang; Mao, Yangwu; Xu, Yuan Lai

2015-04-01

a-axis-, c-axis-, (103)/(110)- and (113)-oriented YBa2Cu3O7-δ (YBCO) films were pareared by spray atomizing and coprecipitating laser chemical vapor deposition. The surface of the a-axis-oriented YBCO film consisted of rectangular needle-like grains whose in-plane epitaxial growth relationship was YBCO [100] // STO [001] (YBCO [001] // STO [100]), and that of the c-axis-oriented YBCO film consisted of dense flat surface with epitaxial growth relationship of YBCO [001] // STO [001] (YBCO [100] //STO [100]). For the (103)/(110)-oriented and (113)-oriented YBCO film, they showed wedge-shaped and triangle-shaped grains, with corresponding in-plane epitaxial growth relationship of YBCO [110] // STO [110] (YBCO [010] // STO [010]) and YBCO [100] // STO [100] (YBCO [113] // STO [111], respectively.

Preparation and Characterization of Chitosan-coated Fe3O4 Nanoparticles using Ex-Situ Co-Precipitation Method and Tripolyphosphate/Sulphate as Dual Crosslinkers

Science.gov (United States)

Wulandari, Ika O.; Mardila, Vita T.; Santjojo, D. J. Djoko H.; Sabarudin, Akhmad

2018-01-01

The unique properties of nanomaterial provide great opportunities to develop in several fields. Several types of nanoparticles have been proven beneficial for biomedical and therapeutic agent development. Particularly for clinical use, nanoparticles must be biocompatible and non-toxic. Iron oxide nanoparticles consist of either magnetite (Fe3O4) or maghemite (γ-Fe2O3) was eligible to use for in vivo application including targeting drug delivery. Due to their distinct properties, these nanoparticles could be directed to the specific target under external magnetic field. However, nanoparticles have a tendency to form agglomeration. Therefore, surface modification was required to reduce the agglomeration. In this study, nanoparticles of Fe3O4 were produced and coated by biomaterial (chitosan) using ex-situ co-precipitation method. Nanoparticles of Fe3O4 were synthesized by adding ammonia water into iron ferric and ferrous solution. Synthesis process of Fe3O4 was conducted prior to adding chitosan. Chitosan was then cross-linked by a combination of tripolyphosphate/sulphate. The different composition ratio and crosslinking time provide the different physical and magnetic characteristics of nanoparticles. Particle and crystallite size was determined by using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) respectively, whereas magnetic characteristic was determined by Electron Spin Resonance (ESR). The results showed that the ratio enhancement between chitosan: Fe3O4 increase the particle size, while decreased the crystallite size. Morphology and particle size were influenced by the ratio of crosslinkers. It was found that the higher tripolyphosphate content was contributed to the small size and more spherical morphology. In addition, the influence of crosslinking time toward crystallite size was determined by altering stirring time. The longer duration of crosslinking time, provide the larger crystallite size of chitosan-Fe3O4. There was an interesting

Crystallite growth kinetics of TiO2 surface modification with 9 mol% ZnO prepared by a coprecipitation process

International Nuclear Information System (INIS)

Ko, Horng-Huey; Hsi, Chi-Shiung; Wang, Moo-Chin; Zhao, Xiujian

2014-01-01

Highlights: • TiO 2 powder surface modification with 9 mol% ZnO was obtained. • Phase transformation from anatase to rutile was hindered by ZnO added. • Growth kinetic of anatase TiO 2 nanocrystallites in T-9Z powders was described as: D A,9 2 =2.42×10 5 ×exp(-39.9×10 3 /RT). • Growth kinetic of rutile TiO 2 nanocrystallites in T-9Z powders was described as: D R,9 2 =8.49×10 5 ×exp(-47.6×10 3 /RT) rutile TiO 2 . -- Abstract: The nanocrystallite growth of TiO 2 surface modification with 9 mol% ZnO prepared by a coprecipitation process has been studied. Thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–VIS–NIR spectrophotometry have been utilized to characterize the TiO 2 nanocrystallites surface modification with 9 mol% ZnO (denoted by T-9Z). The DTA result shows that the anatase TiO 2 first formed at 533 K and the completion of anatase TiO 2 crystallization occurred at 745 K for the T-9Z freeze-dried precursor powders. XRD results reveal that the anatase and rutile TiO 2 coexist when the T-9Z freeze-dried precursor powders were calcined at 523–973 K for 2 h. When the T-9Z freeze-dried precursor powders were calcined at 973 K for 2 h, rutile TiO 2 was the major phase, and the minor phases were anatase TiO 2 and Zn 2 Ti 3 O 8 . The phase was composed of the rutile TiO 2 and Zn 2 TiO 4 for the T-9Z freeze-dried precursor powders after calcination at 1273 K for 2 h. The growth kinetics of TiO 2 nanocrystallites in T-9Z powders were described as: D A,9 2 =2.42×10 5 ×exp(-39.9×10 3 /RT)and D R,9 2 =8.49×10 5 ×exp(-47.6×10 3 /RT) for anatase and rutile TiO 2 nanocrystallites respectively. The analysis results of UV/VIS/NIR spectra reveal that the T-9Z freeze-dried precursor powders after calcination have a red-shifted effect with increasing calcination temperature and can be used as a UVA-attenuating agent

Synthesis and Evaluation of Microspherical Li1.2Mn0.54Co0.13Ni0.13O2 through Carbon Dioxides-assisted Co-precipitation Method for Lithium-ion Battery

International Nuclear Information System (INIS)

Yan, Wenchao; Jiang, Jicheng; Liu, Wei; Yan, Xiao; Sun, Deye; Jin, Yongcheng; Wang, Jing; Xiang, Lan; Munakata, Hirokazu; Kanamura, Kiyoshi

2016-01-01

Lithium-rich layered electrode materials are of interest as a promising candidate of cathodes for lithium-ion batteries because of their excellent electrochemical properties. The electrochemical performance of these materials is mainly regulated by preparation conditions during synthesis and calcination process. Here, microspherical Li 1.2 Mn 0.54 Co 0.13 Ni 0.13 O 2 (LMNCO) particles are synthesized through steady pH value control with carbon dioxides bubbling method in co-precipitation process using a simple reactor. SEM images present that CP-LMNCO sample prepared through the assistance of carbon dioxides has spherical particle morphology, while sample (TP-LMNCO) without carbon dioxides assistance shows large nanoparticles agglomeration. The CP-LMNCO electrode demonstrates superior electrochemical performance, which exhibits capacity retention of 97.76% after 100 cycles compared with only 81.94% for TP-LMNCO electrode at 1C (250 mA g −1 ). Even at a higher current density (5C), the CP-LMNCO electrode shows reversible capacity up to 105.4 mA h g −1 . The remarkably improved electrochemical performance of CP-LMNCO electrode is ascribed to spherical morphology with small surface area which decreases side reactions with electrolyte during cycling and smaller primary sizes which reduce lithium ion (Li + ) diffusion distance. Furthermore, the synthesis of spherical materials using metal sulfate with high concentration (up to 5 M) as starting agents are attempted under carbon dioxides assisted conditions, and as-prepared materials also show improved performance.

ENCAPSULATION OF EXTRACT FROM WINERY INDUSTRY RESIDUE USING THE SUPERCRITICAL ANTI-SOLVENT TECHNIQUE

Directory of Open Access Journals (Sweden)

N. Mezzomo

Full Text Available Abstract Grape pomace (seed, skin and stem is a winery byproduct with high levels of biologically active compounds, such as antioxidants and antimicrobials, that could be converted into high added-value products. Since these components are easily degraded by oxygen, light and high temperature exposure, stabilization is important, for instance, by a microencapsulation process. Therefore, the objective of this study was to investigate the influence on the particle characteristics of the operational conditions applied in the Supercritical Anti-Solvent (SAS process for the co-precipitation of grape pomace extract and poly(-lactic-co-glycolic acid (PLGA. The morphology and size of the particles formed, their stability and thermal profile were evaluated, and also the co-precipitation efficiency. The conditions studied allowed the production of microparticles with spherical shape for all operational conditions, with estimated particle size between 4 ± 2 and 11 ± 5 µm, and very good co-precipitation efficiencies (up to 94.4 ± 0.6%. The co-precipitated extract presented higher stability compared to the crude extract, indicating the effectiveness of the co-precipitation process and coating material against degradation processes.

A new oxalate co-conversion technology based on liquid/liquid extraction columns

International Nuclear Information System (INIS)

Borda, Gilles; Ode, Denis; Duhamet, Jean; Allegri, Patrick

2008-01-01

The current objective of fabricating non proliferating nuclear fuel by 'direct' coprecipitation of uranium, plutonium and minor actinides requires a new process to replace the (co)precipitation step. The technological impact of an increased capacity on the work zone could require the development of a different concept for a continuous device capable of ensuring the proposed goal. A new type of device designed and patented by the Cea was tested in 2007. The patent is for organic confinement in a pulsed column. First, precipitation of cerium or neodymium alone has been carried out in this device, with satisfactory results. Moreover, a recent test campaign demonstrated that a uranium-cerium co-precipitate easily forms when the two nitrates are mixed in a pulsed column of the same size operating under very similar process conditions. Qualitatively, the co-precipitate meets the process requirements. (authors)

Structural and Morphological Properties of Zn{sub 1−x}Zr{sub x}O with Room-Temperature Ferromagnetism and Fabricated by Using the Co-Precipitation Technique

Energy Technology Data Exchange (ETDEWEB)

Hassan, M.; Irfan, R.; Riaz, S.; Naseem, S.; Hussain, S. S. [University of the Punjab, Lahore (Pakistan); Murtaza, G. [Government College University, Lahore (Pakistan)

2017-03-15

In this study, ZnO was doped with various concentrations of zirconium (x{sub Zr} = 0 - 5 mole%), by using the co-precipitation method so as to achieve successful formation of a single-phase diluted magnetic semiconductor. X-Ray diffraction results showed that the crystal structure of Zn{sub 1−x}Zr{sub x}O was that of hexagonal wurtzite. The structural properties showed no additional phases at low impurity contents (x{sub Zr} < 3%); however, impurity peaks belonging to ZrO{sub 2} appeared at high impurity contents (x{sub Zr} ≥ 3%). The calculated ZnO lattice constants 'a' and 'c' were found to be 3.256 Å and 5.203 Å, respectively, which are in close match to the values found in the literature. For undoped ZnO, the average calculated particle size was 75.35 nm, and calculated bond length was 1.98 Å. The residual strains and the secondary phases of ZrO{sub 2} were found to affect the lattice parameters and the bond lengths. The scanning electron microscopy images showed a porous structure with non-uniform surface morphology. However, a few nano-scale dendrite-type structures were also present, indicating the potential applications of Zr-doped ZnO in nano-devices. Vibrating sample magnetometry (VSM) was employed to measure the magnetic properties, and the measurements showed undoped ZnO to be diamagnetic; however, doping with Zr induced a small ferromagnetic character at small magnetic fields. On the other hand, a paramagnetic behavior was evident at higher magnetic fields. The magnetization at 1T was observed to degrade with increasing Zr content in the ZnO host lattice, which was due to the residual strains and the secondary phases.

Thermal behavior and phase transformation of ZrO2–10%SiO2 precursor powder prepared by a co-precipitation route without adding stability agent

International Nuclear Information System (INIS)

Chu, Hsueh-Liang; Hwang, Weng-Sing; Wang, Cheng-Li; Wang, Moo-Chin; Lee, Kuen-Chan; Huang, Hong-Hsin; Lee, Huey-Er

2014-01-01

Highlights: • The precursor powders contained about 68.3 wt% ZrO 2 , which corresponds to ZrO 2 ·1/8 H 2 O. • The exothermic peak temperature of tetragonal ZrO 2 formation occurred at 1014 K. • The activation energy of ZrO 2 –10%SiO 2 precursors crystallization is 993.7 kJ/mol. • Only the tetragonal ZrO 2 formed when the precursor calcined at 1173–1373 K for 2 h. • As calcined at 1473 K for 2 h, tetragonal ZrO 2 fully converted to monoclinic ZrO 2 . - Abstract: Thermal behavior and phase transformation of ZrO 2 –10%SiO 2 precursor powder prepared by a co-precipitation route without adding stability agent has been studied using different thermal analysis/thermogravimetry (DTA/TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED), high-resolution TEM (HRTEM) and energy-dispersive X-ray spectrometer (EDS). The TG results show that four weight loss regions were from 298 to 443 K, 443 to 743 K, 743 to 793 K and 793 to 1400 K. The DTA result shows that the ZrO 2 freeze-dried precursor powders crystallization at 1014 K. The activation energy of 993.7 kJ/mol was obtained for tetragonal ZrO 2 crystallization using a non-isothermal process. The XRD result shows that only a single phase of tetragonal ZrO 2 appears when the freeze-dried precursor powders after calcination between 1173 and 1373 K for 2 h. Moreover, when calcined at 1473 K for 2 h, the phase transformation from tetragonal ZrO 2 fully converted to monoclinic ZrO 2 occurred

Characteristics and properties of a novel in situ method of synthesizing mesoporous TiO2 nanopowders by a simple coprecipitation process without adding surfactant

International Nuclear Information System (INIS)

Yeh, Shang-Wei; Ko, Horng-Huey; Chiang, Hsiu-Mei; Chen, Yen-Ling; Lee, Jian-Hong; Wen, Chiu-Ming; Wang, Moo-Chin

2014-01-01

Highlights: • The TiO 2 precursor powder contained anatase and 19.5% NH 4 Cl. • Mesoporous anatase TiO 2 nanopowders were successfully synthesized. • Uncalcined precursor powder contained the phases of type I NH 4 Cl and anatase TiO 2 . • Anatase size increases from 3.3 to 14.3 nm when calcined at 473–773 K for 2 h. • The average pore size between 3.80 and 14.0 nm when calcined between 473 and 773 K. - Abstract: In situ synthesis of mesoporous TiO 2 nanopowders using titanium tetrachloride (TiCl 4 ) and NH 4 OH as initial materials has been successfully fabricated by a coprecipitation process without the addition of surfactant. Characteristics and properties of the mesoporous TiO 2 nanopowders were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Barrent–Joyner–Halenda (BJH) analyses, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high resolution TEM (HRTEM). The results of TG and XRD showed that the NH 4 Cl decomposed between 513 and 673 K. XRD results showed that the anatase TiO 2 only contained a single phase when the calcination temperature of the precursor powder was less than 673 K. Whereas phases of anatase and rutile TiO 2 coexist after calcining at 773 K for 2 h. The crystalline size of the anatase and rutile TiO 2 was 14.3 and 26.6 nm, respectively, when the precursor powder was calcined at 773 K for 2 h. The BET and BJH results showed a significant increase in surface area and pore volumes when the NH 4 Cl was completely decomposed. The maximum values of BET specific surface area and volume were 172.8 m 2 /g and 0.392 cm 3 /g, respectively. The average pore sizes when calcination was at 473 and 773 K for 2 h were 3.8 and 14.0 nm, respectively

A new oxalate co-conversion technology based on liquid/liquid extraction columns

Energy Technology Data Exchange (ETDEWEB)

Borda, Gilles; Ode, Denis; Duhamet, Jean; Allegri, Patrick [CEA Nuclear Energy Division - Fuel Cycle Technology Division - System and Chemical Engineering Device Marcoule - 30207 Bagnols sur Ceze (France)

2008-07-01

The current objective of fabricating non proliferating nuclear fuel by 'direct' coprecipitation of uranium, plutonium and minor actinides requires a new process to replace the (co)precipitation step. The technological impact of an increased capacity on the work zone could require the development of a different concept for a continuous device capable of ensuring the proposed goal. A new type of device designed and patented by the Cea was tested in 2007. The patent is for organic confinement in a pulsed column. First, precipitation of cerium or neodymium alone has been carried out in this device, with satisfactory results. Moreover, a recent test campaign demonstrated that a uranium-cerium co-precipitate easily forms when the two nitrates are mixed in a pulsed column of the same size operating under very similar process conditions. Qualitatively, the co-precipitate meets the process requirements. (authors)

Bulk and Surface Structures of Palladium-Modified Copper-Zinc Oxides ex Hydroxycarbonate Precursors

NARCIS (Netherlands)

López Granados, M.; Melián-Cabrera, I.; Fierro, J.L.G.

2002-01-01

(Pd)-Cu-Zn ex hydroxycarbonate precursors were prepared and characterized by several bulk and surface techniques. A palladium-free Cu-Zn precursor (CZ) was prepared by coprecipitation. Two Pd-Cu-Zn samples were prepared by coprecipitation (PCZ-CP) and sequential precipitation (PCZ-SP). It is shown

High Tap Density Spherical Li[Ni0.5Mn0.3Co0.2]O2 Cathode Material Synthesized via Continuous Hydroxide Coprecipitation Method for Advanced Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Shunyi Yang

2012-01-01

Full Text Available Spherical [Ni0.5Mn0.3Co0.2](OH2 precursor with narrow size distribution and high tap density has been successfully synthesized by a continuous hydroxide coprecipitation, and Li[Ni0.5Mn0.3Co0.2]O2 is then prepared by mixing the precursor with 6% excess Li2CO3 followed by calcinations. The tap density of the obtained Li[Ni0.5Mn0.3Co0.2]O2 powder is as high as 2.61 g cm−3. The powders are characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, scanning electron microscope (SEM, particle size distribution (PSD, and charge/discharge cycling. The XRD studies show that the prepared Li[Ni0.5Mn0.3Co0.2]O2 has a well-ordered layered structure without any impurity phases. Good packing properties of spherical secondary particles (about 12 μm consisted of a large number of tiny-thin plate-shape primary particles (less than 1 μm, which can be identified from the SEM observations. In the voltage range of 3.0–4.3 V and 2.5–4.6 V, Li[Ni0.5Mn0.3Co0.2]O2 delivers the initial discharge capacity of approximately 175 and 214 mAh g−1 at a current density of 32 mA g−1, and the capacity retention after 50 cycles reaches 98.8% and 90.2%, respectively. Besides, it displays good high-temperature characteristics and excellent rate capability.

Co-precipitation in aqueous medium of La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} via inorganic precursors

Energy Technology Data Exchange (ETDEWEB)

Pelosato, Renato; Cristiani, Cinzia; Dotelli, Giovanni; Latorrata, Saverio; Zampori, Luca [CMIC - Dipartimento di Chimica, Materiali e Ingegneria Chimica ' ' G. Natta' ' , Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milano (Italy); Ruffo, Riccardo [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy)

2010-12-15

A simple and inexpensive co-precipitation route in aqueous medium is proposed to prepare La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 02}O{sub 3-{delta}} ionic conductor (LSGM). Different synthetic procedures and operating parameters (i.e. nature and amount of the precipitating agents, HNO{sub 3} addition and temperature) have been evaluated in order to underline their influence on the composition and microstructure of the final phase. Intermediate and final products were characterized by Thermal-Gravimetry, IR-spectroscopy, X-ray Powder Diffraction, Rietveld analysis and Scanning Electron Microscopy. The electrical properties were measured by Impedance Spectroscopy in the temperature range 250-800 C. Slight variations of the synthetic procedure (such as precipitating agent amount or no HNO{sub 3} addition) have a considerable and detrimental effect on the ions losses and the subsequent achievement of the final phase. The use NH{sub 4}OH as an alternative precipitating agent is dramatically disadvantageous. Ions losses during precipitation must be controlled (i) to avoid understoichiometry in the LSGM phase and (ii) to prevent the formation of large amounts of secondary phases. In fact, both affect the total electrical conductivity. The use of large excess of (NH{sub 4}){sub 2}CO{sub 3} precipitating agent and the addition of HNO{sub 3} lead to the best material characterized by a rhombohedral structure, small amount of side phases, a relative density of 98% and a total conductivity of 6.44 x 10{sup -2} S cm{sup -1} at 800 C and 1.13 x 10{sup -2} S cm{sup -1} at 600 C. (author)

Binding of Cd by ferrihydrite organo-mineral composites: Implications for Cd mobility and fate in natural and contaminated environments.

Science.gov (United States)

Du, Huihui; Peacock, Caroline L; Chen, Wenli; Huang, Qiaoyun

2018-09-01

Adsorption and coprecipitation of organic matter with iron (hydr)oxides can alter iron (hydr)oxide surface properties and their reactivity towards nutrient elements and heavy metals. Organo-mineral composites were synthesized using humic acid (HA) and iron oxide, during coprecipitation with ferrihydrite (Fh) and adsorption to pre-formed Fh with two C loadings. The Fh-HA coprecipitated composites have a higher C content and smaller surface area compared to the equivalent adsorbed composites. NanoSIMS shows there is a high degree of spatial correlation between Fe and C for both composites, but C distribution is more uniform in the coprecipitated composites. The C 1s NEXAFS reveals a similar C composition between the Fh-HA coprecipitated and adsorbed composites. However composites at high carbon loading are more enriched in aromatic C, likely due to preferential binding of carboxyl functional groups on aromatic rings in the HA. The amount of Cd sorbed is independent of the composite type, either coprecipitated or adsorbed, but is a function of the C loading. Composites with low C loading show Cd sorption that is almost identical to pure Fh, while composites with high C loading show Cd sorption that is intermediate between pure Fh and pure HA, with sorption significantly enhanced over pure Fh at pH < 6.5. A bidentate edge-sharing binding was identified for Cd on pure Fh and Cd-carboxyl binding on pure HA. These findings have significant implications not only for the sequestration of Cd in contaminated environments but also the coupled biogeochemical cycling of Cd, Fe and C in the critical zone. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Chemical treatment of wastewaters produced during separation of iodine 131; Traitement chimique des eaux residuaires provenant de la preparation d'iode-131

Energy Technology Data Exchange (ETDEWEB)

Cohen, P.; Marcaillou, J.; Amavis, R.

1959-06-22

The authors report the development and assessment of a chemical treatment of radioactive wastewaters by co-precipitation. This treatment is aimed at replacing a treatment based on the use of calcium phosphate which proved to be insufficient for wastewaters resulting from the production of iodine 131. After a presentation of the characteristics of the effluents to be processed, the authors report co-precipitation tests performed on effluents before release in the storage vessel (by using barium hydroxide, lead acetate or lead sulfate) and on effluents diluted on the storage vessel. They show that a co-precipitation method based on the use of lead sulfate in alkaline medium gives the best results.

Chemical treatment of wastewaters produced during separation of iodine 131

International Nuclear Information System (INIS)

Cohen, P.; Marcaillou, J.; Amavis, R.

1959-01-01

The authors report the development and assessment of a chemical treatment of radioactive wastewaters by co-precipitation. This treatment is aimed at replacing a treatment based on the use of calcium phosphate which proved to be insufficient for wastewaters resulting from the production of iodine 131. After a presentation of the characteristics of the effluents to be processed, the authors report co-precipitation tests performed on effluents before release in the storage vessel (by using barium hydroxide, lead acetate or lead sulfate) and on effluents diluted on the storage vessel. They show that a co-precipitation method based on the use of lead sulfate in alkaline medium gives the best results

Thermal behavior and phase transformation of ZrO{sub 2}–10%SiO{sub 2} precursor powder prepared by a co-precipitation route without adding stability agent

Energy Technology Data Exchange (ETDEWEB)

Chu, Hsueh-Liang [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, Cheng-Li [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Lee, Kuen-Chan [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Huang, Hong-Hsin [Department of Electrical Engineering, Cheng Shiu University, 840 Cheng Ching Road, Niaosong, Kaohsiung 83347, Taiwan (China); Lee, Huey-Er, E-mail: huerle@kmu.edu.tw [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan (China)

2014-12-15

Highlights: • The precursor powders contained about 68.3 wt% ZrO{sub 2}, which corresponds to ZrO{sub 2}·1/8 H{sub 2}O. • The exothermic peak temperature of tetragonal ZrO{sub 2} formation occurred at 1014 K. • The activation energy of ZrO{sub 2}–10%SiO{sub 2} precursors crystallization is 993.7 kJ/mol. • Only the tetragonal ZrO{sub 2} formed when the precursor calcined at 1173–1373 K for 2 h. • As calcined at 1473 K for 2 h, tetragonal ZrO{sub 2} fully converted to monoclinic ZrO{sub 2}. - Abstract: Thermal behavior and phase transformation of ZrO{sub 2}–10%SiO{sub 2} precursor powder prepared by a co-precipitation route without adding stability agent has been studied using different thermal analysis/thermogravimetry (DTA/TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED), high-resolution TEM (HRTEM) and energy-dispersive X-ray spectrometer (EDS). The TG results show that four weight loss regions were from 298 to 443 K, 443 to 743 K, 743 to 793 K and 793 to 1400 K. The DTA result shows that the ZrO{sub 2} freeze-dried precursor powders crystallization at 1014 K. The activation energy of 993.7 kJ/mol was obtained for tetragonal ZrO{sub 2} crystallization using a non-isothermal process. The XRD result shows that only a single phase of tetragonal ZrO{sub 2} appears when the freeze-dried precursor powders after calcination between 1173 and 1373 K for 2 h. Moreover, when calcined at 1473 K for 2 h, the phase transformation from tetragonal ZrO{sub 2} fully converted to monoclinic ZrO{sub 2} occurred.

Treatability of inorganic arsenic and organoarsenicals in groundwater

International Nuclear Information System (INIS)

Kuhlmeier, P.D.; Sherwood, S.P.

1996-01-01

A 2-year three-phase study into methods for treatment of mixed inorganic and organic arsenic species to drinking water levels was conducted at a former pesticide facility in Houston, Tex. The species present include monomethylarsinic acid, dimethylarsinic acid, arsenate, and arsenite. Phase One studies reported here included the evaluation of four adsorbents using bottle roll and column flow through techniques, oxidation through the application of Fenton's reagent followed by coprecipitation, coprecipitation without oxidation, and ultraviolet (UV)/ozone tests. The four adsorbents tested were activated carbon, activated alumina, ferrous sulfide, and a strongly basic ion exchange resin. All adsorbents removed some arsenic, but none except ferrous sulfide was sufficiently effective to warrant follow-up studies. Two small ferrous sulfide column tests, run under different conditions, removed arsenic but not to the levels and loading capacities needed to make this method practical. Organic compound destruction was tested using Fenton's reagent (a mixture of hydrogen peroxide and ferrous iron) before coprecipitation. Arsenic was reduced to 170 ppb in the treated liquor. Coprecipitation without oxidative pretreatment produced a liquor containing 260 ppb arsenic. A two-stage Fenton-type coprecipitation procedure produced a supernatant containing 110 ppb total arsenic. Preliminary tests with a second-stage oxidative process, using ozone and UV radiation, showed approximately 80% destruction of an organic-arsenic surrogate (cacodylic acid) in 1 hour

Evaluation of the structure and microstructure of Ni{sub x}Mg{sub 1-x}O oxides obtained by co-precipitation; Evaluacion de la estructura y microestructura de oxidos de Ni{sub x}Mg{sub 1-x}O obtenidos por co-precipitacion

Energy Technology Data Exchange (ETDEWEB)

Martinez L, G.; Kryshtab, T. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, Av. Instituto Politecnico Nacional s/n, Edif. 9, 07738 Mexico D. F. (Mexico); Hesiquio G, M. [IPN, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, Av. Instituto Politecnico Nacional s/n, Edif. 6, 07738 Mexico D. F. (Mexico); Kryvko, A., E-mail: marloz7@yahoo.com.mx [IPN, Escuela Superior de Ingenieria Mecanica y Electrica, Departamento de Sistemas, Av. Instituto Politecnico Nacional s/n, Edif. Z-4, 07738 Mexico D. F. (Mexico)

2013-06-01

Ni{sub x}Mg{sub 1-x}O oxides were prepared by thermal treatment at temperatures of 400, 600 and 800 C from a hydrotalcite-like precursor obtained by co-precipitation at constant ph. The oxides obtained were characterized by X-ray diffraction methods. From the obtained results we concluded that the oxides calcined at temperatures of 400, and 600 C are unstable that means that there exists the effect of memory and with a time they return to the precursor. Presence of Ni in Mg oxide provides stability of the compounds thermally treated at 800 C. In order to analyze the structure and microstructure, the reflections 111, 200 and 220 were used. The positions of the maxima of the diffraction peaks are shifted with respect to the simulated ones for Mg O and Ni O. This result reveals that in solid solutions studied compressive strains or vacation are present. The parameters of the microstructure (coherent domain size and micro deformations) were evaluated. The coherent domain size was found to be in the range of 8 - 10 nm and the presence of residual strains of micro deformation can be associated with the existence of extended defects. (Author)

Crystallite growth kinetics of TiO{sub 2} surface modification with 9 mol% ZnO prepared by a coprecipitation process

Energy Technology Data Exchange (ETDEWEB)

Ko, Horng-Huey [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Hsi, Chi-Shiung [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Zhao, Xiujian, E-mail: opluse@whut.edu.cn [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China)

2014-03-05

Highlights: • TiO{sub 2} powder surface modification with 9 mol% ZnO was obtained. • Phase transformation from anatase to rutile was hindered by ZnO added. • Growth kinetic of anatase TiO{sub 2} nanocrystallites in T-9Z powders was described as: D{sub A,9}{sup 2}=2.42×10{sup 5}×exp(-39.9×10{sup 3}/RT). • Growth kinetic of rutile TiO{sub 2} nanocrystallites in T-9Z powders was described as: D{sub R,9}{sup 2}=8.49×10{sup 5}×exp(-47.6×10{sup 3}/RT) rutile TiO{sub 2}. -- Abstract: The nanocrystallite growth of TiO{sub 2} surface modification with 9 mol% ZnO prepared by a coprecipitation process has been studied. Thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–VIS–NIR spectrophotometry have been utilized to characterize the TiO{sub 2} nanocrystallites surface modification with 9 mol% ZnO (denoted by T-9Z). The DTA result shows that the anatase TiO{sub 2} first formed at 533 K and the completion of anatase TiO{sub 2} crystallization occurred at 745 K for the T-9Z freeze-dried precursor powders. XRD results reveal that the anatase and rutile TiO{sub 2} coexist when the T-9Z freeze-dried precursor powders were calcined at 523–973 K for 2 h. When the T-9Z freeze-dried precursor powders were calcined at 973 K for 2 h, rutile TiO{sub 2} was the major phase, and the minor phases were anatase TiO{sub 2} and Zn{sub 2}Ti{sub 3}O{sub 8}. The phase was composed of the rutile TiO{sub 2} and Zn{sub 2}TiO{sub 4} for the T-9Z freeze-dried precursor powders after calcination at 1273 K for 2 h. The growth kinetics of TiO{sub 2} nanocrystallites in T-9Z powders were described as: D{sub A,9}{sup 2}=2.42×10{sup 5}×exp(-39.9×10{sup 3}/RT)and D{sub R,9}{sup 2}=8.49×10{sup 5}×exp(-47.6×10{sup 3}/RT) for anatase and rutile TiO{sub 2} nanocrystallites respectively. The analysis results of UV/VIS/NIR spectra reveal that the T-9Z freeze

Growth mechanisms for spherical mixed hydroxide agglomerates prepared by co-precipitation method: A case of Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3}(OH){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Yang, Yue [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Xu, Shengming, E-mail: smxu@stinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Xie, Ming [The State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Precious Metals, Kunming 650106 (China); He, Yinghe, E-mail: yinghe.he@jcu.edu.au [School of Engineering and Physical Sciences, James Cook University, Douglas, Queensland 4811 (Australia); Huang, Guoyong [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Yang, Youcai [The State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Precious Metals, Kunming 650106 (China)

2015-01-15

Highlights: • Anisotropic growth of Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3}(OH){sub 2} along the [0 0 1] direction was revealed. • DFT calculation results show crystal surface energies of (0 0 1) plane is highest. • A new model was proposed to explain the formation of spherical agglomerates. - Abstract: Spherical Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3}(OH){sub 2} agglomerates were synthesized by the co-precipitation method in the presence of ammonia. The results show that the growth mechanism of spherical agglomerates follows three-stages, i.e. nucleation and anisotropic growth of single crystals; agglomeration of polycrystalline crystallites agglomerated by single crystal grains as primary particles to form embryonic agglomerates; formation, growth and consolidation of spherical agglomerates or particles by agglomeration of embryonic agglomerates, continued growth of individual crystals in the agglomerates and further attachment of primary particles. The first two stages are very fast while the last stage takes almost the entire process to complete. The main reason for the anisotropic growth of Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3}(OH){sub 2} crystal is that crystal surface energy of E{sub (001)}, E{sub (100)}, E{sub (101)} and E{sub (102)} is different with E{sub (001)} being the highest. The morphology of the final spherical agglomerates is explained by partial re-crystallization of contacting primary particles. The growth process of spherical agglomerates was examined by X-ray diffraction, scanning electron microscope, transmission electron microscope and calculation of crystal surface energy using density function theory.

Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

International Nuclear Information System (INIS)

Gyergyek, Saso; Makovec, Darko; Kodre, Alojz; Arcon, Iztok; Jagodic, Marko; Drofenik, Miha

2010-01-01

The Co-ferrite nanoparticles having a relatively uniform size distribution around 8 nm were synthesized by three different methods. A simple co-precipitation from aqueous solutions and a co-precipitation in an environment of microemulsions are low temperature methods (50 o C), whereas a thermal decomposition of organo-metallic complexes was performed at elevated temperature of 290 o C. The X-ray diffractometry (XRD) showed spinel structure, and the high-resolution transmission electron microscopy (HRTEM) a good crystallinity of all the nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) showed the composition close to stoichiometric (∼CoFe 2 O 4 ) for both co-precipitated nanoparticles, whereas the nanoparticles prepared by the thermal decomposition were Co-deficient (∼Co 0.6 Fe 2.4 O 4 ). The X-ray absorption near-edge structure (XANES) analysis showed Co valence of 2+ in all the samples, Fe valence 3+ in both co-precipitated samples, but average Fe valence of 2.7+ in the sample synthesized by thermal decomposition. The variations in cation distribution within the spinel lattice were observed by structural refinement of X-ray absorption fine structure (EXAFS). Like the bulk CoFe 2 O 4 , the nanoparticles synthesized at elevated temperature using thermal decomposition displayed inverse spinel structure with the Co ions occupying predominantly octahedral lattice sites, whereas co-precipitated samples showed considerable proportion of cobalt ions occupying tetrahedral sites (nearly 1/3 for the nanoparticles synthesized by co-precipitation from aqueous solutions and almost 1/4 for the nanoparticles synthesized in microemulsions). Magnetic measurements performed at room temperature and at 10 K were in good agreement with the nanoparticles' composition and the cation distribution in their structure. The presented study clearly shows that the distribution of the cations within the spinel lattice of the ferrite nanoparticles, and consequently their magnetic

Bench-scale treatability studies for simulated incinerator scrubber blowdown containing radioactive cesium and strontium

International Nuclear Information System (INIS)

Coroneos, A.C.; Taylor, P.A.; Arnold, W.D. Jr.; Bostick, D.A.; Perona, J.J.

1994-12-01

The purpose of this report is to document the results of bench-scale testing completed to remove 137 Cs and 90 Sr from the Oak Ridge K-25 Site Toxic Substances Control Act (TSCA) Incinerator blowdown at the K-25 Site Central Neutralization Facility, a wastewater treatment facility designed to remove heavy metals and uranium from various wastewaters. The report presents results of bench-scale testing using chabazite and clinoptilolite zeolites to remove cesium and strontium; using potassium cobalt ferrocyanide (KCCF) to remove cesium; and using strontium chloride coprecipitation, sodium phosphate coprecipitation, and calcium sulfate coprecipitation to remove strontium. Low-range, average-range, and high-range concentration blowdown surrogates were used to complete the bench-scale testing

Obtainment of zirconium oxide and partially stabilized zirconium oxide with yttrium and rare earth oxides, from Brazilian zirconite, for ceramic aim

International Nuclear Information System (INIS)

Ribeiro, S.

1991-05-01

This work presents experimental results for processing of brazilian zirconite in order to obtain zirconium oxide with Yttrium and Rare Earth oxide by mutual coprecipitation for ceramics purposes. Due to analysis of experimental results was possible to obtain the optimum conditions for each one of technological route stage, such as: alkaline fusion; acid leaching; sulfactation and coprecipitation. (author)

Chemical processes for the extreme enrichment of tellurium into marine ferromanganese oxides

Science.gov (United States)

Kashiwabara, Teruhiko; Oishi, Yasuko; Sakaguchi, Aya; Sugiyama, Toshiki; Usui, Akira; Takahashi, Yoshio

2014-04-01

Tellurium, an element of growing economic importance, is extremely enriched in marine ferromanganese oxides. We investigated the mechanism of this enrichment using a combination of spectroscopic analysis and adsorption/coprecipitation experiments. X-ray Absorption Near-Edge Structure (XANES) analysis showed that in adsorption/coprecipitation systems, Te(IV) was oxidized on δ-MnO2 and not oxidized on ferrihydrite. Extended X-ray Absorption Fine Structure (EXAFS) analysis showed that both Te(IV) and Te(VI) were adsorbed on the surface of δ-MnO2 and ferrihydrite via formation of inner-sphere complexes. In addition, Te(VI) can be structurally incorporated into the linkage of Fe octahedra through a coprecipitation process because of its molecular geometry that is similar to the Fe octahedron. The largest distribution coefficient obtained in the adsorption/coprecipitation experiments was for the Te(VI)/ferrihydrite coprecipitation system, and it was comparable to those calculated from the distribution between natural ferromanganese oxides and seawater. Our XAFS and micro-focused X-ray fluorescence (μ-XRF) mapping of natural ferromanganese oxides showed that Te was structurally incorporated as Te(VI) in Fe (oxyhydr)oxide phases. We conclude that the main process for the enrichment of Te in ferromanganese oxides is structural incorporation of Te(VI) into Fe (oxyhydr)oxide phases through coprecipitation. This mechanism can explain the unique degree of enrichment of Te compared with other oxyanions, which are mainly enriched via adsorption on the surface of the solid structures. In particular, the great contrast in the distributions of Te and Se is caused by their oxidized species: (i) the similar geometry of the Te(VI) molecule to Fe octahedron, and (ii) quite soluble nature of Se(VI). Coexisting Mn oxide phases may promote structural incorporation of Te(VI) by oxidation of Te(IV), although the surface oxidation itself may not work as the critical enrichment process as

Characteristics and properties of a novel in situ method of synthesizing mesoporous TiO{sub 2} nanopowders by a simple coprecipitation process without adding surfactant

Energy Technology Data Exchange (ETDEWEB)

Yeh, Shang-Wei [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80782, Taiwan (China); Department of Life Science, National University of Kaohsiung, 700 Kaohsiung University Road, Kaohsiung 811, Taiwan (China); Ko, Horng-Huey [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80782, Taiwan (China); Chiang, Hsiu-Mei [Department of Cosmeceutics, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan (China); Chen, Yen-Ling, E-mail: yelichen@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80782, Taiwan (China); Lee, Jian-Hong [Clean Energy and Eco-Technology Center, Industrial Technology Research Institute, 8 Gongyan Road, Tainan 734, Taiwan (China); Wen, Chiu-Ming [Department of Life Science, National University of Kaohsiung, 700 Kaohsiung University Road, Kaohsiung 811, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80782, Taiwan (China)

2014-11-15

Highlights: • The TiO{sub 2} precursor powder contained anatase and 19.5% NH{sub 4}Cl. • Mesoporous anatase TiO{sub 2} nanopowders were successfully synthesized. • Uncalcined precursor powder contained the phases of type I NH{sub 4}Cl and anatase TiO{sub 2}. • Anatase size increases from 3.3 to 14.3 nm when calcined at 473–773 K for 2 h. • The average pore size between 3.80 and 14.0 nm when calcined between 473 and 773 K. - Abstract: In situ synthesis of mesoporous TiO{sub 2} nanopowders using titanium tetrachloride (TiCl{sub 4}) and NH{sub 4}OH as initial materials has been successfully fabricated by a coprecipitation process without the addition of surfactant. Characteristics and properties of the mesoporous TiO{sub 2} nanopowders were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Barrent–Joyner–Halenda (BJH) analyses, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high resolution TEM (HRTEM). The results of TG and XRD showed that the NH{sub 4}Cl decomposed between 513 and 673 K. XRD results showed that the anatase TiO{sub 2} only contained a single phase when the calcination temperature of the precursor powder was less than 673 K. Whereas phases of anatase and rutile TiO{sub 2} coexist after calcining at 773 K for 2 h. The crystalline size of the anatase and rutile TiO{sub 2} was 14.3 and 26.6 nm, respectively, when the precursor powder was calcined at 773 K for 2 h. The BET and BJH results showed a significant increase in surface area and pore volumes when the NH{sub 4}Cl was completely decomposed. The maximum values of BET specific surface area and volume were 172.8 m{sup 2}/g and 0.392 cm{sup 3}/g, respectively. The average pore sizes when calcination was at 473 and 773 K for 2 h were 3.8 and 14.0 nm, respectively.

Characterisation of Catfish (Clarias Batrachus) Oil: β-Cyclodextrin Inclusion Complex

International Nuclear Information System (INIS)

Zaibunnisa Abdul Haiyee; Nor Izzatul Adyani Yahya; Norizzah Abd Rashid; Dzulkifly Mat Hashim

2016-01-01

Catfish is a cheap source of essential omega-3 fatty acids especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Catfish oil was extracted and clean-up using pressurised liquid extraction (PLE) from the viscera of catfish (Clarias batrachus). However, the characteristics of catfish oils are sticky, strong fishy odour and can easily be oxidised with short shelf-life. In this study, catfish oil was converted into powder by formation of inclusion complex with β-cyclodextrin. Inclusion complex was prepared by using co-precipitation and kneading methods and compared with physical mixture. The inclusion complex formed were characterised by using field emission scanning electron microscopy (FESEM), differential scanning calorimeter (DSC) and fourier transform infrared spectroscopy (FTIR). FESEM images revealed that inclusion complex using co-precipitation and kneading methods has smaller in crystal sizes and appeared as different morphology compared to physical mixture. DSC proved that co-precipitation method was able to form new solid phase due to shifting of melting point to higher temperature (145.22 degree Celcius). FTIR supported the result by proving strengthening of carbonyl group (C=O). Therefore, co-precipitation method was able to successfully produce inclusion complex of catfish oil, β-cyclodextrin. (author)

A new co conversion technology based on liquid/liquid extraction column

Energy Technology Data Exchange (ETDEWEB)

Borda, Gilles; Ode, Denis; Duhamet, Jean; Brackx, Emmanuelle [CEA Valrho - Marcoule - BP 17171 - 30207 Bagnols sur Ceze Cedex (France)

2009-06-15

The current objective of implementing 'direct' coprecipitation of uranium, plutonium and minor actinides for nuclear fuel re-fabrication leads to reconsider the (co)precipitation step, and more precisely its adaptability to new flowrates' specifications. Indeed, coprecipitation of a uranium fraction together with plutonium results in an appreciable increase in the process flow rates for this step. The technological impact of the increase in capacity could require the development of a different concept for a continuous device capable of ensuring the proposed process. A new type of device designed and patented by the CEA has been tested since 2007. The patent is for organic confinement in a pulsed column (PC) or Couette column (CC). The precipitation reaction between the oxalate complexing agent and a surrogate nitrate-cerium(II) or neodymium(III) alone, or coprecipitated uranium(IV) and cerium(III), occurs within an emulsion created in the device by these two phases flowing with a counter-current chemically inert organic phase (for example TPH) produced by the stirring action of the pulsator (PC) or the central rotor (CC). The precipitate is confined and thus does not form deposits on the vessel walls (which are also water-repellent); it flows downward by gravity and exits the column continuously into a settling tank. This paper describes the recent results obtained with this new technology for precipitation of Ce and Nd and coprecipitation of U + Ce in pulsed column and Couette column. It describes a first modeling allowing further extrapolation of this device to high capacities. (authors)

The Sr-90 waste treatment by using sodium carbonat as a carrier

International Nuclear Information System (INIS)

Suroto.

1978-01-01

The coprecipitation processes of the Sr-90 wastes, with the lime-soda treatment, that followed by the mechanism of isomorph substitution, have shown a good performance in pH 7-8. Excess of natrium carbonate in the lime-soda treatment caused the decrease of the decontamination factor. This research shows that the coprecipitation by calcite-phosphate was better than the lime-soda treatment. (author)

Co-precipitation synthesis and upconversion luminescence ...

Indian Academy of Sciences (India)

Introduction. Researches of rare-earth-doped upconversion (UC) materials as fluorescent labels, temperature-sensing probes, solid-state lasers and new generation television screens have recently started to be considered1,2 due to their enhanced luminescent properties induced by the small size. UC process is the gener-.

Effect of agglomeration during coprecipitation: Delayed ...

Indian Academy of Sciences (India)

Administrator

Department of Ceramic Technology, Government College of Engineering and Ceramic Technology,. Kolkata 700 ... Different wet chemical routes have been developed in the recent ..... magnesium with hydrous aluminium oxide, Ph D Thesis,.

Co-precipitation synthesis and upconversion luminescence ...

Indian Academy of Sciences (India)

... light: strong green (539 nm), weak red (670 nm) and near-infrared (760 nm). The upconversion luminescence is based on two-photon absorption by the energy transfer from the donor (Yb3+) to the acceptor (Ho3+). All the results indicate that ZrO2:Yb3+-Ho3+ phosphors could be a promising biological labelling material.

Synthesis and functionalisation of metal and metal oxide nanoparticles for theranostics

OpenAIRE

Mundell, VJ

2013-01-01

Metal and metal oxide nanoparticles including calcium oxide, gold, and superparamagnetic iron oxide nanoparticles (SPIOs) were synthesised using a range of techniques including reduction, co-precipitation and spinning disc technology. SPIOs were primarily synthesised via a co-precipitation method using iron (II) chloride, iron (III) chloride and ammonia; a spinning disc reactor and gaseous ammonia were trialled successfully for scale up, producing spherical particles of 10-40 nm in diameter a...

Steam Reforming of Ethylene Glycol over Ni/Al2O3 Catalysts: Effect of the Preparation Method and Reduction Temperature

International Nuclear Information System (INIS)

Choi, Dong Hyuck; Park, Jung Eun; Park, Eun Duck

2015-01-01

The effect of preparation method on the catalytic activities of the Ni/Al 2 O 3 catalysts on steam reforming of ethylene glycol was investigated. The catalysts were prepared with various preparation methods such as an incipient wetness impregnation, wet impregnation, and coprecipitation method. In the case of coprecipitation method, various precipitants such as KOH, K 2 CO 3 , and NH 4 OH were compared. The prepared catalysts were characterized by using N 2 physisorption, inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, temperature programmed reduction, pulsed H 2 chemisorption, temperature-programmed oxidation, scanning electron microscopy, and thermogravimetric analysis. Among the catalysts reduced at 773 K, the Ni/Al 2 O 3 catalyst prepared by a coprecipitation with KOH or K 2 CO 3 as precipitants showed the best catalytic performance. The preparation method affected the particle size of Ni, reducibility of nickel oxides, catalytic performance (activity and stability), and types of coke formed during the reaction. The Ni/Al 2 O 3 catalyst prepared by a coprecipitation with KOH showed the increasing catalytic activity with an increase in the reduction temperature from 773 to 1173 K because of an increase in the reduction degree of Ni oxide species even though the particle size of Ni increased with increasing reduction temperature

Electromagnetic properties of NiZn ferrite nanoparticles and their polymer composites

Energy Technology Data Exchange (ETDEWEB)

Parsons, P. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Duncan, K. [U.S. Army, Communications-Electronics Research, Development and Engineering Center, Space and Terrestrial Communications Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Giri, A. K. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Bowhead Science and Technology, LLC, Belcamp, Maryland 21017 (United States); Xiao, J. Q. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Karna, S. P., E-mail: shashi.p.karna.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States)

2014-05-07

The magnetic properties of polycrystalline NiZn ferrite nanoparticles synthesized using a polyol-reduction and coprecipitation reaction methods have been investigated. The effects on magnetization of synthesis approach, chemical composition, processing conditions, and on the size of nanoparticles on magnetization have been investigated. The measured room-temperature magnetization for the as-prepared magnetic nanoparticles (MNP) synthesized via polyol-reduction and coprecipitation is 69 Am{sup 2} kg{sup −1} and 14 Am{sup 2} kg{sup −1}, respectively. X-ray diffraction measurements confirm spinel structure of the particles with an estimated grain size of ∼80 nm obtained from the polyol-reduction and 28 nm obtained from these coprecipitation techniques. Upon calcination under atmospheric conditions at different temperatures between 800 °C and 1000 °C, the magnetization, M, of the coprecipitated MNP increases to 76 Am{sup 2} kg{sup −1} with an estimated grain size of 90 nm. The MNP-polymer nanocomposites made from the synthesized MNP in various loading fraction and high density polyethylene exhibit interesting electromagnetic properties. The measured permeability and permittivity of the magnetic nanoparticle-polymer nanocomposites increases with the loading fractions of the magnetic nanoparticles, suggesting control for impedance matching for antenna applications.

Use of a pulsed column contactor as a continuous oxalate precipitation reactor

International Nuclear Information System (INIS)

Borda, Gilles; Brackx, Emmanuelle; Boisset, Laurence; Duhamet, Jean; Ode, Denis

2011-01-01

Research highlights: → A new type of continuous precipitating device was patented by CEA and tested with reaction between a surrogate nitrate cerium(III) or neodymium(III) and oxalate complexing agent. → Precipitate is confined in aqueous phase emulsion in tetrapropylene hydrogen and does not form deposit on the vessel walls. → Measure size of the precipitate ranges from 20 to 40 μm, it meets the process requirements to filter, and the precipitation reaction is complete. → The laboratory design can be extrapolated to an industrial uranium(IV) and minor actinide(III) coprecipitating column. - Abstract: The current objective of coprecipitating uranium, and minor actinides in order to fabricate a new nuclear fuel by direct (co)precipitation for further transmutation, requires to develop specific technology in order to meet the following requirements: nuclear maintenance, criticity, and potentially high flowrates due to global coprecipitation. A new type of device designed and patented by the CEA was then tested in 2007 under inactive conditions and with uranium. The patent is for organic confinement in a pulsed column (PC). Actually, pulsed columns have been working for a long time in a nuclear environment, as they allow high capacity, sub-critical design (annular geometry) and easy high activity maintenance. The precipitation reaction between the oxalate complexing agent and a surrogate nitrate - cerium(III) or neodymium(III) alone, or coprecipitated uranium(IV) and cerium(III) - occurs within an emulsion created in the device by these two phases flowing with a counter-current chemically inert organic phase (for example tetrapropylene hydrogen-TPH) produced by the stirring action of the column pulsator. The precipitate is confined and thus does not form deposits on the vessel walls (which are also water-repellent); it flows downward by gravity and exits the column continuously into a settling tank. The results obtained for precipitation of cerium or

Determination of americium in urine

International Nuclear Information System (INIS)

Shvydko, N.S.; Mikhajlova, O.A.; Popov, D.K.

1988-01-01

A technique has been developed for the determination of americium 241 in urine by a raiochemical purification of the nuclide from uranium (upon co-precipitation of americium 241 with calcium and lanthanum), plutonium, thorum, and polonium 210 (upon co-precipitation of these radionuclides with zirconium iodate). α-Radioactivity was measured either in a thick layer of the americium 241 precipitate with a nonisotope carrier or in thin-layer preparations after electrolytic precipitation of americium 241 on a cathode

An easy method for the determination of Ra isotopes and actinide alpha emitters from the same water sample

International Nuclear Information System (INIS)

Moron, M.C.; Garcia-Tenorio, R.; Garcia-Montano, E.; Garcia-Leon, M.; Madurga, G.

1986-01-01

Radium isotopes and actinide α emitters are easily determined from the same water sample. The Ra fraction is obtained by coprecipitation with Ba, while a Fe coprecipitation is used for the actinides. Both fractions are measured with a gas-flow proportional counter. Additionally the isotopic Ra composition is obtained by measuring at two or three different times the α activity from the Ra-fraction. The method is applied to rain water and drinking water samples. (author)

Investigation on the measurement of radioactivities of 131I in milk

International Nuclear Information System (INIS)

Kimura, Syojiro; Morimoto, Junko

1990-01-01

The analytical method combined with chemical treatment (ion exchange, solvent extraction, coprecipitation) and measurement of β radiation by a low back ground counter has been adopted in 'Standard Method of Analysis for Hygienic Chemicals' as the analytical method of 131 I in milk. However, it was difficult to apply this method to the analysis of some kinds of milk on the market, because some colloidal phenomena appeared at the coprecipitation step. As a result of detection by use of thin layer chromatography and mass spectrometry, it is guessed that this is caused by materials possessing surface active action, such as fatty acids which constitute milk fat (e.g., palmitic acid, stearic acid etc.), and surface active agents added to dairy products. Therefore, after the removal with ether of these surfactants before the coprecipitation step, the measurement of radioactivities of 131 I can be carried out without trouble. (author)

Barium Staminate as Semiconductor Working Electrodes for Dye-Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

Fu-an Guo

2010-01-01

Full Text Available Dye-sensitized solar cells (DSSCs are fabricated with perovskite-type BaSnO3 as the photoelectrode materials. Different preparation methods including coprecipitation, hydrothermal, and solid state reaction are employed to synthesize BaSnO3 particles to optimize the photoelectric activities of electrode materials. The photoelectric properties of BaSnO3 particles and the performances of DSSCs are investigated by surface photovoltage spectroscopy and current-voltage measurements. The light-to-electricity conversion of 1.1% is preliminarily reached on the DSSC made of the coprecipitation-derived BaSnO3 particles. Large current density of hole injection into the HOMO level of N719 dye from the valence band of BaSnO3 and reduced photogenerated charge recombination in BaSnO3 could be responsible for the observed solar cell performance of the DSSC fabricated from the coprecipitation-derived BaSnO3 particles.

Manganese oxide as a promoter for C2-C4 olefin production in the hydrogenation of carbon dioxide

International Nuclear Information System (INIS)

Kim, C.; Chen, K.; Hanson, F.V.; Oblad, A.G.; Tsai, Y.

1986-01-01

A number of active research and development programs have been initiated to explore the potential of CO hydrogenation process as a source of low molecular weight (C 2 -C 4 ) olefins. Metal catalysts such as Co-Mn, Ni-zeolite, Rd and Mo have been evaluated for low molecular weight olefin selectivity. The coprecipitated Fe-Mn system (Mn/Fe=9/1) was reported to be highly olefin selective. Recently, many investigators reported supporting evidence for the promotional effect of Mn for precipitated Fe catalysts. In this study, Raney Fe promoted with Mn has been evaluated for C 2 -C 4 olefin selectivity in the hydrogenation of CO relative to coprecipitated Fe-Mn catalysts. Catalyst characterization, including BET surface area, X-ray diffraction, selective chemisorption and ESCA, has been carried to provide insight into the role of manganese in both the Coprecipitated and Raney catalyst systems

Effect of Co2+ and Y3+ ions insertion on the microstructure development and magnetic properties of Ni0.5Zn0.5Fe2O4 powders synthesized using Co-precipitation method

Science.gov (United States)

Rashad, M. M.; Rayan, D. A.; Turky, A. O.; Hessien, M. M.

2015-01-01

Nanocrystalline Ni0.5Zn0.5-xCoxFe2-zYzO4 powders (x=0-0.3 and z from 0 to 0.3) have been synthesized via a facile co-precipitation technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) are utilized in order to study the effect of variation of cobalt and yttrium substitutions and its impact on crystalline size, lattice parameter, X-ray density, microstructure and magnetic properties of the formed powders. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase for the formed precursors precipitated at pH 10 annealed at 1000 oC for 2 h. The lattice parameter and the unit cell were decreased linearly with increasing Co content whereas they were increased with increasing the Y incorporation. Additionally, the porosity was increased with increasing Co concentration while it was decreased with increasing the Y insertion. The mean ionic radii and hopping and bond lengths was decreased with the value of Co2+ and they were increased with the value of Y3+ ion as well as both of Y3+ and Co2+ ions. The microstructures of the produced powders were found to be cubic like structure. The addition of Y3+ ion suppressed the grain size whereas addition of Co2+ ion enhanced the grain growth availably. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Co and Y concentrations incorporation up to x=0.3. Meanwhile, the formed powders exhibited superparamagnetic characteristics. A high saturation magnetization (77.0 emu/g) was achieved for Ni0.5Zn0.2Co0.3Fe2O4 sample annealed at 1000 oC for 2 h.

A Highly Efficient Adsorbent Cu-Perusian Blue@Nanodiamond for Cesium in Diluted Artificial Seawater and Soil-Treated Wastewater.

Science.gov (United States)

Matsumoto, Kazuko; Yamato, Hideyuki; Kakimoto, Seishiro; Yamashita, Takeshi; Wada, Ryutaro; Tanaka, Yoshiaki; Akita, Masakazu; Fujimura, Tadamasa

2018-04-11

A new adsorbent Cu-Perussian blue@Nanodiamond (Cu-PB@DND) for Cs + removal was prepared and characterized with IR, SEM, X-ray diffraction, particle size analysis, and zeta-potential. The adsorbent consists of a core of aggregated detonation nanodiamond (DND) particles with the surface treated with Cu-PB. Cesium adsorption was studied in two modes; a co-precipitation mode and a batch mode. In the co-precipitation mode, DND, CuCl 2 , and K 4 [Fe(CN) 6 ] were added sequentially to a Cs + solution in diluted artificial seawater. In the batch mode, adsorbent Cu-PB@DND was dispersed into a Cs + solution with stirring. The distribution coefficient (K d ) of the co-precipitation mode was 8.8 × 10 7 (mL/g) at Cs + 6.6 ppm in 0.07% seawater. The K d value of the batch mode was 1.3 × 10 6 (mL/g). Precipitation of Cs + -incorporated particles was complete, and post filtration was not necessary. Excess copper and iron ions were completely removed and were not detected in the supernatant. The adsorption data for Cu-PB@DND were analyzed by assuming Langmuir isotherm and a good fit was obtained with a maximum adsorption capacity Q max of 759 mg/g. The co-precipitation method was also applied to soil-treated wastewater.

Chromium containing silica: effect of ultrasonic and purification methods on color products

International Nuclear Information System (INIS)

Martines, M.A.U.; Jafelicci Junior, M.; Davolos, M.R.

1990-01-01

Chromium containing silica has numerous applications, such as: fiber-optics, luminescent materials, catalysts and pigments. In paint and ceramic pigments, chromate and dichromate ions, and silica are largely used. In this paper, it has been investigated the effect of pH, heating methods, and ultrasonic stirring on chromium oxidation states coprecipitated with silica. The material has been obtained from the coprecipitation of an aqueous diluted sodium silicate solution and acid chromium nitrate solution, purified by extractions and dialysis, and dried with microwave oven. Products have been characterized by X-ray powder diffraction, infrared vibrational spectroscopy and nitrogem adsorption isotherm (BET). Coprecipitates are non cristalline and the specific surface area value for sample obtained by conventional heating is smaller than the one for sample obtained by ultrasonic method. It is possible to obtain silica with different colors from blue due to the Cr(III), to yellow due to the Cr (VI), depending on the precipitation, purification and drying methods. (author) [pt

Synthesis and characterization of hydroxyapatite-gelatine composite materials for orthopaedic application

International Nuclear Information System (INIS)

Yanovska, A.; Kuznetsov, V.; Stanislavov, A.; Husak, E.; Pogorielov, M.; Starikov, V.; Bolshanina, S.; Danilchenko, S.

2016-01-01

The composite materials based on hydroxyapatite (HA) and gelatine (Gel) with addition of silver and zirconium oxide were obtained. The study investigates a combination of low powered ultrasonic irradiation and low concentration of gelatine in the co-precipitation synthesis. These composites have different weight ratios of organic/inorganic components and may be synthesized in two ways: simple mixing and co-precipitation. Both of which were compared. The estimation of porosity, in vivo testing, surface morphology and phase composition as well as the IR-analysis were provided. Hydroxyapatite was the main crystalline phase in obtained composites. While around powdered HA-Gel composite the connective tissue capsule is formed without bone tissue formation, HA-Gel-Ag porous composite implantation leads to formation of new bone tissue and activation of cell proliferation. Addition of silver ions into composite material allows decreasing inflammation on the first stage of implantation and has positive effect on bone tissue formation. Some of the obtained composite materials containing silver or ZrO_2 are biocompatible. bio-resorbable and osteoconductive with high level of porosity (75–85%). - Highlights: • Hydroxyapatite-gelatine composites with addition of Ag"+ and ZrO_2 were obtained. • Composites were synthesized in two ways: simple mixing and co-precipitation. • Co-precipitation synthesis combined ultrasonic treatment and low concentration of gelatine. • Obtained composites have different weight ratios of organic/inorganic components. • Some composites are osteoconductive and all of them have high level of porosity (75–85%).

Macroscopic and microscopic investigation of Ni(II) sequestration on diatomite by batch, XPS, and EXAFS techniques.

Science.gov (United States)

Sheng, Guodong; Yang, Shitong; Sheng, Jiang; Hu, Jun; Tan, Xiaoli; Wang, Xiangke

2011-09-15

Sequestration of Ni(II) on diatomite as a function of time, pH, and temperature was investigated by batch, XPS, and EXAFS techniques. The ionic strength-dependent sorption at pH < 7.0 was consistent with outer-sphere surface complexation, while the ionic strength-independent sorption at pH = 7.0-8.6 was indicative of inner-sphere surface complexation. EXAFS results indicated that the adsorbed Ni(II) consisted of ∼6 O at R(Ni-O) ≈ 2.05 Å. EXAFS analysis from the second shell suggested that three phenomena occurred at the diatomite/water interface: (1) outer-sphere and/or inner-sphere complexation; (2) dissolution of Si which is the rate limiting step during Ni uptake; and (3) extensive growth of surface (co)precipitates. Under acidic conditions, outer-sphere complexation is the main mechanism controlling Ni uptake, which is in good agreement with the macroscopic results. At contact time of 1 h or 1 day or pH = 7.0-8.0, surface coprecipitates occur concurrently with inner-sphere complexes on diatomite surface, whereas at contact time of 1 month or pH = 10.0, surface (co)precipitates dominate Ni uptake. Furthermore, surface loading increases with temperature increasing, and surface coprecipitates become the dominant mechanism at elevated temperature. The results are important to understand Ni interaction with minerals at the solid-water interface, which is helpful to evaluate the mobility of Ni(II) in the natural environment.

Mutual complementation between water chemistry and isotope techniques

International Nuclear Information System (INIS)

Matthess, G.

1976-01-01

In the water chemistry and isotope methods which applied together enable more extensive statements to be made than each on its own, the following regions of cooperation are brought out: 1) Isotopes as conservative indicators a) microbial decomposition of organic substances in the anaerobic and aerobic region; b) precipitation and coprecipitation; c) mechanical filtration, adsorption and coprecipitation; d) gas exchange; e) dilution by infiltration; 2) geochemical observations as additional basis for isotope investigations; 3) the investigation of the water content substances as additional help to isotope hydrology. (HK/LH) [de

The effect of doping Mg2+ on structure and properties of Sr(1.992-x)MgxSiO4: 0.008Eu2+ blue phosphor synthesized by co-precipitation method

Science.gov (United States)

Yang, Lingxiang; Wang, Jin-shan; Zhu, Da-chuan; Pu, Yong; Zhao, Cong; Han, Tao

2018-01-01

In order to improve the luminescence property of silicate phosphors, a series of Sr(1.992-x)MgxSiO4: 0.008Eu2+(x = 0, 0.25, 0.50, 0.75) blue phosphors have been synthesized using one-step calcination of a precursor prepared by chemical co-precipitation. And then the crystal structure and luminescence properties of the phosphors are investigated by means of X-Ray Diffraction and spectrophotometer. The results show that β-phase existed in the mixed phases of Sr2SiO4 (β+α‧) would transform to α‧-phase with Mg2+ ions doping into the silicate host until it disappeared. On the other hand, the introduction of Mg2+ ions can enhance the intensity of the excitation spectrum and promote the excitation sensitivity of Sr(1.992-x)MgxSiO4: 0.008Eu2+ phosphors in NUV region. Under NUV excitation at 350 nm, all samples exhibit a broadband emission in range of 400-550 nm due to the 4f65d1→4f7(8S7/2) transition of Eu2+ ions. According to Multi-peak fitting to emission spectra by Gauss method, the broad emission band consists of two single bands with peaks Em1 and Em2 locating at 460 and 490 nm, which corresponds to Eu2+ ions occupying the ten-fold oxygen-coordinated Sr1 site and the nine-fold oxygen-coordinated Sr2 site, respectively. The luminescence intensity of Sr(1.992-x)MgxSiO4:0.008Eu2+(x = 0, 0.25, 0.50, 0.75) blue phosphors has been enhanced remarkably after Mg2+ ions are added. Meanwhile, the chromaticity coordinates change from the blue-green region to the blue region as x moves from 0 to 0.75. Moreover, the decay curves are measured and can be well fitted with double exponential decay equation. It shows that the average lifetime is extended with the concentration of Mg2+ ions increasing. These results indicate that Sr(1.992-x)MgxSiO4: 0.008Eu2+(x = 0, 0.25, 0.50, 0.75) can be used as a potential blue phosphor in near UV-excited white LEDs.

Caracterização estrutural, textural e morfológica de aluminato de lítio (LiAlO2 sintetizado por coprecipitação Structural, textural and morphological characterization of lithium aluminate (LiAlO2 synthesized by coprecipitation

Directory of Open Access Journals (Sweden)

A. C. Nascimento

2012-12-01

Full Text Available Aluminato de lítio (LiAlO2 foi sintetizado por coprecipitação. O material foi calcinado em diferentes temperaturas e caracterizado por difração de raios X, espectroscopia na região do infravermelho com transformada de Fourier, adsorção gasosa, microscopia eletrônica de varredura (MEV e microscopia eletrônica de transmissão (MET, possibilitando sua caracterização estrutural, morfológica e textural. Diferentes fases cristalinas foram observadas à medida que a temperatura foi elevada de 550 para 1150 ºC. Texturalmente o material foi classificado como não-poroso e particulado a 550 e 750 ºC, apresentando microporos a 950 ºC. Análises comparativas de imagens de MET e MEV possibilitaram a identificação nanoflocos e microfolhas como as principais morfologias presentes no material.Lithium aluminate (LiAlO2 was synthesized by coprecipitation. The material was calcined at different temperatures and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, gas adsorption, scanning electron microscopy (SEM and transmission electron microscopy (TEM, providing a structural, morphological and textural characterization. Different crystalline phases were observed as the temperature was raised from 550 to 1150 ºC. Texturally, the material was classified as non-porous and particulate at 550 and 750 ºC showing micropores at 950 ºC. Comparative analysis of TEM and SEM images allowed the identification of nanoflakes and microsheets as the main morphology present in the material.

Purification processes of cadmium based quantum dots in aqueous medium: a comparative study

Science.gov (United States)

Petris, Dimitri; Freitas, Denilson V.; dos Santos, Rayany K. V.; Dias, Jéssica M. M.; Navarro, Marcelo

2017-07-01

Three different purification methods for CdTe-MPA quantum dot (QD) were performed in aqueous medium: acid titration (HCl, HClO4, H2SO4 and CH3COOH), non-selective precipitation by addition of acetone and co-precipitation of the QD in the presence of inorganic salts. The QD stock solutions were prepared by an electrochemical method of synthesis, in four different heating times (1 h, 4 h, 8 h and 12 h). After purifications, the QD solids were redispersed in distilled water and analyzed by absorption and emission spectra. The λ abs and λ em of the purified QDs showed similar data observed for QD stock solutions, and the recovery rate varied from 71% to 99%. Co-precipitation method showed some advantages: quantum yield maintenance of the QD redispersed solution, longer period of storage (over 6 months) in solution and in solid state (QD embedded into the KCl crystal lattice). CdSe-MPA and CdS-MPA solutions were also purified by co-precipitation method with KCl, showing good results as observed for CdTe-MPA.

Decontamination by ultrafiltration of low radioactivity waste water from fuel element fabrication

International Nuclear Information System (INIS)

Muller, H.M.

1984-01-01

It could be demonstrated that waste waters which contain uranium in a filterable form, such as laundry and floor-cleaning waste, can be sufficiently decontaminated by means of ultra-filtration. In the case of process waste solutions, which contain uranium in a dissolved form, high decontamination factors could be achieved by means of flocculation or coprecipitation. The following methods were tested: - flocculation with Fe (OH) 3 , - coprecipitation with CaHPO 4 , - precipitation with K 4 (Fe(CN) 6 ). The phosphate precipitation, whereby the uranium is probably coprecipitated as Ca(UO 2 ) 2 (PO 4 ) 2 , was found to be the most reliable method. Difficulties were encountered when complex-forming anions, notably carbonate, oxalate and fluoride were present. These necessitate specific pretreatment steps. Whether ultrafiltration then still remains an economical option must be judged in each individual case. The application of the methods so far developed on combined waste streams remains an object for further research. In combination with a phosphate precipitation, ultrafiltration is a suitable method for the decontamination of low-activity, uranium-contaminated waste waters

Magnetic and Structural Investigations of Nanocrystalline Cobalt-Ferrite

Directory of Open Access Journals (Sweden)

I. Sharifi

2012-10-01

Full Text Available Cobalt ferrite is an important magnetic material due to their large magneto-crystalline anisotropy, high cohercivity, moderate saturation magnetization and chemical stability.In this study, cobalt ferrites Nanoparticles have been synthesized by the co-precipitation method and a new microemulsion route. We examined the cation occupancy in the spinel structure based on the “Rietveld with energies” method. The Xray measurements revealed the production of a broad single ferrite cubic phase with the average particle sizes of about 12 nm and 7nm, for co-precipitation and micro-emulsion methods, respectively. The FTIR measurements between 400 and 4000 cm-1 confirmed the intrinsic cation vibrations of the spinelstructure for the two methods. Furthermore, the Vibrating Sample Magnetometer (VSM was carried out at room temperature to study the structural and magnetic properties. The results revealed that by changing the method from co-precipitation to the reverse micelle the material exhibits a softer magnetic behavior in such a way that both saturation magnetization and coercivity decrease from 58 to 29 emu/g and from 286 to 25 Oe, respectively.

Controlled synthesis of La1−xSrxCrO3 nanoparticles by hydrothermal method with nonionic surfactant and their ORR activity in alkaline medium

International Nuclear Information System (INIS)

Choi, Bo Hyun; Park, Shin-Ae; Park, Bong Kyu; Chun, Ho Hwan; Kim, Yong-Tae

2013-01-01

Graphical abstract: We demonstrate that Sr-doped LaCrO 3 nanoparticles were successfully prepared by the hydrothermal synthesis method using the nonionic surfactant Triton X-100 and the applicability of La 1−x Sr x CrO 3 to oxygen reduction reaction (ORR) electrocatalysis in an alkaline medium. Compared with the nanoparticles synthesized by the coprecipitation method, they showed enhanced ORR activity. - Highlights: • Sr-doped LaCrO 3 nanoparticles were successfully prepared by the hydrothermal method using the nonionic surfactant. • Homogeneously shaped and sized Sr-doped LaCrO 3 nanoparticles were readily obtained. • Compared with the nanoparticles synthesized by the coprecipitation method, they showed an enhanced ORR activity. • The main origin was revealed to be the decreased particle size due to the nonionic surfactant. - Abstract: Sr-doped LaCrO 3 nanoparticles were prepared by the hydrothermal method with the nonionic surfactant Triton X-100 followed by heat treatment at 1000 °C for 10 h. The obtained perovskite nanoparticles had smaller particle size (about 100 nm) and more uniform size distribution than those synthesized by the conventional coprecipitation method. On the other hand, it was identified with the material simulation that the electronic structure change by Sr doping was negligible, because the initially unfilled e g -band was not affected by the p-type doping. Finally, the perovskite nanoparticles synthesized by hydrothermal method showed much higher ORR activity by over 200% at 0.8 V vs. RHE than those by coprecipitation method

Trace Metals in Groundwater and the Vadose Zone Calcite: In Situ Containment and Stabilization of Strontium-90 and Other Divalent Metals and Radionuclides at Arid West DOE

International Nuclear Information System (INIS)

Smith, Robert W.

2004-01-01

Radionuclide and metal contaminants such as strontium-90 are present beneath U.S. Department of Energy (DOE) lands in both the groundwater (e.g., 100-N area at Hanford, WA) and vadose zone (e.g., Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory). In situ containment and stabilization of these contaminants is a cost-effective treatment strategy. However, implementing in situ containment and stabilization approaches requires definition of the mechanisms that control contaminant sequestration. We are investigating the in situ immobilization of radionuclides or contaminant metals (e.g., strontium-90) by their facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Our facilitated approach, shown schematically in Figure 1, relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity. Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface urea hydrolyzing microorganisms. Because the precipitation process tends to be irreversible and many western aquifers are saturated with respect to calcite, the co-precipitated metals and radionuclides will be effectively removed from the aqueous phase over the long-term. Another advantage of the ureolysis approach is that the ammonium ions produced by the reaction can exchange with radionuclides sorbed to subsurface minerals, thereby enhancing the availability of the radionuclides for re-capture in a more stable solid phase (co-precipitation rather than adsorption)

Synthesis and characterization of hydroxyapatite-gelatine composite materials for orthopaedic application

Energy Technology Data Exchange (ETDEWEB)

Yanovska, A., E-mail: biophy@yandex.ru [Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40000, Sumy (Ukraine); Sumy State University, Ministry of Education and Science of Ukraine, 2 R. Korsakova Str., 40007, Sumy (Ukraine); Kuznetsov, V. [Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40000, Sumy (Ukraine); Sumy State University, Ministry of Education and Science of Ukraine, 2 R. Korsakova Str., 40007, Sumy (Ukraine); Stanislavov, A. [Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40000, Sumy (Ukraine); Husak, E. [Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40000, Sumy (Ukraine); Sumy State University, Ministry of Education and Science of Ukraine, 2 R. Korsakova Str., 40007, Sumy (Ukraine); Pogorielov, M. [Sumy State University, Ministry of Education and Science of Ukraine, 2 R. Korsakova Str., 40007, Sumy (Ukraine); Starikov, V. [National Technical University ”Kharkov Polytechnic Institute”, 21 Frunze Str., 61002, Kharkov (Ukraine); Bolshanina, S. [Sumy State University, Ministry of Education and Science of Ukraine, 2 R. Korsakova Str., 40007, Sumy (Ukraine); Danilchenko, S. [Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40000, Sumy (Ukraine)

2016-11-01

The composite materials based on hydroxyapatite (HA) and gelatine (Gel) with addition of silver and zirconium oxide were obtained. The study investigates a combination of low powered ultrasonic irradiation and low concentration of gelatine in the co-precipitation synthesis. These composites have different weight ratios of organic/inorganic components and may be synthesized in two ways: simple mixing and co-precipitation. Both of which were compared. The estimation of porosity, in vivo testing, surface morphology and phase composition as well as the IR-analysis were provided. Hydroxyapatite was the main crystalline phase in obtained composites. While around powdered HA-Gel composite the connective tissue capsule is formed without bone tissue formation, HA-Gel-Ag porous composite implantation leads to formation of new bone tissue and activation of cell proliferation. Addition of silver ions into composite material allows decreasing inflammation on the first stage of implantation and has positive effect on bone tissue formation. Some of the obtained composite materials containing silver or ZrO{sub 2} are biocompatible. bio-resorbable and osteoconductive with high level of porosity (75–85%). - Highlights: • Hydroxyapatite-gelatine composites with addition of Ag{sup +} and ZrO{sub 2} were obtained. • Composites were synthesized in two ways: simple mixing and co-precipitation. • Co-precipitation synthesis combined ultrasonic treatment and low concentration of gelatine. • Obtained composites have different weight ratios of organic/inorganic components. • Some composites are osteoconductive and all of them have high level of porosity (75–85%).

Controlled synthesis of La{sub 1−x}Sr{sub x}CrO{sub 3} nanoparticles by hydrothermal method with nonionic surfactant and their ORR activity in alkaline medium

Energy Technology Data Exchange (ETDEWEB)

Choi, Bo Hyun; Park, Shin-Ae [Energy System Major, School of Mechanical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Park, Bong Kyu [GIFT Center, Pusan National University, Busan, 609-735 (Korea, Republic of); Chun, Ho Hwan, E-mail: chunahh@pusan.ac.kr [Global Core Research Center for Ships and Offshore Plants(GCRC-SOP), Pusan National University, Busan, 609-735 (Korea, Republic of); Kim, Yong-Tae, E-mail: yongtae@pusan.ac.kr [Energy System Major, School of Mechanical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

2013-10-15

Graphical abstract: We demonstrate that Sr-doped LaCrO{sub 3} nanoparticles were successfully prepared by the hydrothermal synthesis method using the nonionic surfactant Triton X-100 and the applicability of La{sub 1−x}Sr{sub x}CrO{sub 3} to oxygen reduction reaction (ORR) electrocatalysis in an alkaline medium. Compared with the nanoparticles synthesized by the coprecipitation method, they showed enhanced ORR activity. - Highlights: • Sr-doped LaCrO{sub 3} nanoparticles were successfully prepared by the hydrothermal method using the nonionic surfactant. • Homogeneously shaped and sized Sr-doped LaCrO{sub 3} nanoparticles were readily obtained. • Compared with the nanoparticles synthesized by the coprecipitation method, they showed an enhanced ORR activity. • The main origin was revealed to be the decreased particle size due to the nonionic surfactant. - Abstract: Sr-doped LaCrO{sub 3} nanoparticles were prepared by the hydrothermal method with the nonionic surfactant Triton X-100 followed by heat treatment at 1000 °C for 10 h. The obtained perovskite nanoparticles had smaller particle size (about 100 nm) and more uniform size distribution than those synthesized by the conventional coprecipitation method. On the other hand, it was identified with the material simulation that the electronic structure change by Sr doping was negligible, because the initially unfilled e{sub g}-band was not affected by the p-type doping. Finally, the perovskite nanoparticles synthesized by hydrothermal method showed much higher ORR activity by over 200% at 0.8 V vs. RHE than those by coprecipitation method.

Behavior of americium, curium, and certain fission products in fluoride melts in the presence of s olid extraction agents

International Nuclear Information System (INIS)

Alekseev, V.A.; Klokman, V.R.; Morozova, Z.E.; Ziv, V.S.

1986-01-01

The authors consider the behavior of americium, curium, and certain fission products (europium, cerium, yttrium, and strontium) in fluoride and chlode-fluoride melts in the presence of nonisomorphous solid phases: calcium fluoride and lanthanum and zirconium oxides. It is shown that the trace components enter the solid calcium fluoride in a regular fashion only in the presence of an adequate amount of oxygen in the melt. The effect of oxygen on the coprecipitation with calcium fluoride occurs because oxygen compounds of the elements must be formed in the melt, and these are then coprecipitated with the calcium fluoride

Preconcentration of plutonium radionuclides from natural waters

International Nuclear Information System (INIS)

Wong, K.M.; Nioshkin, V.E.; Jokela, T.A.

1978-02-01

A large volume water sampler using manganese dioxide impregnated cartridges for the in situ separation of plutonium in sea water and ground water was studied. Plutonium concentrations obtained by this technique are compared with a radiochemical coprecipitation method. Consistent results were obtained between the two methods for water samples from the Pacific Ocean and Enewetak lagoon. Different results were noted from samples collected in the Enewetak reef and ground water stations. Using this preconcentration technique and the coprecipitation method it was shown that the physical-chemical characteristics of Pu in Enewetak reef and ground water are different from the lagoon and open ocean

Determination of plutonium in environmental samples by controlled valence in anion exchange

DEFF Research Database (Denmark)

Chen, Q.J.; Aarkrog, A.; Nielsen, S.P.

1993-01-01

The title method was successfully used for collecting Pu-239, Pu-249 from 200 litres of seawater by coprecipitation with 16 g FeSO4 . 7H2O under reducing conditions without filtering. The plutonium is leached by concentrated HNO3 + HCI from the coprecipitate and the solid particles. The precipita...... stripped by H20, NaOH, 2N HNO3 and 0.5N HNO3 containing 0.01M NaNO3. The chemical yield of plutonium for a 200 l seawater sample is 60-80%. The resolution of the electroplated thin source is very good....

Processing of radioactive ruthenium with aluminosilicate gels

International Nuclear Information System (INIS)

Kanno, Takuji; Ichinose, Yasuhiro; Ito, Katsuo

1979-01-01

Coprecipitation of radioactive Ru with hydroxides has been studied for the purpose of the management of the high level waste from the nuclear fuel reprocessing. Aluminosilicate gel used as coprecipitant was prepared by addition of aqueous sodium hydroxide to sodium aluminate-sodium silicate solution containing ruthenium nitrate. Ruthenium quantitatively precipitates under the conditions, aluminate > 4 x 10 -2 M, Al/Si 0 C. However, volatilization rate of Ru is suppressed by coating with mullite phase into which aluminosilicate gel transformes above 900 0 C. The amount of Ru volatilized in Ar-flow was reduced to about 10% of that in air-flow. (author)

The role of powder preparation method in enhancing fracture toughness of zirconia ceramics with low alumina amount

International Nuclear Information System (INIS)

Danilenko, I.; Konstantinova, T.; Volkova, G.; Burkhovetski, V.; Glazunova, V.

2015-01-01

In most cases zirconia-alumina composites for scientific investigations and industry are prepared by means of mechanical mixing of powders, compaction and sintering. In our opinion, this is one of the reasons for the low values for fracture toughness of the sintered materials. In this study, we investigated the effect of nanopowder synthesis methods on the structure and mechanical properties of 3Y-TZP/alumina ceramic composites and determined the mechanisms involved in composite toughening. We show that the addition of a small amount of alumina (1 - 2 wt%) to zirconia ceramics has the potential to increase the fracture toughness of zirconia ceramics. The starting powders were obtained by means of co-precipitation and ball milling. It turned out that at equal density, bending strength and hardness values, the fracture toughness in ceramic composites sintered from co-precipitated nanopowders is higher in comparison with fracture toughness values in matrix material and traditional 3Y-TZP/alumina composites. We believed that the role of the crack deflection process in ceramic composites sintered from co-precipitated nanopowders increased significantly. This can be conditioned by means of a series of processes for composite structure formation during precipitation, crystallization, and sintering of nanopowders.

Automated methods for thorium determination in liquids, solids and aerosols

International Nuclear Information System (INIS)

Robertson, R.; Stuart, J.E.

1984-01-01

Methodology for determining trace thorium levels in a variety of sample types for compliance purposes was developed. Thorium in filtered water samples is concentrated by ferric hydroxide co-precipitation. Aerosols on glass-fibre, cellulose ester or teflon filters are acid digested and thorium is concentrated by lanthanum fluoride co-precipitation. Chemical separation and measurement are then done on a Technicon AAII-C auto-analyzer via TTA-solvent extraction and colorimetry using the thorium-arsenazo III colour complex. Solid samples are acid digested and thorium is concentrated and separated using lanthanum fluoride co-precipitation followed by anion-exchange chromatography. Measurement is then carried out on the autoanalyzer by direct development of the thorium-arsenazo III colour complex. Chemical yields are determined through the addition of thorium-234 tracer with assay by gamma-ray spectrometry. The sensitivities of the methods for liquids, aerosols and solids are approximately 1μg/L,0.5μg and 0.5 μg/g respectively. At thorium levels about ten times the detection limits, accuracy and reproducibility are typically +-10 percent for liquids and aerosols and +- 15 percent for solid samples

The role of powder preparation method in enhancing fracture toughness of zirconia ceramics with low alumina amount

Energy Technology Data Exchange (ETDEWEB)

Danilenko, I.; Konstantinova, T.; Volkova, G.; Burkhovetski, V.; Glazunova, V. [NAS of Ukraine, Donetsk (Ukraine). Donetsk Inst. for Physics and Engineering

2015-07-01

In most cases zirconia-alumina composites for scientific investigations and industry are prepared by means of mechanical mixing of powders, compaction and sintering. In our opinion, this is one of the reasons for the low values for fracture toughness of the sintered materials. In this study, we investigated the effect of nanopowder synthesis methods on the structure and mechanical properties of 3Y-TZP/alumina ceramic composites and determined the mechanisms involved in composite toughening. We show that the addition of a small amount of alumina (1 - 2 wt%) to zirconia ceramics has the potential to increase the fracture toughness of zirconia ceramics. The starting powders were obtained by means of co-precipitation and ball milling. It turned out that at equal density, bending strength and hardness values, the fracture toughness in ceramic composites sintered from co-precipitated nanopowders is higher in comparison with fracture toughness values in matrix material and traditional 3Y-TZP/alumina composites. We believed that the role of the crack deflection process in ceramic composites sintered from co-precipitated nanopowders increased significantly. This can be conditioned by means of a series of processes for composite structure formation during precipitation, crystallization, and sintering of nanopowders.

Gelatine-assisted synthesis of magnetite nanoparticles for magnetic hyperthermia

Energy Technology Data Exchange (ETDEWEB)

Alves, André F.; Mendo, Sofia G. [Universidade de Lisboa, Centro de Química e Bioquímica, Faculdade de Ciências (Portugal); Ferreira, Liliana P. [Universidade de Lisboa, Biosystems and Integrative Sciences Institute, Faculdade de Ciências (Portugal); Mendonça, Maria Helena [Universidade de Lisboa, Centro de Química e Bioquímica, Faculdade de Ciências (Portugal); Ferreira, Paula [University of Aveiro, Department of Materials and Ceramic Engineering, CICECO - Aveiro Institute of Materials (Portugal); Godinho, Margarida; Cruz, Maria Margarida [Universidade de Lisboa, Biosystems and Integrative Sciences Institute, Faculdade de Ciências (Portugal); Carvalho, Maria Deus, E-mail: mdcarvalho@ciencias.ulisboa.pt [Universidade de Lisboa, Centro de Química e Bioquímica, Faculdade de Ciências (Portugal)

2016-01-15

Magnetite nanoparticles were synthesized by the co-precipitation method exploring the use of gelatine and agar as additives. For comparison, magnetite nanoparticles were also prepared by standard co-precipitation, by co-precipitation with the addition of a surfactant (sodium dodecyl sulphate) and by the thermal decomposition method. The structure and morphology of the synthesized nanoparticles were investigated by powder X-ray diffraction and transmission electron microscopy. Their magnetic properties were studied by SQUID magnetometry and {sup 57}Fe Mössbauer spectroscopy. The nanoparticles potential for applications in magnetic hyperthermia was evaluated through heating efficiency under alternating magnetic field. The results show that all synthesis methods produce Fe{sub 3−x}O{sub 4} nanoparticles with similar sizes. The nanoparticles synthesized in the gelatine medium display the narrowest particle size distribution, the lowest oxidation degree, one of the highest saturation magnetization values and the best hyperthermia efficiency, proving that this gelatine-assisted synthesis is an efficient, environmental friendly, and low-cost method to produce magnetite nanoparticles. Graphical Abstract: A new gelatine-assisted method is an efficient and low-cost way to synthesize magnetite nanoparticles with enhanced magnetic hyperthermia.

Speciation of As in calcite by micro-XAFS: Implications for remediation of As contamination in groundwater

International Nuclear Information System (INIS)

Yokoyama, Y; Takahashi, Y; Iwatsuki, T; Terada, Y

2013-01-01

To evaluate the role of calcite as a host phase of arsenic (As) in As-contaminated groundwater, distribution behavior of Asbetween natural calcite and groundwater in deep underground was investigated based on As oxidation state. Speciation analyses of As in natural calcite by μ-XRF-XAFS analyses showed (i) preferentialarsenate uptake by calcite, and (ii) promptness of arsenate uptake by minor iron (Fe) carbonate minerals coprecipitated with calcite. These findings suggest that the effect of calcite on As remediation of the As-contamination systems stronglydepends on arsenite to arsenate ratio (i.e., redox condition) in groundwater, and maybe governed bythe amount of Fe coprecipitated with calcite.

Chromium isotope fractionation during coprecipitation with calcium carbonate

DEFF Research Database (Denmark)

Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

The chromium (Cr) isotopic composition of carbonates can potentially be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenvironmental changes, for example related to the rise of oxygen during the Ar...... et al., 2007, Water Air Soil Poll. 179, 381-390. [2] Sánchez-Pastor et al., 2011, Cryst. Growth Des. 11, 3081-3089.......The chromium (Cr) isotopic composition of carbonates can potentially be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenvironmental changes, for example related to the rise of oxygen during...... the Archaean and Protoerozoic, needs careful assessment of the signal robustness and necessitates a thorough understanding of the Cr cycle in Earth system processes. We conducted experiments testing the incorporation and isotopic fractionation of chromate into the calcite lattice. Our experiments indicate...

Study of calcium carbonate and sulfate co-precipitation

KAUST Repository

Zarga, Y.; Ben Boubaker, H.; Ghaffour, NorEddine; Elfil, Hamza

2013-01-01

of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic

Composition and microstructure of zirconium and hafnium germanates obtained by different chemical routes

International Nuclear Information System (INIS)

Utkin, A.V.; Prokip, V.E.; Baklanova, N.I.

2014-01-01

The phase composition and morphology of zirconium and hafnium germanates synthesized by ceramic and co-precipitation routes were studied. The products were characterized using high-temperature X-ray diffraction analysis (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and thermal (TG/DTA) analysis. To investigate the phase composition and stoichiometry of compounds the unit cell parameters were refined by full-profile Rietveld XRD analysis. The morphology of products and its evolution during high-temperature treatment was examined by SEM analysis. It was stated that there is the strong dependence of the phase composition and morphology of products on the preparation route. The ceramic route requires a multi-stage high-temperature treatment to obtain zirconium and hafnium germanates of 95% purity or more. Also, there are strong diffusion limitations to obtain hafnium germanate Hf 3 GeO 8 by ceramic route. On the contrary, the co-precipitation route leads to the formation of nanocrystalline single phase germanates of stoichiometric composition at a relatively low temperatures (less than 1000 °C). The results of quantitative XRD analysis showed the hafnium germanates are stoichiometric compounds in contrast to zirconium germanates that form a set of solid solutions. This distinction may be related to the difference in the ion radii of Zr and Hf. - Graphical abstract: The phase composition and morphology of zirconium and hafnium germanates synthesized by ceramic and co-precipitation routes were studied. It was stated that there is the strong dependence of the phase composition and morphology of products on the preparation route. Display Omitted - Highlights: • Zr and Hf germanates were synthesized by ceramic and co-precipitation routes. • The morphology of products depends on the synthesis parameters. • Zirconium germanates forms a set of solid solutions. • Hafnium germanates are stoichiometric compounds

Single and combined effects of phosphate, silicate, and natural organic matter on arsenic removal from soft and hard groundwater using ferric chloride

Science.gov (United States)

Chanpiwat, Penradee; Hanh, Hoang Thi; Bang, Sunbaek; Kim, Kyoung-Woong

2017-06-01

In order to assess the effects of phosphate, silicate and natural organic matter (NOM) on arsenic removal by ferric chloride, batch coprecipitation experiments were conducted over a wide pH range using synthetic hard and soft groundwaters, similar to those found in northern Vietnam. The efficiency of arsenic removal from synthetic groundwater by coprecipitation with FeCl3 was remarkably decreased by the effects of PO4 3-, SiO4 4- and NOM. The negative effects of SiO4 4- and NOM on arsenic removal were not as strong as that of PO4 3-. Combining PO4 3- and SiO4 4- increased the negative effects on both arsenite (As3+) and arsenate (As5+) removal. The introduction of NOM into the synthetic groundwater containing both PO4 3- and SiO4 4- markedly magnified the negative effects on arsenic removal. In contrast, both Ca2+ and Mg2+ substantially increased the removal of As3+ at pH 8-12 and the removal of As5+ over the entire pH range. In the presence of Ca2+ and Mg2+, the interaction of NOM with Fe was either removed or the arsenic binding to Fe-NOM colloidal associations and/or dissolved complexes were flocculated. Removal of arsenic using coprecipitation by FeCl3 could not sufficiently reduce arsenic contents in the groundwater (350 μg/L) to meet the WHO guideline for drinking water (10 μg/L), especially when the arsenic-rich groundwater also contains co-occurring solutes such as PO4 3-, SiO4 4- and NOM; therefore, other remediation processes, such as membrane technology, should be introduced or additionally applied after this coprecipitation process, to ensure the safety of drinking water.

Advances in the catalysts development in base of mixed oxides for control reactions of N2O

International Nuclear Information System (INIS)

Garcia, M.A.; Perez, R.; Gomez, A.; Diaz, G.

2000-01-01

The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were prepared by the precipitation and coprecipitation techniques. The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were characterized by several techniques for to determine texture (BET), crystallinity (XRD), chemical composition (SEM), FTIR and it was evaluated their total acidity by the reaction with 2-propanol. It was continued with the cobalt addition by Impregnation and coprecipitation and it was evaluated its catalytic activity in the N 2 O decomposition reaction. Also it was realized the N 2 O reduction with Co using these catalysts. (Author)

Study of total oxidation of ethanol using the perovskite-type oxides LaBO{sub 3} (B= Mn, Ni, Fe); Estudo da oxidacao total do etanol usando oxidos tipo perovskita LaBO{sub 3} (B= Mn, Ni, Fe)

Energy Technology Data Exchange (ETDEWEB)

Soares, Ana Brigida [Centro Federal de Educacao Tecnologica do Espirito Santo, Vitoria, ES (Brazil). Centro de Ciencias e Tecnologias Quimicas]. E-mail: brigida@cefetes.br; Silva, Paulo Roberto Nagipe da [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Centro de Ciencias e Tecnologia; Freitas, Jair C.C. [Universidade Federal do Espirito Santo, Vitoria, ES (Brazil). Centro de Ciencias Exatas. Dept. de Fisica; Almeida, Clara Muniz de [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Fisica

2007-09-15

The present work investigated the effect of coprecipitation-oxidant synthesis on the specific surface area of perovskite-type oxides LaBO{sub 3} (BMn, Ni, Fe) for total oxidation of ethanol. The perovskite-type oxides were characterized by X-ray diffraction, nitrogen adsorption (BET method), thermogravimetric analysis (TGA-DTA), TPR and X-ray photoelectron spectroscopy (XPS). Through method involving the coprecipitation-oxidant was possible to obtain catalysts with different BET specific surface areas, of 33-51 m{sup 2}/g. The results of the catalytic test confirmed that all oxides investigated in this work have specific catalytic activity for total oxidation of ethanol, though the temperatures for total conversion change for each transition metal. (author)

Single-step Preparation of Nano-homogeneous NiO/YSZ Comp osite Ano de for Solid Oxide Fuel Cells

Institute of Scientific and Technical Information of China (English)

Jung-Hoon Song; Mi Young Park; Hye Won Park; Hyung-Tae Lim

2013-01-01

Homogeneous co-precipitation and hydrothermal treatment were used to prepare nano-and highly dispersed NiO/YSZ (yttria-stabilized zirconia) composite powders. Composite powders of size less than 100 nm were successfully prepared. This process did not require separate sintering of the YSZ and NiO to be used as the raw materials for solid oxide fuel cells. The performance of a cell fabricated using the new powders (max. power density∼0.87 W/cm2) was higher than that of a cell fabricated using conventional powders (max. power density∼0.73 W/cm2). Co-precipitation and hydrothermal treatment proved to be very effective processes for reducing cell production costs as well as improving cell performance.

Effects of Residual Lithium in the precursors of Li[Ni1/3Co1/3Mn1/3]O2 on their lithium-ion battery performance

Science.gov (United States)

Jo, Minsang; Ku, Heesuk; Park, Sanghyuk; Song, Junho; Kwon, Kyungjung

2018-07-01

Li[Ni1/3Co1/3Mn1/3]O2 cathode active materials are synthesized from co-precipitated hydroxide precursors Lix[Ni1/3Co1/3Mn1/3]1-x(OH)2, and the effect of residual Li in the precursors on the lithium-ion battery (LIB) performance of their corresponding cathode active materials is investigated. Three kinds of precursors that contain different amounts of Li are selected depending on different conditions of the solution composition for the co-precipitation and washing process. It is confirmed that the introduction of Li to the precursors reduces the degree of structural perfection by X-ray diffraction analysis. Undesirable cation mixing occurs with the increasing Li content of the precursors, which is inferred from a decline in lattice parameters and the calculated intensity ratio of (003) and (104) peaks. In the voltage range of 3.0-4.3 V, the initial charge/discharge capacities and the rate capability of the cathode active materials are aggravated when Li exists in the precursors. Therefore, it could be concluded that the strict control of Li in a solution for co-precipitation of precursors is necessary in the resynthesis of cathode active materials from spent LIBs.

Comparison of different methodologies for obtaining nickel nanoferrites

Energy Technology Data Exchange (ETDEWEB)

Galindo, R.; Menendez, N. [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Crespo, P.; Velasco, V. [Instituto de Magnetismo Aplicado, UCM, ADIF CSIC, E-28230 Madrid (Spain); Bomati-Miguel, O.; Díaz-Fernández, D. [Departamento de Física Aplicada and Instituto Nicolás Cabrera, Facultad de Ciencias Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)

2014-06-01

Nickel nanoferrites were obtained by means of four different synthetic wet-routes: co-precipitation (CP), sonochemistry (SC), sonoelectrochemistry (SE) and electrochemistry (E). The influence of the synthesis method on the structural and magnetic properties of nickel ferrite nanoparticles is studied. Although similar experimental conditions such as temperature, pH and time of synthesis were used, a strong dependence of composition and microstructure on the synthesis procedure is found, as electron microscopy, X-ray diffraction and Mössbauer spectroscopy studies reveal. Whereas by means of the CP and SC methods particles of a small size around 5–10 nm, respectively, and composed by different phases are obtained, the electrochemical routes (E and SE) allow obtaining monodisperse nanoparticles, with sizes ranging from 30 to 40 nm, and very close to stoichiometry. Magnetic characterization evidences a superparamagnetic behavior for samples obtained by CP and SC methods, whereas the electrochemical route leads to ferromagnetic ferrite nanoparticles. - Highlights: • Electrochemical synthesis produces pure NiFe{sub 2}O{sub 4} nanonoparticles with 40 nm particle size. • Coprecipitation and sonochemistry techniques generate NiFe{sub 2}O{sub 4} nanoparticles with impurities. • Nanoparticles obtained by coprecipitation and sonochemistry are superparamagnetic. • Electrochemical and sonoelectrochemical methods produce ferromagnetic nanoparticles.

Effect of Co-Contaminants Uranium and Nitrate on Iodine Remediation

Energy Technology Data Exchange (ETDEWEB)

Szecsody, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lee, Brady D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawter, Amanda R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qafoku, Nikolla [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Resch, Charles T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Baum, Steven R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Leavy, Ian I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Freedman, Vicky L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-09-01

The objective of this study is to evaluate the significance of co-contaminants on the migration and transformation of iodine species in the Hanford subsurface environment. These impacts are relevant because remedies that target individual contaminants like iodine, may not only impact the fate and transport of other contaminants in the subsurface, but also inhibit the effectiveness of a targeted remedy. For example, iodine (as iodate) co-precipitates with calcite, and has been identified as a potential remedy because it immobilizes iodine. Since uranium also co-precipitates with calcite in field sediments, the presence of uranium may also inhibit iodine co-precipitation. Another potentially significant impact from co-existing contaminants is iodine and nitrate. The presence of nitrate has been shown to promote biogeochemical reduction of iodate to iodide, thereby increasing iodine species subsurface mobility (as iodide exhibits less sorption). Hence, this study reports on both laboratory batch and column experiments that investigated a) the change in iodate uptake mass and rate of uptake into precipitating calcite due to the presence of differing amounts of uranium, b) the amount of change of the iodate bio-reduction rate due to the presence of differing nitrate concentrations, and c) whether nitrite can reduce iodate in the presence of microbes and/or minerals acting as catalysts.

Effect of selected ligands on the U(VI) immobilization by zerovalent iron

International Nuclear Information System (INIS)

Noubactep, C.

2006-01-01

The effect of Cl - , CO 3 2- , EDTA, NO 2 - , NO 3 - , PO 4 3- , SO 4 2- , and humic substances (HS) on the U(VI) co-precipitation from aqueous solutions by zerovalent iron (ZVI) was investigated in the neutral pH range.Batch experiments without shaking were conducted for 14 days mostly with five different ZVI materials (15 g/l), selected ligands (10mM) and an U(VI) solution (20 mg/l, 0.084mM). Apart from Cl - , all tested ligands induced a decrease of U(VI) coprecipitation. This decrease is attributed to the surface adsorption and complexation of the ligands at the reactive sites on the surface of ZVI and their corrosion products. The decrease of U(VI) removal was not uniform with the five ZVI materials. Generally, groundwater with elevated EDTA concentration could not be remediated with the ZVI barrier technology. The response of the system on the pre-treating by two ZVI materials in 250mM HCl indicated that in situ generated corrosion products favor an irreversible U(VI) uptake. Thus for the long term performance of ZVI barrier, the iron dissolution should continue in such a way that fresh iron oxide be always available for U(VI) coprecipitation. (author)

Ferrihydrite-associated organic matter (OM stimulates reduction by Shewanella oneidensis MR-1 and a complex microbial consortia

Directory of Open Access Journals (Sweden)

R. E. Cooper

2017-11-01

Full Text Available The formation of Fe(III oxides in natural environments occurs in the presence of natural organic matter (OM, resulting in the formation of OM–mineral complexes that form through adsorption or coprecipitation processes. Thus, microbial Fe(III reduction in natural environments most often occurs in the presence of OM–mineral complexes rather than pure Fe(III minerals. This study investigated to what extent does the content of adsorbed or coprecipitated OM on ferrihydrite influence the rate of Fe(III reduction by Shewanella oneidensis MR-1, a model Fe(III-reducing microorganism, in comparison to a microbial consortium extracted from the acidic, Fe-rich Schlöppnerbrunnen fen. We found that increased OM content led to increased rates of microbial Fe(III reduction by S. oneidensis MR-1 in contrast to earlier findings with the model organism Geobacter bremensis. Ferrihydrite–OM coprecipitates were reduced slightly faster than ferrihydrites with adsorbed OM. Surprisingly, the complex microbial consortia stimulated by a mixture of electrons donors (lactate, acetate, and glucose mimics S. oneidensis under the same experimental Fe(III-reducing conditions suggesting similar mechanisms of electron transfer whether or not the OM is adsorbed or coprecipitated to the mineral surfaces. We also followed potential shifts of the microbial community during the incubation via 16S rRNA gene sequence analyses to determine variations due to the presence of adsorbed or coprecipitated OM–ferrihydrite complexes in contrast to pure ferrihydrite. Community profile analyses showed no enrichment of typical model Fe(III-reducing bacteria, such as Shewanella or Geobacter sp., but an enrichment of fermenters (e.g., Enterobacteria during pure ferrihydrite incubations which are known to use Fe(III as an electron sink. Instead, OM–mineral complexes favored the enrichment of microbes including Desulfobacteria and Pelosinus sp., both of which can utilize lactate and

Ferrihydrite-associated organic matter (OM) stimulates reduction by Shewanella oneidensis MR-1 and a complex microbial consortia

Science.gov (United States)

Cooper, Rebecca Elizabeth; Eusterhues, Karin; Wegner, Carl-Eric; Totsche, Kai Uwe; Küsel, Kirsten

2017-11-01

The formation of Fe(III) oxides in natural environments occurs in the presence of natural organic matter (OM), resulting in the formation of OM-mineral complexes that form through adsorption or coprecipitation processes. Thus, microbial Fe(III) reduction in natural environments most often occurs in the presence of OM-mineral complexes rather than pure Fe(III) minerals. This study investigated to what extent does the content of adsorbed or coprecipitated OM on ferrihydrite influence the rate of Fe(III) reduction by Shewanella oneidensis MR-1, a model Fe(III)-reducing microorganism, in comparison to a microbial consortium extracted from the acidic, Fe-rich Schlöppnerbrunnen fen. We found that increased OM content led to increased rates of microbial Fe(III) reduction by S. oneidensis MR-1 in contrast to earlier findings with the model organism Geobacter bremensis. Ferrihydrite-OM coprecipitates were reduced slightly faster than ferrihydrites with adsorbed OM. Surprisingly, the complex microbial consortia stimulated by a mixture of electrons donors (lactate, acetate, and glucose) mimics S. oneidensis under the same experimental Fe(III)-reducing conditions suggesting similar mechanisms of electron transfer whether or not the OM is adsorbed or coprecipitated to the mineral surfaces. We also followed potential shifts of the microbial community during the incubation via 16S rRNA gene sequence analyses to determine variations due to the presence of adsorbed or coprecipitated OM-ferrihydrite complexes in contrast to pure ferrihydrite. Community profile analyses showed no enrichment of typical model Fe(III)-reducing bacteria, such as Shewanella or Geobacter sp., but an enrichment of fermenters (e.g., Enterobacteria) during pure ferrihydrite incubations which are known to use Fe(III) as an electron sink. Instead, OM-mineral complexes favored the enrichment of microbes including Desulfobacteria and Pelosinus sp., both of which can utilize lactate and acetate as an electron

Enhancement of In Vitro Skin Transport and In Vivo Hypoglycemic ...

African Journals Online (AJOL)

... (PVP) for the enhancement of the transdermal delivery of glimepiride (GMD). Methods: Matrix-type transdermal patches containing GMD, drug coprecipitate ... evaluation of the formulations was conducted using automated diffusion system.

Fulltext PDF

Indian Academy of Sciences (India)

The magnetic nanoparticles prepared by the co-precipitation method show superior performances in respect of heat dissipation capability, saturation of magnetization values and .... The structural characterization including size and crystal.

Introduction of a cation in aqueous solution by electrolytic dissolution of metal. Applications to the decontamination of radioactive effluents

International Nuclear Information System (INIS)

Gauchon, Jean-Paul

1979-01-01

This research thesis aims at comparing results obtained in chemical decontamination of radioactive effluents with a metallic cation introduced by metal electro-dissolution or by dose addition. After an overview of methods used for the purification of radioactive effluents and a more precise presentation of chemical co-precipitation, the author reports preliminary tests of the application of chemical co-precipitation to the decontamination of radioactive effluents, reports the analysis of iron, zinc and copper behaviour in aqueous environment by means of thermodynamic diagrams and current-voltage curves. He reports the design and use of two electro-dissolution sets, and the application of copper electrolytic dissolution to the elimination of ruthenium in radioactive effluents. He finally addresses the purification treatment of effluents of nuclear reactors

Development of a method employing chitosan to remove metallic ions from wastewater

International Nuclear Information System (INIS)

Janegitz, Bruno Campos; Lourencao, Bruna Claudia; Lupetti, Karina Omuro; Fatibello-Filho, Orlando

2007-01-01

In this work a method was developed for removing metallic ions from wastewaters by co-precipitation of Cu 2+ , Pb 2+ , Cd 2+ , Cr 3+ and Hg 2+ with chitosan and sodium hydroxide solution. Solutions of these metallic ions in the range from 0.55 to 2160 mg L -1 were added to chitosan dissolved in 0.05 mol L -1 HCl. For the co-precipitation of metal-chitosan-hydroxide a 0.17 mol L -1 NaOH solution was added until pH 8.5-9.5. A parallel study was carried out applying a 0.17 mol L -1 NaOH solution to precipitate those metallic ions. Also, a chitosan solid phase column was used for removing those metallic ions from wastewaters. (author)

Synthesis and characterization of superparamagnetic nanoparticles obtained by precipitation in inverse microemulsion for biomedical applications

International Nuclear Information System (INIS)

Puca Pacheco, Mercedes; Guerrero Aquino, Marco; Tacuri Calanchi, Enrique; Lopez Campos, Raul G.

2013-01-01

In this work the preparation of nanoparticles of magnetite by methods of precipitation in inverse microemulsions and the conventional method 'Chemical Co-precipitation' is reported. Magnetite nanoparticles were characterized by X-ray diffraction, Moessbauer spectroscopy and vibrating sample magnetometer (VSM). The results showed that the nanoparticles obtained by the method of precipitation in inverse microemulsion showed a superparamagnetic behavior and had a particle average diameter of 9 nm, while by the conventional method 'Chemical Co-precipitation' were 17 nm. In addition, other benefits observed in the application of the method of precipitation in inverse microemulsion with regard to the conventional method is that it allowed obtaining spheroidal magnetite nanoparticles, monodisperse and with magnetic and chemical properties which might have better results in medical applications. (author)

Interferences in the radiochemical determination of 230Th

International Nuclear Information System (INIS)

Burk, R.C.; Jong, I.G. de; Wiles, D.R.

1983-01-01

Earlier work on the coprecipitation of 230 Th and 234 Th with BaSO 4 has been confirmed and in particular the influence of other ions was investigated. Potassium ions, both in the solution and in the crystals, promote the coprecipitation, while polyvalent cations tend to prevent it. It is shown that increased concentration of K + causes a marked change in the BaSO 4 crystal from, with a concomitant increase in the surface area. At the same time, the rate of exchange of 133 Ba 2 + with the BaSO 4 surface is also increased. It is roughly caused by the change in surface area. It is conjectured that an equilibrium occurs involving foreign cations in the lattice. (author)

Emerging investigator series: As( v ) in magnetite: incorporation and redistribution

Energy Technology Data Exchange (ETDEWEB)

Huhmann, Brittany L. [Department of Civil and Environmental Engineering; University of Iowa; Iowa City; USA; Neumann, Anke [School of Engineering; Newcastle University; Newcastle upon Tyne; UK; Boyanov, Maxim I. [Biosciences Division; Argonne National Laboratory; Argonne; USA; Institute of Chemical Engineering; Kemner, Kenneth M. [Biosciences Division; Argonne National Laboratory; Argonne; USA; Scherer, Michelle M. [Department of Civil and Environmental Engineering; University of Iowa; Iowa City; USA

2017-01-01

As coprecipitated with magnetite remained incorporated over time whereas sorbed As was redistributed and became increasingly incorporated into magnetite, both the absence and presence of aqueous Fe(ii).

Readiness plan, Hanford 300 Area Treated Effluent Disposal Facility: Revision 1

International Nuclear Information System (INIS)

Storm, S.J.

1994-01-01

The 300 Area Treated Effluent Disposal Facility (TEDF) is designed for the collection, treatment, and eventual disposal of liquid waste from the 300 Area Process Sewer (PS) system. The PS currently discharges water to the 300 Area Process Trenches. Facilities supported total 54 buildings, including site laboratories, inactive buildings, and support facilities. Effluent discharges to the process sewer from within these facilities include heating, ventilation, and air conditioning systems, heat exchangers, floor drains, sinks, and process equipment. The wastewaters go through treatment processes that include iron coprecipitation, ion exchange and ultraviolet oxidation. The iron coprecipitation process is designed to remove general heavy metals. A series of gravity filters then complete the clarification process by removing suspended solids. Following the iron coprecipitation process is the ion exchange process, where a specific resin is utilized for the removal of mercury. The final main unit operation is the ultraviolet destruction process, which uses high power ultraviolet light and hydrogen peroxide to destroy organic molecules. The objective of this readiness plan is to provide the method by which line management will prepare for a Readiness Assessment (RA) of the TEDF. The self-assessment and RA will assess safety, health, environmental compliance and management readiness of the TEDF. This assessment will provide assurances to both WHC and DOE that the facility is ready to start-up and begin operation

Preconcentration and Speciation of Trace Elements and Trace-Element Analogues of Radionuclides by Neutron Activation Analysis

International Nuclear Information System (INIS)

Chatt, A.

1999-01-01

We have developed a number of preconcentration neutron activation analysis (PNAA) methods in our laboratory for the determination of trace elements in a variety of complex sample matrices. We developed a number of cocrystallization and coprecipitation methods for the determination of trace elements in water samples. We developed several methods for the determination of I in foods and diets. We have developed a number of PNAA methods in our laboratory We determined As and Sb in geological materials and natural waters by coprecipitation with Se and Au in silicate rocks and ores by coprecipitation with Te followed by NAA. We developed an indirect NAA method for the determination of B in leachates of borosilicate glass. We have been interested in studying the speciation of Am, Tc, and Np in simulated vitrified groundwater leachates of high-level wastes under oxid and anoxic conditions using a number of techniques. We then used PNAA methods to study speciation of trace-element analogues of radionuclides. We have been able to apply biochemical techniques and NAA for the separation, preconcentration, and characterization of metalloprotein and protein-bound trace-element species in subcellular fractions of bovine kidneys. Lately, we have concentrated our efforts to develop chemical and biochemical methods in conjunction with NAA, NMR, and MS for the separation and identification of extractable organohalogens (EOX) in tissues of beluga whales, cod, and northern pink shrimp

Treatment of low level radioactive liquid waste containing appreciable concentration of TBP degraded products.

Science.gov (United States)

Valsala, T P; Sonavane, M S; Kore, S G; Sonar, N L; De, Vaishali; Raghavendra, Y; Chattopadyaya, S; Dani, U; Kulkarni, Y; Changrani, R D

2011-11-30

The acidic and alkaline low level radioactive liquid waste (LLW) generated during the concentration of high level radioactive liquid waste (HLW) prior to vitrification and ion exchange treatment of intermediate level radioactive liquid waste (ILW), respectively are decontaminated by chemical co-precipitation before discharge to the environment. LLW stream generated from the ion exchange treatment of ILW contained high concentrations of carbonates, tributyl phosphate (TBP) degraded products and problematic radio nuclides like (106)Ru and (99)Tc. Presence of TBP degraded products was interfering with the co-precipitation process. In view of this a modified chemical treatment scheme was formulated for the treatment of this waste stream. By mixing the acidic LLW and alkaline LLW, the carbonates in the alkaline LLW were destroyed and the TBP degraded products got separated as a layer at the top of the vessel. By making use of the modified co-precipitation process the effluent stream (1-2 μCi/L) became dischargeable to the environment after appropriate dilution. Based on the lab scale studies about 250 m(3) of LLW was treated in the plant. The higher activity of the TBP degraded products separated was due to short lived (90)Y isotope. The cement waste product prepared using the TBP degraded product was having good chemical durability and compressive strength. Copyright © 2011 Elsevier B.V. All rights reserved.

β-cyclodextrin inclusion complexes containing Citrus sinensis (L.) Osbeck essential oil: An alternative to control Aedes aegypti larvae

Energy Technology Data Exchange (ETDEWEB)

Galvão, J.G., E-mail: julianaggalvao@gmail.com [Pharmacy Department, Federal University of Sergipe, 49100-000 São Cristóvão, SE (Brazil); Silva, V.F.; Ferreira, S.G. [Pharmacy Department, Federal University of Sergipe, 49100-000 São Cristóvão, SE (Brazil); França, F.R.M. [Chemical Engineering Department, Federal University of Sergipe, 49100-000 São Cristóvão, SE (Brazil); Santos, D.A.; Freitas, L.S.; Alves, P.B. [Chemistry Department, Federal University of Sergipe, 49100-000 São Cristóvão, SE (Brazil); Araújo, A.A.S.; Cavalcanti, S.C.H.; Nunes, R.S. [Pharmacy Department, Federal University of Sergipe, 49100-000 São Cristóvão, SE (Brazil)

2015-05-20

Highlights: • Thermal analysis was useful to determine the formation of inclusion complexes by paste and co-precipitation methods. • HS/GC-FID quantitative analysis revealed that the best method of obtaining a CSEO/β-CD complex was the PWE, with the largest inclusion content [78.5%]. • The inclusion complex revealed LC{sub 50} of 23.01 ppm, close to CSEO LC{sub 50} 21.5 ppm. - Abstract: The development of β-cyclodextrin (β-CD) complexes is an interesting way for increasing the aqueous solubility of essential oils. The aim of this study was to prepare inclusion complexes of Citrus sinensis essential oil (CSEO) with β-CD using paste complexation (with and without co-solvent) and co-precipitation methods. Additionally, the physicochemical properties of the inclusion complexes using thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were evaluated. Furthermore, CSEO content (%) and solubility of complexes were measured. The biological activity against the Aedes aegypti Linn. larvae was further evaluated. For comparison purposes, a physical mixture between β-CD and CSEO was prepared and evaluated. Thermal analysis clearly indicated the formation of complexes by paste and co-precipitation methods. The headspace/gas chromatography quantitative analysis showed inclusions contents higher than 50%. On the other hand, the product revealed LC{sub 50} of 23.01 ppm, close to CSEO LC{sub 50} 21.5 ppm.

β-cyclodextrin inclusion complexes containing Citrus sinensis (L.) Osbeck essential oil: An alternative to control Aedes aegypti larvae

International Nuclear Information System (INIS)

Galvão, J.G.; Silva, V.F.; Ferreira, S.G.; França, F.R.M.; Santos, D.A.; Freitas, L.S.; Alves, P.B.; Araújo, A.A.S.; Cavalcanti, S.C.H.; Nunes, R.S.

2015-01-01

Highlights: • Thermal analysis was useful to determine the formation of inclusion complexes by paste and co-precipitation methods. • HS/GC-FID quantitative analysis revealed that the best method of obtaining a CSEO/β-CD complex was the PWE, with the largest inclusion content [78.5%]. • The inclusion complex revealed LC 50 of 23.01 ppm, close to CSEO LC 50 21.5 ppm. - Abstract: The development of β-cyclodextrin (β-CD) complexes is an interesting way for increasing the aqueous solubility of essential oils. The aim of this study was to prepare inclusion complexes of Citrus sinensis essential oil (CSEO) with β-CD using paste complexation (with and without co-solvent) and co-precipitation methods. Additionally, the physicochemical properties of the inclusion complexes using thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were evaluated. Furthermore, CSEO content (%) and solubility of complexes were measured. The biological activity against the Aedes aegypti Linn. larvae was further evaluated. For comparison purposes, a physical mixture between β-CD and CSEO was prepared and evaluated. Thermal analysis clearly indicated the formation of complexes by paste and co-precipitation methods. The headspace/gas chromatography quantitative analysis showed inclusions contents higher than 50%. On the other hand, the product revealed LC 50 of 23.01 ppm, close to CSEO LC 50 21.5 ppm

Pure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization

International Nuclear Information System (INIS)

Gosavi, Priti V.; Biniwale, Rajesh B.

2010-01-01

Three different wet chemistry routes, namely co-precipitation, combustion and sol-gel methods were used to synthesize LaFeO 3 perovskite with improved surface area. The synthesized perovskite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Brunauer-Emmett-Teller (BET) nitrogen adsorption, ultraviolet diffused reflectance spectroscopy (UVDRS) and Fourier transform infrared (FTIR) spectroscopy techniques. Improved surface area was observed for all three methods as compared to the previously reported values. The perovskite synthesized using sol-gel method yields comparatively pure, crystalline phase of LaFeO 3 and relatively higher surface area of 16.5 m 2 g -1 and porosity. The material synthesized using co-precipitation method yielded other phases in addition to the targeted phase. The morphology of perovskite synthesized using co-precipitation method was uniform agglomerates. Combustion method yields flakes type morphology and that of sol-gel method was open pore type morphology. The selection of method for perovskite synthesis largely depends on the targeted application and the desired properties of perovskites. The results reported in this study are useful for establishing a simple scalable method for preparation of high surface area LaFeO 3 as compared to solid-oxide method. Further, the typical heating cycle followed for calcinations resulted in relatively high surface area in the case of all three methods.

Rapid determination of actinides in seawater samples

International Nuclear Information System (INIS)

Maxwell, S.L.; Culligan, B.K.; Hutchison, J.B.; Utsey, R.C.; McAlister, D.R.

2014-01-01

A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti +3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1-2 weeks and provide chemical yields of ∼30-60 %. This new sample preparation method can be performed in 4-8 h with tracer yields of ∼85-95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort. (author)

Controlled release of ibuprofen using Mg Al LDH nano carrier

Science.gov (United States)

Dasgupta, Sudip

2017-08-01

In the present study, NSAID (non-steroidal anti-inflammatory drugs) such as ibuprofen in anionic form has been intercalated in-situ into the interlayer space of Mg Al LDH nanoparticle during co-precipitation of hydroxides. LDH nanohybrids are characterized by XRD, FTIR and UV spectroscopy. Mg1-xAlx(NO3)x(OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Ibuprofen was intercalated in inter layer space of Mg-Al LDH during coprecipitation of drug LDH conjugate in nitrogen atmosphere. The nanopowders synthesised were in the size range between 25 to 90 nm with an average particle size of 55 nm. XRD analysis proved that there is an increase in d003 spacing from 7.89 Å for pristine LDH to 14.71 Å for ibuprofen intercalated LDH due to the intercalation of bigger ibuprofen molecule in the interlayer space of LDH. FTIR analysis showed hydroxyl and carbonyl stretching of ibuprofen in LDH-IBU sample confirming the intercalation of ibuprofen in the interlayer structure of LDH. The drug release study in phosphate buffer solution at pH 7.4 using UV-Vis spectroscopy demonstrated that 50 % drug molecules were released in 15 hours and more than 85 % release was achieved after 36 hours.

Moessbauer study of CO-precipitated Fischer-Tropsch iron catalysts

International Nuclear Information System (INIS)

Rao, K.R.P.M.; Huggins, F.E.; Mahajan, V.; Huffman, G.P.; Bukur, D.B.; Rao, V.U.S.

1994-01-01

Moessbauer spectroscopy studies of precipitated Fischer-Tropsch (FT) iron catalysts, viz. 100 Fe/5 Cu/4.2 K/x SiO 2 , where x = 0, 8, 16, 24, 25, 40, or 100, have shown that reduction of the oxide precursor in CO gives rise to χ-carbide Fe 5 C 2 whose amount decreases with an increase of SiO 2 content. The χ-carbide is converted into magnetite Fe 3 O 4 while catalyzing the FT synthesis reaction. A correlation between FT activity and the content of χ-carbide in the catalysts was found, which indicated that χ-carbide is active for FT synthesis reaction. (orig.)

and aluminum-substituted cobalt ferrite prepared by co-precipitation ...

Indian Academy of Sciences (India)

Spinal ferrites having the general formula Co1-ZnFe2-AlO4 ( = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) were prepared using the wet chemical co-operation technique. The samples were annealed at 800°C for 12 h and were studied by means of X-ray diffraction, magnetization and low field AC susceptibility measurements.

Evaluation of the Suspending Properties of the Coprecipitate of ...

African Journals Online (AJOL)

The suspending ability of the different ratios was evaluated in magnesium trisilicate suspension, and compared with a suspension prepared with Compound Tragacanth Powder BP (CTP) as well as a commercially available magnesium trisilicate suspension (MTS). The parameters tested were sedimentation rate, flow rate, ...

Magnetic and microwave-absorbing properties of SrAl 4 Fe 8 O 19 ...

Indian Academy of Sciences (India)

The SEM analysis revealed that the coprecipitation process yielded a powder ... Ministry of Education, Shaanxi University of Science and Technology, Xi'an, ... Manuscript received: 12 September 2010; Manuscript revised: 16 January 2011 ...

Effect of the preparation method on the structural and catalytic properties of spinel cobalt-iron oxide

Energy Technology Data Exchange (ETDEWEB)

Hammiche-Bellal, Yasmina, E-mail: yasminahammiche@gmail.com [Laboratoire des Matériaux Catalytiques et Catalyse en Chimie Organique, Faculté de Chimie, USTHB, BP32 El Alia, Bab Ezzouar, 16111, Alger (Algeria); Djadoun, Amar [Laboratoire de Géophysique, FSTGAT, USTHB, BP32 El Alia, Bab Ezzouar, 16111, Alger (Algeria); Meddour-Boukhobza, Laaldja; Benadda, Amel [Laboratoire des Matériaux Catalytiques et Catalyse en Chimie Organique, Faculté de Chimie, USTHB, BP32 El Alia, Bab Ezzouar, 16111, Alger (Algeria); Auroux, Aline [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de Recherches sur la Catalyse et l' Environnement de Lyon, 2 Avenue Albert Einstein, F-69626, Villeurbanne (France); Berger, Marie-Hélène [Centre des Matériaux PIERRE-MARIE Fourt, UMR 7633, Paris (France); Mernache, Fateh [UDEC-CRND, COMENA, BP 43 Draria, 16050, Alger (Algeria)

2016-07-01

Spinel cobalt-iron oxide was synthesized by co-precipitation and hydrothermal routes. The effect of the co-precipitation experimental conditions, the calcination temperature and the hydrothermal synthesis time and temperature on the properties of the solids was studied. The prepared powders were evaluated as catalysts in the ethanol combustion reaction, and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM/EDX), nitrogen adsorption–desorption isotherms (BET, BJH) and temperature programmed reduction (TPR) techniques. Using chloride salts as starting materials and sodium hydroxide as precipitating agent, the CoFe{sub 2}O{sub 4} prepared powders displayed a mesoporous structure with a pore distribution strongly dependent on the experimental conditions. A monophasic spinel phase in the case of the calcined solids was obtained while the hydrothermal process led to the formation of a mixture of single oxides in addition to the spinel phase. The variation of the crystallite size and the lattice parameter as a function of calcination temperature was similar, whereas this variation found to be irregular when the synthesis residence time in autoclave was increased. The hydrothermally treated solids show the best catalytic performance in the total oxidation of ethanol. The catalytic behavior was correlated with the crystallite size and the reduction temperature of cobalt species determined by the TPR analysis. - Highlights: • Pure CoFe{sub 2}O{sub 4} phase is obtained by co-precipitation method at calcination temperatures 500–900 °C. • The temperature of co-precipitation procedure influences strongly the growth of the solids during the calcination step. • The hydrothermal synthesis gives a mixture of oxides; CoFe{sub 2}O{sub 4} is the predominant phase. • The CoFe{sub 2}O{sub 4} spinel showed a good catalytic reactivity in the ethanol combustion reaction. • The catalysts prepared by hydrothermal process are more reactive and

Recovery of indium ions by nanoscale zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Chen, Wen; Su, Yiming [Tongji University, State Key Laboratory of Pollution Control and Resources Reuse (China); Wen, Zhipan [Wuhan Institute of Technology, School of Chemistry and Environmental Engineering (China); Zhang, Yalei; Zhou, Xuefei, E-mail: zhouxuefei@tongji.edu.cn; Dai, Chaomeng, E-mail: daichaomeng@tongji.edu.cn [Tongji University, State Key Laboratory of Pollution Control and Resources Reuse (China)

2017-03-15

Indium and its compounds have plenty of industrial applications and high demand. Therefore, indium recovery from various industrial effluents is necessary. It was sequestered by nanoscale zero-valent iron (nZVI) whose size mainly ranged from 50 to 70 nm. Adsorption kinetics and isotherm, influence of pH, and ionic strength were thoroughly investigated. The reaction process was well fitted to a pseudo second-order model, and the maximum adsorption capacity of In(III) was 390 mg In(III)/g nZVI similar to 385 mg In(III)/g nZVI at 298 K calculated by Langmuir model. The mole ratio of Fe(II) released to In(III) immobilized was 3:2, which implied a special chemical process of co-precipitation combined Fe(OH){sub 2} with In(OH){sub 3}. Transmission electron microscopy with an energy-disperse X-ray (TEM-EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize surface morphology, corrosion products, and valence state of indium precipitate formed on nanoparticles. The structural evolution changed from core-shell structure of iron oxide to sheet structure of co-precipitation, to sphere structure that hydroxide gradually dissolved as the pH decreased, and to cavity structures for the pH continually decreased. Furthermore, below pH 4.7, the In(III) enrichment was inhibited for the limited capacity of co-precipitation. Also, it was found that Ca{sup 2+} and HPO{sub 4}{sup 2−} have more negative influence on In(III) recovery compared with Na{sup +}, NO{sub 3}{sup −}, HCO{sub 3}{sup −}, and SO{sub 4}{sup 2−}. Therefore, the In(III) recovery can be described by a mechanism which consists of adsorption, co-precipitation, and reduction and was over 78% even after 3 cycles. The results confirmed that it was applicable to employ nZVI for In(III) immobilization.

A sensitive nonenzymatic hydrogen peroxide sensor based on Fe 3 ...

Indian Academy of Sciences (India)

... were prepared by the co-precipitation method and followed by calcination process. ... Key Laboratory of Enhanced Oil & Gas Recovery of Ministry of Education, ... Manuscript received: 31 January 2014; Manuscript revised: 12 April 2014 ...

Influence of the preparation route on the magnetic and structural properties of cobalt ferrites

International Nuclear Information System (INIS)

Revoredo Junior, Frederico Alves; Silva Junior, Jose Holanda da; Hernandez, Eduardo Padron

2014-01-01

Cobalt ferrite nanoparticles were produced using two methods of preparation, co-precipitation and reaction in the solid state. In synthesis made by solid state reaction was performed by heat treatment at 1200 ° C for four hours alternating with triturations to increase the efficiency of the process. The synthesis by coprecipitation was made with different flows of addition of alkali (NaOH). All samples were structurally characterized by X-ray diffraction and the average size of the crystals was obtained by Scherrer's formula and the Williamson-Hall method. The magnetic measurements were made as a function of applied magnetic field and temperature. Qualitative analyzes of energy dispersive spectroscopy defined the elements of sampling and analysis. Finally, Mössbauer spectroscopy analysis defined the magnetic character of the samples. (author)

Study of the mineral absorbent precipitation phenomena used in decontamination of radioactive effluents; Etude des phenomenes de precipitation d'adsorbants mineraux utilises en decontamination d'effluents radioactifs

Energy Technology Data Exchange (ETDEWEB)

Pacary, V. [Institut National Polytechnique, 54 - Nancy (France)]|[CEA Valrho, Lab. des Procedes Avances de Decontamination (LPAD), 30 - Marcoule (France)

2006-07-01

The aim of this work is to determine the optimal conditions of the reactor running (feed rate, reagents concentration..) for which the effluent decontamination is the most efficient. Thus will be in particular studied the coprecipitation mechanisms and the influence of the physico-chemical conditions on these mechanisms. On the other hand, the processes occurred in the coprecipitation phenomenon being complex, the elaboration of a model is indispensable to guide and interpret the experimental work. This model will be based on the knowledge developed in precipitation and will allow to simulate the decontamination in two reactors types: the reactor fed in continuous in reagents and in effluents as the Hague's ones and the closed reactor fed only in reagents as the Marcoule's ones. (O.M.)

Synthesis of Fe3O4 particle-chain microwires in applied magnetic field

International Nuclear Information System (INIS)

Li Fashen; Wang Ying; Wang Tao

2007-01-01

Fe 3 O 4 particle-chain microwires are firstly synthesized under magnetic field by a simple coprecipitation method. The increase of magnetic field caused the lengthening of the wires, and doubled densities of starting solution lead to a halved diameter. It was supposed that the magnetic field gradient and the particular growing process of particles are the main factors of the formation of these microwires. Magnetic hysteresis curves of Fe 3 O 4 microwires were also measured. - Graphical abstract: Fe 3 O 4 particle-chain microwires are firstly synthesized under magnetic field by a simple coprecipitation method. It was supposed that the magnetic field gradient and the particular growing process of particles are the main factors of the formation of these microwires. Magnetic hysteresis curves of Fe 3 O 4 microwires were also measured

Advances in the catalysts development in base of mixed oxides for control reactions of N{sub 2}O; Avances en el desarrollo de catalizadores a base de oxidos mixtos para reacciones de control de N{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Garcia, M.A.; Perez, R.; Gomez, A.; Diaz, G. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, C.P. 11801 Mexico D.F. (Mexico)

2000-07-01

The catalytic supports Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-La{sub 2}O{sub 3} were prepared by the precipitation and coprecipitation techniques. The catalytic supports Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-La{sub 2}O{sub 3} were characterized by several techniques for to determine texture (BET), crystallinity (XRD), chemical composition (SEM), FTIR and it was evaluated their total acidity by the reaction with 2-propanol. It was continued with the cobalt addition by Impregnation and coprecipitation and it was evaluated its catalytic activity in the N{sub 2}O decomposition reaction. Also it was realized the N{sub 2}O reduction with Co using these catalysts. (Author)

Neutron activation analysis for the determination of arsenic and mercury in petroleum and petroleum distillates

International Nuclear Information System (INIS)

Resnizky, Sara M.

1999-01-01

A radiochemical separation procedure to determine As and Hg in petroleum and petroleum distillates is described. The procedure uses the formation of HgS to co-precipitate the As and Hg activities produced during the irradiation. (author)

Determination of trace elements in ground water by two preconcentration methods using atomic absorption spectrometry

International Nuclear Information System (INIS)

Elhag, A. Y.

2004-01-01

This is a comparative study between two different methods of preconcentration done to separate the trace elements cadmium, nickel. chromium, manganese, copper, zinc, and lead in drinking (ground) water samples taken from different locations in Gezira State, central Sudan (the map); these methods are (coprecipitation) with aluminium hydroxide and by Ammonium Pyrrolidine Dithiocarbamate (APDC) using Methyl Isobutyl Ketone (MIBK) as an organic solvent; and subsequent analysis by Atomic Absorption Spectrometry (AAS) for both methods. The result of comparison showed the superiority of the (APDC) coprecipitation method over the aluminium hydroxide coprecipitation method in the total percentage recoveries of the studied trace elements in drinking (ground) water samples, such results confirm previous studies. This study also involves direct analysis of these water samples by atomic absorption spectrometry to determine the concentrations of trace elements Cadmium, Nickel, Chromium, Manganese, Copper, Zinc and Lead and compare it to the corresponding guide line values described by the World Health Organization and the maximum concentrations of trace elements in drinking water permitted by the Sudanese Standards and Metrology Organizations (SSMO), where the concentrations of some elements in some samples were found to be different than the described values by both of the organizations. The study includes a trial to throw light on the effect of the proximity of the water samples sources to the Blue Nile river on its trace elements concentrations; no relation was proved to exist in that respect.(Author)

A New Superalloy Enabling Heavy Duty Gas Turbine Wheels for Improved Combined Cycle Efficiency

Energy Technology Data Exchange (ETDEWEB)

Detor, Andrew [General Electric Company, Niskayuna, NY (United States). GE Global Research; DiDomizio, Richard [General Electric Company, Niskayuna, NY (United States). GE Global Research; McAllister, Don [The Ohio State Univ., Columbus, OH (United States); Sampson, Erica [General Electric Company, Niskayuna, NY (United States). GE Global Research; Shi, Rongpei [The Ohio State Univ., Columbus, OH (United States); Zhou, Ning [General Electric Company, Niskayuna, NY (United States). GE Global Research

2017-01-03

The drive to increase combined cycle turbine efficiency from 62% to 65% for the next-generation advanced cycle requires a new heavy duty gas turbine wheel material capable of operating at 1200°F and above. Current wheel materials are limited by the stability of their major strengthening phase (gamma double prime), which coarsens at temperatures approaching 1200°F, resulting in a substantial reduction in strength. More advanced gamma prime superalloys, such as those used in jet engine turbine disks, are also not suitable due to size constraints; the gamma prime phase overages during the slow cooling rates inherent in processing thick-section turbine wheels. The current program addresses this need by screening two new alloy design concepts. The first concept exploits a gamma prime/gamma double prime coprecipitation reaction. Through manipulation of alloy chemistry, coprecipitation is controlled such that gamma double prime is used only to slow the growth of gamma prime during slow cooling, preventing over-aging, and allowing for subsequent heat treatment to maximize strength. In parallel, phase field modeling provides fundamental understanding of the coprecipitation reaction. The second concept uses oxide dispersion strengthening to improve on two existing alloys that exhibit excellent hold time fatigue crack growth resistance, but have insufficient strength to be considered for gas turbine wheels. Mechanical milling forces the dissolution of starting oxide powders into a metal matrix allowing for solid state precipitation of new, nanometer scale oxides that are effective at dispersion strengthening.

Soft-chemical synthesis and catalytic activity of Ni-Al and Co-Al layered double hydroxides (LDHs intercalated with anions with different charge density

Directory of Open Access Journals (Sweden)

Takahiro Takei

2014-09-01

Full Text Available Co-Al and Ni-Al layered double hydroxides (LDHs intercalated with three types of anionic molecules, dodecylsulfate (C12H25SO4−, DS, di-2-ethylsulfosuccinate ([COOC2H3EtBu]2C2H3SO3−, D2ES, and polytungstate (H2W12O4210−, HWO were prepared by means of ion-exchange and co-precipitation processes. With the use of DS and D2ES as intercalation agents, high crystallinity was maintained after intercalation into the LDHs. In the case of HWO, the intercalated LDHs could be obtained by ion-exchange as well as co-precipitation with a decline in the crystallinity; however, unreacted LDH was detected in the ion-exchange samples, and some unwanted phases such as hydroxide and pyrochlore were generated by the co-precipitation process. The maximum specific surface area and pore volume of the Ni-Al sample with intercalated HWO, prepared by the ion-exchange process were 74 m2/g and 0.174 mL/g, respectively. The occupancies of DS, D2ES, and HWO within the interlayer space were approximately 0.3–0.4, 0.5–0.6, and 0.1–0.2, respectively, in the Co-Al and Ni-Al LDHs. Analysis of the catalytic activity demonstrated that the DS-intercalated Ni-Al LDH sample exhibited relatively good catalytic activity for conversion of cyclohexanol to cyclohexanone.

New hydrotalcite-like compounds containing yttrium

Energy Technology Data Exchange (ETDEWEB)

Fernandez, J.M.; Barriga, C.; Ulibarri, M.A. [Universidad de Cordoba (Spain)] [and others

1997-01-01

The synthesis of hydrotalcite-type compounds containing yttrium was carried out by the coprecipitation of Mg(II), Al(III), and Y(III) cations at 60 degrees C with strong alkaline solutions. Thermal treatments were applied and changes studied.

Effect of PdS on Photocatalytic Hydrogen Evolution of Nanostructured CdS under Visible Light Irradiation

Directory of Open Access Journals (Sweden)

Qingyun Chen

2013-01-01

Full Text Available To investigate the effect of PdS as a cocatalyst for photocatalytic hydrogen evolution, nanostructured PdS/CdS were prepared by an in situ coprecipitation and hydrothermal method, respectively. The as-prepared photocatalysts were characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD, UV-visible absorption spectra, and photoluminescence spectra (PL. With PdS highly dispersed in the CdS nanostructures, the photoactivity was evaluated by hydrogen evolution from aqueous solution containing Na2S/Na2SO3 as sacrificial reagents under visible light irradiation. When the concentration of PdS was 1% by weight, PdS/CdS, prepared by the in situ coprecipitation, showed the highest photocatalytic activity, while that prepared by hydrothermal method showed the most stability for hydrogen evolution. The effect of highly dispersed PdS on the photoactivity was discussed.

Method for determination of radium-226 in water by liquid scintillation counting

International Nuclear Information System (INIS)

Suomela, J.

1993-07-01

The chemical procedure involves the isolation or radium from the sample solution by co-precipitation with lead sulphate. The precipitate is dissolved in alkaline DTPA. The radium isotopes are separated from other radionuclides by co-precipitation with barium sulphate. The barium/radium precipitate is dissolved in alkaline EDTA, the solution is transfered to a liquid scintillation vial and the organic scintillant is added. After sealing, the sample is left until equilibrium between Ra-226 and Rn-222 is established or until a suitable ingrowth time has elapsed. The alpha activity of Rn-222 and its short-lived daughters, Po-218 and Po-214, are measured by the use of a commercial liquid scintillation counter. By using the following procedure and a low level LSC a lover limit of detection of 2 mBq/sample can be achieved

Radium migration of thorium deposit of Morro do Ferro (Pocos de Caldas, MG, Brazil) under conditions of no rainfall (baseflow regime)

International Nuclear Information System (INIS)

Campos, M.J.M.T. de.

1984-01-01

The mechanisms of radium leaching and transport at the Morro do Ferro are investigated to estimate the 228 Ra mobilization rate, under conditions of no rainfall (baseflow regime). Radium was analysed in solution and in suspended solids, in surface and ground waters at the Morro do Ferro general basin Ra-226 was determined by the radon emanation method and 228 Ra through the radiometry of its first daughter 228 Ac. Initially, a radiochemical procedure was employed for 228 Ra, which performs the purification of radium by coprecipitation with BaSO 4 , and the separation of 228 Ac by coprecipitation with LaF 3 , which is then beta counted. At the later phase of this work the samples were analyzed by the radiometric method which is based on the radiometry of β-γ 228 Ac coincidence transitions. (M.A.C.) [pt

Corrosion inhibition by lithium zinc phosphate pigment

International Nuclear Information System (INIS)

Alibakhshi, E.; Ghasemi, E.; Mahdavian, M.

2013-01-01

Highlights: •Synthesis of lithium zinc phosphate (LZP) by chemical co-precipitation method. •Corrosion inhibition activity of pigments compare with zinc phosphate (ZP). •LZP showed superior corrosion inhibition effect in EIS measurements. •Evaluation of adhesion strength and dispersion stability. -- Abstract: Lithium zinc phosphate (LZP) has been synthesized through a co-precipitation process and characterized by XRD and IR spectroscopy. The inhibitive performances of this pigment for corrosion of mild steel have been discussed in comparison with the zinc phosphate (ZP) in the pigment extract solution by means of EIS and in the epoxy coating by means of salt spray. The EIS and salt spray results revealed the superior corrosion inhibitive effect of LZP compared to ZP. Moreover, adhesion strength and dispersion stability of the pigmented epoxy coating showed the advantage of LZP compared to ZP

Technical liaison with the Institute of Physical Chemistry (Russian Academy of Science)

International Nuclear Information System (INIS)

Delegard, C.H.

1995-12-01

The Institute of Physical Chemistry of the Russian Academy of Science (IPC/RAS) is engaged by the DOE to conduct studies of the fundamental and applied chemistry of the transuranium elements (TRU; primarily neptunium, plutonium, and americium; Np, Pu, Am) and technetium T c in alkaline media. This work is being supported by the DOE because the radioactive wastes stored in underground tanks at DOE sites (Hanford, Savannah River, and Oak Ridge) contain TRU and T c , are alkaline, and the chemistries of TRU and T c are not well developed in this system. Previous studies at the IPC/RAS centered on the fundamental chemistry and on coprecipitation. Work continuing in FY 1996 will focus more on the applied chemistry of the TRU and T c in alkaline media and continue effort on the coprecipitation task

Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium

Czech Academy of Sciences Publication Activity Database

Smolkova, I.S.; Kazantseva, N.E.; Babayan, V.; Smolka, P.; Parmar, H.; Vilcakova, J.; Schneeweiss, Oldřich; Pizúrová, Naděžda

2015-01-01

Roč. 374, JAN (2015), s. 508-515 ISSN 0304-8853 Institutional support: RVO:68081723 Keywords : Iron oxide nanoparticles * Coprecipitation * Magnetic interactions * Specific loss power * Hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.357, year: 2015

Maghemite decorated with ultra-small palladium nanoparticles (γ-Fe2O3–Pd): applications in the Heck–Mizoroki olefination, Suzuki reaction and allylic oxidation of alkenes

Science.gov (United States)

A nanocatalyst comprising ultra-small Pd/PdO nanoparticles (<5 nm) supported on maghemite was prepared by a co-precipitation protocol using inexpensive raw materials and was deployed successfully in various significant synthetic transformations, namely the Heck–Mizoroki olefinati...

Platinum-group elements in the Eastern Deccan volcanic province ...

Indian Academy of Sciences (India)

This study is the first detailed investigation of the platinum-group elements (PGE) at the eastern mar- ... A Zr vs. Pd scattergram found a strong positive correlation for these two elements ..... and the PGE and Au collected by co-precipitation.

Preparation of rifampicin/poly(d,l-lactice) nanoparticles for sustained release by supercritical assisted atomization technique

CSIR Research Space (South Africa)

Labuschagne, Philip W

2014-11-01

Full Text Available In this work supercritical assisted atomization (SAA) process was used for the co-precipitation of poly(d,l-lactide) (PDLLA) and rifampicin (RIF) as nanoparticles for sustained release applications. The effect of the variation of PDLLA/RIF ratio...

Continuous flow hydrogenation of nitroarenes, azides and alkenes using maghemite-Pd nanocomposites

Science.gov (United States)

Maghemite-supported ultra-fine Pd (1-2 nm) nanoparticles, prepared by a simple co-precipitation method, find application in the catalytic continuous flow hydrogenation of nitroarenes, azides, and alkenes wherein they play an important role in reduction of various functional group...

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

1151. Yb and Er co-doped Y2Ce2O7 nanoparticles: synthesis and spectroscopic properties ... Co-precipitation synthesis and upconversion luminescence properties of ZrO2:Yb-Ho · Jinsheng Liao Shaohua Liu Liling Nie Suijun Liu Junxiang Fu.

Influencing the solubility of oxalates for the preparation of ceramic powders from mixed precipitates

International Nuclear Information System (INIS)

Krueger, C.; Fischer, S.; Fischer, St.; Chebani, M.Kh.

1991-01-01

Based on investigations of the solubility of oxalate with 140 Ba, 64 Cu and 59 Fe, techniques for quantitative oxalate coprecipitation were developed. Addition of organic solvents lowers the solubility and leads to a smaller particle size of products. (orig.) [de

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

... nanoparticles prepared by co-precipitation and hydrothermal methods ... Chemically ordered face-centred tetragonal Fe–Pt nanoparticles embedded SiO2 films .... Synthesis and characterization of carboxymethyl chitosan hydrogel: .... Chemically deposited TiO2/CdS bilayer system for photoelectrochemical properties.

Raney copper catalysts for the water-gas shift reaction - II. Initial catalyst optimisation

CSIR Research Space (South Africa)

Mellor, JR

1997-12-23

Full Text Available The initial Raney copper WGS activity based on catalyst volume has been shown to be comparable to industrial and co-precipitated alternatives under varying reaction conditions. The presence of zinc oxide in the Raney copper structure was shown...

Crystal structure transformation of TiO2 in presence of Fe2O3 and ...

Indian Academy of Sciences (India)

Unknown

The activation energy for this transformation was also calculated. The method of ... The samples were prepared by two different methods, viz. co-precipitation and ..... Kolthoff J M, Elving P J and Sandell E B 1961 Treat. Anal. Chem. 5 49.

The synthesis and characterization of mixed Y2O3-doped ZrO2 and ¿-Fe2O3 nanosized powders

NARCIS (Netherlands)

Raming, T.P.; Winnubst, Aloysius J.A.; Verweij, H.

2002-01-01

Several wet chemical precipitation methods used to synthesise nanocrystalline composite powders containing zirconium oxide, yttrium oxide and iron(III) oxide are described. The crystallisation and phase composition of the precipitates were studied as a function of temperature. A co-precipitation

Synthesis, characterization and photocatalytic activity of WO3/TiO2 for NO removal under UV and visible light irradiation

NARCIS (Netherlands)

Luevano Hipolito, E.; Martínez-de la Cruz, A.; López-Cuellar, E.; Yu, Q.L.; Brouwers, H.J.H.

2014-01-01

Samples with different proportions WO3/TiO2 were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and

Size dependence of photocatalytic oxidation reactions of Rh nanoparticles dispersed on (Ga1-xZnx)(N1-xOx) support

NARCIS (Netherlands)

Zhang, Y.; Ligthart, D.A.J.M.; Liu, P.; Gao, L.; Verhoeven, M.W.G.M.; Hensen, E.J.M.

2014-01-01

Mixed Ga–Zn oxynitrides were synthesized using coprecipitation, wet-precipitation, and solid-solution methods. The oxynitrides were used as supports for Rh nanoparticle catalysts in photocatalytic water splitting, CO oxidation, and H2 oxidation. Mixed Ga–Zn oxynitrides produced by wet precipitation

Implementation of suitable flow injection/sequential injection on-line sample pretreatment schemes. Separation and preconcentration procedures for the determination of trace metal concentrations by ETAAS and/or ICPMS

DEFF Research Database (Denmark)

Hansen, Elo Harald; Wang, Jianhua

are feasible, such as liquid-liquid extraction, (co)precipitation with collection in knotted reactors, adsorption, hydride generation, or the use of ion-exchange columns. Apart from hydride generation, where the analyte is converted into a gaseous species, the common denominator for these approaches...

Inorganic layered double hydroxides as a 4-hexyl resorcinol delivery system for topical applications

CSIR Research Space (South Africa)

Mosangi, Damodar

2016-08-01

Full Text Available In this study, the hydrophobic even skin tone active, 4-hexylresorcinol (HR), was intercalated into a zinc aluminium layered double hydroxide (ZnAl-LDH) by a co-precipitation method and used as a controlled release ingredient in skin care...

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 30; Issue 4 ... Microwave materials; ceramic dielectric resonators; polytitanates; co-precipitation. ... hypotheses viz. diffusion, high surface and nucleation energy, potential barrier, non-stoichiometry etc as critical factors limiting formation of 2 : 9 as single-phase material.

Highly efficient catalytic reductive degradation of various organic ...

Indian Academy of Sciences (India)

aDepartment of Applied Sciences (Chemical Science Division), GUIST, Gauhati University, ... Highly improved catalytic reductive degradation of different organic dyes, in the ... was prepared by a facile co-precipitation method using ultra-high dilute aqueous solutions. ...... face chemical-modification for engineering the intrin-.

Precipitation diagram of calcium carbonate polymorphs: its construction and significance

International Nuclear Information System (INIS)

Kawano, Jun; Shimobayashi, Norimasa; Miyake, Akira; Kitamura, Masao

2009-01-01

In order to interpret the formation mechanism of calcium carbonate polymorphs, we propose and construct a new 'precipitation diagram', which has two variables: the driving force for nucleation and temperature. The precipitation experiments were carried out by mixing calcium chloride and sodium carbonate aqueous solutions. As a result, a calcite-vaterite co-precipitation zone, a vaterite precipitation zone, a vaterite-aragonite co-precipitation zone and an aragonite precipitation zone can be defined. Theoretical considerations suggest that the steady state nucleation theory can explain well the appearance of these four zones, and the first-order importance of the temperature dependency of surface free energy in the nucleation of aragonite. Furthermore, the addition of an impurity will likely result in the change of these energies, and this precipitation diagram gives a new basis for interpreting the nature of the polymorphs precipitated in both inorganic and biological environments.

Preparation of mixed oxides (Th,U)O2: an evaluation of different techniques

International Nuclear Information System (INIS)

Ayoub, Jamil Mahmoud Said

1999-01-01

An evaluation of different ways of obtaining (Th-U)O 2 mixed oxides is described. Coprecipitation, mechanical mixing of uranium and thorium powders, and the sol-gel technique were studied in order to get a large spectrum of knowledge of the process performance. The use of ultrasonic waves for the homogenization of the hydroxide mixture and microwave heating for powder drying was also investigated. Sol-gel showed the best results regarding the specific area for obtained samples. Oxide drying by microwave is an effective method to get mixed oxides for fuel fabrication. Neither coprecipitation nor mechanical mixing of the thorium and uranium oxide powders is suitable for the purpose. The obtained data are less than 70% than those achieved when sol-gel process is performed. Electronic microscopy, X-ray fluorescence and diffraction, thermogravimetry, specific gravidity and specific area determination (BET) used for sample characterization were convenient and accomplished good results. (author)

Municipal compost-based mixture for acid mine drainage bioremediation: Metal retention mechanisms

Energy Technology Data Exchange (ETDEWEB)

Oriol Gibert; Joan de Pablo; Jose Luis Cortina; Carlos Ayora [Universitat Politecnica de Catalunya, Barcelona (Spain). Departament d' Enginyeria Qumica

2005-09-15

An upflow packed column was operated to evaluate the potential of a mixture of municipal compost and calcite to promote sulphidogenesis in the remediation of a simulated mine water at high flows (>0.1 m d{sup -1}). Results showed that the pH was neutralised and metals (Fe, Al, Zn, Cu) were significantly removed. Metal removal was attributed to the combined result of precipitation as metal (oxy)hydroxides and carbonates, co-precipitation with these (oxy)hydroxides and sorption onto the compost surface rather than to precipitation as metal sulphides. The two last mechanisms are especially significant for Zn, whose hydroxide is not expected to precipitate at pH 6-7. Before the saturation of compost sorption sites, 60% of the influent Zn was estimated to have been removed by co-precipitation with Fe- and Al-(oxy)hydroxide and 40% by sorption onto the municipal compost.

Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

Energy Technology Data Exchange (ETDEWEB)

Arratia-Quijada, Jenny [Departamento de Ciencias de la Salud, Centro Universitario Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico No. 555, C.P. 48525, Tonalá, Jalisco (Mexico); Sánchez Jiménez, Cecilia [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, St. Petersburg State University, Universitetskiy pr. 26, 198504 St. Petersburg (Russian Federation); NMR Core Lab, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Pérez Centeno, Armando; Ceja Andrade, Israel [Departamento de Física, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

2016-01-15

Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

International Nuclear Information System (INIS)

Arratia-Quijada, Jenny; Sánchez Jiménez, Cecilia; Gurinov, Andrey; Pérez Centeno, Armando; Ceja Andrade, Israel; Carbajal Arízaga, Gregorio Guadalupe

2016-01-01

Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate

DEFF Research Database (Denmark)

Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

2015-01-01

Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenviro......Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track...