WorldWideScience

Sample records for cerium dioxide preparation

  1. Cerium dioxide with large particle size prepared by continuous precipitation

    Institute of Scientific and Technical Information of China (English)

    李梅; 王觅堂; 柳召刚; 胡艳宏; 吴锦绣

    2009-01-01

    Cerium dioxide(CeO2) has attracted much attention and has wide applications such as automotive exhaust catalysts,polishing materials for optical glasses and additives for advanced glasses,as well as cosmetic materials.The particle size and its distribution are key factors to the performance of the materials in the functional applications.However,control of particle size is still a challenge in materials synthesis.Therefore,continuous precipitation of cerium oxalate(precursor of ceria) was carried out at dif...

  2. Fire retardancy of emulsion polymerized poly (methyl methacrylate)/cerium(IV) dioxide and polystyrene/cerium(IV) dioxide nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Guipeng [Department of Chemistry and Fire Retardant Research Facility, Marquette University, PO Box 1881, Milwaukee, WI 53201 (United States); Lu, Hongdian [Department of Chemical and Materials Engineering, Hefei University, Hefei, Anhui 230022 (China); Zhou, You; Hao, Jianwei [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Wilkie, Charles A., E-mail: charles.wilkie@marquette.edu [Department of Chemistry and Fire Retardant Research Facility, Marquette University, PO Box 1881, Milwaukee, WI 53201 (United States)

    2012-12-10

    Highlights: Black-Right-Pointing-Pointer We prepare PMMA and PS containing ceria. Black-Right-Pointing-Pointer Characterization by XRD and TEM shows that some of the ceria is well-dispersed in the polymers. Black-Right-Pointing-Pointer The addition of ceria to both polymers leads to reduced thermal stability. Black-Right-Pointing-Pointer In PMMA, the fire retardancy is enhanced but there is little effect in PS. - Abstract: In situ emulsion polymerization was employed to obtain poly (methyl methacrylate) (PMMA)/cerium(IV) dioxide and polystyrene (PS)/cerium(IV) dioxide nanocomposites at two different cerium(IV) dioxide loadings (2.3 wt% and 4.6 wt%). Transmission electron microscope results indicated uniform dispersion of cerium (IV) dioxide in the polymer matrix. Both PMMA and PS nanocomposites exhibit lower thermal stability than the pristine polymers. Microscale combustion calorimeter (MCC) and cone calorimetry are used to evaluate the fire retardancy of the polymer nanocomposites. PMMA/cerium(IV) dioxide showed significant heat release rate (HRR) reduction at low loadings (<5 wt%), while PS/cerium(IV) dioxide exhibits less HRR reduction at the same loadings. An explanation of the role of cerium (IV) dioxide in fire retardancy of polymer/ceria nanocomposites based on XPS results is suggested.

  3. Ultrathin, epitaxial cerium dioxide on silicon

    Science.gov (United States)

    Flege, Jan Ingo; Kaemena, Björn; Höcker, Jan; Bertram, Florian; Wollschläger, Joachim; Schmidt, Thomas; Falta, Jens

    2014-03-01

    It is shown that ultrathin, highly ordered, continuous films of cerium dioxide may be prepared on silicon following substrate prepassivation using an atomic layer of chlorine. The as-deposited, few-nanometer-thin Ce2O3 film may very effectively be converted at room temperature to almost fully oxidized CeO2 by simple exposure to air, as demonstrated by hard X-ray photoemission spectroscopy and X-ray diffraction. This post-oxidation process essentially results in a negligible loss in film crystallinity and interface abruptness.

  4. Pure cerium dioxide preparation for use as spectrochemical standard and analysed by inductively coupled plasma mass spectrometry (SF ICP-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Carlos A. da S.; Abrao, Alcidio; Rocha, Soraya M.R. da; Vasconcellos, Mari E. de; Seneda, Jose A.; Forbicini, Christina A.L.G. de O. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: cqueiroz@ipen.br; Pedreira, Walter R.; Boaventura, Geraldo R. [Brasilia Univ., DF (Brazil). Dept. de Geociencias; Pimentel, Marcio M. [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Sao Paulo, SP (Brazil)]. E-mail: walter.pedreira@fundacentro.gov.br

    2005-11-15

    several years, IPEN/CNEN-SP has been working in the separation of the Rare Earth (RE) elements. A simple and economic procedure for the purification of technical grade cerium concentrate is described. The highly pure cerium dioxide is designed to be used as spectrochemical standard. It is obtained by association of the fractional precipitation technique, in the system RECl{sub 3}/NH{sub 4}OH/ Air/H{sub 2}O{sub 2}, to enrich the cerium up to 90% and then it is upgraded by ion exchange technique to 99.99% CeO{sub 2}. The quality control warranty was accomplished by inductively coupled mass spectrometry (ICP-MS) and neutron activation analysis. The collected values for the accompanying Rare Earth elements in a CeO{sub 2} sample are the following (ppm): La(36), Pr(19), Nd(161), Sm(11), Eu(5.3), Gd(113), Tb(89), Dy(2), Ho(0.05), Er(1), Tm(<0.05), Yb(11), Lu(19) and Y(2.1), respectively. The purity of this cerium oxide is comparable to the international spectrographic standards. (author)

  5. Cerium Dioxide Thin Films Using Spin Coating

    Directory of Open Access Journals (Sweden)

    D. Channei

    2013-01-01

    Full Text Available Cerium dioxide (CeO2 thin films with varying Ce concentrations (0.1 to 0.9 M, metal basis were deposited on soda-lime-silica glass substrates using spin coating. It was found that all films exhibited the cubic fluorite structure after annealing at 500°C for 5 h. The laser Raman microspectroscopy and GAXRD analyses revealed that increasing concentrations of Ce resulted in an increase in the degree of crystallinity. FIB and FESEM images confirmed the laser Raman and GAXRD analyses results owing to the predicted increase in film thickness with increasing Ce concentration. However, porosity and shrinkage (drying cracking of the films also increased significantly with increasing Ce concentrations. UV-VIS spectrophotometry data showed that the transmission of the films decreased with increasing Ce concentrations due to the increasing crack formation. Furthermore, a red shift was observed with increasing Ce concentrations, which resulted in a decrease in the optical indirect band gap.

  6. Molecular and physiological responses to titanium dioxide and cerium oxide nanoparticles in arabidopsis

    Science.gov (United States)

    - Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that e...

  7. Preparing Process of Cerium Acetate and Rare Earth Acetate

    Institute of Scientific and Technical Information of China (English)

    Qiao Jun; Ma Ying; Xu Yanhui; Zhang Jun; Chang Shu; Hao Xianku

    2004-01-01

    Preparing process was presented and the influences of concentration of acetic acid, reaction temperature, the ratio of cerium carbonate and acetic acid, heat preservation time to the yield of cerium acetate were discussed.The crystalline cerium acetate and rare earth acetate such as ( La, Ce, Pr, Nd) (Ac) 3, ( Ce, Pr, Nd) (Ac) 3, ( Pr, Nd, Er,Y) (Ac) 3 and yttrium acetate were prepared under this condition.The shape, structure and composition of the crystals were determined by the methods of SEM, TG-DTA, X-ray diffraction and chemical analysis.The optimum prepared conditions of cerium acetate were described.This prepared process has characteristics such as simple process route, low cost, high yield, good quality, no pollution to environment, etc.

  8. Fate of cerium dioxide nanoparticles in endothelial cells: exocytosis

    Energy Technology Data Exchange (ETDEWEB)

    Strobel, Claudia, E-mail: Claudia.Strobel@med.uni-jena.de [Jena University Hospital – Friedrich Schiller University Jena, Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology (Germany); Oehring, Hartmut [Jena University Hospital – Friedrich Schiller University Jena, Institute of Anatomy II (Germany); Herrmann, Rudolf [University of Augsburg, Department of Physics (Germany); Förster, Martin [Jena University Hospital – Friedrich Schiller University Jena, Department of Internal Medicine I, Division of Pulmonary Medicine and Allergy/Immunology (Germany); Reller, Armin [University of Augsburg, Department of Physics (Germany); Hilger, Ingrid, E-mail: ingrid.hilger@med.uni-jena.de [Jena University Hospital – Friedrich Schiller University Jena, Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology (Germany)

    2015-05-15

    Although cytotoxicity and endocytosis of nanoparticles have been the subject of numerous studies, investigations regarding exocytosis as an important mechanism to reduce intracellular nanoparticle accumulation are rather rare and there is a distinct lack of knowledge. The current study investigated the behavior of human microvascular endothelial cells to exocytose cerium dioxide (CeO{sub 2}) nanoparticles (18.8 nm) by utilization of specific inhibitors [brefeldin A; nocodazole; methyl-β-cyclodextrin (MβcD)] and different analytical methods (flow cytometry, transmission electron microscopy, inductively coupled plasma mass spectrometry). Overall, it was found that endothelial cells were able to release CeO{sub 2} nanoparticles via exocytosis after the migration of nanoparticle containing endosomes toward the plasma membrane. The exocytosis process occurred mainly by fusion of vesicular membranes with plasma membrane resulting in the discharge of vesicular content to extracellular environment. Nevertheless, it seems to be likely that nanoparticles present in the cytosol could leave the cells in a direct manner. MβcD treatment led to the strongest inhibition of the nanoparticle exocytosis indicating a significant role of the plasma membrane cholesterol content in the exocytosis process. Brefeldin A (inhibitor of Golgi-to-cell-surface-transport) caused a higher inhibitory effect on exocytosis than nocodazole (inhibitor of microtubules). Thus, the transfer from distal Golgi compartments to the cell surface influenced the exocytosis process of the CeO{sub 2} nanoparticles more than the microtubule-associated transport. In conclusion, endothelial cells, which came in contact with nanoparticles, e.g., after intravenously applied nano-based drugs, can regulate their intracellular nanoparticle amount, which is necessary to avoid adverse nanoparticle effects on cells.

  9. Phenotypic and genomic responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis germinants

    Science.gov (United States)

    The effects of exposure to two nanoparticles (NPs) -titanium dioxide (nano-titania) and cerium oxide (nano-ceria) at 500 mg NPs L-1 on gene expression and growth in Arabidopsis thaliana germinants were studied using microarrays and phenotype studies. After 12 days post treatment,...

  10. Preparation and characterization of gelatin/cerium(Ⅲ) film

    Institute of Scientific and Technical Information of China (English)

    黄崇军; 黄雅钦; 田娜; 童元建; 殷瑞贤

    2010-01-01

    A novel gelatin film with antibacterial activity was prepared by electrostatic crosslinking using cerium (Ⅲ) nitrate hexahydrate as the crosslinking agent. The structure and properties of the films were investigated by Fourier transform infrared spectra, tensile tests, thermogravimetric analysis, static drop contact angle and disc diffusion method. The results showed that cross-linking could not only improve the thermal and mechanical properties and lower the hydrophilic property of the films, but also make...

  11. Preparation, Characterization and Antibacterial Property of Cerium Substituted Hydroxyapatite Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Lin Yingguang; Yang Zhuoru; Cheng Jiang

    2007-01-01

    Nanoparticles of hydroxyapatite (HAP) and cerium substituted hydroxyapatite (CeHAP) with the atomic ratio of Ce/[Ca+Ce] (xCe) from 0 to 0.2 were prepared by sol-gel-supercritical fluid drying (SCFD) method. The nanoparticles were characterized by TEM, XRD, and FT-IR, and the effects of cerium on crystal structure, crystallinity, and particle shape were discussed. With the tests of bacterial inhibition zone and antibacterial ratio, the antibacterial property of HAP and CeHAP nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results showed that the nanoparticles of HAP and CeHAP could be made by sol-gel-SCFD, cerium could partially substitute for calcium and enter the structure of HAP. After substitution, the crystallinity, the IR wavenumbers of bonds in CeHAP decreased gradually with increase of cerium substitution, and the morphology of the nanoparticles changed from the short rod-shaped HAP to the needle-shaped CeHAP. The nanoparticles of HAP and CeHAP with xCe below 0.08 had antibacterial property only forcibly contacting with the test bacteria at the test concentration of 0.1 g·ml-1, however, the CeHAP nanoparticles had antibacterial ability at that concentration no matter statically or dynamically contacting with the test bacteria when xCe was above 0.08, and the antibacterial ability gets better with the increase of xCe, indicating that the antibacterial property was improved after calcium was partially substituted by cerium. The improved antibacterial effects of CeHAP nanoparticle on Lactobacillus showed its potential ability to anticaries.

  12. The PL "violet shift" of cerium dioxide on silicon

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CeO2 thin film was fabricated by dual ion beam epitaxial technique. The phenomenon of PL violet shift at room temperature was observed, and the distance of shift was about 65 nm. After the analysis of crystal structure and valence in the compound were carried out by XRD and XPS technique, it was concluded that the PL shift was related with valence of cerium ion in the oxides. When the valence of cerium ion varied from tetravalence to trivalence, the PL peak position would move from blue region to violet region and the phenomenon of "violet shift" was observed.

  13. Effect of oxygen defects on thermal conductivity of thorium-cerium dioxide solid solutions

    Science.gov (United States)

    Muta, Hiroaki; Kado, Hirohisa; Ohishi, Yuji; Kurosaki, Ken; Yamanaka, Shinsuke

    2017-01-01

    Thermal conductivity of thorium-cerium dioxide solid solutions has been measured and analyzed using the relaxation time approximation. Despite the presence of oxygen defects, the partially reduced Th0.8Ce0.2O1.97 exhibited higher thermal conductivity than the stoichiometric one, Th0.8Ce0.2O2.00, showing the same tendency as that previously reported for Th0.7Pu0.3O2-δ. The increase in thermal conductivity with the oxygen defects can be explained by assuming that cerium ions have an average ionic radius of the ionic radii of Ce3+ and Ce4+ in the description of phonon-impurity scattering. This result indicates that the small reduction of (Th,Pu)O2-δ fuel increases the thermal conductivity, especially at high temperatures.

  14. Preparation and visible-light-driven photocatalytic performance of cerium-doped titanium dioxide%Ce掺杂TiO2的制备及其可见光光催化性能

    Institute of Scientific and Technical Information of China (English)

    富好; 罗秀针; 袁霞; 施俊新; 高碧芬

    2013-01-01

    Ce-doped TiO2 nanoparticles were prepared by sol-gel method.The structure and physicochemical properties of the catalysts were investigated by means of XRD,FT-IR,XPS,UV-Vis DRS,etc.The photocat-alytic activities of Ce-doped TiO2 were evaluated by the degradation of acid red under visible light irradiation. The experiment results show that Ce-O-Ti bonds are formed on the interface of cerium oxide and TiO2 ,so that the crystallization and phase transition processes of the catalyst are impeded.Ce-TiO2 has a significant ab-sorption in the visible region and the recombination of the photo-generated electron and hole pairs was greatly inhibited.Hence,the visible-light-driven photocatalytic efficiency of Ce-TiO2 was significantly enhanced.The catalyst doped with 20% Ce presents the best activity when calcinated at 400 ℃.%采用溶胶-凝胶法制备 Ce 掺杂 TiO2(Ce-TiO2)纳米颗粒,借助 XRD、XPS、UV-Vis、DRS 等手段对催化剂的结构和理化性质进行分析表征,并以酸性红染料作为模型污染物,考察 Ce-TiO2在可见光作用下的催化活性。实验结果表明,在 CeO2和 TiO2界面形成了Ce-O-Ti键,从而抑制了催化剂的晶化和相转变过程,并在 TiO2的禁带中引入了 Ce4f 掺杂能级。Ce-TiO2在可见光区具有显著吸收,且光生载流子的复合受到有效抑制,因此,Ce 掺杂明显提高了TiO2降解污染物的效率。当 Ce 掺杂量为20%(摩尔分数),煅烧温度为400℃时,催化剂的活性达到最佳。

  15. Evaluation of titanium dioxide and cerium oxide as anodes for the electrooxidation of toluene A theoretical approach of the electrode process

    Energy Technology Data Exchange (ETDEWEB)

    D' Elia, Luis F.; Rincon, L.; Ortiz, R

    2004-09-30

    Cerium oxide and titanium dioxide were prepared by thermal decomposition of the precursor salts and thermal treatment of titanium plates. In aqueous medium, the metal oxides show a well-defined electrochemical reaction; a solid state redox process takes place in the cathodic range of potentials and only water discharge reaction occurs in the anodic region. At the experimental conditions, the prepared materials were not totally active for the electrooxidation of toluene. The theoretical modeling suggests that the lack of activity is due to the weak interaction between toluene and the metal oxide surface.

  16. Cerium (IV) oxide nanotubes prepared by low temperature deposition at normal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Boehme, M; Fu, G; Ionescu, E; Ensinger, W, E-mail: mboehme@ca.tu-darmstadt.de [Department of Materials Science, Darmstadt University of Technology, D-64287 Darmstadt (Germany)

    2011-02-11

    This paper reports the synthesis of cerium dioxide nanotubes (CeNTs) by electroless deposition using ion-track-etched polycarbonate templates. To achieve nanotubes with thin walls and small surface roughness the tubes were generated by a several-step-containing procedure under aqueous conditions. The approach reported below will process open end nanotubes with well-defined outer diameter and wall thickness.

  17. Cerium (IV) oxide nanotubes prepared by low temperature deposition at normal pressure.

    Science.gov (United States)

    Boehme, M; Fu, G; Ionescu, E; Ensinger, W

    2011-02-11

    This paper reports the synthesis of cerium dioxide nanotubes (CeNTs) by electroless deposition using ion-track-etched polycarbonate templates. To achieve nanotubes with thin walls and small surface roughness the tubes were generated by a several-step-containing procedure under aqueous conditions. The approach reported below will process open end nanotubes with well-defined outer diameter and wall thickness.

  18. [The changes of the motor function of the stomach and the colon under the action of the nanocrystalline cerium dioxide].

    Science.gov (United States)

    Iefimenko, O Iu; Savchenko, Iu O; Falalieieva, T M; Berehova, T V; Shcherbakov, O B; Ivanov, V K; Zholobak, N M; Maliukin, Iu V; Spivak, M Ia

    2014-01-01

    We investigated the effect of nanocrystalline cerium dioxide on parameters of spontaneous and stimulated motility of the stomach and colon in rats. It was found that administration of nanocrystalline cerium dioxide for 10 days increased the amplitude of contractions of stimulated motility in the stomach by 33.0 +/- 2.4% and the frequency of contractions of the colon by 80.3 +/- 7.5%. In this group, the introduction of carbachol also increased the frequency of the contractions by 274.0 +/- 22.9%, compared to the control group. The administration of nanocrystalline cerium dioxide increased the index of motor activity of spontaneous and stimulated motility of the stomach by 19.8 +/- 1.4 and 14.5 +/- 9.0%, respectively. In the colon, the motor activity increased by 14.3 +/- 1.1 and 11.1 +/- 0.8%, respectively. We also found that the nanocrystalline cerium dioxide rebuilt morphological condition of the mucous of the colon.

  19. Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles

    Science.gov (United States)

    Ten agronomic plant species were exposed to different concentrations of nano titanium dioxide (nTiO2) or nano cerium oxide (nCeO2) (0, 250, 500 and 1000 mg/L) to examine potential effects on germination and early seedling development. We modified a standard test protocol develop...

  20. Nanocrystalline cerium dioxide efficacy for prophylaxis of erosive and ulcerative lesions in the gastric mucosa of rats induced by stress.

    Science.gov (United States)

    Golyshkin, Dmytro; Kobyliak, Nazarii; Virchenko, Oleksandr; Falalyeyeva, Tetyana; Beregova, Tetyana; Ostapchenko, Lyudmyla; Caprnda, Martin; Skladany, Lubomir; Opatrilova, Radka; Rodrigo, Luis; Kruzliak, Peter; Shcherbokov, Alexandr; Spivak, Mykola

    2016-12-01

    In our previous works, the important therapeutic properties of nanocrystalline cerium dioxide such as strong antioxidant ability, prebiotical and antibiotic activity were shown. Such properties were obtained due to stabilization of nanoparticles with precise size 3-7nm. Such modification of nanocrystalline cerium dioxide has contributed to its remarkable efficacy and low toxicity. We have carried out the investigation of toxicity of the nanodrug and revealed that in the condition of the acute toxicity test, LD 50 was 2000mg/kg when it was administered per os. This indicator is approximately 1000 times greater than effective dose of the compound that proved the possibility of its usage for humans. Considering the strong antioxidant properties of this substance, we have performed the investigation of the influence of nanocrystalline cerium dioxide on the erosive-ulcerative lesions in gastric mucosa of rats induced by Selye's restraint stress. It was established that the studied compound significantly reduced the lesions area by 58.3% (p<0.05) induced by Selye's restraint stress. The attenuation of inflammation and decrease of lipid peroxidation in the conditions of gastric lesions and prophylactic administration of nanocrystalline cerium dioxide were shown. That was confirmed by the decrease of pro-inflammatory cytokines content (interleukin (IL) 1β, 12B p40) and raise of anti-inflammatory cytokines content (IL-10 and transforming growth factor β). Measurement of lipid peroxidation products has proved the antioxidant properties of nanocrystalline cerium dioxide as it decreased the content of conjugated dienes and thiobarbituric acid active products in the conditions of gastric ulceration induced by stress.

  1. Comparison of lead dioxide and cerium dioxide as mediators for carbon paste electrodes in flow injection-amperometric detection of hydrogen peroxide

    OpenAIRE

    Mihić-Necin, Bojana; Guzsvány, Valéria; Kalcher, Kurt

    2010-01-01

    Carbon paste electrodes (graphite / paraffin oil), bulk-modified with lead dioxide and cerium dioxide, were used as sensors for the amperometric determination of hydrogen peroxide in flow injection analysis. Experimental parameters, such as applied working potential, flow rate of the carrier and injection volume were optimized with a thin-layer flow-through cell. The method was validated with respect to calibration curve, linear dynamic range, detection limit, repeatability and...

  2. Preparation of Nano-TiO2 Doped with Cerium and Its Photocatalytic Activity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis diffuse reflectance spectra (DRS). The photocatalytic activity was evaluated by photocatalytic degradation of phenol in water. The results of XRD, TEM, and DRS show that pure TiO2 and Ce-doped TiO2 powder crystallines are a mixture of anatase and rutile;the doping can retard the development of the grain size of TiO2 and decrease the diameter of TiO2 from more than 20nm of pure TiO2 to about 10 nm;the doped TiO2 can improve the light absorption of TiO2 and suitable doping content tends to move the DRS spectrum of TiO2 towards visible light, but too much doping is not good for the light absorption ability.The results of the photocatalytic experiments show that doping with Ce content of 0.08 % ~ 0.4 % can increase the photocatalytic activity of TiO2;however, doping with Ce content of 0.5 % ~ 2.5 % can significantly decrease the photocatalytic activity of TiO2. The favorite doping content is 0.4 % in the range of our experiments.

  3. The Preparation and Characterization of Mesoporous Cerium Dioxide and Its Properties in the Oxidation of CO%介孔二氧化铈的制备、表征以及对CO的氧化性能研究

    Institute of Scientific and Technical Information of China (English)

    田俊杰; 纳薇; 王华; 高文桂; 刘自松; 郭伟

    2013-01-01

    以无机盐硝酸铈和柠檬酸为原料,CTAB(十六烷基三甲基溴化铵)为模板剂,采用水热法制备了大比表面积的介孔CeO2,结合X射线粉末衍射(XRD)、N2吸附与脱附、H2程序升温还原(H2-TPR)和CO2程序升温脱附(CO2-TPD)等表征手段研究了CTAB加入及焙烧温度对介孔CeO2晶型结构和比表面积的影响,并对CO氧化催化机理进行了初步探讨.结果表明:前驱体与焙烧样品都具有晶型较好的CeO2立方萤石晶相结构和较大的比表面积,CTAB的加入不仅增大了样品的比表面积和孔容,而且在一定程度上提高了样品的结晶度;与其他样品相比,加入CTAB焙烧后的样品具有较好的催化效果.%High surface area mesoporous CeO2 was synthesized using inorganic salt nitric acid cerium and citric acid as raw materials and CTAB (hexadecyl trimethyl ammonium bromide) as template via hydrothermal method. The X-ray powder diffraction (XRD), N2 adsorption and desorption, H2 temperature programmed reduction(H2-TPR) and CO2 temperature programmed desorption(CO2-TPD) were used to study the crystal structure and surface area as well as the mechanism of CO oxidation of the obtained mesoporous CeO2 samples. The results show that all of the samples have pure CeO2 cubic fluorite crystalline structure and a high surface area. The addition of CTAB has not only improved surface area and pore volume of the products, but also enhanced the crystallinity of obtained CeO2. The sample which in the presence of CTAB exhibits a more excellent catalytic activity for CO oxidation rather than the other samples.

  4. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  5. Ultrastructural Interactions and Genotoxicity Assay of Cerium Dioxide Nanoparticles on Mouse Oocytes

    Directory of Open Access Journals (Sweden)

    Blandine Courbiere

    2013-10-01

    Full Text Available Cerium dioxide nanoparticles (CeO2 ENPs are on the priority list of nanomaterials requiring evaluation. We performed in vitro assays on mature mouse oocytes incubated with CeO2 ENPs to study (1 physicochemical biotransformation of ENPs in culture medium; (2 ultrastructural interactions with follicular cells and oocytes using Transmission Electron Microscopy (TEM; (3 genotoxicity of CeO2 ENPs on follicular cells and oocytes using a comet assay. DNA damage was quantified as Olive Tail Moment. We show that ENPs aggregated, but their crystal structure remained stable in culture medium. TEM showed endocytosis of CeO2 ENP aggregates in follicular cells. In oocytes, CeO2 ENP aggregates were only observed around the zona pellucida (ZP. The comet assay revealed significant DNA damage in follicular cells. In oocytes, the comet assay showed a dose-related increase in DNA damage and a significant increase only at the highest concentrations. DNA damage decreased significantly both in follicular cells and in oocytes when an anti-oxidant agent was added in the culture medium. We hypothesise that at low concentrations of CeO2 ENPs oocytes could be protected against indirect oxidative stress due to a double defence system composed of follicular cells and ZP.

  6. Preparation and properties on rare-earth element cerium doped nano-titanium dioxide photocatalyst%Ce-TiO2光催化剂的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    燕宁宁; 张莹; 龚昌杰; 朱忠其; 柳清菊

    2012-01-01

    采用溶胶-凝胶法制备了稀土Ce离子掺杂的纳米TiO2光催化剂(Ce-TiO2),通过XRD、FT-IR、UV-Vis、PL、Nano-sizer纳米粒度分析仪等对Ce-TiO2样品进行了表征和分析,并以亚甲基蓝(MB)作为目标降解物,考察了不同掺杂浓度及经不同温度热处理后的Ce-TiO2样品对MB的光催化降解效果,结果表明所制备样品的晶型均为锐钛矿相和金红石相的混晶相,Ce离子的掺杂拓展了TiO2在可见光区的光谱响应范围,提高了TiO2光催化活性。当pH值为1.5,Ce的掺杂量为n(Ce)∶n(TiO2)=1∶300,热处理温度为600℃条件下制备的样品其催化活性显著高于Degussa P25。%The nano-TiO2 doped with Ce was prepared by sol-gel method.The samples were analyzed by X-ray diffraction(XRD),FT-IR,UV-Vis,PL,Nano-sizer nano particle size analyzer,etc.The photocatalytic activity of Ce-TiO2 was investigated at different doping dosage and different calcinated temperatures by measuring the degradation rate of methyl blue(MB) under the irradiation of fluorescent lamp,the results show that crystal phase of Ce-TiO2 samples are all mixed phase of anatase and rutile.The existence of the doped element Ce expands TiO2's spectrum absorption under the visible light,and increases the photocatalytic activity of TiO2.Meanwhile,the photocatalytic activity of the sample at pH=1.5,n(Ce)∶n(TiO2)=1∶300 and the calcinated temperature of 600℃ is the best,and it is obvious higher than that of P25.

  7. CO Responses of Sensors Based on Cerium Oxide Thick Films Prepared from Clustered Spherical Nanoparticles

    OpenAIRE

    Woosuck Shin; Takafumi Akamatsu; Toshio Itoh; Ichiro Matsubara; Noriya Izu

    2013-01-01

    Various types of CO sensors based on cerium oxide (ceria) have been reported recently. It has also been reported that the response speed of CO sensors fabricated from porous ceria thick films comprising nanoparticles is extremely high. However, the response value of such sensors is not suitably high. In this study, we investigated methods of improving the response values of CO sensors based on ceria and prepared gas sensors from core-shell ceria polymer hybrid nanoparticles. These hybrid nano...

  8. Study of gels of molybdenum with cerium in the preparation of generators of 99Mo - 99mTc

    OpenAIRE

    Vanessa Moraes; Bárbara Marczewski; Carla Roberta Dias; João Alberto Osso Junior

    2005-01-01

    99mTc has ideal nuclear properties for organ imaging in nuclear medicine, and it is obtained from the 99Mo-99mTc generator. Four different types of generators are available: chromatographic that uses 99Mo from fission of uranium; MEK solvent extraction; Tc2O7 sublimation; gel chromatographic. This work presents the preparation of gel generators of molybdenum with cerium and characterization of the gels: mass ratio between molybdenum and cerium, structure, size of particles and elution percent...

  9. Cerium dioxide as a new reactive sorbent for fast degradation of parathion methyl and some other organophosphates

    Institute of Scientific and Technical Information of China (English)

    Pavel Janos; Lubos Vrtoch; Pavel Kuran; Martin Kormunda; Vaclav Stengl; Tomas Matys Grygar; Marek Dosek; Martin Stastny; Jakub Ederer; Vera Pilarova

    2014-01-01

    Cerium dioxide was used for the first time as reactive sorbent for the degradation of the organophosphate pesticides para-thion methyl, chlorpyrifos, dichlofenthion, fenchlorphos, and prothiofos, as well as of some chemical warfare agents-nerve gases soman and O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX). CeO2 specimens were prepared by calcination of basic cerous carbonate obtained by precipitation from an aqueous solution. The CeO2 samples containing certain amounts (1 wt.%-5 wt.%) of the neighboring lanthanides (La, Pr, Nd) were prepared in a similar way from pure lanthanide salts. It was shown that ceria accelerated markedly the decomposition of parathion methyl causing the cleavage of the P-O-aryl bond in the pesticide molecule. A similar reaction mechanism was proposed for the degradation of other organophosphate pesticides and nerve agents. The degradation times (reaction half-times) were in an order of minutes in the presence of CeO2, compared to hours or days under common environ-mental conditions. The reaction in suitable organic solvents allowed conversions of about 90%for parathion methyl loading of 20 mg pesticide/g CeO2 within 2 h with a reactant half-life in the order of 0.1 min. The key parameter governing the degradation efficiency of CeO2 was the temperature during calcination. At optimum calcination temperature (about 773.15 K), the produced ceria retained a sufficiently high surface area, and attained an optimum degree of crystallinity (related to a number of crystal defects, and thus poten-tial reactive sites). The presence of other lanthanides somewhat decreased the reaction rate, but this effect was not detrimental and permitted the possible use of chemically impure ceria as a reactive sorbent. A fast organophosphate degradation was demonstrated not only in non-polar solvents (such as heptane), but also in polar aprotic solvents (acetonitrile, acetone) that are miscible with water. This opens new possibilities for

  10. Adsorption behavior of lead on aquatic sediments contaminated with cerium dioxide nanoparticles.

    Science.gov (United States)

    Wang, Chao; Fan, Xiulei; Wang, Peifang; Hou, Jun; Ao, Yanhui; Miao, Lingzhan

    2016-12-01

    Aquatic sediments serve as an important sink for engineered nanomaterials (ENMs), such as metal oxide nanoparticles (MeO NPs) and carbon nanotubes (CNTs). Owing to their remarkable properties, ENMs demonstrate significant potential to disturb the adsorption behavior of other contaminants in aquatic sediments, thereby altering the bioavailability and toxicity of these contaminants. Thus far, most studies have investigated the effect of CNTs on the adsorption of other contaminants on sediments. Cerium dioxide nanoparticles (CeO2 NPs), as one of the important MeO NPs, are also inevitably discharged into aquatic sediments because of their widespread use. In this study, we investigated the adsorption behavior of Pb(2+) on sediments spiked with CeO2 NPs at a weight ratio of 5.0%. The results showed that the adsorption rates at three stages occurring during adsorption clearly increase for sediments contaminated with CeO2 NPs. Moreover, the results obtained from the adsorption isotherms indicated that the Langmuir isotherm model best fits the isotherm data for both sediments and those contaminated with CeO2 NPs. After spiking the sediments with CeO2 NPs, the theoretical maximum monolayer adsorption capacity (Qmax) for Pb(2+) increased from 4.433 to 4.995 mg/g and the Langmuir isotherm coefficient (KL) decreased from 8.813 to 7.730 L/g. The effects of CeO2 NPs on the surface charge and pore surface properties of sediments were also studied as these properties affect the adsorption of several chemicals in sediments. The results showed that pHzpc, SBET, Sext, and average pore size of sediments clearly decrease for sediments contaminated with CeO2 NPs. Hence, the strong adsorption capacity of CeO2 NPs and the changes of sediment surface charge and pore surface properties caused by CeO2 NPs are important factors affecting the adsorption behavior of Pb(2+). The potential risk of Pb(2+) in aquatic environment may increase with CeO2 NPs buried in sediments.

  11. Cerium dioxide nanoparticle exposure improves microvascular dysfunction and reduces oxidative stress in spontaneously hypertensive rats

    Directory of Open Access Journals (Sweden)

    Valerie C Minarchick

    2015-11-01

    Full Text Available The elevated production of reactive oxygen species (ROS in the vascular wall is associated with cardiovascular diseases such as hypertension. This increase in oxidative stress contributes to various mechanisms of vascular dysfunction, such as decreased nitric oxide bioavailability. Therefore, anti-oxidants are being researched to decrease the high levels of ROS, which could improve the microvascular dysfunction associated with various cardiovascular diseases. From a therapeutic perspective, cerium dioxide nanoparticles (CeO2 NP hold great anti-oxidant potential, but their in vivo activity is unclear. Due to this potential anti-oxidant action, we hypothesize that injected CeO2 NP would decrease microvascular dysfunction and oxidative stress associated with hypertension. In order to simulate a therapeutic application, spontaneously hypertensive (SH and Wistar-Kyoto (WKY rats were intravenously injected with either saline or CeO2 NP (100 µg suspended in saline. Twenty-four hours post-exposure mesenteric arteriolar reactivity was assessed via intravital microscopy. Endothelium-dependent and –independent function was assessed via acetylcholine and sodium nitroprusside. Microvascular oxidative stress was analyzed using fluorescent staining in isolated mesenteric arterioles. Finally, systemic inflammation was examined using a multiplex analysis and venular leukocyte flux was counted. Endothelium-dependent dilation was significantly decreased in the SH rats (29.68 ± 3.28%, maximal response and this microvascular dysfunction was significantly improved following CeO2 NP exposure (43.76 ± 4.33%, maximal response. There was also an increase in oxidative stress in the SH rats, which was abolished following CeO2 NP treatment. These results provided evidence that CeO2 NP act as an anti-oxidant in vivo. There were also changes in the inflammatory profile in the WKY and SH rats. In WKY rats, IL-10 and TNF-α were increased following CeO2 NP treatment

  12. Preparation and Characterization of Cerium (III Doped Captopril Nanoparticles and Study of their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Ghamami Shahriar

    2016-01-01

    Full Text Available In this research Ce3+ doped Captopril nanoparticles (Ce3+ doped CAP-NP were prepared by a cold welding process and have been studied. Captopril may be applied in the treatment of hypertension and some types of congestive heart failure and for preventing kidney failure due to high blood pressure and diabetes. CAP-NP was synthesized by a cold welding process. The cerium nitrate was added at a ratio of 10% and the optical properties have been studied by photoluminescence (PL. The synthesized compounds were characterized by Fourier transform infrared spectroscopy. The size of CAP-NP was calculated by X-ray diffraction (XRD. The size of CAP-NP was in the range of 50 nm. Morphology of surface of synthesized nanoparticles was studied by scanning electron microscopy (SEM. Finally the luminescence properties of undoped and doped CAP-NP were compared. PL spectra from undoped CAP-NP show a strong pack in the range of 546 nm after doped cerium ion into the captopril appeared two bands at 680 and 357 nm, which is ascribed to the well-known 5d–4f emission band of the cerium.

  13. Nano-cerium-element-doped titanium dioxide induces apoptosis of Bel 7402 human hepatoma cells in the presence of visible light

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To investigate the apoptotic effect of photoexcited titanium dioxide (TiO2) nanoparticles in the presence of visible light on human hepatoma cell line (Bel 7402) and to study the underlying mechanism.METHODS: Cerium-element-doped titanium dioxide nanoparticles were prepared by impregnation method.Bel 7402 human hepatoma cells were cultured in RPMI 1640 medium in a humidified incubator with 50 mL/L CO2 at 37℃. A 15 W fluorescent lamp with continuous wavelength light was used as light source in the photocatalytic test. Fluorescence morphology and agarose gel eletrophoresis pattern were performed to analyze apoptotic cells.RESULTS: The Ce (Ⅳ)-doped TiO2 nanoparticles displayed their superiority, The adsorption edge shifted to the 400-450 nm region. With visible light illuminated for 10 min, 10 μg/cm3 Ce (Ⅳ)-doped TiO2 induced micronuclei and significant apoptosis in 4 and 24 h,respectively. Hochest 33258 staining of the fixed cells revealed typical apoptotic structures (apoptotic bodies),agarose gel electrophoresis showed typical DNA ladder pattern in treated cells but not in untreated ones.CONCLUSION: Ce (Ⅳ) doped TiO2 nanoparticles can induce apoptosis of Bel 7402 human hepatoma cells in the presence of visible light.

  14. Recovery of Cerium Dioxide from Spent Glass-Polishing Slurry and Its Utilization as a Reactive Sorbent for Fast Degradation of Toxic Organophosphates

    Directory of Open Access Journals (Sweden)

    Pavel Janoš

    2015-01-01

    Full Text Available The recovery of cerium (and possibly other rare earth elements from the spent glass-polishing slurries is rather difficult because of a high resistance of polishing-grade cerium oxide toward common digestion agents. It was shown that cerium may be extracted from the spent polishing slurries by leaching with strong mineral acids in the presence of reducing agents; the solution may be used directly for the preparation of a ceria-based reactive sorbent. A mixture of concentrated nitric acid and hydrogen peroxide was effective in the digestion of partially dewatered glass-polishing slurry. After the removal of undissolved particles, cerous carbonate was precipitated by gaseous NH3 and CO2. Cerium oxide was prepared by a thermal decomposition of the carbonate precursor in an open crucible and tested as reactive sorbent for the degradation of highly toxic organophosphate compounds. The samples annealed at the optimal temperature of approximately 400°C exhibited a good degradation efficiency toward the organophosphate pesticide fenchlorphos and the nerve agents soman and VX. The extraction/precipitation procedure recovers approximately 70% of cerium oxide from the spent polishing slurry. The presence of minor amounts of lanthanum does not disturb the degradation efficiency.

  15. Structural Characteristics of Cerium Oxide Nanocrystals Prepared by the Microemulsion Method

    Institute of Scientific and Technical Information of China (English)

    J.Zhang; X.Ju; Z.Y.Wu; T.Liu; T.D.Hu; Y.N.Xie

    2001-01-01

    The aim of this work is to investigate the microstructure development of erium oxide nanocrystal,prepared by the microemulsion process,as a function of annealing temperature in air.Combined with the HRTEM and the thermogravimetric-differential thermal analysis in air.Combined withthe HRTEm and the thremogravimetric-differential thermal analysis(TG-DTA),the XRD patterns reveal that the sample annealed at 623 K is amorphous,and the formation of cerium oxide nanocrystal occurs above 773 K.The local structural and electronic properties in the nanocrystallization process are probed by X-ray absorption spectra (XAS) at the Ce L3 edge.It is found that the phase structure changes from triclinic to cubic (CeO2),and the electroic structure changes from Ce3 to Ce4 upon increasing the annealing temperature.

  16. CO responses of sensors based on cerium oxide thick films prepared from clustered spherical nanoparticles.

    Science.gov (United States)

    Izu, Noriya; Matsubara, Ichiro; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2013-03-08

    Various types of CO sensors based on cerium oxide (ceria) have been reported recently. It has also been reported that the response speed of CO sensors fabricated from porous ceria thick films comprising nanoparticles is extremely high. However, the response value of such sensors is not suitably high. In this study, we investigated methods of improving the response values of CO sensors based on ceria and prepared gas sensors from core-shell ceria polymer hybrid nanoparticles. These hybrid nanoparticles have been reported to have a unique structure: The core consists of a cluster of ceria crystallites several nanometers in size. We compared the characteristics of the sensors based on thick films prepared from core-shell nanoparticles with those of sensors based on thick films prepared from conventionally used precipitated nanoparticles. The sensors prepared from the core-shell nanoparticles exhibited a resistance that was ten times greater than that of the sensors prepared from the precipitated nanoparticles. The response values of the gas sensors based on the core-shell nanoparticles also was higher than that of the sensors based on the precipitated nanoparticles. Finally, improvements in sensor response were also noticed after the addition of Au nanoparticles to the thick films used to fabricate the two types of sensors.

  17. Exposure and Health Effects Review of Engineered Nanoscale Cerium and Cerium Dioxide Associated with its Use as a Fuel Additive - NOW IN PRINT IN THE JOURNAL

    Science.gov (United States)

    Advances of nanoscale science have produced nanomaterials with unique physical and chemical properties at commercial levels that are now incorporated into over 1000 products. Nanoscale cerium (di) oxide (Ce02) has recently gained a wide range of applications which includes coatin...

  18. Mobility of nanosized cerium dioxide and polymeric capsules in quartz and loamy sands saturated with model and natural groundwaters.

    Science.gov (United States)

    Petosa, Adamo Riccardo; Ohl, Carolin; Rajput, Faraz; Tufenkji, Nathalie

    2013-10-01

    The environmental and health risks posed by emerging engineered nanoparticles (ENPs) released into aquatic environments are largely dependent on their aggregation, transport, and deposition behavior. Herein, laboratory-scale columns were used to examine the mobility of polyacrylic acid (PAA)-coated cerium dioxide nanoparticles (nCeO2) and an analogous nanosized polymeric capsule (nCAP) in water saturated quartz sand or loamy sand. The influence of solution ionic strength (IS) and cation type (Na(+), Ca(2+), or Mg(2+)) on the transport potential of these ENPs was examined in both granular matrices and results were also compared to measurements obtained using a natural groundwater. ENP suspensions were characterized using dynamic light scattering and nanoparticle tracking analysis to establish aggregate size, and laser Doppler electrophoresis to determine ENP electrophoretic mobility. Regardless of IS, virtually all nCeO2 particles suspended in NaNO3 eluted from the quartz sand-packed columns. In contrast, heightened nCeO2 and nCAP particle retention and dynamic (time-dependent) transport behavior was observed with increasing concentrations of the divalent salts and in the presence of natural groundwater. Enhanced particle retention was also observed in loamy sand in comparison to the quartz sand, emphasizing the need to consider the nature of the aqueous matrix and granular medium in evaluating contamination risks associated with the release of ENPs in natural and engineered aquatic environments.

  19. Preparation and integration of nanostructured titanium dioxide

    KAUST Repository

    Zeng, Hua Chun

    2011-10-01

    Titanium dioxide (TiO2) is a chemically stable nontoxic transition-metal oxide associated with a wide range of existing chemical engineering processes. In this short review, recent research endeavors in preparation and integration of nanostructured TiO2 materials system will be featured and discussed for their potential new applications. Because material development always plays pivotal roles in the progress of a particular engineering discipline, the reviewed subjects will provide useful information to stimulate nanoscale research of chemical engineering, linking established fundamentals with practical applications. Some critical issues and challenges regarding further development of this important functional material for nanotechnology will also be addressed. © 2011 Elsevier Ltd. All rights reserved.

  20. Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

    KAUST Repository

    Nanda, Himansu

    2016-11-03

    The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

  1. Preparation and evaluation of cerium oxide-bovine hydroxyapatite composites for biomedical engineering applications.

    Science.gov (United States)

    Gunduz, O; Gode, C; Ahmad, Z; Gökçe, H; Yetmez, M; Kalkandelen, C; Sahin, Y M; Oktar, F N

    2014-07-01

    The fabrication and characterization of bovine hydroxyapatite (BHA) and cerium oxide (CeO2) composites are presented. CeO2 (at varying concentrations 1, 5 and 10wt%) were added to calcinated BHA powder. The resulting mixtures were shaped into green cylindrical samples by powder pressing (350MPa) followed by sintering in air (1000-1300°C for 4h). Density, Vickers microhardness (HV), compression strength, scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies were performed on the products. The sintering behavior, microstructural characteristics and mechanical properties were evaluated. Differences in the sintering temperature (for 1wt% CeO2 composites) between 1200 and 1300°C, show a 3.3% increase in the microhardness (564 and 582.75HV, respectively). Composites prepared at 1300°C demonstrate the greatest compression strength with comparable results for 5 and 10wt% CeO2 content (106 and 107MPa) which are significantly better than those for 1wt% and those that do not include any CeO2 (90 and below 60MPa, respectively). The results obtained suggest optimal parameters to be used in preparation of BHA and CeO2 composites, while also highlighting the potential of such materials in several biomedical engineering applications.

  2. Preparation and investigation of structural, magnetic and microwave absorption properties of cerium doped barium hexaferrite

    Directory of Open Access Journals (Sweden)

    P Kameli

    2015-01-01

    Full Text Available In this study the structure, magnetic and microwave absorption properties of cerium (Ce doped barium hexaferrite with general formulae BaCexFe12-xO19 (x=0.0, 0.05, 0.1, 0.15, 0.2 have been investigated. These samples have been prepared by sol- gel method. Influence of replacing Fe+3 ion by rare- earth Ce+3 ion on the structural, magnetic and microwave absorption properties have been investigated by X- ray diffraction (XRD, Fourier transform infrared (FT-IR, Vibrating sample magnetometer (VSM and vector network analyzer (VNA. X-ray diffraction analysis indicated that the samples are of single phase with space group p63/mmc. The magnetic properties of samples indicated that with the Ce doping the saturation magnetization show no regular behavior. Moreover, coercivity (Hc first decreased and reached to the minimum value for x=0.1 sample and then increased with Ce content increasing. Also, measurement of electromagnetic wave absorption in X and Ku frequency bands indicated that the maximum of reflection loss obtained for x=0.15 sample. Moreover, result indicated that absorption peak shifted toward a lower frequency when thickness was increased.

  3. Preparation and properties of a cerium-containing hydroxyapatite coating on commercially pure titanium by micro-arc oxidation

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong; WANG Yingjun; NING Chengyun; NAN Kaihui; HAN Yong

    2008-01-01

    A porous cerium-containing hydroxyapatite coating on commercially pure titanium was prepared by micro-arc oxidation (MAO) in an electrolytic solution containing calcium acetate, β-glycerol phosphate disodium salt pentahydrate (β-GP), and cerium nitrate. The thickness, phase, composition morphology, and biocompatibility of the oxide coating were characterized by X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS), and cell culture. The thickness of the MAO film is about 15-25μm, and the coating is porous and uneven, without any apparent interface to the titanium substrates. The results of XRD and EDS show that the porous coating is made up of hydroxyapatite (HA) film containing Ce. The favorable osteoblast cell affinity makes the Ce-HA film have a good biocompatibility. The Ce-HA film is expected to have significant medical applications as dental implants and artificial bone joints.

  4. Reinforcement of natural rubber latex with silica modified by cerium oxide:preparation and properties

    Institute of Scientific and Technical Information of China (English)

    张福全; 廖禄生; 王永周; 汪月琼; 黄红海; 李普旺; 彭政; 曾日中

    2016-01-01

    Variable masses of nano cerium oxide (CeO2) were added into nano silica (SiO2) to prepare the well-dispersed SiO2-CeO2 suspension (SiO2-CeO2), cetyltrimethyl ammonium bromide (CTAB) was used to adjust the compatibility of SiO2-CeO2 with rubber matrix, then SiO2-CeO2 modified by CTAB and curing formulas were mixed with fresh natural rubber (NR) latex to prepare NR/SiO2-CeO2 nanocomposites that contained 0–10 parts of CeO2 by a new emulsion compounding method. The morphologies, cure characteristics, mechanical properties and thermal-oxidative stability of NR/SiO2-CeO2 nanocomposites were investigated. The re-sults revealed that the presence of CeO2 in NR/SiO2-CeO2nanocomposites was favorable for enhancing the interaction between NR matrix and fillers, helped to get smaller SiO2-CeO2 particles with narrower particle size distribution, further improved the crosslink densities and mechanical properties of NR/SiO2-CeO2 nanocomposites vulcanizates. Meanwhile, the addition of CeO2 increased the active energy at least 4.66%, obviously improved the thermal-oxidative aging-inhibiting properties of NR/SiO2-CeO2 nanocomposites. Additionally, nanocomposites containing CeO2 promotedTg shift to high temperature direction, causing the nanocomposites featured higher tanδ at 0 ºC and lower tanδ at 60 ºC and exhibited comparable wet grip and lower rolling resistance when NR/SiO2-CeO2nano-composites were used in tire tread compound.

  5. Preparation,characterization and photocatalytic activities of boron-and cerium-codoped TiO2

    Institute of Scientific and Technical Information of China (English)

    WEI Chao-hai; TANG Xin-hu; LIANG Jie-rong; TAN Shu-ying

    2007-01-01

    Boron- and cerium-codoped TiO2 photocatalysts were synthesized using modified sol-gel reaction process and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), particle size distribution (PSD), diffuse reflectance spectra (DRS), and Brunauer-Emmett-Teller (BET). The photocatalytic activities were evaluated by monitoring the degradation of dye Acid Recd B (ARB). The results showed that the prepared photocatalysts were mixed oxides mainly consisting of titania, ceria, and boron oxide. The structure of TiO2 could be transformed from amorphous to anatase and then to rutile by increasing calcination temperature; the transformation being accompanied by the growth of particle size without any obvious change in phase structure of CeO2. The XPS of B1.6Ce1.0-TiO2 prepared at 500℃ showed that a few boron atoms incorporated into titania and ceria lattice, whereas others existed as B2O3. Cerium ions existed in two states, Ce3+ and Ce4+, and the atomic ratio of Ce3+/Ce4+ was 1.86. When boron and cerium were doped, the UV-Vis adsorption band wavelength showed an obvious shift toward the visible range (≤526 nm). As the atomic ratio of Ce/Ti increased to 1.0, the absorbance edge wavelength also increased to 481 nm. The absorbance edge wavelength decreased for higher cerium doping levels (Ce/Ti = 2.0),. The particles size ranged from 122 to 255 nm with a domain at 168 nm (39.4%). The degradation of ARB dye indicated that the photocatalytic activities of boron- and cerium-codoped TiO2 were much higher than those of P25 (a standard TiO2 powder). The activities increased as the boron doping increased, whereas decreased when the Ce/Ti atomic ratio was greater than 0.5. The optimum atomic ratio of B/Ti and Ce/Ti was 1.6 and 0.5, respectively.

  6. Preparation of perlite-based carbon dioxide absorbent.

    Science.gov (United States)

    He, H; Wu, L; Zhu, J; Yu, B

    1994-02-01

    A new highly efficient carbon dioxide absorbent consisting of sodium hydroxide, expanded perlite and acid-base indicator was prepared. The absorption efficiency, absorption capacity, flow resistance and color indication for the absorbent were tested and compared with some commercial products. The absorbent can reduce the carbon dioxide content in gases to 3.3 ppb (v/v) and absorbs not less than 35% of its weight of carbon dioxide. Besides its large capacity and sharp color indication, the absorbent has an outstanding advantage of small flow resistance in comparison with other commercial carbon dioxide absorbents. Applications in gas analysis and purification were also investigated.

  7. CuO/CeO{sub 2} catalysts prepared with different cerium supports for CO oxidation at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chi-Yuan [School of Public Health, Chung Shan Medical University, Taichung 402, Taiwan, ROC (China); Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan, ROC (China); Chang, Wen-Chi [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Wey, Ming-Yen, E-mail: mywey@dragon.nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China)

    2013-08-15

    The activity of a catalyst depends on the nature of its support, its active site, and its preparation method. This study aimed to employ various types of CeO{sub 2} supports such as commercial CeO{sub 2} and self-prepared CeO{sub 2} for the preparation of copper catalysts. The CuO/CeO{sub 2} catalysts were prepared using the polyol process and impregnation method. The catalysts were characterized using Brunauer–Emmett–Teller analysis, scanning electron microscopy, and X-ray analysis, and their catalytic activity for CO removal was evaluated in a microcatalytic reactor. The experimental results showed that the catalytic activity of the CuO/CeO{sub 2} catalysts with different calcination temperatures decreased in the following order: 500 °C > 300 °C > 700 °C. Compared to the impregnation method, the polyol process generated well-dispersed metal particles over the support and showed higher CO removal efficiency with low activation energy. Compared to CuO/CeO{sub 2} catalysts with commercial CeO{sub 2}, those with CeO{sub 2} that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO{sub 2} and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO{sub 2}-P (pyrolysis) > CuO/CeO{sub 2}-C (commercial) > CuO/CeO{sub 2}-D (deposition precipitation). CuO/CeO{sub 2}-P catalysts showed good activity even at low temperature. The CuO/CeO{sub 2}-P(300)-P-120 min catalyst was found to possess the good CO removal rate when the oxygen content was 6%, CO concentration was 500 ppm, catalyst weighed 1.0 g, pollutant gas velocity was 500 mL min{sup −1}, SV was 3.7 × 10{sup 4} h{sup −1}, and reaction temperature was 150 °C. - Highlights: • CuO/CeO{sub 2} catalysts were prepared using polyol and impregnation methods. • The supports of catalyst were self-prepared cerium oxide and commercial cerium oxide. • Pyrolysis and deposition precipitation methods were used for cerium preparation.

  8. Self-healing Performance of Composite Coatings Prepared by Phosphating and Cerium Nitrate Post-sealing

    Institute of Scientific and Technical Information of China (English)

    LIN Bilan; LU Jintang

    2015-01-01

    The phosphated and cerium nitrate post-sealed galvanized steel was ifrstly scratched to expose zinc layer and then placed in neutral salt spray (NSS) chamber for different durations. The microstructure and compositions of the scratches were investigated using SEM and EDS. The phases of the corrosion products were examined through XRD. The self-healing mechanism of the composite coatings was discussed. The experimental results show that the composite coatings have an excellent corrosion resistance. The corrosion products increase with corrosion time and ifnally cover the whole scratch. They contain phosphorous, cerium, oxygen, chloride and zinc, and are ifne needle and exceedingly compact. The composite coatings are favorable self-healing. During corrosion, the self-healing ions such as Ce3+, Ce4+, PO43-, Zn2+ in the composite coatings were dissolved, migrated, recombined, and covered the exposed zinc, impeding zinc corrosion. The self-healing process of the scratches on the composite coatings can be divided into three stages, about 2 h, 4 h, and 24 h, respectively.

  9. Fabrication of Cerium Oxide and Uranium Oxide Microspheres for Space Nuclear Power Applications

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey A. Katalenich; Michael R. Hartman; Robert C. O' Brien

    2013-02-01

    Cerium oxide and uranium oxide microspheres are being produced via an internal gelation sol-gel method to investigate alternative fabrication routes for space nuclear fuels. Depleted uranium and non-radioactive cerium are being utilized as surrogates for plutonium-238 (Pu-238) used in radioisotope thermoelectric generators and for enriched uranium required by nuclear thermal rockets. While current methods used to produce Pu-238 fuels at Los Alamos National Laboratory (LANL) involve the generation of fine powders that pose a respiratory hazard and have a propensity to contaminate glove boxes, the sol-gel route allows for the generation of oxide microsphere fuels through an aqueous route. The sol-gel method does not generate fine powders and may require fewer processing steps than the LANL method with less operator handling. High-quality cerium dioxide microspheres have been fabricated in the desired size range and equipment is being prepared to establish a uranium dioxide microsphere production capability.

  10. Preparation of calcium carbonate particles coated with titanium dioxide

    Institute of Scientific and Technical Information of China (English)

    Hai Lin; Ying-bo Dong; Le-yong Jiang

    2009-01-01

    The preparation of a new mineral composite material, calcium carbonate particles coated with titanium dioxide, was stud-ied. The mechanism of the preparation process was proposed. The new mineral composite material was made by the mechanochemi-eal method under the optimum condition that the mass ratio of calcium carbonate particles to titanium dioxide was 6.5:3.5. The mass ratios of two different types of titanium dioxide (anatase to rutile) and grinding media to grinded materials were 8:2 and 4:1 respec-tively, and the modified density was 60%. Under this condition, the new material was capable of forming after 120-min modification.The hiding power and oil absorption of this new material were 29.12 g/m~2 and 23.30%, respectively. The results show that the modi-fication is based on surface hydroxylation. After coating with titanium dioxide, the hiding power of calcium carbonate can be im-proved greatly. The new mineral composite materials can be used as the substitute for titanium dioxide.

  11. Preparation and characterization of nitrogen-doped titanium dioxides

    Institute of Scientific and Technical Information of China (English)

    ZHU GuoPing; ZHOU KangGen

    2007-01-01

    A type of high visible-light active titanium oxinitride (TiO2_xNx) powder was prepared by a simple process: the calcination of the hydrated titanium dioxide at the atmosphere of ammonia-argon using a tubular electric furnace at high temperatures. The hydrated titanium dioxide was synthesized as the precursor of TiO2_xNx using titanic acid as raw material, which came from sulfate technique of producing titanium white. The effects of temperature and reaction time on the nitrogen content, grain size and crystal structure were studied. The visible-light activity and photocatalysis capability of the powder were also investigated.

  12. PREPARATION OF SPHERICAL URANIUM DIOXIDE PARTICLES

    Science.gov (United States)

    Levey, R.P. Jr.; Smith, A.E.

    1963-04-30

    This patent relates to the preparation of high-density, spherical UO/sub 2/ particles 80 to 150 microns in diameter. Sinterable UO/sub 2/ powder is wetted with 3 to 5 weight per cent water and tumbled for at least 48 hours. The resulting spherical particles are then sintered. The sintered particles are useful in dispersion-type fuel elements for nuclear reactors. (AEC)

  13. Simple cerium-triethanolamine complex: Synthesis, characterization, thermal decomposition and its application to prepare ceria support for platinum catalysts used in methane steam reforming

    Science.gov (United States)

    Wattanathana, Worawat; Nootsuwan, Nollapan; Veranitisagul, Chatchai; Koonsaeng, Nattamon; Laosiripojana, Navadol; Laobuthee, Apirat

    2015-06-01

    Cerium-triethanolamine complex was synthesized by simple complexation method in 1-propanol solvent using cerium(III) chloride as a metal source and triethanolamine as a ligand. The structures of the prepared complex were proposed based on FT-IR, FT-Raman and ESI-MS results as equimolar of triethanolamine and cerium chelated complex having monomeric tricyclic structure with and without chloride anion as another coordinating group known as ceratrane. The complex was used as a precursor for ceria material done by thermal decomposition. XRD result revealed that when calcined at 600 °C for 2 h, the cerium complex was totally turned into pure ceria with cubic fluorite structure. The obtained ceria was then employed to synthesize platinum doped ceria catalysts for methane steam reforming. Various amounts of platinum i.e. 1, 3, 5 and 10 mol percents were introduced on the ceria support by microwave-assisted wetness impregnation using ammonium tetrachloroplatinate(II). The platinum-impregnated ceria powders were subjected to calcination in 10% hydrogen/helium atmosphere at 500 °C for 3 h to reduce platinum(II) to platinum(0). XRD patterns of the catalysts confirmed that the platinum particles doped on the ceria support were in the form of platinum(0). Catalytic activity test showed that the catalytic activities got higher as the amounts of platinum doped increased. Besides, the portions of coke formation on the surface of catalysts were reduced as the amounts of platinum doped increased.

  14. Metal Nanoparticles Preparation In Supercritical Carbon Dioxide Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Harry W. Rollins

    2004-04-01

    The novel optical, electronic, and/or magnetic properties of metal and semiconductor nanoparticles have resulted in extensive research on new methods for their preparation. An ideal preparation method would allow the particle size, size distribution, crystallinity, and particle shape to be easily controlled, and would be applicable to a wide variety of material systems. Numerous preparation methods have been reported, each with its inherent advantages and disadvantages; however, an ideal method has yet to emerge. The most widely applied methods for nanoparticle preparation include the sonochemical reduction of organometallic reagents,(1&2) the solvothermal method of Alivisatos,(3) reactions in microemulsions,(4-6) the polyol method (reduction by alcohols),(7-9) and the use of polymer and solgel materials as hosts.(10-13) In addition to these methods, there are a variety of methods that take advantage of the unique properties of a supercritical fluid.(14&15) Through simple variations of temperature and pressure, the properties of a supercritical fluid can be continuously tuned from gas-like to liquid-like without undergoing a phase change. Nanoparticle preparation methods that utilize supercritical fluids are briefly reviewed below using the following categories: Rapid Expansion of Supercritical Solutions (RESS), Reactive Supercritical Fluid Processing, and Supercritical Fluid Microemulsions. Because of its easily accessible critical temperature and pressure and environmentally benign nature, carbon dioxide is the most widely used supercritical solvent. Supercritical CO2 is unfortunately a poor solvent for many polar or ionic species, which has impeded its use in the preparation of metal and semiconductor nanoparticles. We have developed a reactive supercritical fluid processing method using supercritical carbon dioxide for the preparation of metal and metal sulfide particles and used it to prepare narrowly distributed nanoparticles of silver (Ag) and silver sulfide

  15. Effects of cerium dioxide nanoparticles in Oncorhynchus mykiss gills after an acute exposure: assessment of oxidative stress, genotoxicity and histological alterations

    Directory of Open Access Journals (Sweden)

    Alberto Teodorico Correia

    2015-12-01

    Full Text Available Data about the toxicological effects of cerium dioxide nanoparticles (CeO2 NP in fish are scarce. This work aimed to assess the CeO2 NP possible deleterious effects on the gills of Oncorhynchus mykiss. A semi-continuous acute test was conducted to expose the rainbow trout to a freshwater control, 0.25, 2.50 and 25.00 mg/L CeO2 NPs for up to 96 hours. Gills pathological index showed a dose-effect relationship for the individuals exposed to CeO2. Gills showed aneurisms, epithelial lifting and hyperplasia. Furthermore exposure to CeO2 NPs caused statistical differences in some biomarkers determinations, namely a significant increase in the catalase activity and genotoxicity the higher concentrations. No significant changes were however observed in thiobarbituric acid reactive substances content, Na+-K+ ATPase and glutathione s-transferase activities. This study suggests that CeO2 nanoparticles are toxic compounds that can lead to histological, biochemical and genotoxic alterations.

  16. [THE INFLUENCE OF NANODISPERSE CERIUM DIOXIDE ON ONTOGENETIC CHANGES OF ANTIOXIDANT SYSTEM IN THE MUCOSA OF THE STOMACH AND COLON IN RATS].

    Science.gov (United States)

    Iefimenko, O Yu; Savchenko, I O; Falalyeyeva, T M; Beregova, T V; Zholobak, N M; Shcherbakov, O B; Malyukin, Yu V; Spivak, M Ya

    2015-01-01

    It was established that with age the content of lipid peroxidation products increased in the mucosa of the stomach: Diene conjugates by 30%, products which react to thiobarbituric acid by 285% and Schif bases by 181%. Nanodisperse cerium dioxide (NCD) reduced the content of lipid peroxidation in the gastric mucosa in old rats: Diene conjugates by 43 %, products which react to thiobarbituric acid by 51% and Schif bases by 44% relative to the control group of rats given age. Similarly, it was established that the content of Diene conjugates increased by 40%, products which react to thiobarbituric acid by 114% and Schif bases by 132% in the mucosa of the colon of old rats. NDC significant reduced the content of products which react to thiobarbituric acid by 69% and Schyf basics by 132%. In the stomach superoxide dismutase (by 43%) and catalase activity (by 24%) decreases with age, while in the colon superoxide dismutase activity increases (by 43%). In the colon NCD significant decreased superoxide dismutase (by 34%) and catalase activity (by 21%) relative to controls. Thus, the NDC restores lipid peroxidation in the gastric mucosa and colon, in which develops oxidative stress with age.

  17. Preparation, sintering and leaching of optimized uranium thorium dioxides

    Science.gov (United States)

    Hingant, N.; Clavier, N.; Dacheux, N.; Barre, N.; Hubert, S.; Obbade, S.; Taborda, F.; Abraham, F.

    2009-03-01

    Mixed actinide dioxides are currently studied as potential fuels for several concepts associated to the fourth generation of nuclear reactors. These solids are generally obtained through dry chemistry processes from powder mixtures but could present some heterogeneity in the distribution of the cations in the solid. In this context, wet chemistry methods were set up for the preparation of U1-xThxO2 solid solutions as model compounds for advanced dioxide fuels. Two chemical routes of preparation, involving the precipitation of crystallized precursor, were investigated: on the one hand, a mixture of acidic solutions containing cations and oxalic acid was introduced in an open vessel, leading to a poorly-crystallized precipitate. On the other hand, the starting mixture was placed in an acid digestion bomb then set in an oven in order to reach hydrothermal conditions. By this way, small single-crystals were obtained then characterized by several techniques including XRD and SEM. The great differences in terms of morphology and crystallization state of the samples were correlated to an important variation of the specific surface area of the oxides prepared after heating, then the microstructure of the sintered pellets prepared at high temperature. Preliminary leaching tests were finally undertaken in dynamic conditions (i.e. with high renewal of the leachate) in order to evaluate the influence of the sample morphology on the chemical durability of the final cohesive materials.

  18. PREPARATION OF MESOPOROUS CARBON BY CARBON DIOXIDE ACTIVATION WITH CATALYST

    Institute of Scientific and Technical Information of China (English)

    W.Z.Shen; A.H.Lu; J.T.Zheng

    2002-01-01

    A mesoporous activated carbon (AC) can be successfully prepared by catalytic activa-tion with carbon dioxide. For iron oxide as catalyst, there were two regions of mesoporesize distribution, i.e. 2-5nm and 30-70nm. When copper oxide or magnesium oxidecoexisted with iron oxide as composite catalyst, the content of pores with sizes of 2-5nm was decreased, while the pores with 30 70nm were increased significantly. Forcomparison, AC reactivated by carbon dioxide directly was also investigated. It wasshown that the size of mesopores of the resulting AC concentrated in 2-5nm with lessvolume. The adsorption of Congo red was tested to evaluate the property of the result-ing AC. Furthermore, the factors affecting pore size distribution and the possibility ofmesopore formation were discussed.

  19. Preparation and characterization of nitrogen-doped titanium dioxides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A type of high visible-light active titanium oxinitride(TiO2-xNx) powder was prepared by a simple proc-ess:the calcination of the hydrated titanium dioxide at the atmosphere of ammonia-argon using a tu-bular electric furnace at high temperatures. The hydrated titanium dioxide was synthesized as the precursor of TiO2-xNx using titanic acid as raw material,which came from sulfate technique of produc-ing titanium white. The effects of temperature and reaction time on the nitrogen content,grain size and crystal structure were studied. The visible-light activity and photocatalysis capability of the powder were also investigated.

  20. Electrophoretic painting on AZ31 Mg alloy pretreated in cerium conversion coating solutions prepared in ethanol-water mixtures

    Science.gov (United States)

    Van Phuong, Nguyen; Fazal, Basit Raza; Moon, Sungmo

    2017-01-01

    Electrophoretic painting (E-paint) was prepared on AZ31 Mg alloy samples pretreated in cerium conversion coating (CeCC) solutions with various ratios of ethanol and water mixture and its characteristics, adhesion and corrosion resistance were investigated. It was found that CeCC formed on AZ31 Mg alloy in a CeCC solution without ethanol was partly cracked structure and mainly consisted of Mg(OH)2/MgO, which exhibited weak adhesion with E-painting layer after water immersion test, and low corrosion resistance, as indicated by rapid formation of blisters and paint delamination during salt spray test. The addition of ethanol promoted the growth of a fine nano-crystalline CeO2 layer over the entire substrate surface. The E-paint on AZ31 pretreated in the CeCC solutions with addition of ethanol showed also improved corrosion resistance, as represented by the delayed time for paint delamination and blister formation. The E-paint layers on the CeCC layers formed in solutions containing 50-80 vol% ethanol showed stronger adhesion and better corrosion resistance than those formed on the samples treated in a non-ethanol containing CeCC solution.

  1. Influence of cerium ions on the anatase-rutile phase transition of TiO2 prepared by sol-gel auto-igniting synthesis

    Institute of Scientific and Technical Information of China (English)

    YAN Qingzhi; SU Xintai; ZHOU Yanping; GE Changchun

    2005-01-01

    The anatase-rutile phase transformation of TiO2 doped cerium up to 5 mol% was studied by X-ray diffraction and X-ray photoelectron spectroscopy. The samples were prepared by sol-gel auto-igniting synthesis process from a TiO(NO3)2-Ce(NO3)2-NH4NO3-citric acid complex compound system. The combusted amorphous powders were calcined at different temperatures. Significant structural changes were observed during the various stages of the phase transformation.It was concluded that at low dopant contents, cerium ions were incorporated into the TiO2 structure, and the anatase phase was stabilized; but at larger amounts, part of the dopant was segregated on the surface of TiO2 and the rutile formation was accelerated at elevated calcination temperature.

  2. Study of gels of molybdenum with cerium in the preparation of generators of 99Mo - 99mTc

    Directory of Open Access Journals (Sweden)

    Vanessa Moraes

    2005-10-01

    Full Text Available 99mTc has ideal nuclear properties for organ imaging in nuclear medicine, and it is obtained from the 99Mo-99mTc generator. Four different types of generators are available: chromatographic that uses 99Mo from fission of uranium; MEK solvent extraction; Tc2O7 sublimation; gel chromatographic. This work presents the preparation of gel generators of molybdenum with cerium and characterization of the gels: mass ratio between molybdenum and cerium, structure, size of particles and elution percentage of 99mTc after irradiating the gels. Eight gels were prepared at the same temperature of 50 ºC with concentrations of NaOH of 2 and 4 mol/L, mass ratio of 0.31 and 0.38 and final pH of 3.5 and 4.5. The analysis of the results proved that these gels are not adequate for preparation of the generators of 99Mo-99mTc, since the elution percentages are low, when compared with the gel of molybdenum with zirconium.O 99mTc é o radiofármaco mais utilizado em Medicina Nuclear. Ele é obtido do gerador de 99Mo-99mTc e existem quatro tipos diferentes de geradores: cromatográfico que utiliza 99Mo de fissão; extração por solvente com MKT; sublimação do heptaóxido de tecnécio; cromatográfico tipo gel. Este trabalho apresenta a preparação de geradores tipo gel de molibdênio com cério, a caracterização desses géis com relação à quantidade de molibdênio e de cério, sua estrutura, tamanho das partículas e porcentagem de eluição do 99mTc após o gel ser irradiado. Foram preparados oito géis na temperatura de 50ºC com concentração de NaOH de 2 e 4 mol/L, relação de massa de 0,31 e 0,38 e pH final de 3,5 e 4,5. A análise dos resultados comprovou que esses géis não são adequados para preparação dos geradores de 99Mo-99mTc, já que as porcentagens de eluição são baixas, quando comparadas com o gel de molibdênio com zircônio.

  3. Mechanochemical synthesis of cerium orthophosphate

    Institute of Scientific and Technical Information of China (English)

    A.Matraszek; I.Szczygiei; L.Macalik; J.Hanuza

    2009-01-01

    A facile,simple and rapid preparation method of cerium orthophosphate was presented.The synthesis of low-crystalline CePO4 occurred upon mixing of cerium (Ⅲ) nitrate and sodium phosphate,and was an exchange-type reaction.The phase composition of the obtained powder was checked by the XRD and FTIR methods,indicating the presence of cerium phosphate.Further investigations on thermal behavior of the synthesized cerium salt had shown that the obtained onhophosphate crystallized at first in rhabdophane-type structure.It convetted to monazite (monoclinic symmetry) during heating at the temperatures of above 600 ℃.Oxidation of Ce3+ to Ce4+ was avoided during the syntheses,as confirmed by the XPS experiments.

  4. Preparation and Catalytic Properties of Iron-Cerium Phosphates with Sodium Dodecyl Sulfate

    OpenAIRE

    Hiroaki Onoda; Takeshi Sakumura

    2012-01-01

    Iron phosphate was prepared from iron nitrate and phosphoric acid with sodium dodecyl sulfate at various stirring hours. The chemical composition of the obtained samples was estimated from ICP and XRD measurements. Particle shape and size distribution were observed by SEM images and laser diffraction/scattering methods. Further, the catalytic activity was studied with the decomposition of the complex between formaldehyde, ammonium acetate, and acetylacetone. The peaks of FePO4 were observed i...

  5. Preparation and characterisation of tin dioxide electrocatalysts for electrocatalytic hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Tountian, C.D.; Poillerat, G.; Nkeng, P. [Laboratoire d' electrochimie et de chimie physique de corps solide, Strasbourg (France); Menard, H. [Sherbrooke Univ., PQ (Canada). Dept. de Chimie, Centre de Recherche en Electrochimie et Electrocatalyse

    2006-07-01

    A study was conducted in which tin dioxide (SnO{sub 2}) was used as a support for electrocatalytic hydrogenation (ECH). This support then became a conductor by doping. The electrocatalysts used in this study were palladium (Pb) nanoparticles. Tin dioxide is an n-type semiconductor used in many applications such as solar cells, crystals displays, electrochromic devices, gas sensor and electrode material for electrooxidation of organic or inorganic pollutants in wastewaters. It is chemically stable and has good mechanical strength. The electrocatalyst SnO{sub 2}-based powders were synthesised using a sol-gel technique in order to obtain electrocatalysts in which Pd was in a metallic form. This paper described the preparation of the electrocatalysts of SnO{sub 2} by the polymeric precursor decomposition method. The electrocatalysts were characterized using X-ray diffraction (XRD) and scanning electron micrography (SEM) along with electrical studies in order to determine their physical proprieties before their use for ECH of phenol and cyclohexanol. The hydrogenation of phenol and cyclohexanol used as a model system was carried out in a dynamic cell in which the electrocatalyst composite powder was in continuous contact with a porous disc of reticulated vitreous carbon cathode. This study revealed that the use of these electrocatalysts is a promising new path because SnO{sub 2} obtained is thermodynamically stable.10 refs., 2 figs.

  6. Effect of rare earth element cerium on preparation of tungsten powders

    Institute of Scientific and Technical Information of China (English)

    何文; 谭敦强; 李亚蕾; 杨欣; 陆磊; 陆德平

    2015-01-01

    Tungsten powders and Ce doped powders were prepared by hydrogen reduction combined with the liquid-solid doping method. The phase composition, particle size and powder morphology of Ce doped tungsten powders were analyzed by X-ray diffrac-tion, scanning electron microscopy and transmission electron microscopy, respectively. The results indicated that 10000 ppm Ce doped tungsten oxide powders were consisted of WO3 phase and Ce4W9O33 phase. The hydrogen reduction of Ce doped tungsten powders was basically accomplished at 800 ºC for 3 h. The size of Ce doped W powders was remarkably decreased compared to the undoped W powders. The phase of Ce4W9O33 was reduced to Ce2 (WO4)3 phase and Ce2W2O9 phase during the process of hydrogen reduction. Moreover, Ce2 (WO4)3 phase and Ce2W2O9 phase were observed form their morphologies, where the doping content of Ce was more than 100 ppm. The ternary phase embedding into W particles was assigned to Ce2 (WO4)3, while the ternary phase distrib-uting among W particles corresponded to Ce2W2O9. The phase of Ce2 (WO4)3 might be the nucleus of W particles and increase the number of the nucleus. And the particles of Ce2W2O9 covered WO2 particles and might inhibit the growth of W particles. These two reasons resulted in the decrease of the size of Ce doped W particles. Uniform fine W powders were fabricated with the doping content of Ce more than 100 ppm.

  7. Kinetic studies on dissolution of UO{sub 2} powders in acid solutions by using cerium (IV) or chlorine dioxide as oxidants

    Energy Technology Data Exchange (ETDEWEB)

    Asano, Yuichiro; Kataoka, Makoto; Tomiyasu, Hiroshi [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors; Ikeda, Yasuhisa

    1996-02-01

    The UO{sub 2} powders of 100-150, 150-212, 212-250, and 250-300 {mu}m were dissolved in HNO{sub 3} or HCl solutions containing strong oxidants to examine their effect on the dissolution rates. Cerium(IV) species and ClO{sub 2} were used as oxidants in HNO{sub 3} and HCl solutions, respectively. The Ce(IV) species were prepared by bubbling O{sub 3} gas into HNO{sub 3} solutions containing Ce(NO{sub 3}){sub 3}. All dissolution experiments were carried out under rapid stirring conditions which make it possible to neglect the diffusion effect. Dissolution reactions were analyzed on the assumptions that the UO{sub 2} powders are spherical particles and homogeneously dissolved from their external surface. Dissolution rate constants ({Phi}) in mol{center_dot}cm{sup -2}{center_dot}min{sup -1} were measured at various concentrations of oxidants and temperatures. Furthermore, the effect of acid concentrations on the dissolution rate was also examined. As a result, the dissolution rate constants {Phi} were found to be expressed as {Phi}=k{sub N}[Ce(IV)][H{sup +}]{sup 0.6} for HNO{sub 3} solution([HNO{sub 3}]=1-5M, Temp.{<=}30degC) and {Phi}=k{sub H}[ClO{sub 2}][H{sup +}]{sup -0.3} for HCl solution([HCl]=1-5M, Temp.{<=}30degC), respectively. Activation energies(kJ{center_dot}mol{sup -1}) for the apparent dissolution rate constants are 44.1{+-}1.9 for the HNO{sub 3} solution system and 33.5{+-}2.8 for the HCl solution system, respectively. (author).

  8. Detection of zinc oxide and cerium dioxide nanoparticles during drinking water treatment by rapid single particle ICP-MS methods.

    Science.gov (United States)

    Donovan, Ariel R; Adams, Craig D; Ma, Yinfa; Stephan, Chady; Eichholz, Todd; Shi, Honglan

    2016-07-01

    Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation. Using this technique, information regarding NP size, size distribution, particle concentration, and dissolved ion concentrations was obtained simultaneously. The fates of Zn- and Ce-NPs, including those found in river water and added engineered NPs, were evaluated by simulating a typical drinking water treatment process. Lime softening, alum coagulation, powdered activated carbon sorption, and disinfection by free chlorine were simulated sequentially using river water. Lime softening removed 38-53 % of Zn-containing and ZnO NPs and >99 % of Ce-containing and CeO2 NPs. Zn-containing and ZnO NP removal increased to 61-74 % and 77-79 % after alum coagulation and disinfection, respectively. Source and drinking water samples were collected from three large drinking water treatment facilities and analyzed for Zn- and Ce-containing NPs. Each facility had these types of NPs present. In all cases, particle concentrations were reduced by a minimum of 60 % and most were reduced by >95 % from source water to finished drinking water. This study concludes that uncoated ZnO and CeO2 NPs may be effectively removed by conventional drinking water treatments including lime softening and alum coagulation.

  9. Rain Erosion Behavior of Silicon Dioxide Films Prepared on Sapphire

    Institute of Scientific and Technical Information of China (English)

    Liping FENG; Zhengtang LIU; Wenting LIU

    2005-01-01

    Silicon dioxide (SiO2) films were prepared on sapphire (α-Al2O3) by radio frequency magnetron reactive sputtering in order to in crease both transmission and rain erosion resistant performance of infrared domes of sapphire. Composition and structure of SiO2 films were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD),respectively. The transmittance of uncoated and coated sapphire was measured using a Fourier transform infrared(FTIR) spectrometer. Rain erosion tests of the uncoated and coated sapphire were performed at 211 m/s impact velocity with an exposure time ranging from 1 to 8 min on a whirling arm rig. Results show that the deposited films can greatly increase the transmission of sapphire in mid-wave IR. After rain erosion test, decreases in normalized transmission were less than 1% for designed SiO2 films and the SiO2 coating was strongly bonded to the sapphire substrate. In addition, sapphires coated with SiO2 films had a higher transmittance than uncoated ones after rain erosion.

  10. Effects of current density on preparation of grainy electrolytic manganese dioxide

    Institute of Scientific and Technical Information of China (English)

    GUO Hua-jun; ZHU Bing-quan; LI Xin-hai; ZHANG Xin-ming; WANG Zhi-xing; PENG Wen-jie; LIU Lu-ping

    2005-01-01

    Grainy electrolytic manganese dioxide was prepared by electrodeposition in a 0.9 mol/L MnSO4 and 2.5 mol/L H2SO4 solution. The structure, particle size and appearance of the grainy electrolytic manganese dioxide were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrographs measurements. Current density has important effects on cell voltage, anodic current efficiency and particle size of the grainy electrolytic manganese dioxide, and the optimum current density is 30 A/dm 2. The grainy electrolytic manganese dioxide electrodeposited under the optimum conditions consists of γ-MnO2 with an orthorhombic lattice structure; the grainy electrolytic manganese dioxide has a spherical or sphere-like appearance and a narrow particle size distribution with an average particle diameter of 7.237 μm.

  11. Preparation and characterization of zirconium dioxide catalyst supports modified with rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Masakuni; Kimura, Mareo (Toyota Central Research and Development Labs., Inc., Aichi (Japan))

    1991-08-15

    ZrO{sub 2} catlyst supports modified with rare earth elements were prepared by coprecipitation from an aqueous solution of zirconium oxychloride and rare earth chlorides. The crystallization of amorphous hydrous ZrO{sub 2} was inhibited by doping with rare earths; the crystallization temperature was elevated as the amount and ionic radius of the rare earth modifiers was increased. Only modification using cerium had no effect on the crystallization process. The behavior of cerium was different from that of other rare earth elements with valency +3. A metastable cubic phase was formed for ZrO{sub 2} modified with 10 mol.% lanthanum, neodymium and samarium by heating at 600degC. X-ray diffraction and Raman data indicated that the metastable phase had large microstrain and short-range ordering similar to tetragonal symmetry. Rare earth modified ZrO{sub 2} showed a large surface area and good thermal stability as a catalyst support. The carbon monoxide oxidation activity of iron was enhanced by modification with neodymium of ZrO{sub 2} supports. The results suggest the effectiveness of rare earth modified ZrO{sub 2} as catalyst supports. (orig.).

  12. Some Environmentally Relevant Reactions of Cerium Oxide

    Directory of Open Access Journals (Sweden)

    Janoš Pavel

    2014-12-01

    Full Text Available Reactive forms of cerium oxide were prepared by a thermal decomposition of various precursors, namely carbonates, oxalates and citrates, commercially available nanocrystalline cerium oxide (nanoceria was involved in the study for comparison. Scanning electron microscopy (SEM and x-ray diffraction analysis (XRD were used to examine the morphology and crystallinity of the samples, respectively, whereas the Brunauer-Emmett-Teller (BET method of nitrogen adsorption was used to determine surface areas. Interactions of cerium oxide with some phosphorus-containing compounds were investigated. Some of the examined samples, especially those prepared by annealing from carbonate precursors, exhibited an outstanding ability to destroy highly toxic organophosphates, such as pesticides (parathion methyl, or nerve agents (soman, VX. There were identified some relations between the degradation efficiency of cerium oxides and their crystallinity. It was also shown that cerium oxide is able to destroy one of widely used flame retardants - triphenyl phosphate. A phosphatase-mimetic activity of various cerium oxides was examined with the aid of a standardized phosphatase test.

  13. Study on preparation of the adsorbent of cerium-loaded red mud and its application%赤泥负载铈吸附剂的制备及其应用

    Institute of Scientific and Technical Information of China (English)

    罗道成; 安静

    2012-01-01

    将赤泥通过盐酸改性,得到改性赤泥,以改性赤泥为载体,氧化铈为活性组分,制备了赤泥负载铈吸附剂.在25℃和静态条件下,对赤泥负载铈吸附剂处理含磷废水进行了研究,探讨了赤泥负载铈吸附剂的制备条件、赤泥负载铈吸附剂用量、废水pH值、吸附时间及磷的浓度对除磷效果的影响.结果表明,赤泥负载铈吸附剂的制备条件为:盐酸浓度为6mol/L,赤泥负载铈的反应时间为16h,四水硫酸铈浓度为0.4g/L,焙烧温度为500℃;在废水pH值为5.0,磷浓度0~100mg/L范围内,吸附时间为90min,按磷与赤泥负载铈吸附剂质量比为1︰80投加赤泥负载铈吸附剂进行处理,磷的去除率可达97%以上.利用Langmuir吸附等温式对吸附数据进行拟合,得到25℃下的线性相关性R2=0.9919,吸附剂的饱和吸附量为44.65mg/g.磷在吸附剂表面的吸附是单分子层吸附.%Modified red mud was prepared after red mud was modified by hydrochloric acid.Adsorbent of cerium-loaded red mud was prepared with modified red mud as a carrier and cerium sulfate as an active component.Under the condition of 25 ℃ and static state,the treatment of phosphate-containing wastewater with the adsorbent of cerium-loaded red mud was studied.The effects of preparation conditions of the adsorbent of cerium-loaded red mud,the adsorbent used quantity of cerium-loaded red mud,pH value of wastewater,adsorption time and phosphate concentration was discussed.The results showed that the conditions of the adsorbent of cerium-loaded red mud were as follows:hydrochloric acid concentration was 6 mol/L,reaction time of cerium-loaded red mud was 16 h,cerium sulfate four water concentration was 0.4 g/L and calcination temperature was 500 ℃;the phosphate removing efficiency was above 97% at an adsorption time of 90 min,from the wastewater with a pH value of 5.0,phosphate concentration of 0~100 mg/L in the wastewater,and the phosphate mass ratio to the

  14. Multibiomarker assessment of cerium dioxide nanoparticle (nCeO{sub 2}) sublethal effects on two freshwater invertebrates, Dreissena polymorpha and Gammarus roeseli

    Energy Technology Data Exchange (ETDEWEB)

    Garaud, M. [Université de Lorraine, CNRS UMR 7360, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Campus Bridoux, Rue du Général Delestraint, 57070 Metz (France); International Consortium for the Environmental Implications of Nanotechnology (iCEINT), Aix en Provence (France); Trapp, J.; Devin, S.; Cossu-Leguille, C.; Pain-Devin, S.; Felten, V. [Université de Lorraine, CNRS UMR 7360, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Campus Bridoux, Rue du Général Delestraint, 57070 Metz (France); Giamberini, L., E-mail: laure.giamberini@univ-lorraine.fr [Université de Lorraine, CNRS UMR 7360, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Campus Bridoux, Rue du Général Delestraint, 57070 Metz (France); International Consortium for the Environmental Implications of Nanotechnology (iCEINT), Aix en Provence (France)

    2015-01-15

    Highlights: • Gammarids and mussels both accumulated significant amount of waterborne nCeO{sub 2}. • nCeO{sub 2} decreased catalase, lysosomal system size and lipoperoxidation in mussels. • nCeO{sub 2} could exert antioxidant protecting activity in mussels. • In contrast with mussels, no effects of nCeO{sub 2} were observed on Gammarids. - Abstract: Cerium nanoparticles (nCeO{sub 2}) are widely used in everyday products, as fuel and paint additives. Meanwhile, very few studies on nCeO{sub 2} sublethal effects on aquatic organisms are available. We tried to fill this knowledge gap by investigating short-term effects of nCeO{sub 2} at environmentally realistic concentrations on two freshwater invertebrates; the amphipod Gammarus roeseli and the bivalve Dreissena polymorpha, using an integrated multibiomarker approach to detect early adverse effects of nCeO{sub 2} on organism biology. Differences in the behaviour of the organisms and of nanoparticles in the water column led to differential nCeO{sub 2} bioaccumulations, G. roeseli accumulating more cerium than D. polymorpha. Exposure to nCeO{sub 2} led to decreases in the size of the lysosomal system, catalase activity and lipoperoxidation in mussel digestive glands that could result from nCeO{sub 2} antioxidant properties, but also negatively impacted haemolymph ion concentrations. At the same time, no strong adverse effects of nCeO{sub 2} could be observed on G. roeseli. Further experiments will be necessary to confirm the absence of severe nCeO{sub 2} adverse effects in long-term environmentally realistic conditions.

  15. Preparation of Cerium (III) 12-tungstophosphoric acid/ordered mesoporous carbon composite modified electrode and its electrocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Liu Lin [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Ndamanisha, Jean Chrysostome [Universite du Burundi, Institut de pedagogie appliquee, B.P 5223 Bujumbura (Burundi); Bai Jing [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Guo Liping, E-mail: guolp078@nenu.edu.c [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China)

    2010-03-30

    In this work, a novel structured Cerium (III) 12-tungstophosphoric acid (CePW)/ordered mesoporous carbon (OMC) composite is synthesized. The characterization of the material by the Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical characterization shows that the novel CePW/OMC composite has improved properties based on the combination of CePW and OMC properties. CePW/OMC can be used to modify the glassy carbon (GC) electrode and the CePW/OMC/GC modified electrode shows an enhanced electrocatalytic activity. This property can be applied in the determination of some biomolecules. Especially, the detection and determination of the guanine (G) in the presence of adenine (A) is achieved. The catalytic current of G versus its concentration shows a good linearity with two good linear ranges from 4.0 x 10{sup -6} to 8.0 x 10{sup -5} M and from 8.0 x 10{sup -5} to 1.9 x 10{sup -3} M (correlation coefficient = 0.999 and 0.996) with a detection limit of 5.7 x 10{sup -9} M (S/N = 3). The linear range for adenine is 4.0 x 10{sup -6}-7.0 x 10{sup -4} M with a detection limit of 7.45 x 10{sup -8} M. With good stability and reproducibility, the present CePW/OMC/GC modified electrode should be a good model for constructing a novel and promising electrochemical sensing platform for further electrochemical detection of other biomolecules.

  16. A novel method of preparing metallic Janus silica particles using supercritical carbon dioxide

    NARCIS (Netherlands)

    Yang, Qiuyan; de Vries, Marcel H; Picchioni, Francesco; Loos, Katja

    2013-01-01

    In this study, we demonstrate a novel fabrication method to prepare metallic Janus silica particles by embedding nanosized silica particles on a spherical polystyrene (PS) substrate in supercritical carbon dioxide (sc CO2), followed by labelling with gold nanoparticles on the exposed part of the sil

  17. Environmental Geochemistry of Cerium: Applications and Toxicology of Cerium Oxide Nanoparticles

    OpenAIRE

    2015-01-01

    Cerium is the most abundant of rare-earth metals found in the Earth’s crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydr)oxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 na...

  18. One Step Preparation of Controlled Drug Release Systems in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    CAO Liqin; WANG Chengwei; CHEN Liuping

    2009-01-01

    Drug delivery systems based on copolymers of N-isopropylacrylamide were fn-st prepared by a one step method, in which supercritical carbon dioxide was simultaneously used as a polymerization medium and an impregnation agent. The obtained microspheres were characterized by scanning electronic microscopy (SEM), differential scan-ning calorimetry (DSC), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The release effect of the in situ prepared microgels impregnated with ibuprofen was presented through in vitro release simulation.

  19. Effects of cerium dioxide nanoparticles in Oncorhynchus mykiss liver after an acute exposure: assessment of oxidative stress, genotoxicity and histological alterations

    Directory of Open Access Journals (Sweden)

    Ana Cristina Nunes

    2015-12-01

    Full Text Available At present cerium oxide nanoparticles (CeO2 NP have numerous applications ranging from industry to the household, leading to its wide distribution namely in the aquatic environment. The hereby study aimed to assess the toxic effects of CeO2 NPs in Oncorhynchus mykiss liver following an acute exposure (96h to three different concentrations (0.25, 2.5 and 25 mg/L in terms of the genotoxicity (comet assay, oxidative stress response (Catalase CAT; Glutathione S-Transferases GSTs; Thiobarbituric Acid Reactive Substances TBARS and histopathology. CeO2 NP exposure resulted in genotoxic damage in all exposure treatments, inhibition of CAT in the highest concentration and histopathological changes in all exposure concentrations with predominance of progressive and circulatory alterations. However TBARS and GSTs showed no significant differences comparatively to the control (unexposed group. The results suggest that CeO2 NP are able to cause genotoxicity, biochemical impairment and histological alterations in the liver of rainbow trout.

  20. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  1. Doped Titanium Dioxide Films Prepared by Pulsed Laser Deposition Method

    Directory of Open Access Journals (Sweden)

    Juguang Hu

    2012-01-01

    Full Text Available TiO2 was intensively researched especially for photocatalystic applications. The nitrogen-doped TiO2 films prepared by pulsed laser deposition (PLD method were reviewed, and some recent new experimental results were also presented in this paper. A new optical transmission method for evaluating the photocatalystic activity was presented. The main results are (1 PLD method is versatile for preparing oxide material or complex component films with excellent controllability and high reproducibility. (2 Anatase nitrogen-doped TiO2 films were prepared at room temperature, 200°C, and 400°C by PLD method using novel ceramic target of mixture of TiN and TiO2. UV/Vis spectra, AFM, Raman spectra, and photocatalystic activity for decomposition of methyl orange (MO tests showed that visible light response was improved at higher temperature. (3 The automatic, continuous optical transmission autorecorder method is suitable for detecting the photodecomposition dynamic process of organic compound.

  2. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, Devadoss Mangalam Durai Manoharadoss [Department of Physics, NPR College of Engineering and Technology, Natham, Dindigul, Tamil Nadu (India); Sadaiyandi, Karuppasamy [Department of Physics, Alagappa Government Arts College, Karaikudi, Sivaganga, Tamil Nadu (India); Mahendran, Manickam [Department of Physics, Thiagarajar College of Engineering, Madurai, Tamil Nadu (India); Sagadevan, Suresh, E-mail: duraiphysics2011@gmail.com [Department of Physics, AMET University (India)

    2016-03-15

    Cerium oxide (CeO{sub 2}) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  3. Preparation and Characteristics of Rare Earth Loaded Titanium Dioxide

    Institute of Scientific and Technical Information of China (English)

    张俊平; 王艳; 戚慧心

    2003-01-01

    Composite oxide catalysts Eu/TiO2, Ce/TiO2, Y/TiO2 (RE/TiO2) were prepared by impregnation method and characterized by means of UV-Vis spectroscopy, TEM and BET. The results indicate that the size of TiO2 has different effect on the modification efficiency. The catalytic activity of micron scale TiO2 increases by 136% and 59% owing to the addition of Y and Ce, respectively, while the catalytic activity of nanoscale TiO2 decreases due to the doping of Y and Ce.

  4. METHODOLOGICAL ASPECTS OF MOLASSES SAMPLE PREPARATION IN SULFUR DIOXIDE CONTENT DETERMINING

    Directory of Open Access Journals (Sweden)

    M. I. Egorova

    2015-01-01

    Full Text Available Summary. Molasses is characterized as sugar production by-product from primary or secondary sacchariferous raw materials. The features of the appearance, the chemical composition, molasses and exit directions of its use, depending on the type of production, in which it is formed. The value of molasses is demonstrated according to its total composition as well as its use directions. Statistics on beet molasses amounts in Russia is presented. Described consumer market molasses in Russia and abroad with its exports. Shown regulations contain requirements for the quality and safety of molasses, including sulfur dioxide. The data on sulfur allergenic properties are presented. Showing source of the sulfur dioxide in the residual molasses number of processing aids and the impact of its level in the value of raw molasses for use in biotechnological processes and fodder production. The necessity to develop methodology for determining the sulfur dioxide content in the molasses to control its security. The iodometric method, which is used in practice for determination of sulphur dioxide in foods are characterized. Differences molasses and sugar as objects of iodometric determination of sulfur dioxide, which leads to the inability to ascertain the equivalence point. The variants eliminate interfering background of dark-colored foods common in analytical chemistry. Advantages and disadvantages of the background masking and stripping the determination of sulfur dioxide in the darkcolored products. It was characterized by clarifying sugar solutions in optical control methods. The hypothesis about preferability of its use in sample molasses preparation for equivalence point fixation in iodometric titration is suggested. The tasks of experimental research for the development of sample preparation algorithm molasses in determining the content of sulphurous acid.

  5. Preparation of Aromatic Polycarbonate Nanoparticles using Supercritical Carbon Dioxide

    Science.gov (United States)

    Lee, Jun-Young; Song, Cheong-Hun; Kim, Joong-In; Kim, Jung-Hyun

    2002-04-01

    A novel synthetic process for producing aromatic polycarbonate (PC) nanoparticles using supercritical CO2 was developed. The objective of the present research work was to synthesize high molecular weight PC nanoparticles using transesterification between bisphenol-A (BPA) and diphenyl carbonate (DPC) in supercritical CO2 which is an excellent plasticizing agent and a good solvent for phenol, a by-product of the reaction. Poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) tri-block copolymer with CO2-phobic anchor and CO2-philic tail group was used as a stabilizer for the preparation of stable dispersions of BPA-DPC mixture in a CO2 continuous phase. As the reaction was proceeding, phenol formed from the reaction was dissolved and diffused into supercritical CO2 phase. The PC nanoparticles were isolated by simple venting of the supercritical CO2 from the reactor. Spherical morphology of PC particles was confirmed by scanning electron microscopy. Particle size and morphology of PC particles were modified upon variation of the process conditions. The resulting PC particles with a nano-size of 30-140 nm have a high molecular weight ( M w) of 3.1×105 (g/mol).

  6. Preparation and electrochemical characterization of manganese dioxide-zirconia nanorods

    Science.gov (United States)

    Muthuchudarkodi, R. R.; Vedhi, C.

    2015-04-01

    MnO2-ZrO2 nanorods were prepared by wet chemical method by mixing the solutions of MnSO4 and ZrOCl2 varying in the range (0.05-0.45 M) in aqueous NaOH at an elevated temperature. The morphologies of the synthesized products are characterized by scanning electron microscopy and transmission electron microscopy (TEM). X-ray diffraction (XRD) and energy-dispersive spectroscopic measurements were also employed for the characterization of the nanostructures. The synthesized nanoparticles were also characterized by ultraviolet visible spectroscopy, Fourier transform infrared spectroscopy, electrochemical impedance and cyclic voltammetric studies. The morphological studies of the nanoparticles revealed particle distribution with uniform rod-like structure. Energy-dispersive analysis indicated the presence of Mn, Zr and O. The nanostructures of the product were characterized by TEM studies and the mixed rod and granular structure that was found clearly indicated the presence of MnO2-ZrO2 mixed oxide. The size of the synthesized nanorod was found to be 20 nm. From XRD studies the size of the nanorods was found to be in the range 39-56 nm calculated by Debye-Scherrer's formula. Thermal stability of the nanorods was characterized by thermogravimetric and differential scanning colorimetric analysis. Cyclic voltammetric studies exhibit good adherent behavior on electrode surface and good electroactivity at a pH value of 1.0.

  7. Probing the cerium/cerium hydride interface using nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Brierley, Martin, E-mail: martin.brierley@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Knowles, John, E-mail: john.knowles@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom)

    2015-10-05

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase.

  8. Preparation, Characterization of Dawson-type Heteropoly Acid Cerium (Ⅲ) Salt and Its Catalytic Performance on the Synthesis of n-Butyl Acetate

    Institute of Scientific and Technical Information of China (English)

    CAO Xiaohua; REN Jie; XU Changlong; ZHANG Kanghua; ZHAN Changchao; LAN Jian

    2013-01-01

    A novel cerium (Ⅲ) salt of Dawson type tungstophosphoric acid (Ce2P2W18O62·16H2O) was prepared by doping cerous nitrate in H6P2W18O62.13H2O powder and characterized by thermogravimetry and differential thermal analyses (TG/DTA),Fourier transform infrared spectroscopy (FT-IR),X-ray powder diffraction (XRD),pyridine infrared spectroscopy (Py-IR) and scanning electron microscopy (SEM).Its catalytic activity was evaluated by the probe reaction of synthesis of n-butyl acetate with acetic acid and n-butanol.The effects of various parameters such as molar ratio of n-butanol to acetic acid,reaction temperature,reaction time,and catalyst amount have been studied by single factor experiment.The results show that Ce2P2W18O62·16H2O behaved as an excellent heterogeneous catalyst in the synthesis of n-butyl acetate.The optimum synthetic conditions were determined as follows:molar ratio of n-butanol to acetic acid at 2.0 ∶ 1.0,mass of the catalyst being 1.44% of the total reaction mixture,reaction temperature of 120 ℃ and reaction time of 150 min.Under above conditions,the conversion of acetic acid was above 97.8 %.The selectivity of n-butyl acetate based on acetic acid was,in all cases,nearly 100%.The catalysts could be recycled and still exhibited high catalytic activity with 90.4% conversion after five cycles of reaction.It was found by means of TG-DTA and Py-IR that the catalyst deactivation was due to the adsorption of a complex of by-product on the active sites on catalysts surface or the catalyst loss in its separation from the products.Compared with using sulfuric acid as catalyst,the present procedure with Ce2P2W18O62· 16H2O is a green productive technology due to simple process,higher yield,catalyst recycling and no corrosion for the production facilities.

  9. Temperature dependent structural and magnetic properties of Cerium substituted Co–Cr ferrite prepared by auto-combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Mustafa, Ghulam, E-mail: ghulammustafabzu@gmail.com [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Islam, M.U. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Zhang, Wenli [State Key Laboratory of Electronic Thin Films and Integrated Devices, UESTC, Chengdu 610054 (China); Jamil, Yasir [Department of Physics, University of Agriculture, Faisalabad 38040 (Pakistan); Asif Iqbal, M.; Hussain, Mudassar [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Ahmad, Mukhtar, E-mail: ahmadmr25@yahoo.com [Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2015-03-15

    The effects of heat treatment on a nano-crystalline spinel ferrite with chemical formula CoCr{sub 0.04}Ce{sub x}F{sub e1.96−x}O{sub 4} (x=0.06) were investigated in the present work. The sample was prepared by the auto-combustion method and then heat treated at 700–1200 °C for 8 h. The sample heat treated at these temperatures was investigated using thermo-gravimetric analyses and differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometery. The XRD patterns and IR spectra confirmed that the synthesized materials were of single phase at and above 900 °C. The average particle size was found to be in the range of 30.8–63.8 nm estimated by the Scherer formula. IR studies confirm two main absorption bands in the frequency range of 400–800 cm{sup −1} arising due to the tetrahedral (A-site) and octahedral (B-site) stretching vibrations. The average grain size increased with the increase of temperature while distribution of particles became homogeneous as observed by scanning electron microscope. The saturation magnetization was increased gradually from 7.4 to 59.6 emu/g with the increase of temperature. The coercivity lies in the range of 248–811 Oe as a function of temperature. The obtained results suggest that the investigated materials may be potential candidates for high density recording media applications. - Highlights: • Effects of temperature on structural and magnetic parameters of spinel ferrite are studied. • The XRD patterns confirms that the materials are of single phase at and above 900 °C. • The M{sub s} was increased gradually from 7.4–59.6 emu/g with the increase of temperature. • The values of coercivity lie in the range of 248–811 Oe as a function of temperature. • The results show that materials may have a potential for high density recording media.

  10. Preparation and application of cerium-based composite nano oxides%铈基纳米复合氧化物的研究及其应用进展

    Institute of Scientific and Technical Information of China (English)

    闫玉玲; 李丽华; 张金生; 吴限

    2016-01-01

    综述了以氧化铈为基的纳米复合氧化物的国内外研究进展,阐述了纳米TiO2-CeO2、CeO2-ZnO、ZrO2/CeO2及CeO2与其他氧化物的复合(如Al2 O3、CaO、CuO等)材料的制备与性能,最后对铈基纳米复合材料的研究进行了展望。%Review of the present research status of cerium-based composite nano oxides .The preparation and application of TiO2-CeO2,CeO2-ZnO,ZrO2/CeO2 and other complex oxides (such as CeO2/Al2 O3, CeO2/CaO,CeO2/CuO) are reviewed.Prospects on both research and application of cerium-based com-posite nano oxides are proposed in the end .

  11. Preparation of Bentonite Supported Nano Titanium Dioxide Photocatalysts by Electrostatic Self-assembly Method

    Institute of Scientific and Technical Information of China (English)

    WANG Cheng; SHI Huisheng; LI Yan

    2012-01-01

    Electrostatic self-assembly method (ESAM) was used to prepare bentonite supported-nano titanium dioxide photocatalysts.The materials were characterized by X-ray diffraction (XRD),fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM).Methyl orange was used to estimate the photocatalytic activity of the materials.The effects of the calcination temperature and silane dosage on the photocatalytic activity of the samples were investigated.The experimental results show that the bentonite facilitates the formation of anatase and restrains the transformation of anatase to rutile.Part of nano-size TiO2 particles insert into the galleries of bentonite.The photocatalysts exhibit a synergistic effect of adsorption and photocatalysis on methyl orange.Photocatalysts prepared by ESAM method exhibit higher photocatalytic activity and better recycle ability than those of the traditional method.

  12. Preparation of platinum modified titanium dioxide nanoparticles with the use of laser ablation in water.

    Science.gov (United States)

    Siuzdak, K; Sawczak, M; Klein, M; Nowaczyk, G; Jurga, S; Cenian, A

    2014-08-07

    We report on the preparation method of nanocrystalline titanium dioxide modified with platinum by using nanosecond laser ablation in liquid (LAL). Titania in the form of anatase crystals has been prepared in a two-stage process. Initially, irradiation by laser beam of a titanium metal plate fixed in a glass container filled with deionized water was conducted. After that, the ablation process was continued, with the use of a platinum target placed in a freshly obtained titania colloid. In this work, characterization of the obtained nanoparticles, based on spectroscopic techniques--Raman, X-ray photoelectron and UV-vis reflectance spectroscopy--is given. High resolution transmission electron microscopy was used to describe particle morphology. On the basis of photocatalytic studies we observed the rate of degradation process of methylene blue (MB) (a model organic pollution) in the presence of Pt modified titania in comparison to pure TiO2--as a reference case. Physical and chemical mechanisms of the formation of platinum modified titania are also discussed here. Stable colloidal suspensions containing Pt modified titanium dioxide crystalline anatase particles show an almost perfect spherical shape with diameters ranging from 5 to 30 nm. The TiO2 nanoparticles decorated with platinum exhibit much higher (up to 30%) photocatalytic activity towards the degradation of MB under UV illumination than pure titania.

  13. Preparation of manganese dioxide loaded activated carbon adsorbents and their desulfurization performance

    Science.gov (United States)

    Zhang, Jiaojing; Wang, Guojian; Wang, Wenyi; Song, Hua; Wang, Lu

    2016-12-01

    Manganese dioxide loaded activated carbon adsorbents (MnO2/AC) were prepared and characterized by N2 adsorption-desorption, BET method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy (SEM). Effects of preparation conditions and adsorption conditions on desulfurization performance of the adsorbents were studied in a fixed-bed adsorption apparatus. Experimental results show that the surface area and pore volume of MnO2/AC decreased compared with the unmodified activated carbon, but the adsorption capacity to H2S was improved greatly. A suitable H2S removal activity was obtained with manganese dioxide to activated carbon ratio of 1.1: 1 and the calcination temperature of 250°C. At the adsorption temperature of 40°C and gas flow rate of 20 mL/min, the H2S saturation capacity and H2S removal rate reached up to 713.25 mg/g and 89.9%, respectively.

  14. Preparation, characterisation and dissolution of a CeO2 analogue for UO2 nuclear fuel

    Science.gov (United States)

    Stennett, Martin C.; Corkhill, Claire L.; Marshall, Luke A.; Hyatt, Neil C.

    2013-01-01

    The behaviour of spent nuclear fuel under geological conditions is a major issue underpinning the safety case for final disposal. This work describes the preparation and characterisation of a non-radioactive UO2 fuel analogue, CeO2, to be used to investigate nuclear fuel dissolution under realistic repository conditions as part of a developing EU research programme. The densification behaviour of several cerium dioxide powders, derived from cerium oxalate, were investigated to aid the selection of a suitable powder for fabrication of fuel analogues for powder dissolution tests. CeO2 powders prepared by calcination of cerium oxalate at 800 °C and sintering at 1700 °C gave samples with similar microstructure to UO2 fuel and SIMFUEL. The suitability of the optimised synthesis route for dissolution was tested in a dissolution experiment conducted at 90 °C in 0.01 M HNO3.

  15. Preparation and photocatalytic properties of PI/SnO2 films doping with cerium%掺铈PI/SnO2复合薄膜的制备及光催化性能

    Institute of Scientific and Technical Information of China (English)

    孙博华; 李艳丽; 李青

    2016-01-01

    The PI/SnO2 films doping with cerium were prepared on flexible polyimide (PI) substrate via di⁃rect ion exchange method. The effect of different preparation conditions on the photocatalytic properties of the composite films were studied. Furthermore, the effects of the doping amount of cerium ion and the con⁃centration of ion exchange liquid on photocatalytic performance were also studied. The films were character⁃ized by SEM, EDAX, XRD and FTIR. The photocatalytic performance of the films was evaluated by the degrada⁃tion rate of the methylene blue. The results showed that the PI/SnO2 composite films with 30% (mass frac⁃tion) cerium, 0.4 mol/L total ion exchange solution concentration and calcined at 330 ℃ for 4 h, had perfect photocatalytic performance. The methylene blue degradation rate reached 94.5% at 2 h and TOC removal rate was 75.3%. The films could be recycled and showed a good degradation performance.%以聚酰亚胺(PI)为基体,采用离子交换法制备Ce掺杂PI/SnO2复合薄膜。考察了不同制备条件对其性能的影响,并进一步研究了Ce掺杂量及离子交换液浓度对复合薄膜的影响。利用SEM、EDAX、XRD、FTIR等对复合薄膜进行表征,并且以亚甲基蓝为模拟污染物,根据对亚甲基蓝的降解率评价薄膜的光催化性能。研究结果表明,煅烧温度330℃,煅烧时间4 h,Ce掺杂量为30%,离子交换液浓度0.4 mol/L时,光催化效果最好,光照射2 h亚甲基蓝降解率可达94.5%,TOC去除率75.3%。回收复合薄膜进行二次利用,降解效果良好。

  16. Effect of variable cerium concentration on photoluminescence behaviour in ZrO2 phosphor synthesized by combustion synthesis method

    Science.gov (United States)

    Dubey, Vikas; Kaur, Jagjeet

    2016-05-01

    Present paper reports synthesis and characterization of trivalent cerium (Ce3+) doped zirconium dioxide (ZrO2) phosphors. Effect of variable concentration of cerium on photoluminescence (PL) is studied. Samples were prepared by combustion synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. Starting material used for sample preparation are Zr(NO3)3 and Ce(NO3)3 and urea used as a fuel. All prepared phosphor with variable concentration of Ce3+ (0.1 to 2mol%) was studied by photoluminescence analysis it is found that the excitation spectra of prepared phosphor shows broad excitation centred at 390nm. The excitation spectra with variable concentration of Ce3+ show strong peaks at 447nm. Spectrophotometric determinations of peaks are evaluated by Commission Internationale de I'Eclairage technique. Using this phosphor, the desired CIE values including emissions throughout the violet (390 nm) and blue (427 nm) of the spectra were achieved. Efficient blue light emitting diodes were fabricated using Ce3+ doped phosphor based on near ultraviolet (NUV) excited LED lights.

  17. Preparation and Characterization of Self-Assembled Manganese Dioxide Thin Films

    Directory of Open Access Journals (Sweden)

    Suh Cem Pang

    2011-01-01

    Full Text Available Thin films of manganese dioxide (MnO2 were prepared by self-assembly of MnO2 nanoparticles directly unto nickel-coated poly(ethylene terephthalate flexible films using the newly developed horizontal submersion process. The thickness of deposited thin films was controllable by the deposition duration. This horizontal submersion deposition process for thin-film deposition is relatively easy, simple, and cost effective. Effects of deposition duration and calcination temperatures on the microstructure and electrochemical properties of self-assembled MnO2 thin films were investigated. Optimized MnO2 thin films exhibited high charge capacity, good cycling reversibility, and stability in a mild aqueous electrolyte and are thus promising electrode materials for the fabrication of thin-film electrochemical capacitors.

  18. Preparation and photocatalytic activity of nonmetal Co-doped titanium dioxide photocatalyst

    Science.gov (United States)

    Sun, Xiaogang; Xing, Jun; Qiu, Jingping

    2016-06-01

    A series of boron and sulfur co-doped titanium dioxide (TiO2) photocatalysts were prepared by a sol-gel method using boric acid, thiourea and tetrabutyl titanate [Ti(OC4H9)4] as precursors. The photoabsorbance of as-prepared photocatalysts was measured by UV-Vis diffuse reflectance spectroscopy (DRS), and its microstructure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The prepared photocatalysts consisted of the anatase phase mainly in the form of spherical particles. The photocatalytic performance was studied by photodegradation of methyl blue (MB) in water under UV and visible light irradiation. The calcination temperature and the codoping content influenced the photoactivity. The synergistic effect of boron and sulfur co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of codoped TiO2 was also confirmed, the photocatalytic activity of TiO2 remained above 91% of that of the fresh sample after being used four times. It was shown that the co-doped TiO2 could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants.

  19. Preparation of conductive polypyrrole (PPy) composites under supercritical carbon dioxide conditions

    Institute of Scientific and Technical Information of China (English)

    LI Gang; LIAO Xia; SUN Xinghua; YU Jian; HE Jiasong

    2007-01-01

    Electrically conductive composites were prepared via the chemical oxidative polymerization of the pyrrole monomer in polystyrene (PS) and zinc neutralized sulfonated polystyrene (Zn-SPS) films under supercritical carbon dioxide (SC-CO2) conditions.The strong swelling effect of SCCO2 made polypyrrole (PPy) particles not only form on the surface,but also become incorporated into the film,resulting in a homogeneous structure with a relatively higher conductivity.By comparison,the composite prepared in aqueous solutions shows a skin-core structure and a conductivity of 3 to 4 orders of magnitude lower than that of the former due to the diffusion-controlled process of the pyrrole monomer.The percolation thresholds of PS/PPy and Zn-SPS/PPy composites were 6.2% and 2.7% of the volume fraction of PPy,respectively,much lower than the theoretically predicted value of 16%.Moreover,the conductive composites prepared under SC-CO2 conditions showed higher thermal stability,especially in the high-temperature region.

  20. Cerium doped red mud catalytic ozonation for bezafibrate degradation in wastewater: Efficiency, intermediates, and toxicity.

    Science.gov (United States)

    Xu, Bingbing; Qi, Fei; Sun, Dezhi; Chen, Zhonglin; Robert, Didier

    2016-03-01

    In this study, the performance of bezafibrate (BZF) degradation and detoxification in the aqueous phase using cerium-modified red mud (RM) catalysts prepared using different cerium sources and synthesis methods were evaluated. Experimental results showed that the surface cerium modification was responsible for the development of the catalytic activity of RM and this was influenced by the cerium source and the synthesis method. Catalyst prepared from cerium (IV) by precipitation was found to show the best catalytic activity in BZF degradation and detoxification. Reactive oxygen species including peroxides, hydroxyl radicals, and super oxide ions were identified in all reactions and we proposed the corresponding catalytic reaction mechanism for each catalyst that prepared from different cerium source and method. This was supported by the intermediates profiles that were generated upon BZF degradation. The surface and the structural properties of cerium-modified RM were characterized in detail by several analytical methods. Two interesting findings were made: (1) the surface texture (specific surface area and mesoporous volume) influenced the catalytic reaction pathway; and (2) Ce(III) species and oxygen vacancies were generated on the surface of the catalyst after cerium modification. This plays an important role in the development of the catalytic activity.

  1. Activity Enhancement of Vanadium Catalysts with Ultrasonic Preparation Process for the Oxidation of Sulfur Dioxide

    Institute of Scientific and Technical Information of China (English)

    Zhenxing Chen; Honggui Li; Lingsen Wang

    2003-01-01

    The effect of ultrasonic cavitations on the activity of vanadium catalysts at low temperatures for the oxidation of sulfur dioxide, in which refined carbonized mother liquor had been added, was investigated.Twenty minutes were needed to produce obvious cavitations when the catalyst raw material was treated in the 50 W ultrasonic generator. However, only 10 minutes would be needed in a 150 W ultrasonic generator.The higher the temperature of the wet material, the less time was needed to produce cavitations, and the optimal temperature was 60 ℃. The water content in the wet material mainly affected the quantity of cavitations. Ls-8 catalyst was prepared using ultrasonic. Its activity for conversion of SO2 reached to 52.5% at 410 ℃ and 4.2% at 350 ℃. The differential thermal analyses indicate that both endothermic peaks and exothermic peaks noticeably shifted forward compared with Ls catalyst prepared without ultrasonic, and SEM results show a uniform pore size distribution for Ls-8 catalyst.

  2. New doped tin dioxide electrodes for electrochemical ozone generation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.H.; Li, G.; Liang, Y.R.; Nie, Z.Z.; Chen, Q.Y. [Xi' an Jiaotong Univ., Xi' an (China). State Key Laboratory of Multiphase Flow, Dept. of Environmental Engineering

    2010-07-01

    In this study, nickel (Ni) and antimony (Sb) doped tin dioxide (SnO{sub 2}) were prepared using a dip-coating pyrolysis method. The sol-gel dip coating method was used to prepare the Ni-Sb-SnO{sub 2} electrode. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses were conducted to compare the morphology, crystallinity, composition and oxidation states achieved using the 2 different preparation methods. Results of the evaluation showed that electrodes prepared by the sol-gel method were much different than those prepared using the dip-coating pyrolysis method. Silver (Ag) and cerium (Ce) were doped onto the Ni and Sb doped SnO{sub 2}, and the relations between electrode properties and performance were investigated. Results demonstrated that Ag and Ce doping significantly improved electrode performance. The sol-gel dip coating method also significantly improved electrode performance. 2 refs., 1 fig.

  3. Preparation and Evaluation of Novel Solid Chlorine Dioxide-based Disinfectant Powder in Single-pack

    Institute of Scientific and Technical Information of China (English)

    MIN ZHU; LI-SHI ZHANG; XIAO-FANG PEI; XIN XU

    2008-01-01

    Objective To prepare and evaluate novel chlorine dioxide-based disinfectant powder in single-pack that is more convenient for use and iransportation.Methods Orthogonal experiment was performed to determine the recipe of the disinfectant powder.Stability test,suspension quantitative bactericidal test,simulation neld trial,and animal toxicity test were carried out to observe its bactericidal and toxicological effects.Results The orthogonal experiment showed thatthe type of water solution had no effect on the disinfectant powder and the best ratio of sodium chlorite to solid acid was 1:3.Ten grams of the disinfectant powder was fully dissolved in 20 mL water for 2 mill,and diluted to 500 mL in water.After 5-10 min,the concentration of chlorine dioxide(ClO2)solution was 266 mg/L to 276 mg/L.After stored at 54℃ for 14 d,the average concentration of ClO2 was decreased by 5.03%.Suspension quantitative bactericidal test showed that the average killing logarithm(KL)value for both Staphylococcus aureus and Escherichia coli in 100 mg/L ClO2 solution for 2 min was over 5.00.In simulation field trial,the average descending KL value for Escherichia coli in the solution containing 100 mg/L ClO2 for 5min was ovcr 3.00.The mouse acute LD50 in the solution 5 times exceeded 5000 mg/kg.The disinfectant powder was not toxic and irritativeto rabbit skin and had nomutagenic effect on mouse marrow polychrornafic erythrocytes(PCE).Conclusion The stability and bactericidal efficacy of solid chlorine dioxide-based disinfectant powder in single-pack are good.The solution containing 100mg/L ClO2 can kill vegetative forms of bacteria.The concenwation of ClO2 on the disinfecting surface of objects is 100mg/L.The disinfectant powder is not toxic and irritative.

  4. Co-doping of Iron and Cerium in Titanium Dioxide: Observation of a Cooperative Effect%铁和铈共掺杂二氧化钛中的协同效应

    Institute of Scientific and Technical Information of China (English)

    李哓俊; 司德君; 方均; 姜志全; 黄伟新

    2006-01-01

    The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy,UV-Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the sol-gel method, iron was introduced in the framework of anatase TiO2 whereas cerium was not;interestingly, both iron and cerium were introduced in the framework when co-doping by the sol-gel method.The co-doped TiO2 behaves much more intense surface hydroxyl concentration than the separately-doped and pure TiO2. This observation demonstrates for the first time a cooperative effect in the co-doping of transitional metals in the framework of TiO2.%利用X射线衍射、拉曼光谱、紫外-可见漫反射光谱和X射线光电子能谱研究了铁和铈对TiO2的共掺杂.当利用溶胶-凝胶法进行单独掺杂时,铁离子可以进入锐钛矿TiO2骨架,但铈离子却不能进入TiO2骨架;当铁和铈共掺杂时,铁离子和铈离子可以同时进入TiO2骨架.铁-铈共掺杂的TiO2表面羟基浓度要远高于单独掺杂或者纯的TiO2.第一次观察到过渡金属离子共掺杂进入TiO2骨架的协同效应.

  5. Preparation of titanium dioxide/tungsten disulfide composite photocatalysts with enhanced photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Lili; Zhang, Weiping; Xiao, Xinyan [South China University of Technology, Guangzhou (China)

    2016-01-15

    Titanium dioxide/tungsten disulfide (TiO{sub 2}/WS{sub 2}) composite photocatalysts were fabricated via a one-step hydrothermal synthesis process, using TiCl{sub 4} as titanium source and bulk WS{sub 2} as sensitizer. The morphology, structure, specific surface area and optical absorption properties of the composite photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), specific surface area analyzer and ultraviolet-visible diffuse reflection spectrum (UV-vis DRS), respectively. The photocatalytic activity of as-prepared photocatalysts was evaluated by the degradation of methyl orange (MO) under illumination of 500W Xenon lamp. The results indicated that TiO2/WS2 composite photocatalysts possessed excellent photocatalytic activity, and -95% of the degradation rate for MO was reached when molar ratio of WS{sub 2} to TiO{sub 2} was 0.004 and the irradiation time was 60 min. Moreover, the carrier trapping experiment and fluorescence spectra showed that •O{sup -}{sub 2} was the key component in the photocatalytic degradation process and O{sub 2} was reduced to be •O{sup -}{sub 2} by the electrons from the conduction band of TiO{sub 2} and WS{sub 2} for the degradation of MO.

  6. Preparation and Characterization of Nanotitanium Dioxide Coating Film Doped with Fe3+ Ions on Porous Ceramic

    Institute of Scientific and Technical Information of China (English)

    Kejing Xu

    2005-01-01

    The nanotitanium dioxide (TiO2) photocatalytic and porous ceramic filtering technique is one of the advanced methods to effectively treat organic wastewater. The TiO2 sol doped with Fe3+ ions was prepared by sol-gel processing. The influences of the process conditions of coating nanophotocatalytic material-Fe3+-TiO2 film on the surface of porous ceramic filter by dipping-lift method on the performance of porous ceramic filter were studied. The porous ceramic filters have two functions at the same time,filtration and photocatalytic degradation. The results of this study showed that the pH and viscosity of the sol,amount of Fe3+ ions doped as well as the coating times greatly affect the quality of coating film,the performance parameters and the photocatalytic activity of the porous ceramic filter. When the pH of the sol is 3-4,the viscosity is about 6 mPa·S,the amount of doped Fe3+ ions is about 2.0 g/L,the porous ceramic filter has been shown to have the best filtering performance and photocatalytic activity. In this condition,the porosity of porous ceramic is about 42.5%,the pore diameter is 8-10μm. The degradation of methyl-orange is 74.76% under lighting for 120 min.

  7. Elaborately prepared hierarchical structure titanium dioxide for remarkable performance in lithium storage

    Science.gov (United States)

    Tian, Qinghua; Luo, Dong; Li, Xiaowei; Zhang, Zhengxi; Yang, Li; Hirano, Shin-ichi

    2016-05-01

    Titanium dioxide (TiO2) has been considered to be a promisingly alternative anode material for lithium-ion batteries and thus attracted wide research interest. But, its practical application in lithium-ion batteries is seriously impeded by low capacity and poor rate capability. In the present work, the electrochemical performance of TiO2 is significantly improved by elaborately fabricating hierarchical structures. These as-prepared four hierarchical structure TiO2 assembled by different building blocks (TO2-2 h, TO2-6 h, TO2-18 h and TO2-24 h) all exhibit impressed performance. More importantly, the TO2-6 h constructed by curved nanosheets exhibits the best performance, delivering a capacity of 231.6 mAh g-1 at 0.2C after 200 cycles, and capacities of 187.1 and 129.3 mAh g-1 at 1 and 10C after even 1200 cycles, respectively. The results indicated that design and fabrication of hierarchical structure is an effective strategy for significantly improving the electrochemical performance of TiO2 electrodes, and the electrochemical performance of hierarchical structure TiO2 is heavily dependent on its building blocks. It is suggested that thus excellent electrochemical performance may make TiO2-6 h a promising anode material for advanced lithium-ion batteries with high capacity, good rate capability and long life.

  8. Structural properties of zinc oxide and titanium dioxide nanoparticles prepared by chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Akgul, Guvenc, E-mail: guvencakgul@gmail.com [Bor Vocational School, Nigde University, 51700 Nigde (Turkey); Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Akgul, Funda Aksoy [Physics Department, Nigde University, 51240 Nigde (Turkey); Attenkofer, Klaus [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Winterer, Markus [Nanoparticle Process Technology, Department of Engineering Sciences, and Center for NanoIntegration Duisburg-Essen, CeNIDE, University of Duisburg-Essen (Germany)

    2013-03-25

    Highlights: ► Local structure determination of ZnO and TiO{sub 2} nanostructures by XANES and EXAFS. ► Zn K and Ti K absorption edge XANES investigations of nanopowder samples. ► Investigation of pre-edge peak features of TiO{sub 2} nanosamples. ► Obtaining of local structure parameters of nano ZnO and TiO{sub 2} using EXAFS. ► Good agreement of EXAFS results and crystal structure datas. -- Abstract: Transition metal (TM) oxides provide a wide range of functional materials especially when nanostructured. Titanium dioxide (TiO{sub 2}) and wurtzite type zinc oxide (ZnO) nanostructured materials were fabricated by chemical vapor synthesis (CVS). Crystal and local structures of the prepared nanosamples were ascertained using X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) techniques. Based on the XRD data, a second phase(s) was not found in both samples. A single wurtzite and anatase type structures were observed in ZnO and TiO{sub 2} nanosamples, respectively. Ti K pre-edge features of XANES spectrum indicated the presence of sixfold coordinated Ti in TiO{sub 2} nanosamples. The results showed that CVS is quite useful method to produce high crystalline nanoparticles.

  9. Preparation of Vanadium Dioxide Films for Protection from High-energy Laser Hits

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Vanadium dioxide(VO2)thin films are used for protection from high-energy laser hits due to their semiconductor-to-metal phase transition experienced during heating at temperature of approximately 68℃,which followed by a abrupt change of optical behavior, namely from transparent semiconductor state below 68℃ to highly reflective metallic state beyond 68℃.The preparation and properties of the films are described as well as the primary principle of the device for protection from high energy laser hits. An ion-beam-sputtering system is used to deposit VO2 thin films.The technique is reactive ion beam sputtering of vanadium at temperature of 200℃ on Si, Ge and Si3N4 substrates in a well controlled atmosphere of argon with a partial pressure of O2, followed by a post annealing at 400-550℃ with argon gas.The optical transmittance changes from 60% to 4% are obtained within the temperature range from 50℃ to 70℃. X-ray diffraction (XRD) shows that the films are of single-phase VO2.

  10. Optical and electrical studies of cerium mixed oxides

    Science.gov (United States)

    Sherly, T. R.; Raveendran, R.

    2014-10-01

    The fast development in nanotechnology makes enthusiastic interest in developing nanomaterials having tailor made properties. Cerium mixed oxide materials have received great attention due to their UV absorption property, high reactivity, stability at high temperature, good electrical property etc and these materials find wide applications in solid oxide fuel cells, solar control films, cosmetics, display units, gas sensors etc. In this study cerium mixed oxide compounds were prepared by co-precipitation method. All the samples were doped with Zn (II) and Fe (II). Preliminary characterizations such as XRD, SEM / EDS, TEM were done. UV - Vis, Diffuse reflectance, PL, FT-IR, Raman and ac conductivity studies of the samples were performed.

  11. Optical and electrical studies of cerium mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Sherly, T. R., E-mail: trsherly@gmail.com [Post Graduate Department of Physics, Sanathana Dharma College, Alappuzha, Kerala (India); Raveendran, R. [Nanoscience Research Laboratory, Sree Narayana College, Kollam, Kerala 691001 (India)

    2014-10-15

    The fast development in nanotechnology makes enthusiastic interest in developing nanomaterials having tailor made properties. Cerium mixed oxide materials have received great attention due to their UV absorption property, high reactivity, stability at high temperature, good electrical property etc and these materials find wide applications in solid oxide fuel cells, solar control films, cosmetics, display units, gas sensors etc. In this study cerium mixed oxide compounds were prepared by co-precipitation method. All the samples were doped with Zn (II) and Fe (II). Preliminary characterizations such as XRD, SEM / EDS, TEM were done. UV - Vis, Diffuse reflectance, PL, FT-IR, Raman and ac conductivity studies of the samples were performed.

  12. Electrodeposited cerium film as chromate replacement for tinplate

    Energy Technology Data Exchange (ETDEWEB)

    Huang Xingqiao [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Li Ning [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: lining@hit.edu.cn; Wang Huiyong; Sun Hanxiao; Sun Shanshan; Zheng Jian [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

    2008-01-30

    The cerium film was prepared on tinplate by electrodeposition method. Sulfide-stain resistance of the Ce-passivated, unpassivated and Cr-passivated tinplates was evaluated using a cysteine tarnish test. Corrosion behavior of these tinplates in contact with 3.5% NaCl solution and 0.1 M citric-citrate buffer solution was investigated using Tafel measurement and electrochemical impedance spectroscopy measurement, respectively. The adhesion of epoxyphenolic lacquer to the Ce-passivated tinplate was checked using a cross hatch cutter. The morphology, composition and thickness of the cerium film were studied by atomic force microscopy, X-ray photoelectron spectroscopy and X-ray fluorescence spectrometry. According to the results, the Ce-passivated tinplate shows the best sulfide-stain resistance and the best corrosion protection property compared with the unpassivated and Cr-passivated tinplates. The adhesion of epoxyphenolic lacquer to the Ce-passivated tinplate is good. The cerium film is composed of the closely packed particles of about 50-200 nm in diameter. The film mainly consists of cerium and oxygen, which mainly exist as CeO{sub 2}, Ce{sub 2}O{sub 3} and their hydrates such as Ce(OH){sub 4}, Ce(OH){sub 3}. The total cerium amount of the film is about 0.110 g/m{sup 2}.

  13. Vehicle Exhaust Gas Clearance by Low Temperature Plasma-Driven Nano-Titanium Dioxide Film Prepared by Radiofrequency Magnetron Sputtering

    OpenAIRE

    Shuang Yu; Yongdong Liang; Shujun Sun; Kai Zhang; Jue Zhang; Jing Fang

    2013-01-01

    A novel plasma-driven catalysis (PDC) reactor with special structure was proposed to remove vehicle exhaust gas. The PDC reactor which consisted of three quartz tubes and two copper electrodes was a coaxial dielectric barrier discharge (DBD) reactor. The inner and outer electrodes firmly surrounded the outer surface of the corresponding dielectric barrier layer in a spiral way, respectively. Nano-titanium dioxide (TiO2) film prepared by radiofrequency (RF) magnetron sputtering was coated on t...

  14. Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

    Science.gov (United States)

    Chang, Betty Yea Sze; Huang, Nay Ming; An’amt, Mohd Nor; Marlinda, Abdul Rahman; Norazriena, Yusoff; Muhamad, Muhamad Rasat; Harrison, Ian; Lim, Hong Ngee; Chia, Chin Hua

    2012-01-01

    A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm). Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II) ions in potassium chloride electrolyte. PMID:22848166

  15. Progress of Chlorine Dioxide Preparation Method%二氧化氯制备方法研究进展

    Institute of Scientific and Technical Information of China (English)

    吴建春; 杨佳财

    2012-01-01

    二氧化氯是一种具有高氧化性和强消毒性的化合物,本论文介绍了二氧化氯制备的化学法、电解法以及电化学法,并对几种工艺方法的优缺点进行了分析和比较,适合工业化生产的工艺主要是化学法中的氯酸钠法和亚氯酸钠法。%Chlorine dioxide is a high oxidation resistance and strong disinfection compound.This paper introduces the chemical preparation method of dioxide chlorine,electrolysis method and electrochemical method.The advantages and disadvantages of several processing methods were discussed and compared.The process suitable for industrial production is mainly sodium chlorate and sodium chlorite method.

  16. Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    Wang Xue-Jin; Liang Chun-Jun; Guan Kang-Ping; Li De-Hua; Nie Yu-Xin; Zhu Shi-Oiu; Huang Feng; Zhang Wei-Wei; Cheng Zheng-Wei

    2008-01-01

    This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering,and then aged under circumstance for years.Samples were characterized with several different techniques such as x-ray diffraction,x-ray photoelectron spectroscopy,and Raman,when they were fresh from sputter chamber and aged after years,respectively,in order to determine their structure and composition.It finds that a small amount of sodium occurred on the surface of vanadium dioxide films,which was probably due to sodium ion diffusion from soda-lime glass when sputtering was performed at high substrate temperature.It also finds that aging for years significantly affected the noustoichiometry of vanadium dioxide films,thus inducing much change in Raman modes.

  17. Microporous activated carbons prepared from palm shell by thermal activation and their application to sulfur dioxide adsorption.

    Science.gov (United States)

    Guo, Jia; Lua, Aik Chong

    2002-07-15

    Textural characterization of activated carbons prepared from palm shell by thermal activation with carbon dioxide (CO(2)) gas is reported in this paper. Palm shell (endocarp) is an abundant agricultural solid waste from palm-oil processing mills in many tropical countries such as Malaysia, Indonesia, and Thailand. The effects of activation temperature on the textural properties of the palm-shell activated carbons, namely specific surface area (BET method), porosity, and microporosity, were investigated. The activated carbons prepared from palm shell possessed well-developed porosity, predominantly microporosity, leading to potential applications in gas-phase adsorption for air pollution control. Static and dynamic adsorption tests for sulfur dioxide (SO(2)), a common gaseous pollutant, were carried out in a thermogravimetric analyzer and a packed column configuration respectively. The effects of adsorption temperature, adsorbate inlet concentration, and adsorbate superficial velocity on the adsorptive performance of the prepared activated carbons were studied. The palm-shell activated carbon was found to have substantial capability for the adsorption of SO(2), comparable to those of some commercial products and an adsorbent derived from another biomass.

  18. Evaluation of error sources in a gravimetric technique for preparation of a reference gas mixture (carbon dioxide in synthetic air).

    Science.gov (United States)

    Matsumoto, Nobuhiro; Shimosaka, Takuya; Watanabe, Takuro; Kato, Kenji

    2008-07-01

    One method of preparing a primary reference gas mixture is the gravimetric blending method. Uncertainty of a few mg in mass measurements is unavoidable when preparing reference gas mixtures under current laboratory conditions with our facilities, equipment, and materials. There are many sources of errors when using this method. In this study, several sources of errors were re-evaluated for our process for preparation of carbon dioxide in synthetic air. As a consequence of the re-evaluation, it was found that some sources of errors had significant effects on gravimetric concentrations of the gas mixtures. These sources are: (1) different masses of the reference cylinder and sample cylinder (an error in the readings of the electronic mass comparator), (2) leakage of the inner gas from valves of the cylinders, and (3) cooling of the gas cylinder caused by filling with high-pressure liquefied carbon dioxide gas. When the mass measurements were performed under uncontrolled conditions, the errors due to sources (1), (2), and (3) were as high as 20 mg, 24 mg, and 13 mg, respectively. In this paper, the detailed results from re-evaluation of these sources of errors are discussed.

  19. Preparation of titanium dioxide nanostructures facilitated by poly-L-lysine peptide

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Perez, Carlos A. [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Ciudad Juarez, Avenida del Charro 450 Norte Cd. Juarez, Chih. Mex. C.P. 32310 (Mexico)]. E-mail: camartin@uacj.mx; Garcia-Casillas, Perla E. [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Ciudad Juarez, Avenida del Charro 450 Norte Cd. Juarez, Chih. Mex. C.P. 32310 (Mexico); Camacho-Montes, Hector [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Ciudad Juarez, Avenida del Charro 450 Norte Cd. Juarez, Chih. Mex. C.P. 32310 (Mexico); Monreal-Romero, Humberto A. [Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120 Chihuahua, Chih. Mex. C.P. 31109 (Mexico); Martinez-Villafane, Alberto [Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120 Chihuahua, Chih. Mex. C.P. 31109 (Mexico); Chacon-Nava, Jose [Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120 Chihuahua, Chih. Mex. C.P. 31109 (Mexico)

    2007-05-31

    In this work, we have synthesized titanium dioxide by sol-gel process using titanium isopropoxide as precursor; the shapes obtained were nanorods ranging in size from 20 to 40 nm in presence of poly-L-lysine (PLL) peptide. The resulting materials were calcinated in order to obtain a crystalline phase; afterwards the powders were characterized by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the synthesis of titanium dioxide nanostructures can be achieved in presence of poly-L-lysine.

  20. Preparation of Nano-titanium Dioxide in Propane/Air Diffusion Flame

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; SUN Xue; XIE Hongyong

    2004-01-01

    Titanium dioxide (TiO2) nanoparticles were synthesized by the oxidation of titanium tetrachloride (TiCl4), in propane/air diffusion flame. The propane/air diffusion flame is generated using a multi-port diffusion type burner composed of 4 concentric tubes. Flow rates of TiCl4 and combustion gases such as air, industrial propane and carrier gas were chosen as key experimental variables for the control of the particle size and morphology. Effects of propane/air mole ratio and precursor flow rate on particle size, morphology, structure and carbon dots of titanium dioxide particles were studied.

  1. Environmental geochemistry of cerium: applications and toxicology of cerium oxide nanoparticles.

    Science.gov (United States)

    Dahle, Jessica T; Arai, Yuji

    2015-01-23

    Cerium is the most abundant of rare-earth metals found in the Earth's crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydr)oxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 nanoparticles from industrial processing plants (e.g., electronics and optics manufactures) is likely to reach the terrestrial environment such as landfills and soils. The environmental fate of CeO2 nanoparticles is highly dependent on its physcochemical properties in low temperature geochemical environment. Though there are needs in improving the analytical method in detecting/quantifying CeO2 nanoparticles in different environmental media, it is clear that aquatic and terrestrial organisms have been exposed to CeO2 NPs, potentially yielding in negative impact on human and ecosystem health. Interestingly, there has been contradicting reports about the toxicological effects of CeO2 nanoparticles, acting as either an antioxidant or reactive oxygen species production-inducing agent). This poses a challenge in future regulations for the CeO2 nanoparticle application and the risk assessment in the environment.

  2. Environmental Geochemistry of Cerium: Applications and Toxicology of Cerium Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jessica T. Dahle

    2015-01-01

    Full Text Available Cerium is the most abundant of rare-earth metals found in the Earth’s crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydroxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 nanoparticles from industrial processing plants (e.g., electronics and optics manufactures is likely to reach the terrestrial environment such as landfills and soils. The environmental fate of CeO2 nanoparticles is highly dependent on its physcochemical properties in low temperature geochemical environment. Though there are needs in improving the analytical method in detecting/quantifying CeO2 nanoparticles in different environmental media, it is clear that aquatic and terrestrial organisms have been exposed to CeO2 NPs, potentially yielding in negative impact on human and ecosystem health. Interestingly, there has been contradicting reports about the toxicological effects of CeO2 nanoparticles, acting as either an antioxidant or reactive oxygen species production-inducing agent. This poses a challenge in future regulations for the CeO2 nanoparticle application and the risk assessment in the environment.

  3. Hydrothermal synthesis of cerium titanate nanorods and its application in visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn; Liu, H.D.; Lin, N.; Yu, H.Y., E-mail: yuhy@ahut.edu.cn

    2015-01-15

    Highlights: • Cerium titanate nanorods have been synthesized by a simple hydrothermal process. • The size of the cerium titanate nanorods can be controlled by growth conditions. • Cerium titanate nanorods exhibit good photocatalytic activities for methyl blue. - Abstract: Cerium titanate nanorods have been prepared via a hydrothermal process using sodium dodecyl sulfate (SDS) as the surfactant. The cerium titanate nanorods have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and ultraviolet–visible (UV–vis) diffuse reflectance spectrum. XRD shows that the nanorods are composed of CeTi{sub 21}O{sub 38} phase. Electron microscopy observations indicate that the nanorods have good single crystalline nature. The diameter and length of the nanorods are about 50–200 nm and 1–2 μm, respectively. Cerium titanate nanorods have a band gap of 2.65 eV. The photocatalytic activities of the nanorods have been investigated by degrading methylene blue (MB) under visible light irradiation. MB solution with the concentration of 10 mg L{sup −1} can be degraded totally with the irradiation time increasing to 240 min. Cerium titanate nanorods exhibit great potential in photocatalytic degradation of MB under visible light irradiation.

  4. Novel borothermal route for the synthesis of lanthanum cerium hexaborides and their field emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Menaka [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India); Patra, Rajkumar; Ghosh, Santanu [Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India); Ganguli, Ashok K., E-mail: ashok@chemistry.iitd.ac.in [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2012-10-15

    The present study describes the development of a simple approach to stabilize polycrystalline lanthanum cerium hexaborides without using any flux and at ambient pressure. The nanostructured lanthanum-cerium borides were synthesized using hydroxide precursors. These precursors (La{sub 1-x}Ce{sub x}(OH){sub 3}, x=0.1, 0.2, 0.3 and 0.5) were synthesized via hydrothermal route in the presence of Tergitol (surfactant, nonylphenol ethoxylate) as a capping agent. The precursors on heating with boron at 1300 Degree-Sign C lead to the formation of nanostructures (cubes, rods and pyramids) of lanthanum cerium hexaboride. We have investigated the field emission behaviour of the hexaboride films fabricated by spin coating. It was observed that the pyramidal shaped nanostructures of La{sub 0.5}Ce{sub 0.5}B{sub 6} shows excellent field emission characteristics with high field enhancement factor of 4502. - Graphical abstract: Nanostructured lanthanum cerium hexaboride with efficient field emission have fabricated by low temperature hydroxide precursor mediated route. Highlights: Black-Right-Pointing-Pointer New methodology to prepare lanthanum cerium hexaboride at 1300 Degree-Sign C via borothermal route. Black-Right-Pointing-Pointer Nanostructured lanthanum cerium hexaboride film by spin coating process. Black-Right-Pointing-Pointer Nanopyramids based lanthanum cerium hexaboride shows excellent field emission.

  5. PLUTONIUM-CERIUM-COBALT AND PLUTONIUM-CERIUM-NICKEL ALLOYS

    Science.gov (United States)

    Coffinberry, A.S.

    1959-08-25

    >New plutonium-base teroary alloys useful as liquid reactor fuels are described. The alloys consist of 10 to 20 atomic percent cobalt with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 88 atomic percent; or, of from 10 to 25 atomic percent nickel (or mixture of nickel and cobalt) with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 86 atomic percent. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are a lower melting point and a wide range of permissible plutonium dilution.

  6. Thermal Treatment of Cerium Oxide and Its Properties: Adsorption Ability versus Degradation Efficiency

    Directory of Open Access Journals (Sweden)

    Pavel Janoš

    2014-01-01

    Full Text Available Cerium oxide belongs to the most important heterogeneous catalysts, but its applicability as so-called reactive sorbent for the degradation of toxic chemicals was only recently discovered. For these purposes, cerium oxide is prepared by precipitation of insoluble cerium salts (carbonates with a subsequent thermal decomposition. Properties of cerium oxide prepared from the carbonate precursor are strongly affected by the temperature during the calcination. Main physicochemical properties of cerium oxide (specific surface area, crystallinity, and surface chemistry were examined in dependence on the calcination temperature. As the adsorptive properties of CeO2 are undoubtedly of great importance in the abovementioned applications, the adsorption ability was studied using an azo dye Acid Orange 7 (AO7 as a model compound. The highest sorption efficiency towards AO7 exhibited sorbents prepared at temperatures below 700°C, which was attributed mainly to the presence of hydroxyl groups on the oxide surface. A strong correlation was found between an adsorption efficiency of cerium oxides and their degradation efficiency for organophosphate pesticide parathion methyl. The >Ce–OH groups on the sorbent surface are responsible for the dye binding by the surface-complexation mechanism, and probably also for the nucleophilic cleavage of the P–O–aryl bond in the pesticide molecule.

  7. Direct, preparative enantioselective chromatography of propranolol hydrochloride and thioridazine hydrochloride using carbon dioxide-based mobile phases.

    Science.gov (United States)

    Geiser, F; Schultz, M; Betz, L; Shaimi, M; Lee, J; Champion, W

    1999-12-31

    In this paper, we describe the direct, preparative enantioselective chromatography of racemic (rac)-propranolol hydrochloride (HCI) and rac-thioridazine.HCl using Chiralpak AD chiral stationary phase and mobile phase systems containing carbon dioxide and methanol without the use of basic or acidic additives. Isolated fractions of propranolol.HCl were positively identified by mass spectrometry, Beilstein flame test, melting point, and chemical analysis to be HCI enantiomers of propranolol-HCl salts exhibited characteristic mass spectra peaks at 36 and 38 mass-to-charge ratio in the expected 3:1 isotopic ratio for the solute that were absent in the mass spectra for the free-base forms. To our knowledge, the direct, preparative enantioselective isolation of HCI enantiomeric salts of rac-propranolol and of rac-thioridazine have not been previously demonstrated and published.

  8. Enhancement of cerium and hydrogen storage property of a low-cost Ti-V based BCC alloy prepared by commercial ferrovanadium

    Institute of Scientific and Technical Information of China (English)

    米菁; 吕芳; 刘晓鹏; 蒋利军; 李志念; 王树茂

    2010-01-01

    Based on the analysis of XRD, SEM, P-C-isotherm measurements and absorption kinetics simulation, it was indicated that Ce addition was an effective way to inhibit the formation of C14 Laves phase, improve flatness of the plateau, increase hydrogen diffusion rate and enlarge hydrogen storage capacity. The hydrogenation capacity of Ti27.25Cr28.05V37.25Fe7.45Ce1.0 alloy prepared by commercial ferrovanadium was 3.56 wt.% measured at 298 K. The dehydrogenation capacity was 2.25 wt.% and 2.54 wt.% measured at 343...

  9. Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

    Directory of Open Access Journals (Sweden)

    Chang BYS

    2012-07-01

    Full Text Available Betty Yea Sze Chang,1 Nay Ming Huang,1 Mohd Nor An' amt,2 Abdul Rahman Marlinda,1 Yusoff Norazriena,1 Muhamad Rasat Muhamad,3 Ian Harrison,4 Hong Ngee Lim,5 Chin Hua Chia61Low Dimensional Materials Research Center, Physics Department, University of Malaya, Kuala Lumpur; 2Faculty of Agro Industry and Natural Resources (FASA, Universiti Malaysia Kelantan, Kota Bharu, Kelantan; 3The Chancellery Building, Multimedia University, Persiaran Multimedia, Cyberjaya, Selangor; 4School of Chemical and Environmental Engineering, The University of Nottingham Malaysia Campus, Semenyih, Selangor; 5Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 6School of Applied Physics, Universiti Kebangsaan Malaysia, Bangi, Selangor, MalaysiaAbstract: A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm. Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II ions in potassium chloride electrolyte.Keywords: graphene oxide, titanium oxide, hydrothermal, nanocomposite

  10. Porous poly(D,L-lactic acid) foams with tunable structure and mechanical anisotropy prepared by supercritical carbon dioxide.

    Science.gov (United States)

    Floren, Michael; Spilimbergo, Sara; Motta, Antonella; Migliaresi, Claudio

    2011-11-01

    The design and tunability of tissue scaffolds, such as pore size and geometry, is crucial to the success of an engineered tissue replacement. Moreover, the mechanical nature of a tissue scaffold should display properties similar to the tissue of interest; therefore, tunability of the foam mechanical properties is desirable. Polymeric foams prepared using supercritical carbon dioxide as a blowing agent has emerged in recent years as a promising technique to prepare porous scaffolds. While a number of groups have reported on the tailoring of scaffold morphologies by using gas foaming techniques, few have considered the effects of such processing conditions on the physical and mechanical anisotropy achieved. The aim of this study was to demonstrate the tunability of the structure and mechanical anisotropy of foams prepared using a variety of different gas foaming conditions. Porous poly(D,L lactic acid) foams were prepared by the systematic adjustment of processing conditions, namely pressure, temperature and venting time, resulting in an extensive range of scaffold morphologies. Characterization of sample anisotropy was achieved by mechanical evaluation of foam specimens both longitudinal and transverse to the foaming direction. The obtained mechanical properties demonstrated a strong dependence of the processing conditions on mechanical anisotropy and performance. Furthermore, results indicate that factors other than pore geometry may be necessary to define the mechanical behavior of the foam specimens. The favorable compressive moduli, coupled with large degrees of anisotropy, suggests these foams may have suitable application as scaffolds for bone tissue engineering.

  11. 含硝酸铈的乳化炸药爆轰的制备%Preparation of emulsion explosives with cerium nitrate by detonation method

    Institute of Scientific and Technical Information of China (English)

    解一超; 韩志伟; 解立峰

    2013-01-01

    为研究乳化炸药在爆轰合成纳米氧化铈中的应用,研制了以硝酸铈和硝酸铵为主要氧化剂的乳化炸药.对不同硝酸铈含量的乳化炸药爆速进行了测试,并利用差示扫描量热仪研究了不同硝酸铈含量的乳化炸药基质的放热特性.研究结果表明,硝酸铈含量对乳化炸药的爆速具有显著影响,同时也决定了乳化基质的放热量和放热速率,用于爆轰合成的硝酸铈质量分数以30%~50%为宜.利用硝酸铈质量分数为40%的乳化炸药,采用爆轰法得到了粒径为70 nm、晶型为立方晶系的纳米氧化铈.%In order to study the application of emulsion explosives in synthesizing nanosized ceria, emulsion explosives, in which Ce(NO3)3·6H2O and NH4NO3 acted as the main oxidant, were prepared by detonation method. The detonation velocity of emulsion explosives with different content of Ce(NO3)3·6H2O was measured. Their exothermal character was tested by Differential Scanning Calorimeter(DSC). Results indicated that the detonation velocity of emulsion explosives was significantly affected by the content of Ce(NO3)3·6H2O and the content was suggested to be no more than 50% for emulsion explosives in detonation synthesis. The heat output and the exothermic rate of emulsion base depended on the content of Ce(NO3)3·6H2O in emulsion explosives, which should be kept within 30%-50% in detonation synthesis. The content of Ce(NO3)3·6H2O in emulsion explosives was 40%, the nano ceria size was about 70nm, and crystal form was cubic.

  12. Catalytic conversion of carbon dioxide into dimethyl carbonate using reduced copper-cerium oxide catalysts as low as 353 K and 1.3 MPa and the reaction mechanism

    Directory of Open Access Journals (Sweden)

    Seiki eWada

    2013-06-01

    Full Text Available Synthesis of dimethyl carbonate (DMC from CO2 and methanol under milder reaction conditions was performed using reduced cerium oxide catalysts and reduced copper-promoted Ce oxide catalysts. Although the conversion of methanol was low (0.005–0.11% for 2 h of reaction, DMC was synthesized as low as 353 K and at total pressure of as low as 1.3 MPa using reduced Cu–CeO2 catalyst (0.5 wt% of Cu. The apparent activation energy was 120 kJ mol–1 and the DMC synthesis rates were proportional to the partial pressure of CO2. An optimum amount of Cu addition to CeO2 was 0.1 wt% for DMC synthesis under the conditions at 393 K and total pressure of 1.3 MPa for 2 h (conversion of methanol: 0.15% due to the compromise of two effects of Cu: the activation of H2 during reduction prior to the kinetic tests and the block (cover of the surface active site. The reduction effects in H2 were monitored through the reduction of Ce4+ sites to Ce3+ based on the shoulder peak intensity at 5727 eV in the Ce L3-edge X-ray absorption near-edge structure (XANES. The Ce3+ content was 10% for reduced CeO2 catalyst whereas it increased to 15% for reduced Cu–CeO2 catalyst (0.5wt% of Cu. Moreover, the content of reduced Ce3+ sites (10% associated with the surface O vacancy (defect sites decreased to 5% under CO2 at 290 K for reduced Cu–CeO2 catalyst (0.1wt% of Cu. The adsorption step of CO2 on the defect sites might be the key step in DMC synthesis and thus the DMC synthesis rate dependence on the partial pressure of CO2 was proportional. Subsequent H atom subtraction steps from methanol at the neighboring surface Lewis base sites should combine two methoxy species to the adsorbed CO2 to form DMC, water, and restore the surface O vacancy.

  13. Preparation of titanium dioxide/silver sulfate powder and its antibacterial activity

    Institute of Scientific and Technical Information of China (English)

    PENG Bing; YUAN Chun; CHAI Li-yuan; WEI Shun-wen; YU Yan-fen; SU Wei-feng

    2005-01-01

    Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2 SO4. The granularity of the particles increases from 10.7 nm to 28.7 nm with the temperature of heat-treatment increasing from 300 ℃ to 800 ℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents (MiCs). When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0× 10-4- 1.5 × 10-4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500 ℃. But when the temperature is beyond 600 ℃ the MiCs increase quickly, which shows the inferior antibacterial performance.

  14. Nanostructured Mesoporous Titanium Dioxide Thin Film Prepared by Sol-Gel Method for Dye-Sensitized Solar Cell

    Directory of Open Access Journals (Sweden)

    Yu-Chang Liu

    2011-01-01

    Full Text Available Titanium dioxide (TiO2 paste was prepared by sol-gel and hydrothermal method with various precursors. Nanostructured mesoporous TiO2 thin-film back electrode was fabricated from the nanoparticle colloidal paste, and its performance was compared with that made of commercial P25 TiO2. The best performance was demonstrated by the DSSC having a 16 μm-thick TTIP-TiO2 back electrode, which gave a solar energy conversion efficiency of 6.03%. The ability of stong adhesion on ITO conducting glass substrate and the high surface area are considered important characteristics of TiO2 thin film. The results show that a thin film with good adhesion can be made from the prepared colloidal paste as a result of alleviating the possibility of electron transfer loss. One can control the colloidal particle size from sol-gel method. Therefore, by optimizing the preparation conditions, TiO2 paste with nanoparticle and narrow diameter distribution was obtained.

  15. Magnetic resonance colonography with a limited bowel preparation and automated carbon dioxide insufflation in comparison to conventional colonoscopy: Patient burden and preferences

    Energy Technology Data Exchange (ETDEWEB)

    Paardt, M.P. van der, E-mail: m.p.vanderpaardt@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Boellaard, T.N., E-mail: t.n.boellaard@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Zijta, F.M., E-mail: fmzijta@yahoo.com [Department of Radiology, Medisch Centrum Haaglanden, Den Haag (Netherlands); Baak, L.C., E-mail: l.c.baak@olvg.nl [Department of Gastroenterology and Hepatology, Onze Lieve Vrouwe Gasthuis, Amsterdam (Netherlands); Depla, A.C.T.M., E-mail: actm.depla@slz.nl [Department of Gastroenterology and Hepatology, Slotervaartziekenhuis, Amsterdam (Netherlands); Dekker, E., E-mail: e.dekker@amc.uva.nl [Department of Gastroenterology and Hepatology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Nederveen, A.J., E-mail: a.j.nederveen@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Bipat, S., E-mail: s.bipat@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Stoker, J., E-mail: j.stoker@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands)

    2015-01-15

    Highlights: • MR colonography with a limited bowel preparation and automated carbon dioxide insufflation demonstrated less burden compared to colonoscopy. • When discarding the bowel preparation, the examinations were rated equally burdensome. • The majority of patients preferred MR colonography over colonoscopy for their future examination of the bowel. - Abstract: Objectives: To evaluate patient burden and preferences for MR colonography with a limited bowel preparation and automated carbon dioxide insufflation in comparison to conventional colonoscopy. Methods: Symptomatic patients were consecutively recruited to undergo MR colonography with automated carbon dioxide insufflation and a limited bowel preparation followed within four weeks by colonoscopy with a standard bowel cleansing preparation. Four questionnaires regarding burden (on a five-point scale) and preferences (on a seven-point scale) were addressed after MR colonography and colonoscopy and five weeks after colonoscopy. Results: Ninety-nine patients (47 men, 52 women; mean age 62.3, SD 8.7) were included. None of the patients experienced severe or extreme burden from the MR colonography bowel preparation compared to 31.5% of the patients for the colonoscopy bowel preparation. Colonoscopy was rated more burdensome (25.6% severe or extreme burden) compared to MR colonography (5.2% severe or extreme burden) (P < 0.0001). When discarding the bowel preparations, the examinations were rated equally burdensome (P = 0.35). The majority of patients (61.4%) preferred MR colonography compared to colonoscopy (29.5%) immediately after the examinations and five weeks later (57.0% versus 39.5%). Conclusion: MR colonography with a limited bowel preparation and automated carbon dioxide insufflation demonstrated less burden compared to colonoscopy. The majority of patients preferred MR colonography over colonoscopy.

  16. Titanium dioxide nanoparticles prepared by laser pyrolysis: Synthesis and photocatalytic properties

    Science.gov (United States)

    Figgemeier, E.; Kylberg, W.; Constable, E.; Scarisoreanu, M.; Alexandrescu, R.; Morjan, I.; Soare, I.; Birjega, R.; Popovici, E.; Fleaca, C.; Gavrila-Florescu, L.; Prodan, G.

    2007-12-01

    TiO 2 nanoparticles were synthesized via the laser pyrolysis of titanium tetrachloride-based gas-phase mixtures. In the obtained nanopowders, a mixture of anatase and rutile phases with mean particle size of about 14 nm was identified. Using the thermal heated laser nanopowders, mechanically stable films were produced by immobilizing titania nanopowders on glass substrates (the doctor blading method followed by compression). The photocatalytic activity of the prepared films was tested by the degradation of 4-chlorophenol in an aqueous solution under UV-illumination. By referring to known commercial samples (Degussa P25) similarly prepared, higher photocatalytic efficiency was found for the laser-prepared samples.

  17. Preparation and Corrosion Resistance Evaluation of Cerium Salt/Silane Composite Coating on Hot-Dip Galvanized Steel%热镀锌钢铈盐/硅烷复合膜的制备及其耐蚀性能

    Institute of Scientific and Technical Information of China (English)

    吴海江; 徐国荣; 许剑光; 徐红梅; 吴玉蓉; 颜焕元

    2013-01-01

    热镀锌钢板上单一的铈盐、硅烷钝化膜有一些缺点,对提高其耐蚀性作用不大.为此,将热镀锌钢板先经铈盐溶液处理,再用乙烯基三甲氧基硅烷溶液浸渍,获得了铈盐/硅烷复合钝化膜.采用扫描电镜(SEM)、俄歇电子能谱(AES)、盐水全浸试验和电化学交流阻抗谱(EIS)研究了复合膜层的表面形貌、结构特性和耐蚀性能.结果表明:硅烷膜能较好地填充铈盐转化膜中的裂纹,铈盐/硅烷复合膜层连续、完整、致密,厚400~450 nm,与基体结合较好,复合膜中硅烷膜/铈盐转化膜/锌基体的化学成分呈连续的梯度变化;与热镀锌钢相比,单一铈盐转化膜、硅烷膜的交流阻抗值增加了1个多数量级,复合膜的则增加了约2个数量级,复合膜层的耐蚀性较单一膜层显著增强,且优于常规铬酸盐钝化膜.%Hot-dip galvanized steel was firstly treated in the solution of cerium nitrate and then immersed in vinyltrimethoxysilane solution to obtain composite coating consisting of cerium salt coating and silane coating. The morphology and microstructure of as - obtained composite coating were analyzed by scanning electron microscopy and Auger elec tron spectroscopy, and its corrosion resistance was evaluated based on immersion test in salt water and electrochemical imped ance spectroscopic analysis as well. Results showed that the mi- crocracks in the cerium conversion coating could be well filled up with the silane coating. As-obtained cerium salt/silane composite coating with a thickness of 400 ~ 450 nm was continuous, com plete and compact, and had good adhesion to the steel substrate as well as gradient chemical composition. In the meantime, the electrochemical impedance values of the cerium conversion coat ing and silane coating were increased by more than one order of magnitude as compared with that of hot-dip galvanized steel sub strate, and the electrochemical impedance value of the cerium salt

  18. Gadolinium doped tin dioxide nanoparticles:an efficient visible light active photocatalyst

    Institute of Scientific and Technical Information of China (English)

    Abdullah M Al-Hamdi; Mika Sillanp; Joydeep Dutta

    2015-01-01

    Photocatalytic degradation of phenol with sol-gel prepared rare earth doped tin dioxide (SnO2) nanoparticles was reported. Gadolinium doped tin dioxide (SnO2:Gd) nanoparticles were found to absorb higher visible light compared to lanthanum, neodymium and cerium doped materials that were studied in detail. Photocatalytic degradation of phenol under artificial white light and sunlight in the presence of SnO2:Gd nanoparticles was studied with high performance liquid chromatography (HPLC), capillary electrophoresis (CE), total organic carbon (TOC) measurements and the determination of chemical oxygen demand (COD). Clear correlations be-tween the results obtained from these multiple measurements were found, and a kinetic pathway for the degradation process was pro-posed. Within 150 min of solar irradiation, the TOC of a 10 ppm phenol solution in water was reduced by 95%–99%, thus demon-strating that SnO2:Gd nanoparticles are efficient visible light photocatalysts.

  19. Cerium, manganese and cerium/manganese ceramic monolithic catalysts. Study of VOCs and PM removal

    Institute of Scientific and Technical Information of China (English)

    COLMAN-LERNER Esteban; PELUSO Miguel Andrs; SAMBETH Jorge; THOMAS Horacio

    2016-01-01

    Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aqueous precursor, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) acidity measurements and electrical conductivity. The catalytic activity was evaluated for volatile organic compounds (VOC) (ethanol, methyl ethyl ketone and toluene) oxidation. Additionally, catalysts were tested in particulate matter (PM) combustion. The characterization results indicated that Ce was in the form of Ce4+ and Ce3+, and Mn existed in the form of Mn4+and Mn3+on the surface of the Mn/AC sample and in the form of Mn4+ in the Ce/Mn/AC monolith. VOC oxidation results revealed that the Ce/Mn/AC sample showed an excellent performance compared with ceramic supported CeO2 (Ce/AC) and MnOx (Mn/AC) samples. The PM combustion was also higher on Ce/Mn/AC monoliths. The enhanced catalytic activity was mainly attributed to the Ce and Mn interaction which enhanced the acidity, conductiv-ity and the reducibility of the oxides.

  20. Glow Discharge Plasma-Assisted Preparation of Nickel-Based Catalyst for Carbon Dioxide Reforming of Methane

    Institute of Scientific and Technical Information of China (English)

    Fang Guo; Wei Chu; Jun-qiang Xu; Lin Zhong

    2008-01-01

    A plasma-assisted method was employed to prepare Ni/γ-Al2O3 catalyst for carbon dioxide reforming of methane reaction. The novel catalyst possessed higher activity and better coke-suppression performance than those of the conventional calcination catalyst. To achieve the same CH4 conversion, the conventional catalyst needed higher reaction temperature, about 50 ℃ higher than that of the N2 plasma-treated catalyst.After the evaluation test, the deactivation rate of the novel catalyst was 1.7%, compared with 15.2% for the conventional catalyst. Different from the characterization results of the calcined catalyst, a smaller average pore diameter and a higher specific surface area were obtained for the plasma-treated catalyst.The variations of the reduction peak temperatures and areas indicated that the catalyst reducibility was promoted by plasma assistance. The dispersion of nickel was also remarkably improved, which was helpful for controlling the ensemble size of metal atoms on the catalyst surface. The modification effect of plasmaassisted preparation on the surface property of alumina supported catalyst was speculated to account for the concentration increase of absorbed CO2. An enhancement of CO2 adsorption was propitious to the inhibition of carbon formation. The coke amount deposited on plasma treated catalyst was much smaller than that on the conventional catalyst.

  1. Preparation, Characterization and NO-CO Redox Reaction Studies over Palladium and Rhodium Oxides Supported on Manganese Dioxide

    Directory of Open Access Journals (Sweden)

    M.S. Fal Desai

    2015-03-01

    Full Text Available The catalytic activity of PdO/MnO2 and Rh2O3/MnO2 is investigated for NO-CO redox reaction. Supported catalysts are prepared by wet impregnation method. Among the tested catalysts, PdO/MnO2 shows higher activity for this reaction. Active metal dispersion on MnO2 enhances the selectivity for N2 over N2O in this reaction. The XRD substantiate the formation of MnO2 monophasic phase. SEM images show the formation of elongated particles. TEM images indicate nano-size rod-like morphologies. An increase in the catalytic activity is observed on supported Pd and Rh oxides on MnO2. Temperature programed desorption studies with NO and CO are undertaken to investigate the catalytic surface studies. © 2015 BCREC UNDIP. All rights reservedReceived: 22nd November 2014; Revised: 31st December 2014; Accepted: 2nd January 2015How to Cite: Fal Desai, M.S., Kunkalekar, R.K., Salker, A.V. (2015. Preparation, Characterization and NO-CO Redox Reaction Studies over Palladium and Rhodium Oxides Supported on Manganese Dioxide. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1: 98-103. (doi:10.9767/bcrec.10.1.7802.98-103Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.1.7802.98-103 

  2. Characterization of magnetic biochar amended with silicon dioxide prepared at high temperature calcination

    Directory of Open Access Journals (Sweden)

    Baig Shams Ali

    2016-09-01

    Full Text Available Calcination is considered to increase the hardness of composite material and prevent its breakage for the effective applications in environmental remediation. In this study, magnetic biochar amended with silicon dioxide was calcined at high temperature under nitrogen environment and characterized using various techniques. X-ray diffraction (XRD analysis revealed elimination of Fe3O4 peaks under nitrogen calcination and formation of Fe3Si and iron as major constituents of magnetic biochar-SiO2 composite, which demonstrated its superparamagnetic behavior (>80 A2·kg−1 comparable to magnetic biochar. Thermogravimetric analysis (TGA revealed that both calcined samples generated higher residual mass (>96 % and demonstrated better thermal stability. The presence of various bands in Fourier transform infrared spectroscopy (FT-IR was more obvious and the elimination of H–O–H bonding was observed at high temperature calcination. In addition, scanning electron microscopy (SEM images revealed certain morphological variation among the samples and the presence of more prominent internal and external pores, which then judged the surface area and pore volume of samples. Findings from this study suggests that the selective calcination process could cause useful changes in the material composites and can be effectively employed in environmental remediation measures.

  3. Preparation, Characterization and Photocatalytic Activity of Lanthanum Doped Mesoporous Titanium Dioxide

    Institute of Scientific and Technical Information of China (English)

    Zhong-liang Shi; Hong Lai; Shu-hua Yao; Shao-feng Wang

    2012-01-01

    Lanthanum doped mesoporous titanium dioxide photocatalysts with different La content were synthesized by template method using tetrabutyltitanate (Ti(OC4H9)4) as precursor and Pluronic P123 as template.The catalysts were characterized by thermogravimetric differential thermal analysis,N2 adsorption-desorption measurements,X-ray diffraction,and UV-Vis adsorption spectroscopy.The effect of La3+ doping concentration from 0.1% to 1%on the photocatalytic activity of mesoporous TiO2 was investigated.The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of about 10 nm with high surface area of 165 m2/g.X-ray photoelectron spectroscopy measurements indicated the presence of C in the doped samples in addition to La.Compared with pure mesoporous TiO2,the La-doped samples extended the photoabsorption edge into the visible light region.The results of phenol photodecomposition showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradiation.

  4. Dissolution properties of cerium dibutylphosphate corrosion inhibitors

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The corrosion inhibitor cerium dibutylphosphate, Ce(dbp)3, prevents corrosion by cerium and dbp deposition at the alkaline cathode and acidic anode respectively. The pH dependent Ce(dbp)3 solubility seems to play an essential role in the inhibition degree. We found that Ce(dbp) 3 scarcely dissolves

  5. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    Science.gov (United States)

    Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Arora, Deepawali; Kumar, Sunil; Singh, D. P.

    2016-08-01

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV-Vis absorption spectra and fluorescence spectra (λexc.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO4 units thus supporting the density results. The UV- Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  6. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Parvinder; Kaur, Simranpreet [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Singh, Gurinder Pal [Department of Physics, Khalsa College, Amritsar 143002 (India); Arora, Deepawali; Kumar, Sunil [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Singh, D.P., E-mail: dpsinghdr@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2016-08-15

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV‐Vis absorption spectra and fluorescence spectra (λ{sub exc}.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO{sub 4} units thus supporting the density results. The UV‐ Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  7. Titanium dioxide coated cementitious materials for air purifying purposes: Preparation, characterization and toluene removal potential

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Anibal Maury; De Belie, Nele [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Engineering Faculty, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent (Belgium); Demeestere, Kristof [Research Group EnVOC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653. B-9000 Ghent (Belgium); Maentylae, Tapio; Levaenen, Erkki [Department of Materials Science, Tampere University of Technology, Korkeakoulunkatu 6, FIN-33720 Tampere (Finland)

    2010-04-15

    This work presents promising results for air purification by heterogeneous photocatalysis on new titanium dioxide loaded cementitious materials. A set of eight concretes and plasters is enriched with TiO{sub 2} photocatalyst by dip-coating and/or sol-gel methods. First, the macro-structural features of the cementitious materials have been studied in terms of porosity and roughness. The first parameter has been determined using mercury intrusion porosimetry or by vacuum saturation, and ranged between 9 and 75%, with the highest values obtained for autoclaved aerated white concrete. Surface roughness, determined by laser profilometry, has been characterized by the R{sub a} factor. This expresses the mean deviation of the profile from the centre line and ranged between 0.7 and 252 {mu}m, with the highest value obtained for conventional grey concrete finished with surface brush. Secondly, the weathering resistance of the TiO{sub 2} coatings has been determined by exposing them to different abrasive conditions and by performing SEM-Edax analyses to measure quantitatively the coating's titanium content. Hereby, it is shown that high porosity and roughness are favourable for TiO{sub 2} particles retention. Finally, the preliminary air purification potential of both dip-coated and sol-gel coated TiO{sub 2} enriched concrete samples has been investigated on lab-scale using toluene as a model pollutant. High removal efficiencies (up to 86%) were obtained with the dip-coated samples, indicating their attractive photocatalytic properties for future application as air purifying building materials. (author)

  8. Carbon dioxide adsorption on amine-impregnated mesoporous materials prepared from spent quartz sand.

    Science.gov (United States)

    Su, Yiteng; Peng, Lihong; Shiue, Angus; Hong, Gui-Bing; Qian, Zhang; Chang, Chang-Tang

    2014-07-01

    Mesoporous MCM-41 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and spent quartz sand as the silica source. Modification of the mesoporous structure to create an absorbent was then completed using 3-aminopropyltrimethoxysilane. Amine-Quartz-MCM (The A-Q-MCM) adsorbents were then characterized by N2 adsorption/desorption, elemental analysis (EA), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), as well as the carbon dioxide (CO2) adsorption/desorption performance. In this study, spent quartz sand was utilized to synthesize Quartz-MCM (Q-MCM) and the amine functionalized material, A-Q-MCM, which exhibited a higher uptake of CO2 at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The surface area, pore volume, and pore diameter were found to be as high as 1028 m2/g, 0.907 cm3/g, and 3.04 nm, respectively. Under the condition of CO2 concentration of 5000 ppm, retention time of 50 cc/min, and the dosage of 1 g/cm3, the mean adsorption capacity of CO2 onto A-Q-MCM was about 89 mg/g, and the nitrogen content of A-Q-MCM was 2.74%. The adsorption equilibrium was modeled well using a Freundlich isotherm. Implications: In this study, spent quartz sand was utilized to synthesize Q-MCM. The amine functionalized material exhibited a higher uptake of CO2 at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The adsorption equilibrium was modeled well using a Freundlich isotherm.

  9. Characterization of Ketoprofen/Methyl-β-Cyclodextrin Complexes Prepared Using Supercritical Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Mauro Banchero

    2013-01-01

    Full Text Available Complexes of methyl-β-cyclodextrin and ketoprofen, a crystalline anti-inflammatory drug with poor water solubility, have been prepared for the first time in the presence of supercritical CO2 at 40°C and 20 MPa. The supercritical treatment allows these pharmaceutical formulations to be prepared without the use of any auxiliary agents or organic solvents. The treated samples were characterized through differential scanning calorimetry, X-ray diffractometry, and the Fourier transform infrared spectroscopy to exclude the presence of crystalline drug and check the formation of the complexes. The increase of the drug dissolution rate was investigated performing in vitro release tests in aqueous solutions. The results showed that the supercritical treatment can be an efficient method to obtain inclusion complexes with enhanced release kinetics. The operating methods of the release tests, that is, the “tablet method” or the “dispersed amount method,” affected both the dissolution rate and its dependence on the drug amount in the samples. On the contrary, the variation of the pH of the dissolution medium did not show any effect on the release rate of the supercritical complexes.

  10. Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

    Science.gov (United States)

    Xiang, Lian; Park, Sang-Shik

    2016-12-01

    Al2O3-TiO2 (Al-Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO2 films were prepared on etched Al foils by vacuum infiltration. TiO2 films prepared using a sol-gel process were annealed at various temperatures (450, 500, and 550 °C) for different time durations (10, 30, and 60 min) for 4 cycles, and then anodized at 100 V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al2O3 outer layer, an Al-Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO2 coating, the specific capacitances of the TiO2-coated specimens are increased. The specific capacitance of the anode Al foil with TiO2 coating increased by 42% compared to that of a specimen without TiO2 coating when annealed at 550 °C for 10 min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

  11. Preparation and Characterization of Titanium Dioxide Photoelectrodes for Generation of Hydrogen by Photoelectrochemical Water Splitting

    Directory of Open Access Journals (Sweden)

    Alvaro Realpe

    2015-04-01

    Full Text Available The photoelectrochemical water splitting for the production of hydrogen was evaluated through the preparation of photoelectrodes of different substrates (glass, aluminium, graphite with TiO2 film. The film on each substrate was characterized by scanning electron microscope (SEM and x-ray diffraction (XRD. The results show that the TiO2 was deposited in dispersed form and in small clusters on the surface of the substrate and it had no effect on the crystal structure of the semiconductor; furthermore, good adhesion of the films on substrates was obtained except with graphite substrate. The hydrogen production process was carried out using UV light, halogen light and sunlight as photon sources, and it was evaluated by the current flow through the external circuit of the cell. The highest photocurrent values were obtained with the aluminium photoelectrode, averaging 1092.03 uA.

  12. Hydroxyapatite coatings on nanotubular titanium dioxide thin films prepared by radio frequency magnetron sputtering.

    Science.gov (United States)

    Shin, Jinho; Lee, Kwangmin; Koh, Jeongtae; Son, Hyeju; Kim, Hyunseung; Lim, Hyun-Pil; Yun, Kwidug; Oh, Gyejeong; Lee, Seokwoo; Oh, Heekyun; Lee, Kyungku; Hwang, Gabwoon; Park, Sang-Won

    2013-08-01

    In this study, hydroxyapatite (HA) was coated on anodized titanium (Ti) surfaces through radio frequency magnetron sputtering in order to improve biological response of the titanium surface. All the samples were blasted with resorbable blasting media (RBM). RBM-blasted Ti surface, anodized Ti surface, as-sputtered HA coating on the anodized Ti surface, and heat-treated HA coating on the anodized Ti surface were prepared. The samples were characterized using scanning electron microscopy and X-ray photoemission spectroscopy, and biologic responses were evaluated. The top of the TiO2 nanotubes was not closed by HA particles when the coating time is less than 15 minutes. It was demonstrated that the heat-treated HA was well-crystallized and this enhanced the cell attachment of the anodized Ti surface.

  13. Preparation of graphene oxide-manganese dioxide for highly efficient adsorption and separation of Th(IV)/U(VI).

    Science.gov (United States)

    Pan, Ning; Li, Long; Ding, Jie; Li, Shengke; Wang, Ruibing; Jin, Yongdong; Wang, Xiangke; Xia, Chuanqin

    2016-05-15

    Manganese dioxide decorated graphene oxide (GOM) was prepared via fixation of crystallographic MnO2 (α, γ) on the surface of graphene oxide (GO) and was explored as an adsorbent material for simultaneous removal of thorium/uranium ions from aqueous solutions. In single component systems (Th(IV) or U(VI)), the α-GOM2 (the weight ratio of GO/α-MnO2 of 2) exhibited higher maximum adsorption capacities toward both Th(IV) (497.5mg/g) and U(VI) (185.2 mg/g) than those of GO. In the binary component system (Th(IV)/U(VI)), the saturated adsorption capacity of Th(IV) (408.8 mg/g)/U(VI) (66.8 mg/g) on α-GOM2 was also higher than those on GO. Based on the analysis of various data, it was proposed that the adsorption process may involve four types of molecular interactions including coordination, electrostatic interaction, cation-pi interaction, and Lewis acid-base interaction between Th(IV)/U(VI) and α-GOM2. Finally, the Th(IV)/U(VI) ions on α-GOM2 can be separated by a two-stage desorption process with Na2CO3/EDTA. Those results displayed that the α-GOM2 may be utilized as an potential adsorbent for removing and separating Th(IV)/U(VI) ions from aqueous solutions.

  14. Vanadium dioxide thin films prepared on silicon by low temperature MBE growth and ex-situ annealing

    Science.gov (United States)

    Homm, Pia; van Bilzen, Bart; Menghini, Mariela; Locquet, Jean-Pierre; Ivanova, Todora; Sanchez, Luis; Sanchis, Pablo

    Vanadium dioxide (VO2) is a material that shows an insulator to metal transition (IMT) near room temperature. This property can be exploited for applications in field effect devices, electro-optical switches and nonlinear circuit components. We have prepared VO2 thin films on silicon wafers by combining a low temperature MBE growth with an ex-situ annealing at high temperature. We investigated the structural, electrical and optical characteristics of films with thicknesses ranging from 10 to 100 nm. We have also studied the influence of the substrate cleaning. The films grown with our method are polycrystalline with a preferred orientation in the (011) direction of the monoclinic phase. For the films produced on silicon with a native oxide, an IMT at around 75 °C is observed. The magnitude of the resistance change across the IMT decreases with thickness while the refractive index at room temperature corresponds with values reported in the literature for thin films. The successful growth of VO2 films on silicon with good electrical and optical properties is an important step towards the integration of VO2 in novel devices. The authors acknowledge financial support from the FWO project G052010N10 and EU-FP7 SITOGA project. PH acknowledges support from Becas Chile - CONICYT.

  15. Effect of cerium additive and secondary phase analysis on Ag0.5Bi0.5TiO3 ceramics

    Indian Academy of Sciences (India)

    S Supriya; Antonio J Dos Santos-García; F Fernández-Martinez

    2016-02-01

    Cerium-doped silver bismuth titanate—Ag0.5Bi0.5TiO3 (ABT) ceramics have been synthesized by the high-temperature solid-state reaction method. The structure and elemental examination of the prepared ceramic was analysed by X-ray diffraction (XRD), Fourier transform infrared, scanning electron microscopy and energydispersive spectroscopy. XRD analysis showed the presence of pyrochlore structure and secondary phase when more than 5 mol% cerium was added. The impact of temperature on cerium-doped silver bismuth titanate samples was analysed by differential thermal analysis and differential scanning calorimetry. Cerium doping caused the flaky morphology comparing with undoped sample. The homogeneity of all the samples was discussed in detail by diffuse reflectance spectrum. This is the first time the reflection process is analysed for the cerium-doped ABT system to the best of our knowledge.

  16. Preparation of Stellerite Loading Titanium Dioxide Photocatalyst and Its Catalytic Performance on Methyl Orange

    Directory of Open Access Journals (Sweden)

    Hua Chen

    2015-01-01

    Full Text Available TiO2/stellerite composite photocatalysts were prepared by dispersing TiO2 onto the surface of HCl, NaOH, or NaCl treated stellerite using a sol-gel method. The materials were characterized by scanning electron microscopy (SEM, energy dispersive X-ray (EDX, Fourier transform infrared spectroscopy (FT-IR, BET surface area analysis, and X-ray diffraction (XRD. HCl and NaCl modification result in the promotion of the pore formation at the stellerite surfaces and induced the microscopic changes, while the surface morphology and structure of the stellerite were almost ruined by NaOH modification. Supported TiO2 calcinated at 200°C presented anatase structure. The photocatalytic degradation activities of TiO2 loaded HCl and NaCl modified stellerite were better than that of natural stellerite, accompanied with increasing specific surface area. On the contrary, NaOH modification induced the loss of photocatalytic ability of composite due to the generation of silicates.

  17. Preparation and characterization of tungsten-loaded titanium dioxide photocatalyst for enhanced dye degradation.

    Science.gov (United States)

    Saepurahman; Abdullah, M A; Chong, F K

    2010-04-15

    Tungsten-loaded TiO(2) photocatalyst has been successfully prepared and characterized. TEM analysis showed that the photocatalysts were nanosize with the tungsten species forming layers of coverage on the surface of TiO(2), but not in clustered form. This was confirmed by XRD and FT-Raman analyses where tungsten species were well dispersed at lower loading (12 mol%). In addition, loading with tungsten could stabilize the anatase phase from transforming into inactive rutile phase and did not shift the optical absorption to the visible region as shown by DRUV-vis analysis. PZC value of TiO(2) was found at 6.4, but the presence of tungsten at 6.5 mol% WO(3), decreased the PZC value to 3. Tungsten-loaded TiO(2) was superior to unmodified TiO(2) with 2-fold increase in degradation rate of methylene blue, and equally effective for the degradation of different class of dyes such as methyl violet and methyl orange at 1 mol% WO(3) loading.

  18. Preparation and optical properties of iron-modified titanium dioxide obtained by sol-gel method

    Science.gov (United States)

    Hreniak, Agnieszka; Gryzło, Katarzyna; Boharewicz, Bartosz; Sikora, Andrzej; Chmielowiec, Jacek; Iwan, Agnieszka

    2015-08-01

    In this paper twelve TiO2:Fe powders prepared by sol-gel method were analyzed being into consideration the kind of iron compound applied. As a precursor titanium (IV) isopropoxide (TIPO) was used, while as source of iron Fe(NO3)3 or FeCl3 were tested. Fe doped TiO2 was obtained using two methods of synthesis, where different amount of iron was added (1, 5 or 10% w/w). The size of obtained TiO2:Fe particles depends on the iron compound applied and was found in the range 80-300 nm as it was confirmed by SEM technique. TiO2:Fe particles were additionally investigated by dynamic light scattering (DLS) method. Additionally, for the TiO2:Fe particles UV-vis absorption and the zeta potential were analyzed. Selected powders were additionally investigated by magnetic force microscopy (MFM) and X-ray diffraction techniques. Photocatalytic ability of Fe doped TiO2 powders was evaluated by means of cholesteryl hemisuccinate (CHOL) degradation experiment conducted under the 30 min irradiation of simulated solar light.

  19. Titanium dioxide nanotube films: Preparation, characterization and electrochemical biosensitivity towards alkaline phosphatase.

    Science.gov (United States)

    Roman, Ioan; Trusca, Roxana Doina; Soare, Maria-Laura; Fratila, Corneliu; Krasicka-Cydzik, Elzbieta; Stan, Miruna-Silvia; Dinischiotu, Anca

    2014-04-01

    Titania nanotubes (TNTs) were prepared by anodization on different substrates (titanium, Ti6Al4V and Ti6Al7Nb alloys) in ethylene glycol and glycerol. The influence of the applied potential and processing time on the nanotube diameter and length is analyzed. The as-formed nanotube layers are amorphous but they become crystalline when subjected to subsequent thermal treatment in air at 550°C; TNT layers grown on titanium and Ti6Al4V alloy substrates consist of anatase and rutile, while those grown on Ti6Al7Nb alloy consist only of anatase. The nanotube layers grown on Ti6Al7Nb alloy are less homogeneous, with supplementary islands of smaller diameter nanotubes, spread across the surface. Better adhesion and proliferation of osteoblasts was found for the nanotubes grown on all three substrates by comparison to an unprocessed titanium plate. The sensitivity towards bovine alkaline phosphatase was investigated mainly by electrochemical impedance spectroscopy in relation to the crystallinity, the diameter and the nature of the anodization electrolyte of the TNT/Ti samples. The measuring capacity of the annealed nanotubes of 50nm diameter grown in glycerol was demonstrated and the corresponding calibration curve was built for the concentration range of 0.005-0.1mg/mL.

  20. Characteristics of cerium-gadolinium oxide (CGO) suspensions as a function of dispersant and powder properties

    DEFF Research Database (Denmark)

    Phair, John; Lönnroth, Nadja; Lundberg, Mats;

    2009-01-01

    A series of concentrated suspensions ( = 0.18–0.34) of cerium-gadolinium oxide (CGO) in terpineol were prepared as a function of dispersant, powder surface area and solids concentration. The stability of the suspensions was assessed by rheological measurements including viscosity and oscillatory...

  1. Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

    OpenAIRE

    Yu Mei; Liu Yuxing; Liu Jianhua; Li Songmei; Xue Bing; Zhang You; Yin Xiaolin

    2015-01-01

    The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane (GTMS) and zirconium(IV) n-propoxide (TPOZ). Used as inhibitors for corrosion, three types of cerium salts (Ce(NO3)3, CeCl3, and Ce(CH3COO)3) were doped into the sol–gel coatings. Fourier transform infrared (FTIR) and scanning electron ...

  2. Carbon spheres-assisted strategy to prepare mesoporous manganese dioxide for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Li Siheng [State Key Laboratory of Electroanalytical Chemistry, and Jilin Provincial Key Laboratory of Advanced Low-carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin St., Changchun 130022 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Qi Li, E-mail: qil@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, and Jilin Provincial Key Laboratory of Advanced Low-carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin St., Changchun 130022 (China); Lu Lehui; Wang Hongyu [State Key Laboratory of Electroanalytical Chemistry, and Jilin Provincial Key Laboratory of Advanced Low-carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin St., Changchun 130022 (China)

    2013-01-15

    Mesoporous MnO{sub 2} microstructures with large specific surface area have been successfully synthesized by an in-situ redox precipitation method in the presence of colloidal carbon spheres. The samples of them had much higher specific surface area, pore size and pore volume than those obtained via routes without carbon spheres. The morphology, chemical compositions and porous nature of products were fully characterized. Electrochemical measurements showed that these mesoporous MnO{sub 2} could function well when used as positive electrode materials for supercapacitor. Ideal electrochemical capacitive performances and cyclic stability after 2000 galvanostatic charge-discharge cycles could be observed in 1 M neutral Na{sub 2}SO{sub 4} aqueous electrolyte with a working voltage of 1.7 V. - Graphical Abstract: Mesoporous MnO{sub 2} microstructures with large S{sub BET} were successfully synthesized by in-situ redox precipitation method in the presence of colloidal carbon spheres. Electrochemical measurements showed that these mesoporous MnO{sub 2} could be well used as electrode materials for supercapacitor. Highlights: Black-Right-Pointing-Pointer Mesoporous MnO{sub 2} was prepared by in-situ redox method assisted by carbon spheres. Black-Right-Pointing-Pointer S{sub BET}, pore size and volume were higher than MnO{sub 2} obtained without carbon spheres. Black-Right-Pointing-Pointer They could function well when used as electrode materials for supercapacitor. Black-Right-Pointing-Pointer Ideal capacitive behaviors and long cycling life showed after 2000 charge-discharge.

  3. Effects of precipitate aging time on the cerium-zirconium composite oxides

    Institute of Scientific and Technical Information of China (English)

    钟强; 崔梅生; 岳梅; 王琦; 王磊; 郭荣贵; 龙志奇; 黄小卫

    2014-01-01

    Cerium-zirconium composite oxides with high performance were synthesized by a co-precipitation method, using zirco-nium oxychloride and rare earth chloride as raw materials. The effects of precipitate aging time on the properties of cerium-zirconium composite oxides were investigated. The prepared cerium-zirconium composite oxides were characterized by X-ray diffraction (XRD), BET specific surface area, pulsed oxygen chemical adsorption, H2 temperature-programmed-reduction (H2-TPR), scanning electron microscopy (SEM), etc. The results showed that the precipitate aging time caused great effects on the properties of cerium zirconium composite oxides. With the increase of aging time, the cerium zirconium composite oxides showed enhanced specific sur-face area, good thermal stability, and high oxygen storage capacity (OSC). The best performance sample was obtained while the pre-cipitate aging time up to 48 h, with the specific surface area of 140.7 m2/g, and OSC of 657.24μmolO2/g for the fresh sample. Even after thermal aged under 1000 ºC for 4 h, the aged specific surface area was 41.6 m2/g, moreover with a good OSC of 569.9μmolO2/g.

  4. Oxochloroalkoxide of the Cerium (IV and Titanium (IV as oxides precursor

    Directory of Open Access Journals (Sweden)

    Machado Luiz Carlos

    2002-01-01

    Full Text Available The Cerium (IV and Titanium (IV oxides mixture (CeO2-3TiO2 was prepared by thermal treatment of the oxochloroisopropoxide of Cerium (IV and Titanium (IV. The chemical route utilizing the Cerium (III chloride alcoholic complex and Titanium (IV isopropoxide is presented. The compound Ce5Ti15Cl16O30 (iOPr4(OH-Et15 was characterized by elemental analysis, FTIR and TG/DTG. The X-ray diffraction patterns of the oxides resulting from the thermal decomposition of the precursor at 1000 degreesC for 36 h indicated the formation of cubic cerianite (a = 5.417Å and tetragonal rutile (a = 4.592Å and (c = 2.962 Å, with apparent crystallite sizes around 38 and 55nm, respectively.

  5. Cerium extraction by metallothermic reduction using cerium oxide powder injection

    Institute of Scientific and Technical Information of China (English)

    J.S. Luna A; A. Flores V; R. Mu(n)iz V; A.F. Fuentes; J. Torres; N. Rodríuez R; J.C. Ortiz; P.Orozco

    2011-01-01

    This work presented the feasibility of cerium recovery by Al-Mg alloy through the metallothermic reduction of CeO2 to obtain a master alloy Al-4%Ce. The master alloy obtained in this investigation was for the grain refinement and modification of Al-Si alloys. The reagent was incorporated into a molten alloy using the submerged powder injection technique, and metallic samples were obtained during injection. Chemical and microstructural analyses (by inductively coupled plasma (ICP) and scanning electron microscopy (SEM), respectively) confirmed the possibility of Ce uptake in the bath (0 to 4 wt.%), as CeO2 was reduced through metallothermic reactions in the molten alloys.Based on the characterization of reaction products, the sequence of the reaction was proposed.

  6. 铝基二氧化铅-碳化钨-氧化铈复合电极的电化学性能%Electrochemical performance of aluminum-based lead dioxide-tungsten carbide-cerium(Ⅳ) oxide composite electrode

    Institute of Scientific and Technical Information of China (English)

    王淑雪; 廖登辉

    2013-01-01

    A PbO2-WC-CeO2 composite electrode was prepared on aluminum substrate by composite electrodeposition. The process flow mainly includes degreasing, alkaline etching, pickling, zinc immersing for two times, flash nickel plating, lead plating, anodic oxidation, and composite electroplating. The corrosion resistance, energy-saving ability, and catalytic activity of the novel PbO2-WC-CeO2 composite electrode and traditional Pb-Ag(0.75) alloy electrode were compared by measuring and analyzing the Tafel curves, oxygen evolution curves, cell voltage, exchange current density, and accelerated corrosion test results in electrolytic zinc solution consisting of ZnSO4-7H2O 250-300 g/L, Na2SO4 250 g/L, and H3BO3 15-20 g/L. It is confirmed on a laboratory level that the corrosion resistance, energy saving performance, and catalytic activity of the novel Al-based PbO2-WC-CeO2 composite electrode are greatly improved as compared with the traditional Pb-Ag(0.75) alloy electrode.%采用复合电沉积法制备了铝基PbO2-WC-CeO2复合电极材料,其工艺流程主要包括除油、酸浸、碱浸、两次浸锌、闪镀镍、镀铅、阳极氧化和复合电镀.通过测定和分析电极在电解锌溶液(ZnSO4·7H2O 250~300 g/L,Na2SO4 250 g/L,H3BO3 15~20 g/L)中的Tafel曲线、析氧曲线、槽电压、交换电流密度和强效腐蚀试验等比较了新型PbO2-WC-CeO2复合电极与传统Pb-Ag(0.75)合金电极的耐腐蚀性能、节能性能和催化活性.从实验室水平证明了相对于传统Pb-Ag(0.75)合金电极,新型铝基PbO2-WC-CeO2电极在耐腐蚀性、节能和催化活性方面均有很大改善.

  7. Facile preparation of titanium dioxide nano-capsule arrays used as photo-anode for dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Su, Penglei; Li, Hongyi, E-mail: lhy06@bjut.edu.cn; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Wu, Junshu; Zhao, Bingxin; Wang, Fei

    2015-08-30

    Graphical abstract: - Highlights: • TiO{sub 2} nanoparticles have been introduced into TiO{sub 2} nanotube using a facile liquid phase deposition method at low temperature in atmosphere. • Dye solar cells have been assembled on flexible titanium substrate. • The incident photo-electron conversion efficiency has been improved 76% compared with pure TiO{sub 2} nanotube arrays. - Abstract: To improve titanium dioxide (TiO{sub 2}) nanotube arrays’ performance on dye sensitized solar cells (DSSCs), TiO{sub 2} nano-capsule arrays (TNCP) have been designed and prepared by planting TiO{sub 2} nanoparticles into TiO{sub 2} nanotube (TNT) using a facile liquid phase deposition (LPD) route which does not require any special equipment and both improve the specific surface area and surface energy of TNT at low temperature. It has been found that TiO{sub 2} nanoparticles are homogeneously distributed along the wall of TNT and their crystal size is calculated to be 5–10 nm. The obtained TNCP's specific surface area and surface energy have been increased from 27.1 (for pure TNT) to 33.4 m{sup 2}/g and from 67.7 (for pure TNT) to 76.4 mJ/m{sup 2}, respectively. When used as photo-anodes of DSSCs, TNCP shows higher energy conversion efficiency, which is 1.7 times that of pure TNT. Therefore, the present work provides one effective strategy to better TNT's performance on DSSCs, which can be assembled on metal substrate in large scale.

  8. Vehicle exhaust gas clearance by low temperature plasma-driven nano-titanium dioxide film prepared by radiofrequency magnetron sputtering.

    Directory of Open Access Journals (Sweden)

    Shuang Yu

    Full Text Available A novel plasma-driven catalysis (PDC reactor with special structure was proposed to remove vehicle exhaust gas. The PDC reactor which consisted of three quartz tubes and two copper electrodes was a coaxial dielectric barrier discharge (DBD reactor. The inner and outer electrodes firmly surrounded the outer surface of the corresponding dielectric barrier layer in a spiral way, respectively. Nano-titanium dioxide (TiO2 film prepared by radiofrequency (RF magnetron sputtering was coated on the outer wall of the middle quartz tube, separating the catalyst from the high voltage electrode. The spiral electrodes were designed to avoid overheating of microdischarges inside the PDC reactor. Continuous operation tests indicated that stable performance without deterioration of catalytic activity could last for more than 25 h. To verify the effectiveness of the PDC reactor, a non-thermal plasma(NTP reactor was employed, which has the same structure as the PDC reactor but without the catalyst. The real vehicle exhaust gas was introduced into the PDC reactor and NTP reactor, respectively. After the treatment, compared with the result from NTP, the concentration of HC in the vehicle exhaust gas treated by PDC reactor reduced far more obviously while that of NO decreased only a little. Moreover, this result was explained through optical emission spectrum. The O emission lines can be observed between 870 nm and 960 nm for wavelength in PDC reactor. Together with previous studies, it could be hypothesized that O derived from catalytically O3 destruction by catalyst might make a significant contribution to the much higher HC removal efficiency by PDC reactor. A series of complex chemical reactions caused by the multi-components mixture in real vehicle exhaust reduced NO removal efficiency. A controllable system with a real-time feedback module for the PDC reactor was proposed to further improve the ability of removing real vehicle exhaust gas.

  9. Vehicle exhaust gas clearance by low temperature plasma-driven nano-titanium dioxide film prepared by radiofrequency magnetron sputtering.

    Science.gov (United States)

    Yu, Shuang; Liang, Yongdong; Sun, Shujun; Zhang, Kai; Zhang, Jue; Fang, Jing

    2013-01-01

    A novel plasma-driven catalysis (PDC) reactor with special structure was proposed to remove vehicle exhaust gas. The PDC reactor which consisted of three quartz tubes and two copper electrodes was a coaxial dielectric barrier discharge (DBD) reactor. The inner and outer electrodes firmly surrounded the outer surface of the corresponding dielectric barrier layer in a spiral way, respectively. Nano-titanium dioxide (TiO2) film prepared by radiofrequency (RF) magnetron sputtering was coated on the outer wall of the middle quartz tube, separating the catalyst from the high voltage electrode. The spiral electrodes were designed to avoid overheating of microdischarges inside the PDC reactor. Continuous operation tests indicated that stable performance without deterioration of catalytic activity could last for more than 25 h. To verify the effectiveness of the PDC reactor, a non-thermal plasma(NTP) reactor was employed, which has the same structure as the PDC reactor but without the catalyst. The real vehicle exhaust gas was introduced into the PDC reactor and NTP reactor, respectively. After the treatment, compared with the result from NTP, the concentration of HC in the vehicle exhaust gas treated by PDC reactor reduced far more obviously while that of NO decreased only a little. Moreover, this result was explained through optical emission spectrum. The O emission lines can be observed between 870 nm and 960 nm for wavelength in PDC reactor. Together with previous studies, it could be hypothesized that O derived from catalytically O3 destruction by catalyst might make a significant contribution to the much higher HC removal efficiency by PDC reactor. A series of complex chemical reactions caused by the multi-components mixture in real vehicle exhaust reduced NO removal efficiency. A controllable system with a real-time feedback module for the PDC reactor was proposed to further improve the ability of removing real vehicle exhaust gas.

  10. Pharmacological potential of cerium oxidenanoparticles

    Science.gov (United States)

    Celardo, Ivana; Pedersen, Jens Z.; Traversa, Enrico; Ghibelli, Lina

    2011-04-01

    Nanotechnology promises a revolution in pharmacology to improve or create ex novo therapies. Cerium oxidenanoparticles (nanoceria), well-known as catalysts, possess an astonishing pharmacological potential due to their antioxidant properties, deriving from a fraction of Ce3+ ions present in CeO2. These defects, compensated by oxygen vacancies, are enriched at the surface and therefore in nanosized particles. Reactions involving redox cycles between the Ce3+ and Ce4+oxidation states allow nanoceria to react catalytically with superoxide and hydrogen peroxide, mimicking the behavior of two key antioxidant enzymes, superoxide dismutase and catalase, potentially abating all noxious intracellularreactive oxygen species (ROS) via a self-regenerating mechanism. Hence nanoceria, apparently well tolerated by the organism, might fight chronic inflammation and the pathologies associated with oxidative stress, which include cancer and neurodegeneration. Here we review the biological effects of nanoceria as they emerge from in vitro and in vivo studies, considering biocompatibility and the peculiar antioxidant mechanisms.

  11. Carbon Dioxide Absorbents

    Science.gov (United States)

    1950-05-17

    carbondioxide content of the solution was then determined. A gas mixture containing 2.6% carbon dioxide and 97.4% nitrogen was prepared in the...which carbon dioxide is removed by heat0 Since this step is usually carried out by "steam stripping ", that is, contacting the solution at its boiling...required to produce the steam required for stripping the carbon dioxide from the s olution. The method ueed in this investigation for determining the

  12. Preparation,modification and application of titanium dioxide nanotubes%二氧化钛纳米管的制备、改性及应用

    Institute of Scientific and Technical Information of China (English)

    王俏; 王威; 崔福义; 邵鹏辉; 何皎洁

    2015-01-01

    Titanium dioxide nanotubes have been intensively concerned and studied in recent years due to their special morphology and highly ordered property. This paper reviewed recent advances in titanium dioxide nanotubes. Three kinds of preparation methods were discussed,including template synthesis,electrochemical anodization and hydrothermal synthesis. On this basis,it described the modification methods of titanium dioxide nanotubes in detail,including doping and compositing. The applications of titanium dioxide nanotubes and composites in the field of environment and energy were introduced briefly. Finally,the future studies on the formation mechanism,morphology control and modification of titanium dioxide nanotubes were proposed.%二氧化钛纳米管因其特殊的形貌和高度有序的特性成为了目前研究的热点之一。本文系统回顾了近年来有关二氧化钛纳米管的相关研究,着重阐述了二氧化钛纳米管的制备方法,主要包括模板法、阳极氧化法、水热法;在此基础上,详细论述了掺杂、复合等对二氧化钛纳米管进行改性的方法;并简要介绍了二氧化钛纳米管及其复合材料在环境、能源等领域的应用。最后,展望了二氧化钛纳米管的主要研究方向是对形成机理、管形貌调控、表面改性等方面做进一步研究,以期为后续的研究提供参考。

  13. Room-temperature ferromagnetism in cerium dioxide powders

    Energy Technology Data Exchange (ETDEWEB)

    Rakhmatullin, R. M., E-mail: rrakhmat@kpfu.ru; Pavlov, V. V.; Semashko, V. V.; Korableva, S. L. [Kazan Federal University, Institute of Physics (Russian Federation)

    2015-08-15

    Room-temperature ferromagnetism is detected in a CeO{sub 2} powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO{sub 2} sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  14. High-permitivity cerium oxide prepared by molecular beam deposition as gate dielectric and passivation layer and applied to AlGaN/GaN power high electron mobility transistor devices

    Science.gov (United States)

    Chiu, Yu Sheng; Liao, Jen Ting; Lin, Yueh Chin; Chien Liu, Shin; Lin, Tai Ming; Iwai, Hiroshi; Kakushima, Kuniyuki; Chang, Edward Yi

    2016-05-01

    High-κ cerium oxide (CeO2) was applied to AlGaN/GaN high-electron-mobility transistors (HEMTs) as a gate insulator and a passivation layer by molecular beam deposition (MBD) for high-power applications. From capacitance-voltage (C-V) measurement results, the dielectric constant of the CeO2 film was 25.2. The C-V curves showed clear accumulation and depletion behaviors with a small hysteresis (20 mV). Moreover, the interface trap density (D it) was calculated to be 5.5 × 1011 eV-1 cm-2 at 150 °C. A CeO2 MOS-HEMT was fabricated and demonstrated a low subthreshold swing (SS) of 87 mV/decade, a high ON/OFF drain current ratio (I ON/I OFF) of 1.14 × 109, and a low gate leakage current density (J leakage) of 2.85 × 10-9 A cm-2 with an improved dynamic ON-resistance (R ON), which is about one order of magnitude lower than that of a conventional HEMT.

  15. Nanocrystalline cerium oxide materials for solid fuel cell systems

    Science.gov (United States)

    Brinkman, Kyle S

    2015-05-05

    Disclosed are solid fuel cells, including solid oxide fuel cells and PEM fuel cells that include nanocrystalline cerium oxide materials as a component of the fuel cells. A solid oxide fuel cell can include nanocrystalline cerium oxide as a cathode component and microcrystalline cerium oxide as an electrolyte component, which can prevent mechanical failure and interdiffusion common in other fuel cells. A solid oxide fuel cell can also include nanocrystalline cerium oxide in the anode. A PEM fuel cell can include cerium oxide as a catalyst support in the cathode and optionally also in the anode.

  16. On the chemistry of Ingenol. Pt. 5. Preparation of tritium-labeled 3-O-tetradecanoylingenol ([2O-[sup 3]H]-3-TI)

    Energy Technology Data Exchange (ETDEWEB)

    Roeser, H.; Sorg, B.; Hecker, E. (Inst. of Biochemistry, Deutsches Krebsforschungszentrum, Heidelberg (Germany))

    1992-07-01

    Tritium-labeling of the ingenol monoester 3-O-tetradecanoylingenol (3-TI), the prototype tumor promoter of the ingenane type diterpene esters, is described. The preparation starts with oxidation of 3-TI by manganese dioxide to yield 3-TI-20-aldehyde which is reduced by [[sup 3]H]-sodium borohydride in the presence of equimolar amounts of cerium trichloride hexahydrate to give [20-[sup 3]H]-3-TI. The labeled promoter is obtained in 42% overall yield with a specific radioactivity of 15.8 Ci/mmol. (orig.).

  17. Altering properties of cerium oxide thin films by Rh doping

    Energy Technology Data Exchange (ETDEWEB)

    Ševčíková, Klára, E-mail: klarak.sevcikova@seznam.cz [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); NIMS Beamline Station at SPring-8, National Institute for Materials Science, Sayo, Hyogo 679-5148 (Japan); Nehasil, Václav, E-mail: nehasil@mbox.troja.mff.cuni.cz [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Vorokhta, Mykhailo, E-mail: vorohtam@gmail.com [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Haviar, Stanislav, E-mail: stanislav.haviar@gmail.com [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Matolín, Vladimír, E-mail: matolin@mbox.troja.mff.cuni.cz [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); and others

    2015-07-15

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub x} thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO{sub x} thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub x} thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO{sub x} thin films leads to preparing materials with different properties.

  18. C4000型分析仪在二氧化氯制备装置中的应用%Application of C4000 analyzer in chlorine dioxide preparation apparatus for pulp bleaching

    Institute of Scientific and Technical Information of China (English)

    王国安; 王志法

    2013-01-01

    This paper introduces the working principle of C4000 chlorine dioxide analyzer and its installation, application, maintenance and precautions in chlorine dioxide preparation system.%  介绍了C4000型二氧化氯分析仪的工作原理及在二氧化氯制备装置中的安装、使用、维护、注意事项等。

  19. Growth and characterization of cerium lanthanum oxalate crystals grown in hydro-silica gel

    Energy Technology Data Exchange (ETDEWEB)

    John, M.V.; Ittyachen, M.A. [Mahatma Gandhi Univ., Kerala (India). School of Pure and Applied Physics

    2001-07-01

    Single crystals of mixed cerium lanthanum oxalate (CLO) are grown by gel method. Over the hydrosilica gel prepared by mixing oxalic acid and sodium meta silicate, a mixture of aqueous solutions of cerium nitrate and lanthanum nitrate are poured gently. Cerium and lanthanum ions diffuse into the gel and react with oxalic acid to give colorless, transparent cerium lanthanum oxalate crystals with in a few days. Different growth parameters give crystals of various dimensions. Infrared (IR) spectrum confirms the presence of water molecules and carboxylic acid. X-ray diffraction (XRD) pattern of these samples reveals the crystalline nature. Diffraction peaks are indexed. Unit cell parameters are determined. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) data support the presence of 9 H{sub 2}O molecules attached to the CLO crystal lattice which are lost around 200 C as revealed by the endotherm record. Exothermic peak around 350 C-425 C shows the release of CO and CO{sub 2}. Elemental analysis done by energy dispersive X-ray fluorescence analysis (EDXRF) for the mixed rare earth compound is almost in good agreement with experimental and theoretical values. (orig.)

  20. Aging dependent phase transformation of mesostructured titanium dioxide nanomaterials prepared by evaporation-induced self-assembly process: Implications for solar hydrogen production

    Directory of Open Access Journals (Sweden)

    Luther Mahoney

    2015-08-01

    Full Text Available Mesostructured titanium dioxide materials were prepared by Evaporation-Induced Self-Assembly (EISA method using titanium isopropoxide and a cationic surfactant. The titania phase could be tuned by simply varying the aging time. As the aging time increased, hierarchically structured mesoporous materials with mixed phases of titania were obtained. The rutile content was found to generally increase with length in aging time. The mesostructured materials were evaluated for hydrogen production, and a mixed phase consisting of 95% anatase and 5% rutile showed the highest activity. This study indicates that the aging time is an important parameter for the preparation of mesostructured materials with hierarchical porosities and mixed phase(s of titania.

  1. Combining organometallic reagents, the sulfur dioxide surrogate DABSO, and amines: a one-pot preparation of sulfonamides, amenable to array synthesis.

    Science.gov (United States)

    Deeming, Alex S; Russell, Claire J; Willis, Michael C

    2015-01-19

    We describe a method for the synthesis of sulfonamides through the combination of an organometallic reagent, a sulfur dioxide equivalent, and an aqueous solution of an amine under oxidative conditions (bleach). This simple reaction protocol avoids the need to employ sulfonyl chloride substrates, thus removing the limitation imposed by the commercial availability of these reagents. The resultant method allows access to new chemical space, and is also tolerant of the polar functional groups needed to impart favorable physiochemical properties required for medicinal chemistry and agrochemistry. The developed chemistry is employed in the synthesis of a targeted 70 compound array, prepared using automated methods. The array achieved a 93% success rate for compounds prepared. Calculated molecular weights, lipophilicities, and polar surface areas are presented, demonstrating the utility of the method for delivering sulfonamides with drug-like properties.

  2. Study of Degradation Kinetics of Parathion Methyl On Mixed Nanocrystalline Titania-Zirconium and Titania-Cerium Oxides

    Science.gov (United States)

    Kuráň, Pavel; Pšenička, Martin; Šťastný, Martin; Benkocká, Monika; Janoš, Pavel

    2016-10-01

    The unique surface properties of some nanocrystalline metal oxides and their application for removal of various toxic compounds were reported in early 1990s. Recently, a reliable method for the preparation of reactive cerium dioxide sorbent and its application for degradation of the organophosphate pesticides, such as parathion methyl, chlorpyrifos, dichlofenthion, fenchlorphos, and prothiofos, as well as of some chemical warfare agents-nerve gases soman and O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX) was published. This paper reports on the kinetics study of degradation of parathion methyl as a representative organophosphate on nanocrystalline metal oxides TiO2, ZrO2, CeO2 and their mixtures in different molar ratios of particular elements. The tested sorbents except of CeO2 were prepared by different methods (e.g. sol-gel, precipitation) in cooperation with Institute of Inorganic Chemistry (Rez, Czech Republic). The degradation kinetics of parathion methyl on tested sorbents was followed by HPLC equipped with diode array detector. The basic kinetics parameters (half-lives of parathion methyl degradation, rate constants of degradation product formation) were calculated for each sorbent from Weber-Morris equation of 1st order diffusion kinetic model. The results proved the ability of prepared sorbents to degrade parathion methyl under formation of 4-nitrophenol as the main degradation product. The most efficient sorbents were TiCe (2:8), TiCe (1:1), TiCe (0:1) (50-70 %) followed by TiZr (1:1), TiCe (8:2), TiZr (8:2), TiZr (2:8) (20-30%) and TiO2, ZrO2 (less than 5 %).

  3. Influence of hydroxyl content of binders on rheological properties of cerium-gadolinium oxide (CGO) screen printing inks

    DEFF Research Database (Denmark)

    Marani, Debora; Gadea, Christophe; Hjelm, Johan;

    2015-01-01

    vinyl resins) were selected and characterized in solution via viscosimetry method. A high degree of hyper-entanglement was observed for ethyl cellulose polymers, whereas a mitigated effect characterized the two vinyl resins. Cerium-gadolinium oxides (CGO)-based inks, prepared using the selected binders...

  4. Effect of cerium addition on microstructure and texture of aluminum foil for electrolytic capacitors

    Institute of Scientific and Technical Information of China (English)

    王海燕; 李文学; 任慧平; 黄丽颖; 王向阳

    2010-01-01

    Anode foil of aluminum electrolytic capacitor,which requires large surface area for high capacitance,were prepared by rolling,annealing and electrochemical etching.Effects of cerium addition on the capacitance of aluminum electrolytic capacitors were investigated.Microstructure of the aluminum foil surface was observed by optical microscopy(OM) and scanning electron microscopy(SEM).Electron back scattered diffraction(EBSD) was also employed to reveal texture evolvement of cold-rolled aluminum foil after ann...

  5. CHEMICAL BEHAVIOR OF CERIUM ELEMENT IN ROCK WEATHERING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A study on existing valence state and chemical behavior of cerium element in two categories of rock weathering system in China has been carried out. In the granitoid weathering crust of Southern China,cerium as tetravalent hydroxide absorbed on clay minerals occupies 62.58 % of total amount of cerium and the cerium partitioning in the phase is 69.58 %. The depositing cerium stops its mobility downward, resulting in rare earth partitioning variation, the light rare earth partitioning is high at upper layer of weathering crust, the heavy rare earth partitioning is high at bottom layer of weathering crust, and the extracted product exists cerium lose effect. For Mn2+ as reducing agent existing in black weathering earth of Maoniuping rare earth ore,cerium is trivalent and absorbed on Mn-Fe oxide as colloid phase sediment. Colloid sediment phase can be divided into Mn-Fe combined phase and hydroxide sediment phase with cerium contents of 19.77% and 48.30%, and their cerium partitionings are 80.72% and 37.38% respectively. The Mn-Fe combined phase can selectively absorb cerium.

  6. Effect of ultrasound on the structural and textural properties of copper-impregnated cerium-modified zirconium-pillared bentonite

    Science.gov (United States)

    Tomul, Fatma

    2011-12-01

    In this study, the synthesis of zirconium-pillared bentonite modified with cerium was performed via two different methods by the application of conventional and ultrasonic treatments during the intercalation stage. To synthesise copper-impregnated pillared clays by wet impregnation, cerium-modified zirconium-pillared clays were used as supportive materials after being calcined at 300 °C. Ultrasonic treatment significantly decreased the required processing time compared with the conventional treatment of the synthesised pillared bentonites. Chemical analysis confirmed the incorporation of Zr 4+, Ce 4+ and Cu 2+ species into the pillared bentonites. X-ray diffraction (XRD) patterns of zirconium- and cerium/zirconium-pillared bentonites prepared by conventional treatment show that one large d-spacing above 3.5 nm corresponds to the mesoporous delaminated part, and another small d-spacing above 1.7 nm is indicative of the microporous pillared part. Zirconium- and cerium/zirconium-pillared bentonites prepared via ultrasonic treatment exhibited similar results, with the same high d-spacing but with a second low-intensity d-spacing above 1.9 nm. The delaminated structures of the pillared bentonites synthesised by both methods were conserved after copper impregnation. Nitrogen-adsorption isotherm analysis showed that the textural characteristics of products synthesised by ultrasonic treatment were comparable to those of products synthesised by conventional treatment. Fourier-transform infrared spectroscopy (FTIR) analyses showed the presence of Brønsted- and Lewis-acid sites, and zirconium-pillared clays synthesised by conventional treatment exhibited increased numbers of Brønsted- and Lewis-acid sites after cerium addition and copper impregnation. However, the products synthesised by ultrasonic treatment exhibited an increased number of Brønsted- and Lewis-acid sites after cerium addition, but a decreased number of acid sites after copper impregnation.

  7. Uptake and accumulation of bulk and nanosized cerium oxide particles and ionic cerium by radish (Raphanus sativus L.).

    Science.gov (United States)

    Zhang, Weilan; Ebbs, Stephen D; Musante, Craig; White, Jason C; Gao, Cunmei; Ma, Xingmao

    2015-01-21

    The potential toxicity and accumulation of engineered nanomaterials (ENMs) in agricultural crops has become an area of great concern and intense investigation. Interestingly, although below-ground vegetables are most likely to accumulate the highest concentrations of ENMs, little work has been done investigating the potential uptake and accumulation of ENMs for this plant group. The overall objective of this study was to evaluate how different forms of cerium (bulk cerium oxide, cerium oxide nanoparticles, and the cerium ion) affected the growth of radish (Raphanus sativus L.) and accumulation of cerium in radish tissues. Ionic cerium (Ce(3+)) had a negative effect on radish growth at 10 mg CeCl3/L, whereas bulk cerium oxide (CeO2) enhanced plant biomass at the same concentration. Treatment with 10 mg/L cerium oxide nanoparticles (CeO2 NPs) had no significant effect on radish growth. Exposure to all forms of cerium resulted in the accumulation of this element in radish tissues, including the edible storage root. However, the accumulation patterns and their effect on plant growth and physiological processes varied with the characteristics of cerium. This study provides a critical frame of reference on the effects of CeO2 NPs versus their bulk and ionic counterparts on radish growth.

  8. Synthesis and characterization on titanium dioxide prepared by precipitation and hydrothermal treatment; Sintese e caracterizacao de dioxido de titanio preparado por precipitacao e tratamento hidrotermico

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Andre V.P. dos; Yoshito, Walter K.; Lazar, Dolores R.R.; Ussui, Valter, E-mail: vussui@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-07-01

    Surface properties of titanium dioxide (titania) are outstanding among ceramic materials and enables uses as catalysts, photoelectrochemical devices, solar cells and others. In many of these applications, it is necessary to keep the anatase phase, that is stable only in low temperatures (<400 deg C). In the present work, the influence of hydrothermal treatment on physical characteristics and crystal structure of titania powders synthesized by precipitation was investigated. Characterizations of obtained powders were carried out by X-ray diffraction, surface area analysis by N2 gas sorption (BET) and microstructure of powders and ceramics were analyzed by scanning electron microscopy. As prepared powders were formed as cylindrical pellets by uniaxial pressing and sintered at 1500 deg C for 01 hour. Results showed that anatase phase without formation of rutile phase can be formed in hydrothermally treated samples . Rutile phase is predominant in calcined and/or sintered samples (author)

  9. Synthesis of Cerium-Doped Titania Nanoparticles and Nanotubes.

    Science.gov (United States)

    Cao, Wei; Suzuki, Takuya; Elsayed-Ali, Hani E; Abdel-Fattah, Tarek M

    2015-03-01

    Cerium-doped titania nanoparticles and nanotubes were synthesized via hydrothermal processes. X-Ray Diffraction revealed that cerium-doped titania nanoparticles have an anatase crystal structure, while cerium-doped titania nanotubes have an H2Ti3O7-type structure. Scanning electron microscopy and high resolution transmission electron microscopy showed that both types of titania are well crystallized with relatively uniform size distribution. The photocatalytic degradation of methylthioninium chloride known as methylene blue dye was tested and both cerium-doped titania nanoparticles and nanotubes. The preliminary photocatalytic degradation of Methylene Blue data showed significantly improved visible light photocatalytic activities as compared to commercial titania powders.

  10. Synthesis, characterization and antimicrobial activity of zinc and cerium co-doped α-zirconium phosphate

    Institute of Scientific and Technical Information of China (English)

    DAI Guangjian; YU Aili; CAI Xiang; SHI Qingshan; OUYANG Yousheng; TAN Shaozao

    2012-01-01

    A series of zinc ions or/and cerium ions co-doped a-zirconium phosphate (Zn-Ce@ZrPs) were prepared.The novel Zn-Ce@ZrPs were characterized and the antibacterial activity on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were tested.The results showed that zinc ions (Zn2+) or/and cerium ions (Ce3+) were combined with ZrP,and the Ce3+ was adsorbed on the surface of ZrP through hydrogen bonds,while Zn2+ intercalated into the interlayer of ZrP.Zn-Ce@ZrPs showed excellent synergistic antibacterial activity.When Zn2+/Ce3+ atomic ratio was 0.6,the Zn-Ce@ZrP3 showed the highest synergistic antibacterial efficiency,suggesting great potential application as antibacterial agents in microbial control.

  11. Synthesis of mesoporous cerium-zirconium mixed oxides by hydrothermal templating method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mesoporous cerium-zirconium mixed oxides were prepared by hydrothermal method using cetyl trimethyl ammonium bromide (CTAB) as template.The effects of amount of template,pH value of solution and hydrothermal temperature on mesostructure of samples were systematically investigated.The final products were characterized by XRD,TEM,FT-IR,and BET.The results indicate that all the cerium-zirconium mixed oxides present a meso-structure.At molar ratio of n(CTAB)/n((Ce)+(Zr))=0.15,pH value of 9,and hydrothermal temperature of 120 ℃,the samples obtained possess a specific surface area of 207.9 m2/g with pore diameter of 3.70 nm and pore volume of 0.19 cm3/g.

  12. Structure and synergetic antibacterial effect of zinc and cerium carried sodium zirconium phosphates

    Institute of Scientific and Technical Information of China (English)

    YANG Yunhua; DAI Guangjian; TAN Shaozao; LIU Yingliang; SHI Qingshan; OUYANG Yousheng

    2011-01-01

    Zinc and cerium carried zirconium phosphates (Zn-Ce/ZrPs) were prepared by exchanging zinc and cerium cations into sodium zirconium phosphate (NaZrP) through the ion-exchange method and characterized by X-ray diffraction(XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). Furthermore, the specific surface area, zeta potential and antibacterial activity were tested. The results showed that Zn-Ce/ZrPs were with hexagonal crystal system, and the surface area of Zn-Ce/ZrPs increased much more than that of NaZrP. Zn-Ce/ZrPs showed obvious synergetic antibacterial effect, and have the potential to be used as antibacterial agents in environmental control.

  13. Post treatment of silane and cerium salt as chromate replacers on galvanized steel

    Institute of Scientific and Technical Information of China (English)

    KONG Gang; LU Jintang; WU Haijiang

    2009-01-01

    A complex film on hot-dip galvanized steel sheet (HDG) was prepared by immersing the sheet in 0.1wt.% Ce(NO3)3 solution and 5vol.% silane solution in turn. The corrosion protection of the complex film was evaluated by potentiodynamic linear polarization(LPR), electrochemical impendence spectra (EIS) and natural salt spray (NSS) tests and compared with that of single cerium film and silane film. The results showed that, the presence of these films on the zinc coating hindered corrosion reaction by reducing the rate of both anodic and cathodic reaction in the corrosion process, and the corrosion protection of the complex film was much better than that of single cerium film or silane film and closed to that of chromate film, because the polarization resistance Rp and electrochemical impendence were increased markedly. Microstructure and chemical composition of these pretreated films were also investigated by scanning electron microscopy (SEM) and AES.

  14. Cerium and jojoba in engines?; Cerium et jojoba dans les moteurs?

    Energy Technology Data Exchange (ETDEWEB)

    Massy-Delhotel, E.

    1996-10-01

    The Belgium company CreaTel proposes a new system, called Forac, which can lead to a 10% reduction of fuel consumption in thermal engines together with a quasi-complete reduction of CO, HC, NOx pollutants and CO{sub 2} particulates emission. The system comprises a steam production device and an admission pipe with a cerium alloy whorl inside. The steam produced is mixed with the admission air and tears cerium particles from the inside of the admission pipe to the combustion chamber. The cerium particles act as a catalyst which favours the complete combustion of the fuel. The same company proposes also lubricant additives made from liquid jojoba wax which allow the reduction of pollutant emissions, fuel consumption and noise emissions of diesel engines. (J.S.)

  15. Thermodynamics of congruently subliming cerium-antimony

    Energy Technology Data Exchange (ETDEWEB)

    Schiffman, R.A.; Franzen, H.F.

    1982-01-01

    Congruently vaporizing cerium-antimony has been investigated by vapor pressure measurementa using a simultaneous weight-loss mass-spectrometric Knudsen effusion technique. The melting point of the 1:1 stoichiometry was determined to be 2179 +/- 10 K. The heat of formation at 298 K of CeSb was found to be -128.9 kJ/g-at from thermodynamic measurements in the temperature range 1985-2172 K.

  16. Study of the cerium(IV)-picrate system in acetonitrile.

    Science.gov (United States)

    Kratochvil, B; Tipler, M; McKay, B

    1966-07-01

    A potentiometric and spectrophotometric study has been made of the reaction between hexanitratocerate and picrate in dry acetonitrile. Several cerium(IV)-picrate complexes are formed; the formation constant for the first is estimated to be 4 from spectrophotometric measurements. The catalytic effect of picrate on hydroquinone oxidation by nitratocerate is postulated to be due to more rapid electron transfer by cerium picrate complexes.

  17. Formation and characterization of cerium conversion coatings on magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    LI Lingjie; LEI Jinglei; YU Shenghai; TIAN Yujing; JIANG Qiquan; PAN Fusheng

    2008-01-01

    Chemical conversion treatment by rare earth metal salt solution was considered as an alternative to chromium chemical conversion treatment to improve the corrosion resistance of magnesium alloys. In this study, cerium conversion coatings formed on AZ31 magnesium alloy were characterized and the formation mechanism was discussed. X-ray photoelectron spectroscopy (XPS) analysis showed that cerium conversion coating consisted of cerium hydroxides/oxides, in which both tetravalent cerium Ce(IV) and trivalent cerium Ce(III) species co-existed. Cerium conversion coating was a two-layer structure. Atomic force microscopy (AFM) images revealed that the morphology of the inside layer was different from that of the outside one, which was responsible for the inherent adhesive weakness of the coating. Corrosion potential (Ecorr) measurements indicated that poor adhesion limited the improvement of the corrosion resistance of the coating. During the treating process, the increased pH value of the cerium salt solution led to the precipitation of cerium hydroxides/oxides. The formation kinetics of the coating followed a parabolic curve.

  18. The Genotoxicity of Titanium Dioxide and Cerium Dioxide Nanoparticles in Human Respiratory Epithelial Cells

    Science.gov (United States)

    Due to the exponential growth of the nanomaterial industry, risk assessment of human exposure to nanomaterials in consumer products is of paramount importance. The genotoxicity of nanomaterials is an important aspect of hazard identification and regulatory guidance. However, this...

  19. Genotoxic Effects of Titanium Dioxide and Cerium Dioxide Nanoparticles in Human Respiratory Epithelial Cells

    Science.gov (United States)

    The nanomaterial industry has recently seen rapid growth, therefore, the risk assessment of human exposure to nanomaterials in consumer products is of paramount importance. The genotoxicity of nanomaterials is a fundamental aspect of hazard identification and regulatory guidance....

  20. Synthesis and Characterization of Cerium Doped Titanium Catalyst for the Degradation of Nitrobenzene Using Visible Light

    Directory of Open Access Journals (Sweden)

    Padmini Ellappan

    2014-01-01

    Full Text Available Cerium doped catalyst was synthesized using Titanium isopropoxide as the Titanium source. The metal doped nanoparticles semiconductor catalyst was prepared by sol-sol method with the sol of Cerium. The synthesized catalyst samples were characterized by powder X-ray diffraction, BET surface area, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and UV-vis diffuse reflectance measurements (DRS and compared with undoped TiO2 catalyst. The photocatalytic activity of the sample was investigated for the decomposition of nitrobenzene (NB using visible light as the artificial light source. Cerium doped catalyst was found to have better degradation of nitrobenzene owing to its shift in the band gap from UV to visible region as compared to undoped TiO2 catalyst. The operational parameters were optimized with catalyst dosage of 0.1 g L−1, pH of 9, and light intensity of 500 W. The degradation mechanism followed the Langmuir Hinshelwood kinetic model with the rate constant depending nonlinearly on the operational parameters as given by the relationship Kapp (theoretical = 2.29 * 10−4 * Intensity0.584 * Concentration−0.230 * Dosage0.425 * pH0.336.

  1. Cerium(III-Selective Membrane Electrode Based on Dibenzo-24-crown-8 as a Neutral Carrier

    Directory of Open Access Journals (Sweden)

    Susheel K. Mittal

    2010-01-01

    Full Text Available Cerium(III-selective membrane electrodes have been prepared using dibenzo-24-crown-8 (DB24C8 as an electroactive material. A membrane having a composition: DB24C8 (4.5%, plasticizer (NPOE, 62.5% and PVC (33% gives the best performance. It works well over a wide Ce(III ion-concentration range of 1x10-5 M to 1x10-1 M with a Nernstian slope of 19.0 mV/decade and a detection limit of 3x10-5 M. It has a fast response time of 20 seconds and has an average lifetime of four months. The internal solution concentration does not have a significant effect on the response of the electrode except for a change in intercept of the calibration curves. The working pH range for Ce(III solutions (1x10-2 M and 1x10-3 M is 3.5-8.0. The proposed sensor shows a good selectivity for cerium(III with respect to alkali, alkaline earth, some transition and rare earth metal ions that are normally present along with cerium in its ores. The proposed sensor was investigated in partially non-aqueous media using acetone, methanol and DMSO mixtures with water. The electrode was further used as an indicator electrode for the potentiometric titration of Ce(III solution against oxalic acid solution.

  2. Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

    Directory of Open Access Journals (Sweden)

    Yu Mei

    2015-04-01

    Full Text Available The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane (GTMS and zirconium(IV n-propoxide (TPOZ. Used as inhibitors for corrosion, three types of cerium salts (Ce(NO33, CeCl3, and Ce(CH3COO3 were doped into the sol–gel coatings. Fourier transform infrared (FTIR and scanning electron microscopy (SEM were employed to investigate the structures and morphologies of various coatings, and the corrosion resistances of the coatings were evaluated by electrochemical methods and neutral salt spray tests. Experimental results indicate that the addition of cerium salts can hinder the process of corrosion due to their self-healing abilities. Furthermore, the sol–gel coating doped with Ce(CH3COO3 has the best corrosion resistance because of the promotions of hydrolysis and condensation provided by CH3COO−.

  3. Effect of cerium oxide addition on electrical properties of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, D.M. [National Research Center, Dokki, Giza (Egypt). Dept. of Ceramics; Mounir, M. [Dept. of Physics, Cairo Univ., Giza (Egypt); Mahgoub, A.S. [Cairo Univ., Giza (Egypt). Dept. of Chemistry; Turky, G. [Dept. of Physics, National Research Center, Dokki, Giza (Egypt); El-Desouky, O.A. [Cer. Cleopatra Co., Ramadan City (Egypt)

    2002-07-01

    Mixtures of ZnO and Ce{sub 6} O{sub 11} as additive were prepared by solid state reaction from the calcined oxides with the following proportions: 0.03, 0.08, 0.1, 0.2 and 0.4 mole. Disc specimens 1.2 cm 5 cm in diameter and 0.3 cm thickness were processed under a force of 70 kN and fired at 1150 C/ 30 minutes. XRD revealed the presence of limited solid solution of cerium in ZnO, as evident from the shift in the peaks [0.03-0.04 A ] up to 0.1 mole addition and remains constant. SEM revealed the presence of inter-granular phase. EDAX showed it to be a mixture of ZnO and Ce{sub 6}O{sub 11}. Also cerium was detected in the ZnO grains confirming the XRD results. RCL circuit was used to measure the capacitance and resistance at different frequencies at room temperature. The dielectric constant and conductivity were calculated. The change in resistivity with temperature was followed up to 523 K. The change in dielectric strength with temperature at spot frequency of 10 kHz is demonstrated. The electrical conductivity was found to increase with the proportion of cerium oxide up to 0.2 mole then decreased. (orig.)

  4. Study on the preparation and performance of iron-cerium mixed oxide catalyst%铁铈复合氧化物催化剂的制备及其性能研究∗

    Institute of Scientific and Technical Information of China (English)

    柳召刚; 张蕊; 李梅; 胡艳宏; 王觅堂; 张晓伟

    2016-01-01

    采用改进共沉淀法制备铁铈复合氧化物催化剂,通过 L16(45)正交实验确定最佳工艺条件.研究了不同煅烧温度对催化剂脱硝效率的影响,同时通过XRD、SEM、粒度和比表面积等方法对催化剂进行表征.结果表明,反应终点pH 值是碳酸氢铵-氨水沉淀法制备铁铈催化剂最重要的影响因素,反应温度次之.脱硝实验表明,经400℃焙烧5 h所制备的催化剂,其粒径较小,分布较宽,比表面积较大,SCR 脱硝活性最高,在250℃脱硝活性为93.8%.%The preparation process of catalyst composited with Fe-Ce oxides was studied by improved co-precipi-tation.The optimum conditions were determined by L16 (45 )orthogonal test.The effects of different calcination temperature on SCR of Fe-Ce catalyst were studied,and also the materials were characterized by XRD,SEM, particle size and specific surface area.The results show that the final pH of the reaction is the most important factor for Fe-Ce catalyst precipited from bicarbonate-ammonia system.Reaction temperature is the secondary factor.The denitration experiments showed that catalyst prepared by roasting at 400 ℃ for 5 h with smaller particle size,wider distribution,larger specific surface area and the highest SCR denitration activity.The activi-ty was 9 3 .8% at 2 5 0 ℃.

  5. 21 CFR 73.575 - Titanium dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.575 Section 73.575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared TiO2, free from admixture with other substances. (2)...

  6. Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol−Gel Method

    Directory of Open Access Journals (Sweden)

    Tsuneo Fujii

    2013-04-01

    Full Text Available Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE. The activity of the photocatalyst samples duringthe UV irradiation strongly depended on their crystallinities rather than their specificsurface areas, i.e., adsorption ability. The degradation rate during the visible irradiationdepended on both the adsorption ability and visible absorption of the photocatalystsamples. The visible absorption induced by the sulfate-doping was effective for theTCE degradation.

  7. Preparation and characterization of functional fabrics from bamboo charcoal/silver and titanium dioxide/silver composite powders and evaluation of their antibacterial efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fu-Chu, E-mail: yfc580629@yahoo.com.tw [Army Command Headquarters, MND, Taoyuan, Taiwan (China); Wu, Kuo-Hui [Department of Applied Chemistry and Materials Science, Chung Cheng Institute of Technology, NDU, No. 190, Sanyuan 1st Street, Tahsi, Taoyuan 335, Taiwan (China); Huang, Jen-Wei [Department of Physics, Chinese Military Academy, Fengshan, Kaohsiung, Taiwan (China); Horng, Deng-Nan; Liang, Chia-Feng [Department of Chemistry, Chinese Military Academy, Fengshan, Kaohsiung, Taiwan (China); Hu, Ming-Kuan [School of Pharmacy, National Defense Medical Center, Taipei, Taiwan (China)

    2012-07-01

    Bamboo charcoal supporting silver (BC/Ag) and titanium dioxide supporting silver (TiO{sub 2}/Ag) were prepared by activation and chemical reduction. The BC/Ag and TiO{sub 2}/Ag composites were characterized by silver particle size and distribution and antibacterial properties. The pore and surface properties were studied in terms of BET volumetric measurement with nitrogen adsorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The antibacterial effects of the BC/Ag and TiO{sub 2}/Ag composite powders were assessed from the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs), and an excellent antibacterial performance was discovered. Moreover, these composite powders were deposited via immersion coating onto fabrics (nonwoven and carbon fibers) to improve the antibacterial efficacy and to act as a biologically-protective material. The antibacterial activities of the fabrics supported by BC/Ag and TiO{sub 2}/Ag were studied in zone of inhibition and plate counting tests against Gram-positive Staphylococcus aureus ME/GM/TC Resistant, Bacillus subtilis, Candida albicans, Gram-negative Pseudomonas aeruginosae (CTZ and EM and GM) Res. Clin. Isol., Escherichia coli Juhl, and Klebsiella pneumoniae. The results showed that fabric-BC/Ag and fabric-TiO{sub 2}/Ag possess a strong antibacterial activity and an inhibitory effect on the growth of these bacteria and are therefore believed to have great potential for use as antibacterial fabrics.

  8. Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Fang Guiyin, E-mail: gyfang@nju.edu.cn [Department of Physics, Nanjing University, Hankou Road 22, Nanjing, Jiangsu 210093 (China); Li Hui [Department of Material Science and Engineering, Nanjing University, Nanjing 210093 (China); Liu Xu [Department of Physics, Nanjing University, Hankou Road 22, Nanjing, Jiangsu 210093 (China)

    2010-08-01

    Form-stable lauric acid (LA)/silicon dioxide (SiO{sub 2}) composite phase change materials were prepared using sol-gel methods. The LA was used as the phase change material for thermal energy storage, with the SiO{sub 2} acting as the supporting material. The structural analysis of these form-stable LA/SiO{sub 2} composite phase change materials was carried out using Fourier transformation infrared spectroscope (FT-IR). The microstructure of the form-stable composite phase change materials was observed by a scanning electronic microscope (SEM). The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the LA was well dispersed in the porous network of SiO{sub 2}. The DSC results indicated that the melting latent heat of the form-stable composite phase change material is 117.21 kJ kg{sup -1} when the mass percentage of the LA in the SiO{sub 2} is 64.8%. The results of the TGA showed that these materials have good thermal stability. The form-stable composite phase change materials can be used for thermal energy storage in waste heat recovery and solar heating systems.

  9. Preparation of Titanium Dioxide and The Study on Its Properties%二氧化钛光催化剂的制备及其性能研究

    Institute of Scientific and Technical Information of China (English)

    郑炜

    2012-01-01

    本文采用溶胶-凝胶法(sol-gel)制备了纯相和掺杂不同量Fe3+、Zn2+、Cu2+和S2-的TiO2粉体,并讨论了不同热处理温度、掺杂元素及掺杂量对TiO2粉体光催化性能的影响。以甲基橙溶液为目标降解物,用紫外可见分光光度计对TiO2粉体的光催化性能进行测定。实验结果表明,煅烧温度为450℃、掺入0.25%的Zn2+的TiO2粉体的催化效果最好。%In this paper, the pure and Fe^3+-doped, Zn^2+-doped, Cu^2+-doped and S^2+-doped TiO2 powders were prepared by thesol-gel method. The influences of the different temperature, doping elements and doping amounts on photocatalytic activities of the prepared catalysts were discussed. The photocatalytic properties of titanium dioxide powders to methyl orange is determined by UV-visible spectrophotometer. The results of the experiment showed that the Zn^2+-doped powders had the highest photocatalytic activity when the doping amount was 0.25% and the sintering temperature is 450℃.

  10. Cerium-tannic acid passivation treatment on galvamzed steel

    Institute of Scientific and Technical Information of China (English)

    LIU Guangming; YU Fei; YANG Liu; TIAN Jihong; DU Nan

    2009-01-01

    A novel cerium-tannic acid passivation treatment was performed on galvanized steel. The corrosion resistance of cerium-tannic passivated samples was tested by dropping test with 0.5 wt.% CuSO4 aqueous solution. The mass loss per unit area of passivated samples was measured after the corrosion in 0.5 mol/L NaCl + 0.005 mol/L H2SO4 at room temperature for 96 h. The electrochemical behaviors of cerium, tannic acid, and cerium-tannic acid passivated samples on galvanized steel in 0.5 mol/L NaCI solution were investigated by polarization curves and electrochemical impendence spectra. The corrosion equivalent circuit was established according to the impedance characteristics. The results show that cerium-tannic acid treated samples exhibit better corrosion resistance than the sole cerium or tannic acid treated samples under the same condition. The mechanism of synergistic effect for cerium-tannic acid passivation on galvanized steel was discussed.

  11. Effects of Niobium-Loading on Sulfur Dioxide Gas-Sensing Characteristics of Hydrothermally Prepared Tungsten Oxide Thick Film

    Directory of Open Access Journals (Sweden)

    Viruntachar Kruefu

    2015-01-01

    Full Text Available Nb-loaded hexagonal WO3 nanorods with 0–1.0 wt% loading levels were successfully synthesized by a simple hydrothermal and impregnation process and characterized for SO2 sensing. Nb-loaded WO3 sensing films were produced by spin coating on alumina substrate with interdigitated gold electrodes and annealed at 450°C for 3 h in air. Structural characterization by X-ray diffraction, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis showed that spherical, oval, and rod-like Nb nanoparticles with 5–15 nm mean diameter were uniformly dispersed on hexagonal WO3 nanorods with 50–250 nm diameter and 100 nm–5 µm length. It was found that the optimal Nb loading level of 0.5 wt% provides substantial enhancement of SO2 response but the response became deteriorated at lower and higher loading levels. The 0.50 wt% Nb-loaded WO3 nanorod sensing film exhibits the best SO2 sensing performances with a high sensor response of ~10 and a short response time of ~6 seconds to 500 ppm of SO2 at a relatively low optimal operating temperature of 250°C. Therefore, Nb loading is an effective mean to improve the SO2 gas-sensing performances of hydrothermally prepared WO3 nanorods.

  12. Preparation of a manganese dioxide/carbon fiber electrode for electrosorptive removal of copper ions from water.

    Science.gov (United States)

    Hu, Chengzhi; Liu, Fangyuan; Lan, Huachun; Liu, Huijuan; Qu, Jiuhui

    2015-05-15

    MnO2 is an effective adsorbent for many metal ions and a promising electrode material for electrochemical supercapacitors. In this paper, we successfully combined the two functions through preparing a MnO2/carbon fiber (CF) composite as an electrosorptive electrode. The thin MnO2 film was deposited onto CF by an anodic eletrodeposition method. The MnO2/CF electrodes had ideal pseudocapacitive behavior and high capacitive reversibility. The specific capacitance of the MnO2/CF electrode reached a maximum value of 387 F/g, which is quite competitive compared with literature values. At 0.8 V applied potential, the maximum Cu(2+) adsorption capacity of the MnO2/CF electrode was 172.88 mg/g, which is more than 2 times higher than common MnO2 adsorbents without an electric field imposed. SEM images showed that MnO2 nanoflowers with several "petals" were uniformly distributed on the CF surface. Enhancement of adsorption by the polarization potential and the unique microstructure of the deposited MnO2 may be the source of the outstanding adsorption ability of the MnO2/CF electrode. The MnO2/CF electrode could be regenerated quickly by reversing the voltage. The deposition time of 1000 s was optimum for achieving maximum capacitance and Cu(2+) removal performance. The MnO2/CF composite electrosorptive electrode is a promising candidate for Cu(2+) removal from aqueous solution.

  13. Atomic Transition Probabilities for Neutral Cerium

    Science.gov (United States)

    Chisholm, John; Nitz, D.; Sobeck, J.; Den Hartog, E. A.; Wood, M. P.; Lawler, J. E.

    2010-01-01

    Among the rare earth species, the spectra of neutral cerium (Ce I) and singly ionized cerium (Ce II) are some of the most complex. Like other rare earth species, Ce has many lines in the visible which are suitable for elemental abundance studies. Recent work on Ce II transition probabilities [1] is now being augmented with similar work on Ce I for future studies using such lines from astrophysical sources. Radiative lifetimes from laser induced fluorescence measurements [2] on neutral Ce are being combined with emission branching fractions from spectra recorded using a Fourier transform spectrometer. A total of 14 high resolution spectra are being analyzed to determine branching fractions for 2500 to 3000 lines from 153 upper levels in neutral Ce. Representative data samples and progress to date will be presented. This work was supported by the National Science Foundation's REU program and the Department of Defense's ASSURE program through NSF Award AST-0453442 and NSF Grant CTS0613277. [1] J. E. Lawler, C. Sneden, J. J. Cowan, I. I. Ivans, and E. A. Den Hartog, Astrophys. J. Suppl. Ser. 182, 51-79 (2009). [2] E. A. Den Hartog, K. P. Buettner, and J. E. Lawler, J. Phys. B: Atomic, Molecular & Optical Physics 42, 085006 (7pp) (2009).

  14. Photodissociation of Cerium Oxide Nanocluster Cations.

    Science.gov (United States)

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)).

  15. Experimental determination of water activity for binary aqueous cerium(III) ionic solutions: application to an assessment of the predictive capability of the binding mean spherical approximation model.

    Science.gov (United States)

    Ruas, Alexandre; Simonin, Jean-Pierre; Turq, Pierre; Moisy, Philippe

    2005-12-08

    This work is aimed at a description of the thermodynamic properties of actinide salt solutions at high concentration. The predictive capability of the binding mean spherical approximation (BIMSA) theory to describe the thermodynamic properties of electrolytes is assessed in the case of aqueous solutions of lanthanide(III) nitrate and chloride salts. Osmotic coefficients of cerium(III) nitrate and chloride were calculated from other lanthanide(III) salts properties. In parallel, concentrated binary solutions of cerium nitrate were prepared in order to measure experimentally its water activity and density as a function of concentration, at 25 degrees C. Water activities of several binary solutions of cerium chloride were also measured to check existing data on this salt. Then, the properties of cerium chloride and cerium nitrate solutions were compared within the BIMSA model. Osmotic coefficient values for promethium nitrate and promethium chloride given by this theory are proposed. Finally, water activity measurements were made to examine the fact that the ternary system Ce(NO3)3/HNO3/H2O and the quaternary system Ce(NO3)3/HNO3/N2H5NO3/H2O may be regarded as "simple solutions" (in the sense of Zdanovskii and Mikulin).

  16. Interaction of cerium and calcium-enriched phase in the preparation process of YG6 cemented carbide%铈与YG6硬质合金制备过程中富钙相的交互作用

    Institute of Scientific and Technical Information of China (English)

    何文; 谭敦强; 朱红波; 邝海; 欧阳国霞

    2016-01-01

    在硬质合金的原材料仲钨酸铵(APT)粉末中添加Ca和稀土Ce元素,探讨稀土Ce元素与硬质合金制备过程中富钙相的交互作用。材料的物相组成、显微结构及成分分别通过X射线衍射仪、扫描电子显微镜及能谱进行检测与分析。结果表明:氧化钨还原过程中会产生CaWO4和Ca4.26W10O30两种富钙相,分布在钨颗粒内部和周围,使钨颗粒的棱角钝化,碳化后富钙相转变为Ca4.26W10O30和CaC2相,富钙相可急剧降低YG6硬质合金的性能;添加适量稀土Ce可降低富钙相对钨粉的影响,钨粉颗粒的棱角变得明显,颗粒尺寸变小且分布均匀,稀土Ce与富钙相发生反应生成Ce0.9Ca0.1O1.9三元相;稀土Ce与富钙相的交互作用效果显著,与1% Ca-YG6硬质合金相比,1% Ce+1% Ca-YG6硬质合金的致密度、硬度和断裂韧性分别提高了7.8%,34.3%和67.8%。%The elements of Ca and rare earth Ce were added in APT powder. The interaction of rare earth element Ce with calcium-enriched phase was discussed during the preparation process of cemented carbide. The phase composition, microstructure and element distribution were tested by using X-ray diffractometer, scanning electron microscope and energy disperse spectroscopy, respectively. The results show that two kinds of calcium-enriched phases, CaWO4 and Ca4.26W10O30, are generated in the process of reducing tungsten oxide, which passivate tungsten particles. After carburization, calcium-enriched phases transform into the Ca4.26W10O30 and CaC2 phases. Calcium-enriched phases can sharply reduce the property of YG6 cemented carbide. Adding a moderate amount of rare earth Ce can decrease the influence of calcium-enriched phases on tungsten particles. The edges and corners of tungsten particles become more obvious, and the particle size of tungsten powders becomes smaller and uniform. During carburization process, rare earth Ce reacts with calcium-enriched phase and forms

  17. Study on corrosion resistance of the BTESPT silane cooperating with rare earth cerium on the surface of aluminum-tube

    Institute of Scientific and Technical Information of China (English)

    肖围; 满瑞林; 缪畅; 彭天兰

    2010-01-01

    Bis-3-(triethoxysilyl)propyltetrasulfide(BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method.The performance of composite coatings to protect the aluminum-tube against corrosion was investigated with potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),and salt spray test(SST).The results of potentiodynamic polarization curves and EIS indicated that the self-corrosion current decreased by two orders of magnitude and the i...

  18. 氯酸钠法制备二氧化氯还原剂研究进展%Research progress in reducing agent for preparation of chlorine dioxide by sodium chlorate process

    Institute of Scientific and Technical Information of China (English)

    李建生; 刘炳光; 孙宝丰; 董广前; 王芳

    2012-01-01

    对比介绍了氯酸钠法生产二氧化氯常用还原剂的特点;综述了氯酸钠法制备二氧化氯新还原剂(硫化合物、多元醇、有机酸、碳水化合物、尿素和乙二醛)的研究进展;讨论了氯酸钠法制备二氧化氯有机还原剂甲醇和乙二醛的作用机理;指出采用复合还原剂降低生产成本和采用有机还原剂同时制备两种有用产品是氯酸钠法制备二氧化氯还原剂发展趋势.%Characteristics of reducing agents commonly used in industrially producing chlorine dioxide were introduced with comparison.Research progress in new reducing agents,such as sulfur compound, poly alcohol, organic acid, carbohydrate, urea, and glyoxal for the preparation of chlorine dioxide by sodium chlorate process was summarized.Reaction mechanism of organic reducing agents, methanol and glyoxal, in preparation of chlorine dioxide was discussed.lt was pointed that decreasing production cost by using combined reducing agent as well as preparing two useful products simultaneously by using organic reducing agenl is the tendency of reducing agent development.

  19. UV-Shielding and Catalytic Characteristics of Nanoscale Zinc-Cerium Oxides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fine particles of zinc-cerium oxides (ZCO) used as an ultraviolet filter were prepared via combustion synthesis route. The catalytic activity, UV-shielding performance, surface modification and application of ZCO in polyester varnish were discussed in detail. The experimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV;addition modified ZCO (MZCO) into polyester will enhance the UV-shielding capability of polyester.

  20. Molecular and physiological responses to titanium dioxide ...

    Science.gov (United States)

    - Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that exposure to either nanoparticle altered the transcriptomes of rosette leaves and roots, with comparatively larger numbers of differentially expressed genes (DEGs) found under nano-titania exposure. Nano-titania induced more DEGs in rosette leaves, whereas roots had more DEGs under nano-ceria exposure. MapMan analyses indicated that while nano-titania up-regulated overall and secondary metabolism in both tissues, metabolic processes under nano-ceria remained mostly unchanged. Gene enrichment analysis indicated that both nanoparticles mainly enriched ontology groups such as responses to stress (abiotic and biotic), and defense responses (pathogens), and responses to endogenous stimuli (hormones). Nano-titania specifically induced genes associated with photosynthesis, whereas nano-ceria induced expression of genes related to activating transcription factors, most notably those belonging to the ethylene responsive element binding protein family. Interestingly, there were also increased numbers of rosette leaves and plant biomass under nano-ceria exposure, but not under nano-titania. Other transcriptomic responses did not clearly relate to responses observed at the organism level. This may b

  1. Improvement in corrosion resistance of magnesium coating with cerium treatment

    Institute of Scientific and Technical Information of China (English)

    Samia Ben Hassen; Latifa Bousselmi; Patricc Bercot; El Mustafa Rezrazi; Ezzeddine Triki

    2009-01-01

    Corrosion protection afforded by a magnesium coating treated in cerium salt solution on steel substrate was investigated using open circuit potential, polarization curves, and electrochemical impedance spectroscopy (EIS) in 0.005 M sodium chloride solution (NaCl). The morphology of the surface was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The cerium treated coating was obtained by immersion in CeCl3 solution. The results showed that the corrosion resistance of the treated magnesium coating was improved. The corrosion potential of the treated coating was found to be nobler than that of the untreated magnesium coating and the corrosion current decreased significantly. Impedance results showed that the cerium treatment increased corrosion protection. The improvement of anti-corrosion properties was ataibuted to the formation of cerium oxides and hydroxides that gave to a physical barrier effect.

  2. Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass

    Science.gov (United States)

    Heteroaggregation with indigenous particles is an important process controlling the mobility of engineered nanomaterials in the environment. We studied heteroaggregation of cerium oxide nanoparticles (n-CeO2), which are widely used commercially, with nanoparticles of pyrogenic carbonaceous material ...

  3. Antioxidant Cerium Oxide Nanoparticles in Biology and Medicine

    Directory of Open Access Journals (Sweden)

    Bryant C. Nelson

    2016-05-01

    Full Text Available Previously, catalytic cerium oxide nanoparticles (CNPs, nanoceria, CeO2-x NPs have been widely utilized for chemical mechanical planarization in the semiconductor industry and for reducing harmful emissions and improving fuel combustion efficiency in the automobile industry. Researchers are now harnessing the catalytic repertoire of CNPs to develop potential new treatment modalities for both oxidative- and nitrosative-stress induced disorders and diseases. In order to reach the point where our experimental understanding of the antioxidant activity of CNPs can be translated into useful therapeutics in the clinic, it is necessary to evaluate the most current evidence that supports CNP antioxidant activity in biological systems. Accordingly, the aims of this review are three-fold: (1 To describe the putative reaction mechanisms and physicochemical surface properties that enable CNPs to both scavenge reactive oxygen species (ROS and to act as antioxidant enzyme-like mimetics in solution; (2 To provide an overview, with commentary, regarding the most robust design and synthesis pathways for preparing CNPs with catalytic antioxidant activity; (3 To provide the reader with the most up-to-date in vitro and in vivo experimental evidence supporting the ROS-scavenging potential of CNPs in biology and medicine.

  4. Catalytic properties and biomedical applications of cerium oxide nanoparticles

    KAUST Repository

    Walkey, Carl D.

    2014-11-10

    Cerium oxide nanoparticles (nanoceria) have shown promise as catalytic antioxidants in the test tube, cell culture models and animal models of disease. However given the reactivity that is well established at the surface of these nanoparticles, the biological utilization of nanoceria as a therapeutic still poses many challenges. Moreover the form that these particles take in a biological environment, such as the changes that can occur due to a protein corona, are not well established. This review aims to summarize the existing literature on biological use of nanoceria, and to raise questions about what further study is needed to apply this interesting catalytic material to biomedical applications. These questions include: 1) How does preparation, exposure dose, route and experimental model influence the reported effects of nanoceria in animal studies? 2) What are the considerations to develop nanoceria as a therapeutic agent in regards to these parameters? 3) What biological targets of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are relevant to this targeting, and how do these properties also influence the safety of these nanomaterials?

  5. Preparation of mesoporous titanium dioxide by electrostatic self-assembly%静电组装法制备介孔 TiO2∗

    Institute of Scientific and Technical Information of China (English)

    彭少华; 徐孝文

    2015-01-01

    以 TiCl4和(NH 4)6 Mo7 O 24.4H 2 O 为原料,先通过水解、静电自组装和焙烧得到 TiO 2/MoO 3,再用 NaOH 溶液溶解得到介孔 TiO 2.用 X 射线粉末衍射(XRD)、透射电镜(TEM)、X 射线能量色散仪(EDX)、紫外-可见漫反射光谱(UV-DRS)和比表面及孔隙度分析仪(ASAP)对该材料进行表征,合成的介孔 TiO 2 BET 比表面积为241 m2/g,平均孔直径为3.5 nm.通过光催化降解甲基橙实验,发现介孔 TiO 2具有较高光催化活性.%Mesoporous TiO 2 was prepared with the assistance of Mo7 O 6 -24 as templating agent at room tempera-ture.X-ray diffraction (XRD),transmission electron microscopy (TEM),energy-dispersive X-ray spectroscopy (EDX),surface area and porosity analyzer (ASAP)and ultraviolet-visible diffuse reflection spectrum (UV-DRS)were used for characteration of mesoporous titanium dioxide.It has a moderately high surface area of 241 m2/g and a mesoporous structure with an average pore diameter of 3.5 nm.Its photocatalytic activities were evaluated by the degradation of methyl orange (MO)in aqueous solution under UV light irradiation.

  6. Study on Preparation and Properties of Titanium Dioxide Nanowire%二氧化钛纳米线的制备以及性能研究∗

    Institute of Scientific and Technical Information of China (English)

    吴朝政; 姜淙元; 陈安; 王红侠; 李新星

    2016-01-01

    通过碱热法制备二氧化钛纳米线,用X衍射仪( XRD)、扫描电镜( SEM)和紫外-可见光分度计对样品进行表征,以甲基橙为模拟污染物,在8W紫外光照射下考察不同碱溶液的浓度、水热温度和保温时间对二氧化钛纳米线的光催化性能的影响。研究表明采用碱热法制备的TiO2纳米线,具有较高的光催化活性,其中NaOH溶液浓度为10 mol/L,水热温度为180℃,保温时间为24 h 制备的二氧化钛纳米线的光催化性能最好,在光照80 min,降解甲基橙达到了91%。%Titanium dioxide nanowire was synthesized by alkali method. TiO2 samples were characterized by X-ray diffraction, SEM and ultraviolet visible spectrophotometer. The degradation of methyl orange in aqueous solution under 8 W ultraviolet light irradiation was used to evaluate the effect of photocatalytic activity with different alkali solution concentration, hydrothermal temperature and soaking time. The results showed that the all the prepared samples were functioned as a highly active photocatalysts under the irradiation of ultraviolet degradation, with the solution of 10 M NaOH solution concentration, heated at 180 ℃ for 24 h, the best property of photocatalysis was represented. The percent degradation of MO was ca. 91% under simulated irradiation for 80 min.

  7. Preparation

    Directory of Open Access Journals (Sweden)

    M.M. Dardir

    2014-03-01

    Full Text Available Some hexanamide-mono and di-linoleniate esters were prepared by the reaction of linolenic acid and hexanamide (derived from the reaction of hexanoic acid and diethanolamine. The chemical structure for the newly prepared hexanamide-mono and di-linoleniate esters were elucidated using elemental analysis, (FTIR, H 1NMR and chemical ionization mass spectra (CI/Ms spectroscopic techniques. The results of the spectroscopic analysis indicated that they were prepared through the right method and they have high purity. The new prepared esters have high biodegradability and lower toxicity (environmentally friendly so they were evaluated as a synthetic-based mud (ester-based mud for oil-well drilling fluids. The evaluation included study of the rheological properties, filtration and thermal properties of the ester based-muds formulated with the newly prepared esters compared to the reference commercial synthetic-based mud.

  8. Cerium intermetallics CeTX. Review III

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, Rainer; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux

    2016-05-01

    The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore {sup 119}Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

  9. Exraction and separation of CERIUM(IV)/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    OpenAIRE

    Li, Y; J. G. He; X. X. Xue; Ru, H. Q.; X. W. Huang; Yang, H.

    2014-01-01

    In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  10. AZ91镁合金表面铈盐-硅烷转化膜对比处理研究%Comparison of Surface Treatment of AZ91 Magnesium Alloy with Cerium and Silane Conversion Coatings

    Institute of Scientific and Technical Information of China (English)

    陈言坤; 鲁彦玲; 郭毅; 杜仕国

    2011-01-01

    With different immersion treatment, four kinds of conversion coatings including pure cerium conversion, KH560 silane conversion, cerium - silane conversion and silane - cerium conversion coatings were prepared. The corrosion resistance of four kinds of conversion coatings were studied and compared by use of IR, SEM, EDS, Tafel and EIS. The results showed that there were no interaction between cerium coating and silane coating, and they could form conversion coating independently. The cerium - silane conversion coating and silane - cerium coating showed better corrosion resistance than pure cerium coating and silane coating did. The reason of difference between cerium coating and silane coating needed to be studied further.%利用不同的浸泡处理,制备了单纯铈盐转化膜、KH560硅烷转化膜、铈盐硅烷转化膜和硅烷铈盐4种转化膜,结合FT-IR、SEM、EDS、Tafel、EIS等分析手段,对比考察了4种转化膜对镁合金耐腐蚀能力的情况,结果表明:铈盐转化膜和硅烷转化膜之间没有相互影响,均具有独立成膜的能力;铈盐硅烷转化膜和硅烷铈盐转化膜比单纯的铈盐转化膜和单纯的硅烷转化膜具有更好的耐腐蚀能力;铈盐硅烷转化膜和硅烷铈盐转化膜耐腐蚀能力的差别和原因,尚需要进一步的试验研究.

  11. Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316 L stainless steel

    Science.gov (United States)

    Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

    2012-04-01

    Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316 L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3 wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions.

  12. Spectral tunability of cerium photoluminescence in nano sized LaF{sub 3}:Ce{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, T. K.; Suriyamurthy, N., E-mail: igcarsuri@yahoo.com; Panigrahi, B. S.; Venkatraman, B. [Indira Gandhi Centre for Atomic Research, Kalpakkam – 603 102 (India); Sukumar, A. A. [CCCM, Bhabha Atomic Research Centre, Hyderabad (India)

    2015-06-24

    Nano sized LaF{sub 3}:Ce{sup 3+} was synthesized by adopting co-precipitation technique with nominal composition as well as with different molar ratio of reactants La{sup 3+} (Lanthanum) and F{sup −} (Fluoride). All the samples were subjected to X-ray diffraction (XRD), XRF, UV-Vis absorption, and PL characterizations. XRD analysis did not reveal any significant change in the diffraction profile. Particle size variations were observed with respect to change in lanthanum to fluoride molar ratio. An interesting and intense photoluminescence excitation peaks were observed for the samples prepared non-stoichiometrically. The effect of varying nominal reactant composition demonstrates a possibility of introducing tunability in cerium emission in the same host. Life time of cerium has been measured to be in the order of nano seconds.

  13. 玻璃纤维增强聚对苯二甲酸乙二醇酯/次磷酸铈复合材料的制备及其阻燃性能研究%Preparation and flame retardant properties of glass-fiber reinforced poly(ethylene terephthalate)/cerium hypophosphite composites

    Institute of Scientific and Technical Information of China (English)

    田聪; 杨伟

    2012-01-01

    首先合成并表征了一种新的阻燃剂-次磷酸铈(CHP);然后采用熔融共混的方法制备了玻璃纤维(GF)增强聚对苯二甲酸乙二醇酯(PET)/CHP(PET/GF/CHP)复合材料;探讨了CHP对PET/GF复合材料热稳定性和燃烧性能的影响。材料的热稳定性是由热失重分析(TGA)进行表征的,燃烧性能是通过氧指数(LOI)、垂直燃烧(UL-94)以及锥形量热仪进行测试的,炭渣形貌由扫描电子显微镜(SEM)进行表征。结果表明:CHP的引入保持了PET/GF的热稳定性。含有15wt%CHP的PET/GF材料(PET/GF/CHP15),其LOI为30%,且能达到UL-94V-0级别。此外,与PET/GF相比,PET/GF/CHP15热释放速率峰值和热释放总量分别下降了67%和27%。SEM分析表明CHP的加入使得材料在燃烧后有大量致密的炭渣覆盖在玻璃纤维的表面,这些炭渣不仅降低了玻璃纤维的导热性,而且切断了可燃物质的传送通道,从而提高了材料的阻燃性能。%A novel flame retardant, cerium hypophosphite (CHP), was synthesized and characterized. The glass-fiber reinforced poly(ethylene terephthalate)/CHP (PET/GF/CHP) composites were then prepared by means of melt blending method. The thermal stability and combustion properties were respectively studied by thermogravimetric analysis (TGA) and limiting oxygen index (LOI), Underwriters Laboratories 94 (UL-94), cone calorimeter testing. The char residues after cone calorimeter tes- ting were investigated by scanning electron microscope (SEM). TGA results illustrated that the incorporation of CHP had no influence on the thermal stability of PET/GF composites. For PET/GF containing 15 wt% of CHP (PET/GF/CHP15), it a- chieved a V0 classification with a high LOI (30%). Additionally, the peak heat release rate (PHRR) and total heat release rate (THR) were respectively reduced by around 67% and 27% compared to the results obtained from PET/GF. SEM

  14. Application of preparation process of high pure chlorine dioxide by electrolysis method in water treatment%电解法制高纯二氧化氯工艺在水处理中的应用

    Institute of Scientific and Technical Information of China (English)

    刘艳霞; 韩瑞雄; 赵红; 周俊波

    2011-01-01

    为了开发经济实用的二氧化氯消毒工艺,对电解法制备高纯二氧化氯工艺在水处理中的运用进行了研究.在最佳条件下,电解氯酸盐自动催化循环制备的二氧化氯纯度可达98%左右.通过二氧化氯杀菌除藻试验,讨论了二氧化氯用量以及原水pH对细菌、叶绿素a、藻类的去除率的影响.结果表明,二氧化氯用量在2 mg/L以上时,3者的去除率均达到90%以上.当二氧化氯用量为2 mg/L、原水pH为6~9时,3者的去除率不发生显著变化,并且二氧化氯的剩余质量浓度均控制在0.5 mg/L以下.消毒成本:生产1 kg二氧化氯成本可以控制在6元以内,当二氧化氯用量在0.5 ~2 mg/L时,1 t水的消毒成本为0.003~ 0.012元.%To develop an economical and practical disinfection technology of chlorine dioxide, the application of preparation process of high pure chlorine dioxide by electrolysis method in water treatment was studied. Under the best conditions, the purity of chlorine dioxide, which was prepared by electrolysis of chlorate solution with auto-catalytic cycling,can reach about 98% . Through the experiments of algae removal and sterilization,the influences of concentration of chlorine dioxide and pH of raw water on the removal rate of bacteria,chlorophyll A ,and algal were discussed. Results showed that when the mass concentration of chlorine dioxide was above 2 mg/L, the removal rates of bacteria, chlorophyll A, and algal could all reached above 90% . When the mass concentration of chlorine dioxide was 2 mg/L and pH of raw water was at 6 ~9,the removal rates of them could not occur significant change, and the mass concentration of residual chlorine dioxide was all under 0. 5 mg/L. Though accounting for the cost of water disinfection, the cost of per kilogram chlorine dioxide in the process can be controlled less than RMB 6 Yuan. When the invested amount of chlorine dioxide was at 0.5 ~2 mg/L,and the cost of per ton water disinfection

  15. Inhibition of pH fronts in corrosion cells due to the formation of cerium hydroxide

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The effect of cerium-based corrosion inhibitors on the pH front between the alkaline cathode and acidic anode in corrosion cells has been studied. The cerium component of these inhibitors can affect the pH front since it precipitates in an alkaline environment as cerium hydroxide, which is important

  16. Potential for recovery of cerium contained in automotive catalytic converters

    Science.gov (United States)

    Bleiwas, Donald I.

    2013-01-01

    Catalytic converters (CATCONs) are required by Federal law to be installed in nearly all gasoline- and diesel-fueled onroad vehicles used in the United States. About 85 percent of the light-duty vehicles and trucks manufactured worldwide are equipped with CATCONs. Portions of the CATCONs (called monoliths) are recycled for their platinum-group metal (PGM) content and for the value of the stainless steel they contain. The cerium contained in the monoliths, however, is disposed of along with the slag produced from the recycling process. Although there is some smelter capacity in the United States to treat the monoliths in order to recover the PGMs, a great percentage of monoliths is exported to Europe and South Africa for recycling, and a lesser amount is exported to Japan. There is presently no commercial-scale capacity in place domestically to recover cerium from the monoliths. Recycling of cerium or cerium compounds from the monoliths could help ensure against possible global supply shortages by increasing the amount that is available in the supply chain as well as the number and geographic distribution of the suppliers. It could also reduce the amount of material that goes into landfills. Also, the additional supply could lower the price of the commodity. This report analyzes how much cerium oxide is contained in CATCONs and how much could be recovered from used CATCONs.

  17. 基于氧化钛纳米带及钯纳米颗粒的吗啡传感器的制备%Preparation of Morphine Sensor Based on Titanium Dioxide Nanobelts and Palladium Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    徐凤; 李月婷; 司剑飞; 杨丽君; 陶满兰; 杨云慧

    2011-01-01

    Titanium dioxide nanobelts are a new type of high performance functional materials, while synthesis method is the research hot spot. Ethanol thermal solvent was used to synthesize titanium dioxide nanobelts. Scanning electron microscopy was used to characterize the morphology of the nanobelts. Pd nanoparticles were electrodeposited on the glassy carbon electrode modified with obtained titanium dioxide nanobelts/chitosan film to construct morphine electrochemical sensor. The experimental results show that the sensor has good stability, high sensitivity and selectivity, simple preparation procedure and low cost. The sensor is applied to determine morphology with satisfactory.%氧化钛纳米带是一种性能优异的新型功能材料,其合成方法及应用是研究的热点.采用乙醇热溶剂法合成了氧化钛纳米带,并通过扫描电镜观察了纳米带的形貌.将氧化钛纳米带固定到电极表面,采用恒电位沉积钯纳米粒子后制得吗啡电化学传感器.结果表明,该传感器稳定性好、灵敏度高、选择性好、制作简单、成本低,应用于血清中吗啡的测定,结果令人满意.

  18. Mechanical and Thermophysical Properties of Cerium Monopnictides

    Science.gov (United States)

    Bhalla, Vyoma; Singh, Devraj; Jain, S. K.

    2016-03-01

    The ultrasonic attenuation due to phonon-phonon interaction, thermoelastic relaxation and dislocation damping mechanisms has been investigated in cerium monopnictides CeX (X: N, P, As, Sb and Bi) for longitudinal and shear waves along {third-order elastic constants of CeX have also been computed in the temperature range 0 K to 500 K using Coulomb and Born-Mayer potential upto second nearest neighbours. The computed values of these elastic constants have been applied to find out Young's moduli, bulk moduli, Breazeale's non-linearity parameters, Zener anisotropy, ultrasonic velocity, ultrasonic Grüneisen parameter, thermal relaxation time, acoustic coupling constants and ultrasonic attenuation. The fracture/toughness ratio is less than 1.75, which shows that the chosen materials are brittle in nature as found for other monopnictides. The drag coefficient acting on the motion of screw and edge dislocations due to shear and compressional phonon viscosities of the lattice have also been evaluated for both the longitudinal and shear waves. The thermoelastic loss and dislocation damping loss are negligible in comparison to loss due to Akhieser damping (phonon-phonon interaction). The obtained results for CeX are in qualitative agreement with other semi-metallic monopnictides.

  19. Cerium-iron-based magnetic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Chen; Pinkerton, Frederick E.; Herbst, Jan F.

    2017-01-17

    New magnetic materials containing cerium, iron, and small additions of a third element are disclosed. These materials comprise compounds Ce(Fe.sub.12-xM.sub.x) where x=1-4, having the ThMn.sub.12 tetragonal crystal structure (space group I4/mmm, #139). Compounds with M=B, Al, Si, P, S, Sc, Co, Ni, Zn, Ga, Ge, Zr, Nb, Hf, Ta, and W are identified theoretically, and one class of compounds based on M=Si has been synthesized. The Si cognates are characterized by large magnetic moments (4.pi.M.sub.s greater than 1.27 Tesla) and high Curie temperatures (264.ltoreq.T.sub.c.ltoreq.305.degree. C.). The Ce(Fe.sub.12-xM.sub.x) compound may contain one or more of Ti, V, Cr, and Mo in combination with an M element. Further enhancement in T.sub.c is obtained by nitriding the Ce compounds through heat treatment in N.sub.2 gas while retaining the ThMn.sub.12 tetragonal crystal structure; for example CeFe.sub.10Si.sub.2N.sub.1.29 has T.sub.c=426.degree. C.

  20. Cerium-based conversion coatings on magnesium alloys

    Science.gov (United States)

    Castano Londono, Carlos Eduardo

    This research is primarily focused on gaining a better understanding of the deposition and corrosion behavior of cerium-based conversion coatings (CeCCs) on AZ31B and AZ91D Mg alloys. Deposition of homogenous and protective CeCCs was highly dependent on the surface preparation steps. The best results were obtained when Mg samples underwent grinding, acid cleaning, and alkaline cleaning processes. This reduced the number of active cathodic sites and promoted the formation of a protective Al-rich Mg oxide/hydroxide layer. Electrochemical properties of the CeCCs were also strongly correlated with morphological, microstructural, and chemical characteristics. Protective CeCCs were deposited on both AZ31 and AZ91 Mg alloys using a range of deposition times (5 to 180 s) and temperatures (10 to 80 °C). However, shorter deposition times (5 s) and lower deposition temperatures (~10 °C) showed higher impedance and longer bath stability than other deposition conditions. The increase in impedance was related with fewer cracks and smaller nodule sizes. Additional investigations of post-treated CeCCs exposed to NaCl environments showed an increased in the total impedance. The increase in corrosion protection of the CeCCs was associated with an overall increase in coating thickness from 400 to 800 nm. A microstructural evolution from ~3 nm nodular nanocrystals of CeO2/CePO4*H2O embedded in an amorphous matrix to >50 nm CePO4*H2O nanocrystals was responsible for the electrochemically active corrosion protection. Exposure of CeCCs to sunlight in humid environments promoted the reduction of Ce(IV) into Ce(III) species compared to unexposed coatings. This reduction process was related with photocatalytic water oxidation reaction.

  1. Dielectric studies on cerium doped BaLa2Ti3O10

    Directory of Open Access Journals (Sweden)

    Parshuram B. Abhange

    2015-12-01

    Full Text Available The BaLa2-xCexTi3O10 samples (with x = 0.2, 0.4, 0.6 and 0.8 were prepared by hydroxide co-precipitation method and finally sintered at 1150 °C. The structure of the prepared samples was characterized by XRD and SEM. The single phase material was confirmed only for the BaLa1.8Ce0.2Ti3O10 ceramics. However, at higher cerium concentration secondary phase was observed. The characteristic plate-like structure, having grains with submicrometer thickness and high aspect ratio, was clearly observed by SEM. The results of dielectric measurement suggest that the appropriate adjustment of doping (with x between 0.2 and 0.8 will give sufficient high dielectric constant at very low loss. The resistivity of samples decreases with increase in temperature indicating the normal semiconducting electrical behaviour.

  2. Effect of CO2 on the Conversion of Isobutane over Iron, Cerium and Molybdenum Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Daifallah Al-Dhayan

    2016-10-01

    Full Text Available A series of cerium and iron mixed oxide catalysts were prepared by thermal decomposition of Fe1.5PMo12O40 and Ce1.5PMo12O40 heteropolyanions mixture. The prepared catalysts have been characterized and tested for the conversion of isobutane in the presence of CO2. Characterization by XRD showed that besides Fe2O3 and CeO2, α-MoO3 was the main phase formed after thermal treatment. The effect of the support, the reaction temperature, and the presence of H2O in the reactant mixture was investigated. It has been found that the support enhanced both the conversion and isobutene selectivity. As for the reaction temperature and addition of water, it has been found that increasing the temperature increased both the conversion and isobutene selectivity, whereas the presence of water increased the isobutene selectivity but decreased the conversion.

  3. The effects of cerium doping concentration on the properties and photocatalytic activity of bimetallic Mo/Ce catalyst

    Science.gov (United States)

    Allaedini, Ghazaleh; Tasirin, Siti Masrinda; Aminayi, Payam

    2016-10-01

    In this study, the characterization and photocatalytic activity of MoO3 nanoparticles doped with various doping concentrations of cerium have been investigated. The Fourier transform infrared (FT-IR) spectra of the prepared catalysts confirmed that MoO3 particles have been successfully doped by cerium. Field emission scanning electron microscopy (FESEM) was performed to visualize the surface morphology of the obtained catalysts. The XRD patterns suggested that the crystallinity of the sample with the lowest doping concentration of 15 mol % was higher in comparison with samples of higher doping concentrations. The volume-averaged crystal sizes of the obtained catalysts were calculated to be 25, 28, and 32 nm for 15, 35, and 60 mol % samples, respectively. The photocatalytic activity along with the reaction kinetics of Ce-doped MoO3 nanoparticles have also been investigated through the dye degradation of methyl orange. The synthesized Ce-doped MoO3 particles with the lowest dopant concentration of 15 mol % exhibited the highest photocatalytic activity for methyl orange dye degradation. It was observed that photo-degradation activity decreased with an increase in the doping concentration of cerium. The predicted rate constants for samples with 15, 35, and 60 mol % doping concentrations were found to be 0.0432, 0.035, and 0.029 min-1, respectively.

  4. Study of cerium-promoted rhodium alumina catalyst as a steam reforming catalyst for treatment of spent solvents

    Institute of Scientific and Technical Information of China (English)

    Hee-Chul Yang; Min-Woo Lee; Ho-Sang Hwang; Jei-Kwon Moon; Dong-Yong Chung

    2014-01-01

    This study attempted to develop an appropriate catalyst used for the steam reforming of gasified spent solvents. Rh2O3/ CeO2-Al2O3 catalysts with various CeO2 loadings were prepared and heated at different temperatures of 500 and 800 ºC, and their surface properties were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron mi-croscopy (TEM), temperature programmed reduction (TPR) and Brumauer-Emmett-Teller (BET) analyses. Rhodium existed in the form of Rh2O3, regardless of the sample composition as well as the heating temperature. In the tested range of cerium addition (up to 12 times the rhodium mass), no significant changes in BET surface areas and binding energy corresponding to Rh 3d5/2were observed. Instead, the addition of cerium led to a greatly enhanced dispersion of rhodium nanoparticles, and no agglomeration of rhodium was observed for samples heated even at 800 ºC. Honeycomb monolith rhodium catalysts promoted with cerium were fabricated and tested for the steam reforming of a gasified spent solvent, mainly consisting of butylene (C4H8). The test results suggested that a ce-rium-promoted rhodium catalyst could be used as an appropriate reforming catalyst for treating low-quality non-methane hydrocar-bons without the formation of coke at high temperatures of up to 900 ºC.

  5. Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)

    Science.gov (United States)

    Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang; Cen, Kefa

    2014-10-01

    Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N2 sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

  6. Thermodynamic Calculation among Cerium, Oxygen, and Sulfur in Liquid Iron

    Science.gov (United States)

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Su, Yen-Hao; Hwang, Weng-Sing

    2016-10-01

    Thermodynamic calculation has been applied to predict the inclusion formation in molten SS400 steel. When the Cerium addition in liquid iron is 70 ppm and the initial Oxygen and Sulphur are both 110 ppm, the formation of oxides containing Cerium would experience the transformation from Ce2O3 to CeO2 and also the formation of sulfides containing Cerium would experience the transformation from CeS to Ce2S3 and then to Ce3S4. Below 2000 K the most thermodynamic stable matter is CeO2 and the less thermodynamic stable inclusion is CeS. Only when the amount of [O] is extremely low and the amount of [S] and [Ce] is relatively high, Ce2S3 has the possibility to form.

  7. Elaboration and characterization of thin solid films containing cerium

    Science.gov (United States)

    Hamdi, S.; Guerfi, S.; Siab, R.

    2009-11-01

    Cerium oxide films are widely studied as a promising alternative to Cr(VI) based pre-treatments for the corrosion protection of different metals and alloys. Cathodic electrodeposition of Cerium containing thin films was realised on TA6V substrates from a Ce(NO3)3, 6H2O and mixed water-ethyl alcohol solutions at 0.01 M. Experimental conditions to obtain homogeneous and crack free thin films were determined. The deposited cerium quantity appears proportional to the quantity of electricity used, as indicated by the Faraday law. Subsequent thermal treatment lead to a CeO2 coating, expected to provide an increase of TA6V oxidation resistance at high temperatures. The deposits were characterized by differential scanning calorimetry (DSC), optical and scanning electron microscopies.

  8. Synthesis and characterization of magnesium doped cerium oxide for the fuel cell application

    Science.gov (United States)

    Kumar, Amit; Kumari, Monika; Kumar, Mintu; Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Cerium oxide has attained much attentions in global nanotechnology market due to valuable application for catalytic, fuel additive, and widely as electrolyte in solid oxide fuel cell. Doped cerium oxide has large oxygen vacancies that allow for greater reactivity and faster ion transport. These properties make cerium oxide suitable material for SOFCs application. Cerium oxide electrolyte requires lower operation temperature which shows improvement in processing and the fabrication technique. In our work, we synthesized magnesium doped cerium oxide by the co-precipitation method. With the magnesium doping catalytic reactivity of CeO2 was increased. Synthesized nanoparticle were characterized by the XRD and UV absorption techniques.

  9. Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang, E-mail: xgao1@zju.edu.cn; Cen, Kefa

    2014-10-30

    Graphical abstract: - Highlights: • Ordered mesoporous carbon (OMC) and Ce-OMC were used for NO adsorption. • The NO adsorption capacity of OMC was two times larger than that of activated carbon. • With the addition of cerium both adsorption capacity and adsorption rate increased. • The pseudo-second-order model was the most suitable model for NO adsorption on OMC. • Intraparticle diffusion was the rate controlling step for NO adsorption. - Abstract: Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N{sub 2} sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

  10. Visible Light Induced Photocatalysis of Cerium Ion Modified Titania Sol and Nanocrystallites

    Institute of Scientific and Technical Information of China (English)

    Yibing XIE; Chunwei YUAN

    2004-01-01

    The cerium ion(Ce4+) doped titania sol and nanocrystallites were prepared by chemical coprecipitation-peptization and hydrothermal synthesis methods, respectively. The X-ray diffraction pattern shows that Ce4+-TiO2 xerogel powder has semicrystalline structure and thermal sintering sample has crystalline structure. Ce4+-TiO2 nanocrystallites are composed of the major anatase phase titania (88.82 wt pct) and a small amount of crystalline cerium titanate.AFM micrograph shows that primary particle size of well-dispersed ultrafine sol particles is below 15 nm in diameter.The particle sizes are 30 nm for xerogel sample and 70 nm for nanocrystallites sample, which is different from the estimated values (2.41 nm and 4.53 nm) by XRD Scherrer's formula. The difference is mainly due to aggregation of nanocrystallites. The experimental results exhibit that photocatalysts of Ce4+-TiO2 sol and nanocrystallites have the ability to photodegrade reactive brilliant red dye (X-3B) under visible light irradiation with the ion-TiO2/VIS/dye system. Moreover, Ce4+ doped titania sol has shown higher efficiency than the nanocrystallites sample in respect of potocatalytic activity. Meanwhile, dye photodegradation mechanisms are proposed to different photocatalytic reaction systems, which are dye photosensitization, ion-dye photosensitization and interband photocatalysis & dye photosensitization with respect to TiO2 nanocrystallites, Ce4+-TiO2 sol and Ce4+-TiO2 nanocrystallites system.

  11. Cerium(III) molybdate nanoparticles: Synthesis, characterization and radionuclides adsorption studies.

    Science.gov (United States)

    Yousefi, Taher; Khanchi, Ali Reza; Ahmadi, Seyed Javad; Rofouei, Mohamad Kazem; Yavari, Ramin; Davarkhah, Reza; Myanji, Behzad

    2012-05-15

    Cerium(III) molybdate nanostructure with average size about 40nm was prepared by adding cerium(III) chloride and ammonium molybdate solutions under varying conditions. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and Brunauere Emmette Teller (BET) techniques. Ion exchange capacity of the sample for potassium ion and distribution coefficients (K(d)) for 23 metal ions were determined, the K(d) values for Tl(I), Pb(II), Th(IV), U(VI), and Cs(I) ions were found to be sufficiently high for their removal from various effluents. The adsorption behavior of the sample towards Cs(I)(134) species were studied. Finally, the binary separation of Dy(III)-U(VI), Sm(III)-Th(IV) and Cs(I)-Rb(I) and removal of Cs(I)(134) from the real sample were successfully achieved.

  12. Selective catalytic oxidation of ammonia over copper-cerium composite catalyst.

    Science.gov (United States)

    Lou, Jie-Chung; Hung, Chang-Mao; Yang, Sheng-Fu

    2004-01-01

    This work considers the oxidation of ammonia (NH3) by selective catalytic oxidation (SCO) over a copper (Cu)-cerium (Ce) composite catalyst at temperatures between 150 and 400 degrees C. A Cu-Ce composite catalyst was prepared by coprecipitation of copper nitrate and cerium nitrate at various molar concentrations. This study also considers how the concentration of influent NH3 (500-1000 ppm), the space velocity (72,000-110,000 hr(-1)), the relative humidity (12-18%) and the concentration of oxygen (4-20%) affect the operational stability and the capacity for removing NH3. The effects of the O2 and NH3 content of the carrier gas on the catalyst's reaction rate also are considered. The experimental results show that the extent of conversion of NH3 by SCO in the presence of the Cu-Ce composite catalyst was a function of the molar ratio. The NH3 was removed by oxidation in the absence of Cu-Ce composite catalyst, and approximately 99.2% NH3 reduction was achieved during catalytic oxidation over the Cu-Ce (6:4, molar/molar) catalyst at 400 degrees C with an O2 content of 4%. Moreover, the effect of the initial concentration and reaction temperature on the removal of NH3 in the gaseous phase was also monitored at a gas hourly space velocity of less than 92,000 hr(-1).

  13. Isomorphic phase transformation in shocked Cerium using molecular dynamics

    OpenAIRE

    Germann T.C.; Chen S.-P.; Dupont V.

    2011-01-01

    Cerium (Ce) undergoes a significant (∼16%) volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM) potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD) simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plas...

  14. Effect of cerium and thermomechanical processing on microstructure and mechanical properties of Fe–10.5Al–0.8C alloy

    Indian Academy of Sciences (India)

    R G Baligidad; Shivkumar Khaple

    2009-10-01

    The effect of cerium content and thermomechanical processing on structure and properties of Fe–10.5 wt.%Al–0.8 wt%C alloy has been investigated. Alloys were prepared by a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). The ESR ingots were hot-forged and hotrolled at 1373 K as well as warm-rolled at 923 K and heat-treated. Hot-rolled, warm-rolled and heat treated alloys were examined using optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction to understand the microstructure of these alloys. The ternary, Fe–10.5 wt.%Al–0.8 wt.%C alloy showed the presence of two phases; Fe–Al with bcc structure, and large volume fraction of Fe3AlC0.5 precipitates. Addition of cerium to Fe–10.5 wt.%Al–0.8 wt.%C alloy resulted in three phases, the additional phase being small volume fraction of fine cerium oxy-carbide precipitates. Improvement in tensile elongation from 3–6.4% was achieved by increasing the cerium content from 0.01–0.2 wt.% and further improvement in tensile elongation from 6.4–10% was achieved by warm-rolling and heat treatment.

  15. Exraction and separation of CERIUM(IV/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    Directory of Open Access Journals (Sweden)

    Y. Li

    2014-07-01

    Full Text Available In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  16. Processing and Characterization of Sol-Gel Cerium Oxide Microspheres

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Zachary D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Padilla Cintron, Cristina [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-27

    Of interest to space exploration and power generation, Radioisotope Thermoelectric Generators (RTGs) can provide long-term power to remote electronic systems without the need for refueling or replacement. Plutonium-238 (Pu-238) remains one of the more promising materials for thermoelectric power generation due to its high power density, long half-life, and low gamma emissions. Traditional methods for processing Pu-238 include ball milling irregular precipitated powders before pressing and sintering into a dense pellet. The resulting submicron particulates of Pu-238 quickly accumulate and contaminate glove boxes. An alternative and dust-free method for Pu-238 processing is internal gelation via sol-gel techniques. Sol-gel methodology creates monodisperse and uniform microspheres that can be packed and pressed into a pellet. For this study cerium oxide microspheres were produced as a surrogate to Pu-238. The similar electronic orbitals between cerium and plutonium make cerium an ideal choice for non-radioactive work. Before the microspheres can be sintered and pressed they must be washed to remove the processing oil and any unreacted substituents. An investigation was performed on the washing step to find an appropriate wash solution that reduced waste and flammable risk. Cerium oxide microspheres were processed, washed, and characterized to determine the effectiveness of the new wash solution.

  17. Structural, optical and photocatalytic activity of cerium doped zinc aluminate

    Science.gov (United States)

    Sumathi, Shanmugam; Kavipriya, A.

    2017-03-01

    Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl2O4:Ce3+) increased the photocatalytic activity of zinc aluminate.

  18. Purification of cerium, neodymium and gadolinium for low background experiments

    Directory of Open Access Journals (Sweden)

    Boiko R.S.

    2014-01-01

    Full Text Available Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search, 136Ce (2β+ candidate with one of the highest Q2β. The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  19. Electrorheological Effects of Cerium-Doped TiO2

    Institute of Scientific and Technical Information of China (English)

    尹剑波; 赵晓鹏

    2001-01-01

    It is found that the doping of cerium ion into anatase TiO2 can improve the electrorheological (ER) effects of TiO2 and broaden the operational temperature range. Especially, the substitution of 7-11 mol% of the cerium dopant for Ti can obtain a relatively high shear stress, t-7.4kPa (at 4kV/mm), which is ten times larger than that of pure TiO2 ER fluid. Also, the typical Ce-doped TiO2 ER fluid shows the highest shear stress at 80℃, but 40℃ for pure TiO2 ER fluid. The dielectric loss and dielectric constant at a low frequency of TiO2 is improved by the doping of cerium, and the temperature dependence of the dielectric properties shows an obvious differnce between pure and doped TiO2 ER fluids. These can well explain the ER behaviour of doped TiO2. Furthermore, the change of rheological and dielectric properties is discussed on the basis of the lattice distortion and defects in TiO2 arising from the doping of cerium.

  20. Cerium; crystal structure and position in the periodic table.

    Science.gov (United States)

    Johansson, Börje; Luo, Wei; Li, Sa; Ahuja, Rajeev

    2014-09-17

    The properties of the cerium metal have intrigued physicists and chemists for many decades. In particular a lot of attention has been directed towards its high pressure behavior, where an isostructural volume collapse (γ phase → α phase) has been observed. Two main models of the electronic aspect of this transformation have been proposed; one where the 4f electron undergoes a change from being localized into an itinerant metallic state, and one where the focus is on the interaction between the 4f electron and the conduction electrons, often referred to as the Kondo volume collapse model. However, over the years it has been repeatedly questioned whether the cerium collapse really is isostructural. Most recently, detailed experiments have been able to remove this worrisome uncertainty. Therefore the isostructural aspect of the α-γ transition has now to be seriously addressed in the theoretical modeling, something which has been very much neglected. A study of this fundamental characteristic of the cerium volume collapse is made in present paper and we show that the localized [rlhar2 ] delocalized 4f electron picture provides an adequate description of this unique behavior. This agreement makes it possible to suggest that an appropriate crossroad position for cerium in The Periodic Table.

  1. Determination of Impurity Elements in Pure Cerium Oxide Product

    Institute of Scientific and Technical Information of China (English)

    Li Peizhong; Chen Limin; Li Jie

    2004-01-01

    Determination of the rare earth impurity in pure cerium oxide is done by ICP-MS.The interference and other factors which affect analytical results were discussed.The accuracy are between 0.81% ~ 11.98% and the recoveries of standard addition are 96% ~ 112.5%.This method can meet the demand for product inspection.

  2. Study of cyclic oxidation for stainless steels AISI 309 T 253 M A, with low additions of cerium; Estudio de la oxidacion ciclica de los aceros inoxidables AISI 309 T 253 MA, con pequenas adiciones de Cerio

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez F, G.L.; Martinez, M.; Ruiz, A. [Universidad Nacional Experimental Politecnica (UNEXPO) - Vicerrectorado de Puerto Ordaz, Centro de Estudios de Corrosion. Puerto Ordaz. venezuela (Venezuela)

    1998-12-31

    It has been detected that the addition of small amounts (<1%) of the so called `reactive elements` such as Cerium to Fe-Cr alloys that was utilized in oxidating environment at high temperatures improving its resistance to oxidation under isothermal and cyclic conditions. In this work, it was evaluated the behavior under cyclic oxidation conditions for an austenitic stainless steel at chromium-nickel (253MA) with cerium addition, and comparing it with the AISI 310S austenitic stainless steel. The cyclic oxidation essays consist of five cycles by 24 hours each one, following of a cooling in air until ambient temperature from the temperatures of 850, 900 and 950 Centigrade, registering the gain mass of the specimen at end of each cycle. In order to this were prepared samples with dimensions of 20 mm. x 10 mm. x 1 mm. Later to the oxidation essays was evaluated the morphology of the corrosion products layer by scanning electron microscopy. The present phases were identified by X-ray diffraction and by chemical microanalysis by Dispersive energy (EDAX). The results obtained show that the steel with cerium addition, presents a higher adherence and resistance to the spalling noting that the cerium promotes the casting anchor of the oxides layer to matrix and by reducing the grain size of the layer improving its plasticity. Additionally the cerium promotes the preferential oxidation of the forming elements of protective layers like the chromium. (Author)

  3. Effects of electron beam irradiation on tin dioxide gas sensors

    Indian Academy of Sciences (India)

    Zheng Jiao; Xiaojuan Wan; Bing Zhao; Huijiao Guo; Tiebing Liu; Minghong Wu

    2008-02-01

    In this paper, the effects of electron beam irradiation on the gas sensing performance of tin dioxide thin films toward H2 are studied. The tin dioxide thin films were prepared by ultrasonic spray pyrolysis. The results show that the sensitivity increased after electron beam irradiation. The electron beam irradiation effects on tin dioxide thin films were simulated and the mechanism was discussed.

  4. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Energy Technology Data Exchange (ETDEWEB)

    Boshui, Chen, E-mail: boshuichen@163.com; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-30

    Graphical abstract: - Highlights: • Monodispersed stearic acid-capped cerium borate composite nanoparticles were prepared by hydrothermal method. Their morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics were also characterized. • The surface-capped cerium borate nanoparticles exhibited excellent dispersing stability in rapeseed oil. As new lubricating additives, they were also outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil in biodegradable rapeseed oil. The results presented in this paper would be of important significance for developing green lubricants and lubricant additives. • The prominent tribological performances of SA/CeBO{sub 3} in rapeseed oil were investigated and attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species on the tribo-surfaces. - Abstract: Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO{sub 3}, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO{sub 3} were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO{sub 3} as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO{sub 3} were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO{sub 3} nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent

  5. Electrospun cerium nitrate/polymer composite fibres:synthesis, characterization and fibre-division model

    Institute of Scientific and Technical Information of China (English)

    Li Meng-Meng; Long Yun-Ze; Yin Hong-Xing; Zhang Zhi-Ming

    2011-01-01

    Cerium (III)nitrate/poly(vinylpyrrolidone)(Ce(NO3)3/PVP)composite fibres have been prepared by electrospinning. After calcining the composite fibres in air at 500℃, CeO2 nanowires were obtained. The characterizations of the as-spun composite fibres and resultant nanowires have been carried out by a scanning electron microscope (SEM),an infrared spectrometer, an x-ray diffractometer and a fluorescence spectrophotometer. Interestingly, some unusual ribbon-like or twin fibres were observed besides the common fibres with circular or elliptic cross sections. We developed a fibre-division model resulting from Coulomb repulsion and solvent vaporization to interpret the formation of the ribbona or twin fibres, which has been confirmed by the SEM studies. Our results also indicate that the formation of the ribbons or twin fibres is less dependent on operation voltage and work distance.

  6. Valence Control of Ce Ions in Cerium-substituted Yttrium Iron Garnet

    Institute of Scientific and Technical Information of China (English)

    SONG Fengbing; LI Qiang; ZHONG Zhifeng

    2005-01-01

    Cerium-substituted yttrium iron garnet(CexY3-xFe5O12, Ce∶YIG) was prepared via coprecipitation. The structure, morphology, valence state and constituent of Ce ions were investigated respectively. X-ray powder diffraction(XRD) analysis shows that Ce∶YIG was of single cubic YIG phase. The result of X-ray photoelectron spectroscopy(XPS) indicates the Ce ions in Ce∶YIG were in the state of trivalence. Scanning electron microscope(SEM) demonstrates the conglobation of Ce∶YIG particles about 0.2μm scale.The magnetic properties were studied by a vibrating sample magnetometer(VSM) and the result exhibits that substitution of Ce3+ changes the magnetic parameters of YIG. The effects of doping content of Ce ions and synthesis temperature on valence control were discussed in detail.

  7. Solubility of cerium in LaCoO3-influence on catalytic activity.

    Science.gov (United States)

    French, S A; Catlow, C R A; Oldman, R J; Rogers, S C; Axon, S A

    2002-11-21

    The recent interest in the catalytic properties of lanthanum perovskites for methane combustion and three way catalysis has led to considerable debate as to their structure and defect chemistry. We have investigated the doping of LaCoO3 with the tetravalent cerium cation using atomistic simulation techniques. We have compared three routes for cerium insertion and identified the favoured doping mechanism, which explain experimental observations relating to the effect of cerium on catalytic activity.

  8. 溶胶凝胶法制备TiO2实验条件的考察%The Conditions for Preparing Titanium Dioxide by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    任铁强; 孙君; 孙悦

    2012-01-01

    实验以钛酸正丁酯为前驱体,采用溶胶凝胶法制备二氧化钛.设计正交试验,考察水、乙醇、冰醋酸、pH值和凝胶温度对凝胶时间和状态的影响.对凝胶时间的影响程度依次为:pH值、乙醇量、凝胶温度、冰醋酸量、水量.确定溶胶凝胶法合成二氧化钛最佳条件为:pH值为2~3、乙醇的量22~28mL、凝胶温度为55~65℃、冰醋酸的量1.75~2.5mL、水的量2.0~2.5mL.%The titanium dioxide was prepared by sol-gel method with using tetra-n -butyl titanate as precursor. The effects of the amount of ethanol, water and acetic acid, pH value and gelation temperature on gelation time were investigated by orthogonal experiment. The results showed that the order of the influencing factors on gelation time was pH value, amount of ethanol, gelation temperature, amount of acetic acid and water. The best experimental conditions for preparing titanium dioxide by sol-gel method were that pH value was 2 ~3, ethanol was 22-28mL, the gelation temperature was 55~65℃, the amount of acetic acid was 1.75~2.5mL and the amount of water was 2.0~2.5mL.

  9. Study of cerium diffusion in undoped lithium-6 enriched glass with Rutherford backscattering spectrometry

    Science.gov (United States)

    Zhang, Xiaodong; Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D.; Hayward, Jason P.

    2016-07-01

    Undoped lithium-6 enriched glasses coated with pure cerium (99.9%) with a gold protection layer on top were heated at three different temperatures (500, 550, and 600 °C) for varied durations (1, 2, and 4 h). Diffusion profiles of cerium in such glasses were obtained with the conventional Rutherford backscattering technique. Through fitting the diffusion profiles with the thin-film solution of Fick's second law, diffusion coefficients of cerium with different annealing temperatures and durations were solved. Then, the activation energy of cerium for the diffusion process in the studied glasses was found to be 114 kJ/mol with the Arrhenius equation.

  10. Improvement of cerium of photosynthesis functions of maize under magnesium deficiency.

    Science.gov (United States)

    Zhou, Min; Gong, Xiaolan; Wang, Ying; Liu, Chao; Hong, Mengmeng; Wang, Ling; Hong, Fashui

    2011-09-01

    Rare earth elements can promote photosynthesis, but their mechanisms are still poorly understood under magnesium deficiency. The present study was designed to determine the role of cerium in magnesium-deficient maize plants. Maize was cultivated in Hoagland's solution added with cerium with and without adequate quantities of magnesium. Under magnesium-deficient conditions, cerium can prevents inhibition of synthesis of photosynthetic pigment, improves light energy absorption and conversion, oxygen evolution, and the activity of photo-phosphorelation and its coupling factor Ca(2+)-ATPase. These results suggest that cerium could partly substitute magnesium, improving photosynthesis and plant growth.

  11. 3,5-二硝基水杨酸铈的制备、热分解机理及非等温反应动力学%Preparation,Thermal Behavior and Nonisothermal Decomposition Reaction Kinetics of Cerium 3,5-dinitrosalicylate(CeDNS)

    Institute of Scientific and Technical Information of China (English)

    张衡; 赵凤起; 仪建华; 张晓宏; 胡荣祖; 徐司雨

    2009-01-01

    用3,5-二硝基水杨酸和硝酸铈为原料,制备了3,5-二硝基水杨酸铈(CeDNS),采用元素分析、X射线荧光光谱和FTIR对其进行了表征.用TG和DSC以及变温固相原位反应池/傅立叶变换红外光谱(RS-FTIR)联用技术研究了3.5-二硝基水杨酸铈的热分解机理,对主放热反应的DSC峰进行了数学处理.计算得到了动力学参数和动力学方程.结果表明,3,5-二硝基水杨酸铈的分解反应共有3个阶段,其中包括一个脱水吸热过程和一个主放热过程,主分解反应发生在第2阶段,主分解反应的表观活化能E.与指前因子A分别为:159.17 Kj·mol-1和1011.33s-1,主分解阶段的反应机理服从Avrami-Erofeev方程(n=1/4),主分解反应的动力学方程为:da/dt=1011.33×4(1-α)[-In(1-α)]3/4 e-1.92×104/T.%Cerium 3,5-dinitrosalicylate(CeDNS)was synthesized by using 3,5-dinitrosalicylic acid,sodium hydroxide and cerium nitrate as raw materials,and was characterized by elementary analysis,X·ray fluorescence and FTIRspectraoscopy.The thermal decomposition mechanism and kinetm parameters of the decomposition reaction ofCeDNS were investigated by means of TG/DSC and in situ condensed phase thermolysis/FHR(RS-FTIR).The kineticequation of decomposition reaction was obtained.The results show that the decomposition process of CeDNS hasthree stages and the main exothermie decomposition reaction Occurs in the second process.The kinetic parameters ofthe main exothermie decomposition reaction fire:Ea=159.17 kJ·mol-1,A=1011.33 s-1.The kinetic equation can be expressed as:dα/dt=1011.33×4(1-α)[-1n(1-α)]3/4 e -1.92×104/T.

  12. Study of the catalytic activity of pure or cerium-containing thoria in the catalytic oxidation of carbon monoxide (1963); Etude de l'activite catalytique de la thorine pure ou contenant du cerium. Dans l'oxydation de l'oxyde de carbone (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Veron, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    We have undertaken research into the oxidation of carbon monoxide on pure thoria prepared by the decomposition of thorium nitrate, and on the same oxide containing small amounts of cerium. The results we have obtained, both as concerns the chemisorption of the various gases as well as the conductivity of the absorbent and the kinetics of the oxidation itself, appear to be quite coherent. The following steps occur: 1) The carbon monoxide is adsorbed on a clean catalyst surface, the oxygen remaining un-adsorbed. 2) The oxygen is adsorbed on a previously adsorbed carbon, monoxide layer, and reacts to give carbon dioxide (no role being played by the lattice oxygen). This behaviour is usual for a p-type semiconductor. We have in fact confirmed that semi-conductivity is of this type, and the gas-solid interactions can be written: (1) CO{sub (g)} {r_reversible} CO{sup +}{sub (a)} + e{sup -} (2) CO{sup +} 1/2 O{sub 2(g)} + 2 e{sup -} {yields} CO{sup -}{sub 2(a)} (3) CO{sup -}{sub 2(a)} {r_reversible} CO{sub 2(g)} + e{sup -} The kinetic equation obtained by supposing that step (2) is the slowest, makes it possible to deduce correctly the experimental results which can be expressed as: dp / dt = k (P{sup 0.3}{sub CO} x P{sup 0.5}{sub O{sub 2}}) / (1+ k' x P{sub CO{sub 2}}) The influence of the addition of small amounts of cerium can also be explained logically by this process; there is in fact both a decrease in the conductivity and an increase in the catalytic activity, this being characteristic, according to VOLKENSTEIN [52] of an n-type rate-determining reaction occurring on a p-type semi-conductor. We believe that these first results could be advantageously complemented by a study of thoria prepared by other means and doped differently. (author) [French] Nous avons entrepris l'etude de l'oxydation de l'oxyde de carbone sur la thorine pure preparee par decomposition du nitrate de thorium, et sur le meme oxyde renfermant de petites quantites de cerium

  13. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  14. Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316 L stainless steel.

    Science.gov (United States)

    Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

    2012-04-19

    Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316 L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3 wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions.

  15. Isomorphic phase transformation in shocked cerium using molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, Virginie [Los Alamos National Laboratory; Germann, Timothy C [Los Alamos National Laboratory; Chen, Shao - Ping [Los Alamos National Laboratory

    2010-08-12

    Cerium (Ce) undergoes a significant ({approx}16%) volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM) potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD) simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plastic wave. The plastic wave causes the expected fcc-fcc phase transformation. Comparisons to experiments and MD simulations on Cesium (Cs) indicate that three waves could be observed. The construction of the EAM potential may be the source of the difference.

  16. Isomorphic phase transformation in shocked Cerium using molecular dynamics

    Directory of Open Access Journals (Sweden)

    Germann T.C.

    2011-01-01

    Full Text Available Cerium (Ce undergoes a significant (∼16% volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plastic wave. The plastic wave causes the expected fcc-fcc phase transformation. Comparisons to experiments and MD simulations on Cesium (Cs indicate that three waves could be observed. The construction of the EAM potential may be the source of the difference.

  17. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  18. Synthesis and characterization of cerium sulfide thin film

    Institute of Scientific and Technical Information of China (English)

    Ιshak Afsin Kariper

    2014-01-01

    Cerium sulfide (CexSy) polycrystalline thin film is coated with chemical bath deposition on substrates (commercial glass). Transmittance, absorption, optical band gap and refractive index are examined by using UV/VIS. Spectrum. The hexagonal form is observed in the structural properties in XRD. The structural and optical properties of cerium sulfide thin films are analyzed at different pH. SEM and EDX analyses are made for surface analysis and elemental ratio in films. It is observed that some properties of films changed with different pH values. In this study, the focus is on the observed changes in the properties of films. The pH values were scanned at 6–10. The optical band gap changed with pH between 3.40 to 3.60 eV. In addition, the film thickness changed with pH at 411 nm to 880 nm.

  19. Steric and electronic effects of 1,3-disubstituted cyclopentadienyl ligands on metallocene derivatives of Cerium, Titanium, Manganese, and Iron

    Energy Technology Data Exchange (ETDEWEB)

    Sofield, Chadwick Dean [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes. Sterically demanding ligands provided kinetic stabilization for trivalent cerium compounds. Tris(di-t-butylcyclopentadienyl)cerium was prepared and anion competition between halides and cyclopentadienyl groups which had complicated synthesis of the tris(cyclopentadienyl)compound was qualitatively examined. Bis(di-t-butylcyclopentadienyl)cerium methyl was prepared and its rate of decomposition, by ligand redistribution, to tris(di-t-butylcyclopentadienyl)cerium was shown to be slower than the corresponding rate for less sterically demanding ligands. Asymmetrically substituted ligands provided a symmetry label for examination of chemical exchange processes. Tris[trimethylsilyl(t-butyl)cyclopentadienyl]cerium was prepared and the rate of interconversion between the C1 and C3 isomers was examined. The enthalpy difference between the two distereomers is 7.0 kJ/mol. The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me2Si[(Me3C)2C5H3]2), ansa-bis(trimethylsilyl)cyclopentadiene (Me2Si[(Me3Si)2C5H3]2) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography. The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals. A series of 1,3-disubstituted manganocenes was prepared and their electronic states were determined by solid-state magnetic susceptibility, electron paramagnetic resonance, X-ray crystallography, and variable temperature UV-vis spectroscopy. Spin-equilibria in [(Me3C)2C5H3]2Mn and [(Me3

  20. Characterization and activity of visible-light-driven TiO 2 photocatalyst codoped with nitrogen and cerium

    Science.gov (United States)

    Liu, Chao; Tang, Xinhu; Mo, Cehui; Qiang, Zhimin

    2008-04-01

    Nitrogen and cerium codoped TiO 2 photocatalysts were prepared by a modified sol-gel process with doping precursors of cerium nitrate and urea, and characterized by X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray photoelectron spectra (XPS) and ultraviolet-visible light diffuse reflectance spectra (UV-vis DRS). Results indicate that anatase TiO 2 is the dominant crystalline type in as-prepared samples, and CeO 2 crystallites appear as the doping ratio of Ce/Ti reaches to 3.0 at%. The TiO 2 starts to transform from amorphous phase to anatase at 987.1 K during calcination, according to the TG-DSC curves. The XPS show that three major metal ions of Ce 3+, Ce 4+, Ti 4+ and one minor metal ion of Ti 3+ coexist on the surface. The codoped TiO 2 exhibits significant absorption within the range of 400-500 nm compared to the non-doped and only nitrogen-doped TiO 2. The enhanced photocatalytic activity of the codoped TiO 2 is demonstrated through degradation of methyl orange under visible light irradiation.

  1. Antibacterial activity of polymer coated cerium oxide nanoparticles.

    Directory of Open Access Journals (Sweden)

    Vishal Shah

    Full Text Available Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO(4, CaCl(2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO(2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts.

  2. Study of tetravalent cerium incorporation in the monazite structure

    Energy Technology Data Exchange (ETDEWEB)

    Bregiroux, D.; Audubert, F.; Bernache-Assollant, D

    2004-07-01

    The incorporation of tetravalent cerium in the monazite structure (La{sub 1-2x}Ce{sup 4+}{sub x}Ca{sub x}PO{sub 4}) by high temperature solid state synthesis was investigated. First of all, the reaction was followed by DTA-TGA method and X-rays diffraction. It has been shown that CaO first reacts with the phosphate precursor to form Ca(PO{sub 3}){sub 2}. This compound melts near 940 deg C, inducing the dissociation of CeO{sub 2} and the reduction of a large part of cerium IV to cerium III. Two methods have been developed to determine the Ce{sup 4+}/Ce{sup 3+} ratio by using X-ray diffraction and microprobe analysis. We show that Ce{sup 4+} incorporation in LaPO{sub 4} is limited to a Ce{sup 4+}/Ce{sup 3+} = 0.15 value. (authors)

  3. Jet formation in cerium metal to examine material strength

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, B. J., E-mail: bjjensen@lanl.gov; Cherne, F. J.; Prime, M. B.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Fezzaa, K. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Iverson, A. J.; Carlson, C. A. [National Security Technologies LLC, Los Alamos, New Mexico 87544 (United States)

    2015-11-21

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  4. Jet formation in cerium metal to examine material strength

    Science.gov (United States)

    Jensen, B. J.; Cherne, F. J.; Prime, M. B.; Fezzaa, K.; Iverson, A. J.; Carlson, C. A.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G.

    2015-11-01

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2-3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  5. pH-distribution of cerium species in aqueous systems

    Institute of Scientific and Technical Information of China (English)

    B.Bouchaud; J.Balmain; G.Bonnet; F.Pedraza

    2012-01-01

    Cerium-based oxide coalings can be obtained through either chemical or electrochemical processes on various conductor and semiconductor substrates.In both cases the films develop through a precipitation mechanism,which strongly depends on the solution chemistry.In the particular case of the electrolytic approach,the elaboration parameters play a key role on the interfacial pH modification thereby leading to an indirect precipitation mechanism.Indeed,the nucleation and growth mechanisms of crystallites and the composition of the resulting layers have been shown to be also strongly affected by the deposition conditions as well as by the substrate composition,which could in turn modify the protectiveness provided by such coatings.Therefore a better fundamental understanding of the system is required,in particular of the distribution of cerium-containing species in aqueous solution.To this end,the present work intended to develop a diagram showing the distribution as well as the relative amount of Ce(Ⅲ)/Ce(Ⅳ) species in aqueous media as a function of the pH range.The resulting pH-distribution diagram turned out to be a useful tool to predict the relevant precipitation mechanisms and species involved during the growth of cerium-containing films and to draw correlations with the characteristics of the as-deposited films.

  6. Cerium(III) molybdate nanoparticles: Synthesis, characterization and radionuclides adsorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Yousefi, Taher, E-mail: Taher_yosefy@yahoo.com [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of); Tarbiat Moallem University, Mofatteh Ave, Tehran (Iran, Islamic Republic of); Khanchi, Ali Reza; Ahmadi, Seyed Javad [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of); Rofouei, Mohamad Kazem [Tarbiat Moallem University, Mofatteh Ave, Tehran (Iran, Islamic Republic of); Yavari, Ramin; Davarkhah, Reza; Myanji, Behzad [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer A new inorganic nanoparticles with average size about 40 nm were synthesized by chemical method. Black-Right-Pointing-Pointer The morphology studies reveal existing nanowires among dense nanoparticles. Black-Right-Pointing-Pointer Investigation shows it has high stability in rough media and high affinity for Cs(I), U(VI), and Th(IV). Black-Right-Pointing-Pointer It was used for adsorption of radionuclides and removal of {sup 134}Cs from real sample. Black-Right-Pointing-Pointer These findings are important for evaluating human and environmental risk assessment. - Abstract: Cerium(III) molybdate nanostructure with average size about 40 nm was prepared by adding cerium(III) chloride and ammonium molybdate solutions under varying conditions. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and Brunauere Emmette Teller (BET) techniques. Ion exchange capacity of the sample for potassium ion and distribution coefficients (K{sub d}) for 23 metal ions were determined, the K{sub d} values for Tl(I), Pb(II), Th(IV), U(VI), and Cs(I) ions were found to be sufficiently high for their removal from various effluents. The adsorption behavior of the sample towards Cs(I){sub 134} species were studied. Finally, the binary separation of Dy(III)-U(VI), Sm(III)-Th(IV) and Cs(I)-Rb(I) and removal of Cs(I){sub 134} from the real sample were successfully achieved.

  7. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, W.P.S.L.; Mantilaka, M.M.M.G.P.G.; Chathuranga Senarathna, K.G. [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Herath, H.M.T.U. [Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Premachandra, T.N. [Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Ranasinghe, C.S.K. [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Rajapakse, R.P.V.J. [Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Rajapakse, R.M.G., E-mail: rmgr@pdn.ac.lk [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Edirisinghe, Mohan; Mahalingam, S. [Department of Mechanical Engineering, University College London, London WC1E 7JE (United Kingdom); Bandara, I.M.C.C.D. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane 4001, QLD (Australia); Singh, Sanjleena [Central Analytical Research Facility, Institute of Future Environments, Queensland University of Technology, 2 George Street, Brisbane 4001, QLD (Australia)

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO{sub 2} thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. - Highlights: • Colloidal hydroxyapatite nanorods are prepared by a novel method. • Surfaces of titanium metal plates are modified by self-forming TiO{sub 2} thin-films. • Prostheses are prepared by coating hydroxyapatite on surface modified Ti metal. • Bioactivity and noncytotoxicity are increased with surface modifications.

  8. Preparation of activated ceria and its desulfurization performance

    Institute of Scientific and Technical Information of China (English)

    Qing-chun Yu; Yong Deng; Fei Wang; Yue-bin Feng; Xiu-min Chen; Bin Yang; Da-chun Liu

    2015-01-01

    Activated ceria (CeO2/γ-Al2O3) prepared by impregnation was characterized by X-ray diffraction (XRD), scanning electron mi-croscopy (SEM), and hydrogen temperature-programmed reduction (TPR). The desulfurization of the activated ceria was investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TG). The results showed that ceria could be highly dispersed or crystallized on the surface ofγ-alumina. The reduction temperatures of 0.1CeO2/γ-Al2O3, 0.45CeO2/γ-Al2O3, and CeO2 ranged from 250°C to 470°C, 330°C to 550°C, and 350°C to 550°C, respectively. The reduction peak tem-perature of 0.45CeO2/γ-Al2O3 was higher than that of 0.1CeO2/γ-Al2O3, which was consistent with the reduction temperature of CeO2. O2 participated in the reaction between ceria and sulfur dioxide. The desulfurization product was cerium(III) sulfate. The intensity of the hy-droxyl band decreased with the formation of sulfate species.

  9. LUMINESCENT PROPERTIES OF SILICATE GLASSES WITH CERIUM IONS AND ANTIMONY

    Directory of Open Access Journals (Sweden)

    A. M. Klykova

    2014-05-01

    Full Text Available The paper deals with the results of an experimental study of luminescence excitation spectra and luminescence of silicate glasses containing cerium ions and antimony. The aim of this work was to study the features of the luminescence and the effect of UV irradiation and heat treatment on luminescence and the state of cerium ions and antimony in glass. We investigated glass system Na2O-ZnO-Al2O3-SiO2-NaF-NaBr with additives CeO2 and Sb2O3. Synthesis was carried out in platinum crucibles in the air at 14500C. The samples were polished glass plates with a thickness of 0.5-1 mm. UV irradiation was carried out with a mercury lamp having a wide range of radiation in the spectral range 240-390 nm. It was conducted in a Nabertherm muffle furnaces. Luminescence spectra and excitation spectra were measured using a spectrofluorimeter MPF-44A (PerkinElmer at the room temperature. Measured luminescence spectra were corrected in view of the spectral sensitivity of the photodetector for spectrofluorimeter. Adjustment of the excitation spectra for the spectral dependence of the intensity of the excitation source was not carried out. During the experiments it was found that in silicate glasses Sb3+ ions can exist in two energy states, which corresponds to a different environment with oxygen ions. Heat treatment of these glasses in an oxidizing atmosphere leads to an increase in ion concentration of Sb3+ ions with a greater amount of oxygen in the environment. In glasses containing antimony and cerium ions, ultraviolet irradiation causes a change in the valence of cerium ions and antimony, which is accompanied by luminescence quenching. Subsequent heat treatment of glass leads to the inverse processes and restore luminescence excitation spectra. The study of fluorescent properties of silicate glasses with cerium and antimony ions led to the conclusion of the practical significance of this work. Promising multifunctional materials can be created on the basis of

  10. Induction of pulmonary fibrosis by cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jane Y., E-mail: jym1@cdc.gov [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Mercer, Robert R.; Barger, Mark; Schwegler-Berry, Diane; Scabilloni, James [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Ma, Joseph K. [School of Pharmacy, West Virginia University, Morgantown, WV 26506 (United States); Castranova, Vincent [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States)

    2012-08-01

    Cerium compounds have been used as a diesel engine catalyst to lower the mass of diesel exhaust particles, but are emitted as cerium oxide (CeO{sub 2}) nanoparticles in the diesel exhaust. In a previous study, we have demonstrated a wide range of CeO{sub 2}-induced lung responses including sustained pulmonary inflammation and cellular signaling that could lead to pulmonary fibrosis. In this study, we investigated the fibrogenic responses induced by CeO{sub 2} in a rat model at various time points up to 84 days post-exposure. Male Sprague Dawley rats were exposed to CeO{sub 2} by a single intratracheal instillation. Alveolar macrophages (AM) were isolated by bronchial alveolar lavage (BAL). AM-mediated cellular responses, osteopontin (OPN) and transform growth factor (TGF)-β1 in the fibrotic process were investigated. The results showed that CeO{sub 2} exposure significantly increased fibrotic cytokine TGF-β1 and OPN production by AM above controls. The collagen degradation enzymes, matrix metalloproteinase (MMP)-2 and -9 and the tissue inhibitor of MMP were markedly increased in the BAL fluid at 1 day- and subsequently declined at 28 days after exposure, but remained much higher than the controls. CeO{sub 2} induced elevated phospholipids in BAL fluid and increased hydroxyproline content in lung tissue in a dose- and time-dependent manner. Immunohistochemical analysis showed MMP-2, MMP-9 and MMP-10 expressions in fibrotic regions. Morphological analysis noted increased collagen fibers in the lungs exposed to a single dose of 3.5 mg/kg CeO{sub 2} and euthanized at 28 days post-exposure. Collectively, our studies show that CeO{sub 2} induced fibrotic lung injury in rats, suggesting it may cause potential health effects. -- Highlights: ► Cerium oxide exposure significantly affected the following parameters in the lung. ► Induced fibrotic cytokine OPN and TGF-β1 production and phospholipidosis. ► Caused imbalance of the MMP-9/ TIMP-1 ratio that favors fibrosis

  11. Single crystal to single crystal transformation and hydrogen-atom transfer upon oxidation of a cerium coordination compound.

    Science.gov (United States)

    Williams, Ursula J; Mahoney, Brian D; Lewis, Andrew J; DeGregorio, Patrick T; Carroll, Patrick J; Schelter, Eric J

    2013-04-15

    Trivalent and tetravalent cerium compounds of the octamethyltetraazaannulene (H2omtaa) ligand have been synthesized. Electrochemical analysis shows a strong thermodynamic preference for the formal cerium(IV) oxidation state. Oxidation of the cerium(III) congener Ce(Homtaa)(omtaa) occurs by hydrogen-atom transfer that includes a single crystal to single crystal transformation upon exposure to an ambient atmosphere.

  12. Porous Silicon & Titanium Dioxide Coatings Prepared by Atmospheric Pressure Plasma Jet Chemical Vapour Deposition Technique-A Novel Coating Technology for Photovoltaic Modules

    Directory of Open Access Journals (Sweden)

    S. Bhatt

    2011-01-01

    Full Text Available Atmospheric Pressure Plasma Jet (APPJ is an alternative for wet processes used to make anti reflection coatings and smooth substrate surface for the PV module. It is also an attractive technique because of it’s high growth rate, low power consumption, lower cost and absence of high cost vacuum systems. This work deals with the deposition of silicon oxide from hexamethyldisiloxane (HMDSO thin films and titanium dioxide from tetraisopropyl ortho titanate using an atmospheric pressure plasma jet (APPJ system in open air conditions. A sinusoidal high voltage with a frequency between 19-23 kHz at power up to 1000 W was applied between two tubular electrodes separated by a dielectric material. The jet, characterized by Tg ~ 600-800 K, was mostly laminar (Re ~ 1200 at the nozzle exit and became partially turbulent along the jet axis (Re ~ 3300. The spatially resolved emission spectra showed OH, N2, N2+ and CN molecular bands and O, H, N, Cu and Cr lines as well as the NO2 chemiluminescence continuum (450-800 nm. Thin films with good uniformity on the substrate were obtained at high deposition rate, between 800 -1000 nm.s-1, and AFM results revealed that coatings are relatively smooth (Ra ~ 2 nm. The FTIR and SEM analyses were better used to monitor the chemical composition and the morphology of the films in function of the different experimental conditions.

  13. Influence of the surface pre-treatment of aluminum on the processes of formation of cerium oxides protective films

    Science.gov (United States)

    Andreeva, R.; Stoyanova, E.; Tsanev, A.; Stoychev, D.

    2016-03-01

    It is known that there is special interest in the contemporary investigations on conversion treatment of aluminum aimed at promoting its corrosion stability, which is focused on electrolytes on the basis of salts of metals belonging to the group of rare-earth elements. Their application is especially attractive, as it enables a successful substitution of the presently applied highly efficient, but at the same time toxic Cr6+-containing electrolytes. The present paper presents a study on the influence of the preliminary alkaline activation and acidic de-oxidation of the aluminum surface on the processes of immersion formation of protective cerium oxides films on Al 1050. The results obtained show that their deposition from simple electrolytes (containing only salts of Ce3+ ions) on the Al surface, treated only in alkaline solution, occurs at a higher rate, which leads to preparing thicker oxide films having a better protective ability. In the cases when the formation of oxide films is realized in a complex electrolyte (containing salts of Ce3+ and Cu2+ ions), better results are obtained with respect to the morphology and protective action of cerium oxides film on samples that have been consecutively activated in alkaline solution and deoxidized in acidic solution. Electrochemical investigations were carried out in a model corrosion medium (0.1 M NaCl); it was shown that the cerium protective films, deposited by immersion, have a cathodic character with regard to the aluminum support and inhibit the occurrence of the depolarizing corrosion process -- the reaction of oxygen reduction.

  14. Photocatalytic Reaction of Sulfur Dioxide with Heptane in the Gas-phase Over Titanium Dioxide

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The photocatalytic reaction of sulfur dioxide with heptane was carried out with the aid of UV-illuminated titanium dioxide ultrafine particles(UFP) at room temperature.The TiO2 UFP was prepared by means of colloidal chemical method.The structure and the surface state of the as-prepared TiO2 UFP via different heat-treatments were studied.As the calcining temperature decreased,the contents of hydroxyl on the surface increased,which could help to enhance the photocatalytic activity of the TiO2 UFP.The mechanism of the photocatalytic reaction of sulfur dioxide with heptane was proposed,in which there was a competition of photocatalytic oxidation between sulfur dioxide and heptane over the TiO2 UFP.It is inferred that the reactive oxygen species play an important role in the photocatalytic reaction of sulfur dioxide with heptane.

  15. 玻璃纤维负载纳米TiO2的制备及光催化性能%Preparation and Photocatalytic Properties of Nano-titanium Dioxide Supported on Glass Fiber

    Institute of Scientific and Technical Information of China (English)

    林中信; 万隆; 张世英; 李云龙; 方志薇

    2011-01-01

    TiO2/GF composites were prepared by loading titania on the glass fiber with dipping method.The sample was characterized by X-ray diffraction (XRD), thermogravimetric-differential scanning calorimeter ( TG-DSC), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis technologies. The results show that when the calcination temperature below 550 ℃, the titania dioxide crystalline phase were anatase. The titania dioxide gradually transformed into rutile crystal phase with the increasing of the calcination temperatures. The photocatalytic activitie of TiO2/GF composites were evaluated by the photocatalytic decomposition of methylene blue. The composites showed higher photocatalytic activities as P25 commercial pure titania dioxide nanoparticles. The decomposition of methylene blue was more than 80% after repeated use.%采用浸渍-提拉法在玻璃纤维(GF)表面负载纳米TiO2,制备TiO2/GF复合光催化剂.通过X射线衍射(XRD)、热重-差热分析(TG-DSC)、扫描电镜(SEM)及能谱元素分析(EDS)对TiO2/GF复合光催化剂的结构进行了表征.结果表明,经550 ℃以下热处理,TiO2的晶型为锐钛矿相,随着热处理温度的升高,TiO2的晶型逐渐转化为金红石相.以亚甲基蓝的光催化降解为探针反应,评价TiO2/GF复合材料的光催化活性.复合材料的光催化降解活性与P25相当,且经多次使用后,复合光催化剂对亚甲基蓝的降解率仍保持在80%以上.

  16. Effect of natural organic matter on cerium dioxide nanoparticles settling in model fresh water

    NARCIS (Netherlands)

    Quik, J.T.K.; Lynch, I.; Hoecke, van K.; Miermans, C.J.H.; Schamphelaere, de K.A.C.; Janssen, C.R.; Dawson, K.A.; Cohen Stuart, M.A.; Meent, van de D.

    2010-01-01

    The ecological risk assessment of chemicals including nanoparticles is based on the determination of adverse effects on organisms and on the environmental concentrations to which biota are exposed. The aim of this work was to better understand the behavior of nanoparticles in the environment, with t

  17. Existence of three-phase interlines on a cerium dioxide surface

    CERN Document Server

    Osarinmwian, Charles

    2013-01-01

    The three-phase interline described by a statistical continuum limit (i.e. quasi-boundary) has been postulated to gain a deeper insight into the reduction of CeO2 to CeO1.940 in a LiCl-KCl eutectic melt. Fabrication of a CeO2 superstructure by a condensed-phase method provided a CeO2 (111) surface at the nanoscale, which allowed the three-phase interline to be identified given previously reported quantum confinement effects in quasi-stoichiometric CeO2 nanoparticles. Also, the CeO2 superstructure displays the same crystal lattice planes as a bulk CeO2 grain but the triply degenerate Raman-active peak of the grain is higher by a factor of ~ 2.5 with a wider full width at half maximum.

  18. Synthesis of Cerium Dioxide High-k Thin Films as a Gate Dielectric in MOS Capacitor

    Directory of Open Access Journals (Sweden)

    Anil G. Khairnar

    2013-07-01

    Full Text Available In the present study, the Al/CeO2 / p-Si MOS capacitor was fabricated by depositing the Aluminium (Al metal layer by thermal evaporation technique on sol-gel derived CeO2 high-k thin films on p-Si substrate. The deposited CeO2 films were characterized by Ellipsometer to study the refractive index that is determined to be 3.62. The FTIR analysis was carried out to obtain chemical bonding characteristics. Capacitance-voltage measurements of Al/CeO2 /p-Si MOS capacitor were carried out to determine the dielectric constant, equivalent oxide thickness (EOT and flat band shift (VFB for the deposited CeO2 film of 16.22, 1.62 nm and 0.7 V respectively. The conductance voltage curve was used to determine the interface trap density (Dit at the CeO2 / p-Si interface that is calculated to be 1.29 × 1013 cm – 2 eV – 1 for measurement frequency of 500 kHz.

  19. Cerium dioxide and zinc oxide nanoparticles alter the nutritional value of soil cultivated soybean plants.

    Science.gov (United States)

    Peralta-Videa, Jose R; Hernandez-Viezcas, Jose A; Zhao, Lijuan; Diaz, Baltazar Corral; Ge, Yuan; Priester, John H; Holden, Patricia Ann; Gardea-Torresdey, Jorge L

    2014-07-01

    The aim of this study was to determine nutrient elements in soybean (Glycine max) plants cultivated in farm soil amended with nCeO2 at 0-1000 mg kg(-1) and nZnO at 0-500 mg kg(-1). Digested samples were analyzed by ICP-OES/MS. Compared to control, pods from nCeO2 at 1000 mg kg(-1) had significantly less Ca but more P and Cu, while pods from 100 mg kg(-1)nZnO had more Zn, Mn, and Cu. Plants treated with nZnO showed significant correlations among Zn, P, and S in pods with Zn in roots. Correlations among pod Zn/root Zn was r = 0.808 (p ≤ 0.01) and pod P/root P was r = 0.541 (p ≤ 0.05). The correlation among pod S/root S was r = -0.65 (p ≤ 0.01). While nCeO2 treatments exhibited significant correlations between pod Ca/root Ca (r = 0.645, p ≤ 0.05). The data suggest that nCeO2 and nZnO alter the nutritional value of soybean, which could affect the health of plants, humans, and animals.

  20. Exposure to Cerium Dioxide Nanoparticles Differently Affect Swimming Performance and Survival in Two Daphnid Species

    Science.gov (United States)

    Artells, Ester; Issartel, Julien; Auffan, Mélanie; Borschneck, Daniel; Thill, Antoine; Tella, Marie; Brousset, Lenka; Rose, Jérôme; Bottero, Jean-Yves; Thiéry, Alain

    2013-01-01

    The CeO2 NPs are increasingly used in industry but the environmental release of these NPs and their subsequent behavior and biological effects are currently unclear. This study evaluates for the first time the effects of CeO2 NPs on the survival and the swimming performance of two cladoceran species, Daphnia similis and Daphnia pulex after 1, 10 and 100 mg.L−1 CeO2 exposures for 48 h. Acute toxicity bioassays were performed to determine EC50 of exposed daphnids. Video-recorded swimming behavior of both daphnids was used to measure swimming speeds after various exposures to aggregated CeO2 NPs. The acute ecotoxicity showed that D. similis is 350 times more sensitive to CeO2 NPs than D. pulex, showing 48-h EC50 of 0.26 mg.L−1 and 91.79 mg.L−1, respectively. Both species interacted with CeO2 NPs (adsorption), but much more strongly in the case of D. similis. Swimming velocities (SV) were differently and significantly affected by CeO2 NPs for both species. A 48-h exposure to 1 mg.L−1 induced a decrease of 30% and 40% of the SV in D. pulex and D. similis, respectively. However at higher concentrations, the SV of D. similis was more impacted (60% off for 10 mg.L−1 and 100 mg.L−1) than the one of D. pulex. These interspecific toxic effects of CeO2 NPs are explained by morphological variations such as the presence of reliefs on the cuticle and a longer distal spine in D. similis acting as traps for the CeO2 aggregates. In addition, D. similis has a mean SV double that of D. pulex and thus initially collides with twice more NPs aggregates. The ecotoxicological consequences on the behavior and physiology of a CeO2 NPs exposure in daphnids are discussed. PMID:23977004

  1. Toxicity assessment of Titanium Dioxide and Cerium Oxide nanoparticles in Arabidopsis thaliana L.

    Science.gov (United States)

    The production and applications of nanoparticles (NP) in diverse fields has steadily increased in recent decades; however, knowledge about risks of NP to human health and ecosystems is still scarce. In this study, we assessed potential toxicity of two commercially used engineere...

  2. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces.

    Science.gov (United States)

    Wijesinghe, W P S L; Mantilaka, M M M G P G; Chathuranga Senarathna, K G; Herath, H M T U; Premachandra, T N; Ranasinghe, C S K; Rajapakse, R P V J; Rajapakse, R M G; Edirisinghe, Mohan; Mahalingam, S; Bandara, I M C C D; Singh, Sanjleena

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value.

  3. Tuning Reactivity and Electronic Properties through Ligand Reorganization within a Cerium Heterobimetallic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Jerome R.; Gordon, Zachary; Booth, Corwin H.; Carroll, Patrick J.; Walsh, Patrick J.; Schelter, Eric J.

    2014-06-24

    Cerium compounds have played vital roles in organic, inorganic, and materials chemistry due to their reversible redox chemistry between trivalent and tetravalent oxidation states. However, attempts to rationally access molecular cerium complexes in both oxidation states have been frustrated by unpredictable reactivity in cerium(III) oxidation chemistry. Such oxidation reactions are limited by steric saturation at the metal ion, which can result in high energy activation barriers for electron transfer. An alternative approach has been realized using a rare earth/alkali metal/1,1'-BINOLate (REMB) heterobimetallic framework, which uses redox-inactive metals within the secondary coordination sphere to control ligand reorganization. The rational syntheses of functionalized cerium(IV) products and a mechanistic examination of the role of ligand reorganization in cerium(III) oxidation are presented.

  4. Preparation of HZSM-5 membrane packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles for catalysing carbon dioxide hydrogenation to dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rong; Tian, Haifeng; Yang, Aimei; Zha, Fei, E-mail: zhafei@nwnu.edu.cn; Ding, Jian; Chang, Yue

    2015-08-01

    Highlights: • CuO–ZnO–Al{sub 2}O{sub 3} composite nanoparticles were successfully prepared using carbon sphere as template. • HZSM-5@CuO–ZnO–Al{sub 2}O{sub 3} capsule catalyst was prepared hydrothermally. • Zeolite capsule catalysts exhibited an extremely good selectivity for DME compared with the conventional hybrid catalyst. - Abstract: Spherical carbons were prepared successfully from aqueous glucose using hydrothermal method. After covered with aqueous Cu{sup 2+}, Zn{sup 2+} and Al{sup 3+} ions during the co-precipitation treatment, carbons were removed via calcination to yield CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles. HZSM-5 membrane, which was synthesized using tetrapropylammonium hydroxide as templating agent, was packed onto CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles hydrothermally to form HZSM-5 packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles. It was characterized by the method of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen sorption measurement. HZSM-5 packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles were used as catalysts for the CO{sub 2} hydrogenation to dimethyl ether. The catalyst activity was investigated in a fixed-bed reactor. Under the reaction conditions of pressure at 3.0 MPa, space velocity (SV) of 1800 mL g{sub cat}{sup −1} h{sup −1}, volume ratio of CO{sub 2}/H{sub 2} to 1:3 and temperature at 270 °C, the conversion of CO{sub 2} could reach to 48.3%, with a dimethyl ether yield and selectivity of 23.4% and 48.5%, respectively.

  5. Preparation and catalytic properties of ZrO2-Al2O3 composite oxide supported nickel catalysts for methane reforming with carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    HAO Zheng-ping; HU Chun; JIANG Zheng; G. Q. LU

    2004-01-01

    ZrO2-Al2O3 composite oxides and supported Ni catalysts were prepared , and characterized by N2adsorption/desorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy ( XPS ) techniques. Thecatalytic performance and carbon deposition was also investigated. This mesoporous composite oxide is shown to bea promising catalyst support. An increase in the catalytic activity and stability of methane and carbon dioxidereforming reaction was resulted from the zirconia addition, especially at 5wt% ZrO2 content. The Ni catalystsupported ZrO2-Al2O3 has a strong resistance to sintering and the carbon deposition in a relatively long-termreaction.

  6. Effect of cerium additive on aluminum-based chemical conversion coating on AZ91D magnesium alloy

    Science.gov (United States)

    Wang, Ximei; Zhu, Liqun; He, Xiang; Sun, Fenglou

    2013-09-01

    Based on environmentally friendly and recycling of magnesium alloys, chemical conversion coatings were prepared in aluminum nitrate solutions with cerium nitrate additive on AZ91D magnesium alloys surfaces. Effect of additive's concentration on the surface morphology, composition and corrosion resistance of aluminum-based conversion coating on magnesium alloys was studied. The surface morphology, composition, microstructure and corrosion resistance of conversion coatings were investigated using scanning electron microscopy (SEM), X-ray energy dispersion spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical tests respectively. The results show that the cerium content of the conversion coatings surface increased with increasing additive concentration. The conversion coatings’ morphologies first gradually became dense and the micro-cracks on the coating surface became narrow with the increase of the additive concentration. Then the coatings’ morphologies became bad and the micro-cracks widened after the additive concentration reached 0.005 mol/L. When the additive concentration was 0.005 mol/L, the conversion coating consists of Al(OH)3, Al2O3, Mg(OH)2, MgO, CeO2 and Ce2O3; the conversion coating surface morphology was the densest and the micro-cracks were the narrowest, and the corrosion resistance was also the best.

  7. Effect of Cerium on Microstructures and High Temperature Oxidation Resistance of An Nb-Si System In-Situ Composite

    Institute of Scientific and Technical Information of China (English)

    Liu Aiqin; Sun Lu; Li Shusuo; Han Yafang

    2007-01-01

    Nb-16Si-24Ti-6Cr-6Al-2Hf-xCe (x=0, 0.05, 0.1, 0.25, 0.5, 1 (%, atom fraction)) in situ composites were prepared by arc melting. The microstructure and the effect of rare earth element cerium on 1250 ℃ oxidation resistance of the composites were investigated with scanning electron microscopy (SEM) and X-ray energy disperse spectrum (EDS), as well as X-ray diffraction (XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was improved by adding a proper amount of cerium (Ce). The effect of Ce was considered as the concurrent of the following three factors: first, the oxide of Ce formed in the interface reduced the internal oxidation rate; second, the lath shaped oxide containing Ce increased the cracking resistance and reduced the expansion of the oxide scale; and third, the decrease of the silicide volume fraction on account of Ce addition reduces the power of the sample resisting oxy gen penetration.

  8. Enhancement in Activity of a Vanadium Catalyst for the Oxidation of Sulfur Dioxide by Radio Frequency Plasma During the Preparation Process

    Institute of Scientific and Technical Information of China (English)

    Zhenxing Chen; Honggui Li; Lingsen Wang

    2003-01-01

    Radio frequency plasma was used to prepare a vanadium catalyst. The results showed that activating time of the catalyst could be shortened quickly and the catalytic activity was improved to some extent with the use of plasma. Catalyst Ls-9 was prepared under an optimal condition of 40 W discharge power, 10 min discharge time and 8 Pa gas pressure. The catalytic activity was up to 54.7% at 410 ℃,which was 2.2% higher than that of the Ls-8 catalyst. Only 10 min was needed to activate the catalyst with plasma, which was 1/9 of the traditional calcination time. For Ls-9, both the endothermic as well as the exothermic peaks detected by differential thermal analysis shifted to higher temperatures obviously,indicating that its crystal phase could melt easily. There existed an apparent endothermic peak at 283 ℃. SEM photographs showed a uniform size distribution. It is inferred that the quadrivalent vanadium compound may exist mainly in the form of VOSO4.

  9. Spectrophotometric determination of cerium with methylthymol blue in the presence of oxalate and cyanide as masking agents

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Martin, A.; Izquierdo-Hornillos, R.; Quejido-Cabezas, A.J.; Peral-Fernandez, J.L. (Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas)

    1983-04-01

    The spectrophotometric determination of cerium can be carried out by several methods, which involve either the formation of complexes of cerium(III) and cerium(IV) or the oxidation of suitable reagents by cerium(IV) and further measuring the intensity of the colour of the oxidised matter. The latter methods show a lack of selectivity and low sensitivity owing to the nature of the redox reaction. The methods that involve the formation of complexes have also been shown to have low selectivity and sensitivity. However, the most useful methods are those based on the complexes of cerium(III) with Xylenol Orange and Methylthymol Blue (MTB), but they are affected by many interferences. In this work the reaction of cerium(III) with MTB in the presence of oxalate and cyanide ions was studied at pH 10.2, which improves the sensitivity and the selectivity of the determination of cerium.

  10. Electrochemical studies on cerium(Ⅲ) in molten fluoride mixtures

    Institute of Scientific and Technical Information of China (English)

    VIRGIL; CONSTANTIN; ANA-MARIA; POPESCU; MIRCEA; OLTEANU

    2010-01-01

    This study aims to determine the principal electrochemical characteristics of the electrodeposition of cerium metal from molten fluoride systems.The cathodic process of Ce3+ ions in LiF-NaF and LiF-NaF-CaF2 molten salts was studied using electrochemical techniques as steady state and cyclic voltammetry methods.The decomposition potential(Ed) and the overvoltage(η) were determined for NaCeF4 using current-potential curves under galvanostatic conditions.The Ed was found to be 2.025 V in LiF-NaF and 2.045 V in...

  11. Cerium oxide based nanometric powders: synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Ninić M.

    2007-01-01

    Full Text Available Nanometric powders of solid solutions of cerium oxide were obtained by a modified glycine nitrate procedure. Solid solutions of the host compound CeO2 with one or more dopants in the lattice were synthesized. Rare earth cations (Re=Yb, Gd and Sm were added to ceria in total concentration of x= 0.2 that was kept constant. The criterion in doping was to keep the value of lattice parameter of ceria unchanged. The lattice parameters were calculated by using the model that takes into account the existence of oxygen vacancies in the structure.

  12. Options for the recovery of cerium by solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Soldenhoff, K.H. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    This paper reports the results of an experimental program to examine the use of various commercial reagents for the extraction of cerium (IV) from sulphate solutions. Extractants tested include organophosphorus esters (TOPO, Cyanex 923 and Cyanex 925), organophosphorus acids (DEHPA, lonquest 801 and Cyanex 272) and high molecular weight amine, Alamine 336. The suitability of reagents is assessed in terms of process relevant criteria such as extraction dependence on acidity, selectivity over other rare earths and thorium, stability of reagent towards oxidation and loading characteristics. (author) 15 refs., 2 tabs., 5 figs.

  13. Identification of the Charge Carriers in Cerium Phosphate Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Hannah L.; Jonghe, Lutgard C. De

    2010-06-02

    The total conductivity of Sr-doped cerium orthophosphate changes by nearly two orders of magnitude depending on the oxygen and hydrogen content of the atmosphere. The defect model for the system suggests that this is because the identity of the dominant charge carrier can change from electron holes to protons when the sample is in equilibrium with air vs. humidified hydrogen. In this work are presented some preliminary measurements that can help to clarify this exchange between carriers. The conduction behavior of a 2percent Sr-doped CePO4 sample under symmetric atmospheric conditions is investigated using several techniques, including AC impedance, H/D isotope effects, and chronoamperometry.

  14. Properties of hot liquid cerium by LDA + U molecular dynamics.

    Science.gov (United States)

    Siberchicot, Bruno; Clérouin, Jean

    2012-11-14

    We present ab initio simulations of liquid cerium in the framework of the LDA + U formulation. The liquid density has been determined self-consistently by searching for the zero pressure equilibrium state at 1320 K with the same set of parameters (U and J) and occupation matrices as those optimized for the γ phase. We have computed static and transport properties. The liquid produced by the simulations appears more structured than the available measurements. This raises questions regarding the ability of the theory to describe such a complex liquid. Conductivity calculations and temperature dependences are nevertheless in reasonable agreement with data.

  15. Preparation of Zirconia-Ceria Powders with High Specific Surface Area

    Institute of Scientific and Technical Information of China (English)

    Wang Enguo; Mei Fang

    2004-01-01

    Zirconia-ceria mixed oxide powders were prepared by high temperature aging method.The effects of the temperature and the time of aging, cerium content and calcination on powder performance were studied.The result shows that high temperature aging is an efficient way of preparation of ZrO2-CeO2 mixed oxide powders with high specific surface area and good thermal stability, and that addition of a small amount of cerium to hydrous zirconia can promote the preparation of high specific surface area powders.

  16. Preparation of disinfectant containing both chlorine dioxide and chlorine for safe urban reuse%复合二氧化氯的制备及其用于城市污水回用消毒

    Institute of Scientific and Technical Information of China (English)

    樊金红; 王红武; 马鲁铭

    2012-01-01

    在酸性环境中通过NaCl电解协同NaClO2化学氧化方法制备的复合二氧化氯溶液中ClO2和自由氯浓度分别达到70%和20%左右,系统地研究了电流密度(A)、NaClO2与NaCl质量比(B)、电解时间(C)对复合溶液中组分浓度和质量百分数的影响,并将复合溶液用于城市污水二级处理出水的消毒.结果表明,复合溶液中自由氯的浓度主要受因素C和A的影响,ClO2的浓度主要受因素C和B的影响,而A对副产物ClO-2和ClO-3的影响最大.总大肠菌群数在105~108个?L-1的城市污水二级处理出水采用复合溶液消毒时,当其中ClO2投加量为4mg? L-1,自由氯含量不低于1.20 mg?L-1,经30 min接触后出水生物学指标满足GB/T 18920-2002的要求.既降低了消毒剂的使用量,又减少了消毒副产物ClO-2的生成.%To achieve simultaneously maximum disinfection and minimum toxicity a mix disinfectant of chlorine dioxide and chlorine are found to be efficient for disinfection of drinking water and urban reused waste-water. However, transportation and reservation of the mixture may threat to environmental safety. Therefore, on-site preparation is necessary for field use. At present, preparation methods of the mix disinfectant have chemical reduction of sodium chlorate and electrolysis of sodium chloride, and the content of chlorine dioxide in mixture obtained is usually below 30%. To get high chlorine dioxide content, a method for the preparation of the mix disinfectant was proposed : electrolyzing sodium chloride (NaCl) was followed by a chemical oxidation of sodium chlorite (NaClC2) in an undivided electrolysis reactor, in which the content of C1O2 in the mix disinfectant can be controlled. The effect of current density (A), mass ratio of NaCIO2: NaCl (B), electrolysis time (C) on the concentration and mass percentage of CIO2, free chlorine, ClO-2 and C1O-3 was investigated systematically. Under the electrolysis conditions: current density 41. 67-83. 33 A

  17. 染料敏化二氧化钛薄膜电极的制备及其光电性能研究%Preparation of Dye-sensitized Titanium Dioxide Film Electrode and Its Optical Properties

    Institute of Scientific and Technical Information of China (English)

    平从; 吴志明

    2011-01-01

    DSSC电池(染料敏二氧化钛纳米晶太阳能电池)作为一种新型光化学太阳能电池,具有制作工艺简单,制作成本低廉,使用性能稳定等诸多优点,在太阳能电池发展方面具有里程碑式的重要意义.本文针对染料敏化二氧化钛薄膜电极的制备及其光电性能进行了一些研究和探索.%DSSC cell, as a novel photochemical solar cell, has many advantages, such as the simple production process, low production cost, stable performance and so on, which has milestone significance in the development of solar cells. In this paper, the research and exploration on preparation of dye-sensitized titanium dioxide film electrode and its optical properties are conducted.

  18. Carbon dioxide conversion over carbon-based nanocatalysts.

    Science.gov (United States)

    Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

    2013-07-01

    The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.

  19. Pulmonary toxicity of well-dispersed cerium oxide nanoparticles following intratracheal instillation and inhalation

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, Yasuo, E-mail: yasuom@med.uoeh-u.ac.jp; Izumi, Hiroto; Yoshiura, Yukiko; Tomonaga, Taisuke; Oyabu, Takako; Myojo, Toshihiko; Kawai, Kazuaki; Yatera, Kazuhiro [University of Occupational and Environmental Health (Japan); Shimada, Manabu; Kubo, Masaru [Hiroshima University (Japan); Yamamoto, Kazuhiro [National Institute of Advanced Industrial Science and Technology (AIST) (Japan); Kitajima, Shinichi [National Sanatorium Hoshizuka Keiaien (Japan); Kuroda, Etsushi [Osaka University, Laboratory of Vaccine Science, WPI Immunology Frontier Research Center (Japan); Kawaguchi, Kenji; Sasaki, Takeshi [National Institute of Advanced Industrial Science and Technology (AIST) (Japan)

    2015-11-15

    We performed inhalation and intratracheal instillation studies of cerium dioxide (CeO{sub 2}) nanoparticles in order to investigate their pulmonary toxicity, and observed pulmonary inflammation not only in the acute and but also in the chronic phases. In the intratracheal instillation study, F344 rats were exposed to 0.2 mg or 1 mg of CeO{sub 2} nanoparticles. Cell analysis and chemokines in bronchoalveolar lavage fluid (BALF) were analyzed from 3 days to 6 months following the instillation. In the inhalation study, rats were exposed to the maximum concentration of inhaled CeO{sub 2} nanoparticles (2, 10 mg/m{sup 3}, respectively) for 4 weeks (6 h/day, 5 days/week). The same endpoints as in the intratracheal instillation study were examined from 3 days to 3 months after the end of the exposure. The intratracheal instillation of CeO{sub 2} nanoparticles caused a persistent increase in the total and neutrophil number in BALF and in the concentration of cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2, chemokine for neutrophil, and heme oxygenase-1 (HO-1), an oxidative stress marker, in BALF during the observation time. The inhalation of CeO{sub 2} nanoparticles also induced a persistent influx of neutrophils and expression of CINC-1, CINC-2, and HO-1 in BALF. Pathological features revealed that inflammatory cells, including macrophages and neutrophils, invaded the alveolar space in both studies. Taken together, the CeO{sub 2} nanoparticles induced not only acute but also chronic inflammation in the lung, suggesting that CeO{sub 2} nanoparticles have a pulmonary toxicity that can lead to irreversible lesions.

  20. Biosorption potential of cerium ions usingSpirulina biomass

    Institute of Scientific and Technical Information of China (English)

    David Sadovsky; Asher Brenner; Boaz Astrachan; Boaz Asaf; Raphael Gonen

    2016-01-01

    Two types of cyanobacteria of the genusArthrospira (commonly known asSpirulina) were tested for biosorption of ce-rium(III) ions from aqueous solutions. An endemic type (ES) found in the northern Negev desert, Israel, and a commercial powder (CS) were used in this study. Biosorption was evaluated as a function of pH, contact time, initial metal concentration, number of sorp-tion-desorption cycles, and salt concentration. The optimum pH range for biosorption was found to be 5.0–5.5. The kinetic character-istics of bothSpirulina types were found to be highly compatible with a pseudo-second order kinetic model. The adsorption isotherms of both types were found to be well-suited to Langmuir and Freundlich adsorption isotherms. Maximum biosorption uptakes, accord-ing to the Langmuir model, were 18.1 and 38.2 mg/g, for ES and CS, respectively. Sodium chloride concentrations of up to 5 g/L had a minor effect on cerium biosorption. Desorption efficiency was found to be greater than 97% with 0.1 mol/L HNO3 after three sorp-tion-desorption cycles, without significant loss in the biosorption capacity. The results indicated the feasibility of cerium recovery from industrial wastes usingSpirulina biomass.

  1. Cerium fluoride nanoparticles protect cells against oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Shcherbakov, Alexander B.; Zholobak, Nadezhda M. [Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv D0368 (Ukraine); Baranchikov, Alexander E. [Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); Ryabova, Anastasia V. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409 (Russian Federation); Ivanov, Vladimir K., E-mail: van@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); National Research Tomsk State University, Tomsk 634050 (Russian Federation)

    2015-05-01

    A novel facile method of non-doped and fluorescent terbium-doped cerium fluoride stable aqueous sols synthesis is proposed. Intense green luminescence of CeF{sub 3}:Tb nanoparticles can be used to visualize these nanoparticles' accumulation in cells using confocal laser scanning microscopy. Cerium fluoride nanoparticles are shown for the first time to protect both organic molecules and living cells from the oxidative action of hydrogen peroxide. Both non-doped and terbium-doped CeF{sub 3} nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus. - Highlights: • Facile method of CeF{sub 3} and CeF{sub 3}:Tb stable aqueous sols synthesis is proposed. • Naked CeF{sub 3} nanoparticles are shown to be non-toxic and to protect cells from the action of H{sub 2}O{sub 2}. • CeF{sub 3} and CeF{sub 3}:Tb nanoparticles are shown to protect living cells against the vesicular stomatitis virus.

  2. Cerium Tetrafluoride: Sublimation, Thermolysis, and Atomic Fluorine Migration.

    Science.gov (United States)

    Chilingarov, N S; Knot'ko, A V; Shlyapnikov, I M; Mazej, Z; Kristl, M; Sidorov, L N

    2015-08-06

    Saturated vapor pressure p° and enthalpy of sublimation (ΔsH°) of cerium tetrafluoride CeF4 were determined by means of Knudsen effusion mass spectrometry in the range of 750-920 K. It was discovered that sublimation of cerium tetrafluoride from a platinum effusion cell competes with thermal decomposition to CeF3 in the solid phase, but no accompanying release of fluorine to the gas phase occurs. Thus, fluorine atoms migrate within the surface layer of CeF4(s) to the regions of their irreversible drain. We used scanning electron microscopy to study the distribution of the residual CeF3(s) across the inner surface of the effusion cell after complete evaporation of CeF4(s). It was observed that CeF3 accumulates near the edge of the effusion orifice and near the junction of the lid and the body of the cell, that is, in those regions where the fluorine atoms can migrate to a free platinum surface and thus be depleted from the system. Distribution of CeF3(s) solid particles indicates the ways of fluorine atoms migration providing CeF3(s) formation inside the CeF4(s) surface layer.

  3. Functionalization of nanostructured cerium oxide films with histidine.

    Science.gov (United States)

    Tsud, Nataliya; Bercha, Sofiia; Acres, Robert G; Vorokhta, Mykhailo; Khalakhan, Ivan; Prince, Kevin C; Matolín, Vladimír

    2015-01-28

    The surfaces of polycrystalline cerium oxide films were modified by histidine adsorption under vacuum and characterized by the synchrotron based techniques of core and valence level photoemission, resonant photoemission and near edge X-ray absorption spectroscopy, as well as atomic force microscopy. Histidine is strongly bound to the oxide surface in the anionic form through the deprotonated carboxylate group, and forms a disordered molecular adlayer. The imidazole ring and the amino side group do not form bonds with the substrate but are involved in the intermolecular hydrogen bonding which stabilizes the molecular adlayer. The surface reaction with histidine results in water desorption accompanied by oxide reduction, which is propagated into the bulk of the film. Previously studied, well-characterized surfaces are a guide to the chemistry of the present polycrystalline surface and histidine bonds via the carboxylate group in both cases. In contrast, bonding via the imidazole group occurs on the well-ordered surface but not in the present case. The morphology and structure of the cerium oxide are decisive factors which define the adsorption geometry of the histidine adlayer.

  4. 二氧化硫脲为硫源制备硫掺杂二氧化钛及其光催化活性%PREPARATION AND PHOTOCATALYTIC ACTIVITY OF SULFUR-DOPED TITANIA USING THIOUREA DIOXIDE AS SULFUR SOURCE

    Institute of Scientific and Technical Information of China (English)

    王竹梅; 李月明; 沈宗洋; 洪燕; 左建林

    2011-01-01

    以钛酸四丁酯为TiO2的前驱物,二氧化硫脲为掺杂硫的源物质,采用溶胶-凝胶法制备了掺硫改性的TiO2光催化剂.采用XRD对制备的掺硫二氧化钛结构进行了表征,探讨了溶胶-凝胶制备工艺、硫掺杂量及催化剂煅烧温度对该催化剂光催化活性的影响.结果表明,掺硫改性的TiO2经600℃煅烧后光催化活性有了明显提高,且硫的掺杂有一个最佳值,即二氧化硫脲的掺杂质量百分数为4%.经掺硫改性后的TiO2在可见光区具备更强的光催化活性,在波长不低于400nm的可见光作用下,对亚甲基蓝的4 h降解率最高可达89.5%.%Using tetrabutyl titanate as precursor and thiourea dioxide as sulfur source, sulfur-doped titania photocatalyst was prepared by sol-gel method. The crystal structure of the photocatalyst was characterized by XRD. The influences of sol-gel processing technology, sulfur doping amounts and calcined temperatures on the photocatalytic activities under visible-light irradiation were investigated. The results indicated that the photocatalytic activity of the sulfur-doped TiO2 calcined at 600℃ was improved significantly, and there existed an optimized sulfur doping amount, i.e., the content of thiourea dioxide was 4 wt%. The sulfur-doped TiO2 had stronger photocatalytic activity for degradation of methylence blue under visible-light wavelength above 400 nm, and the highest methylence blue degradation rate reached 89.5% after 4 h reaction.

  5. Titrimetric and Spectrophotometric Methods for the Assay of Ketotifen Using Cerium(IV) and Two Reagents

    OpenAIRE

    Madihalli Srinivas Raghu; Kanakapura Basavaiah; Kudige Nagaraj Prashanth; Kanakapura Basavaiah Vinay

    2013-01-01

    One titrimetric and two spectrophotometric methods are described for the determination of ketotifen fumarate (KTF) in bulk drug and in tablets using cerium(IV) as the oxidimetric agent. In titrimetry (method A), the drug was treated with a measured excess of cerium(IV) in H2SO4 medium and after a standing time of 10 min, the surplus oxidant was determined by back titration with iron(II). The spectrophotometric procedures involve addition of a known excess of cerium(IV) to KTF in acid medium f...

  6. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    Science.gov (United States)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  7. Magnetophotonic crystal with cerium substituted yttrium iron garnet and enhanced Faraday rotation angle.

    Science.gov (United States)

    Yoshimoto, Takuya; Goto, Taichi; Isogai, Ryosuke; Nakamura, Yuichi; Takagi, Hiroyuki; Ross, C A; Inoue, M

    2016-04-18

    Magnetophotonic crystals (MPCs) comprising cerium-substituted yttrium iron garnet (CeYIG) sandwiched by two Bragg mirrors were fabricated by vacuum annealing. CeYIG was deposited on Bragg mirrors at room temperature and annealed in 5 Pa of residual air. No ceria or other non-garnet phases were detected. Cerium 3 + ions substituted on the yttrium sites and no cerium 4 + ions were found. The Faraday rotation angle of the MPC was -2.92° at a wavelength of λ = 1570 nm was 30 times larger than that of the CeYIG film. These results showed good agreement with calculated values derived using a matrix approach.

  8. Preparation of nano-titanium dioxide doping phosphorus and its application in degradation of dyes%掺磷纳米TiO2的制备及其在染料降解中的应用

    Institute of Scientific and Technical Information of China (English)

    魏自辉; 黄玲; 姬书亮

    2011-01-01

    The nano-crystalline Tio2 photocatalyst was synthesized using Ti(OBu)4 as precursor, C2H5OH as solvent, and glacial acetic acid as inhibitor.The effects of reaction temperature, pH and assistant dosage on the gelation time were investigated, and the nano-titanium dioxide doping phosphorus was prepared.The morphology of nano-TiO2 was studied using X-ray diffraction (XRD) and ultraviolet-visible (UV-visl spectrophotometer.The photocatalytic experiment was carried out by investigating the photodegradation of methyl orange.The results showed that the optimum reaction conditions for preparing transparent stable TiO2 gelation was: deionized water was dropwised into the mixture of Ti(OBu)4 and alcohol, the temperature was controlled at 40 ℃, the pH of solution was 2.5, the molar ratio of Ti(OBu)4:C2H5OH:H2O:CH3COOH was 1:25:5:1.5.The prepared powder had best UV photocatalysis activity when the dosage of doping phosphours was 4% .%采用溶胶-凝胶法合成了纳米TiO光催化剂,以钛酸丁酯为前驱物,无水乙醇为溶剂,冰醋酸为抑制剂,探讨了不同反应条件(温度、pH、助剂用量等)对其凝胶时间的影响,在此基础上制备了掺磷纳米TiO.利用XRD、UV-vis等测试技术研究了纳米TiO的形态结构,并利用制备的粉体进行了甲基橙紫外光光催化试验.结果显示:制备透明稳定凝胶的最佳条件是将去离子水滴加到混合了钛酸丁酯的乙醇溶液中,并控制温度在40℃,pH为2.5,n(钛酸丁酯):n(无水乙醇):n(水):n(冰醋酸)=1:25:5:1.5,得到的凝胶透明度好;掺磷量为4%时,制备的粉体紫外光光催化活性最好.

  9. TiO2/磁性膨胀石墨的制备及性能研究%Preparation and Properties of Titanium Dioxide Coated Magnetic Exfoliated Graphite

    Institute of Scientific and Technical Information of China (English)

    张晏清; 金诚瀛; 张雄

    2011-01-01

    Titanium dioxide coated magnetic exfoliated graphitefTMEG) was prepared with sol-gel method by depositing nickel ferrite and titanium dioxide on exfoliated graphite. The crystalline structure and particle character of the samples were studied by XRD, SEM and EDS. The adsorption abilitity to diesel oil of TMEG and polymer oil absorber felt was compared. VSM was used to analyze the magnetic property of the samples. The effect on the adsorption and photocatalytic degradation properties of TMEG to methylene blue /methyl orange dye were tested by ultraviolet spectrophotometer. The results showed that nickel ferrite and titanium dioxide particles deposited equably on the surface of exfoliated graphite whose loose porous structure was not influenced too much. TMEG have magnetization, oil adsorption and photocatalytic degradation properties. The specific saturation magnetization and oil adsorption capacity of TMEG are 4.7 emu/g and 17.2 g/g respectively. The degradation of methylene blue dye treated by the samples was 34% after exposing to ultraviolet radiation for 90 minutes and that of methyl orange dye was 55% in the same condition for 60 minutes.%采用溶胶-凝胶法在膨胀石墨表面负载镍铁氧体与TiO2,制备了TiO2/磁性膨胀石墨.采用XRD、SEM及EDS研究产物的晶相 组成与颗粒群特征,测试了TiO2/磁性膨胀石墨对柴机油的吸附性能,采用VSM和紫外分光光度计分析了TiO2/磁性膨胀石墨的磁性能及对亚甲基蓝/甲基橙的光催化降解效果.实验结果表明:铁氧体与TiO2以颗粒形式在膨胀石墨表面与内孔中均匀沉积,对膨胀石墨多孔结构影响不大;TiO2/磁性膨胀石墨具有磁性、吸附油污性与光催化降解性能.TiO2/磁性膨胀石墨的比饱和磁化强度为4.7 emu/g;质量吸油率达17.2 g/g;90min对亚甲基蓝的紫外光降解率为34%,60 min对甲基橙的紫外光降解率为55%.

  10. Flexible substrates as basis for photocatalytic reduction of carbon dioxide

    DEFF Research Database (Denmark)

    Jensen, Jacob; Mikkelsen, Mette; Krebs, Frederik C

    2011-01-01

    A photocatalytic system for converting carbon dioxide into carbon monoxide was designed and constructed. The system relies on thin films of the photocatalyst prepared at low temperature using spray coating. We formulated inks based on the well-known photocatalyst titanium dioxide and characterized...

  11. Cerium oxide nanoparticles coated by surfactant sodium bis(2—ethylhexyl) sulphosuccinate(AOT):local atomic structures and x—ray absorption spectroscopic studies

    Institute of Scientific and Technical Information of China (English)

    ZhonghuaWu; RobertEBenfield; LinGuo; HuanjunLi; QinglinYang; Didier

    2001-01-01

    Cerium oxide nanoparticles coated by sodium bis(2-ethylexyl) sulphosuccinate(AOT) were prepared by using a microemulsion method.Transmission electron microscopy revealed an average particle siae of 2-3nm.X-ray diffraction showed that the cerium oxide nanoparticles retain the CeF2-type cubic structures like the bulk crystal.The intermediate valence offormally tetravalent compounds had been detected by x-ray-absorption near-edge structetravalent compounds had been detected by x-ray-absorption near-dege structure(XANES) spectra of Ce LIII absorption in bulk CeO2 and the cerium oxide nanoparticles.Two well resoved white lines can be assigned to the electron configurations of 4f0L and 4f1L,respectively,where L denotes a ligand hole.At the same time,the cerium oxide nanoparticles also showed the structural featres of trivalent compounds,in comparison to the trivalent Ce(NO3)3·6H2O.Fuor Lorentzian functions and two arctan functions were used to fit the normalized XANES spectra.The extended x-ray-absorption fine-structure(EXAFS) technique was used to probe the local atomic structures around the absorber Ce.The multielectrorn excitation effect on the EXAFS spectra was eliminated.A cor-shell model was used to deduce the near-neighbour structural parameters around cerium.Bulk CeO2 with eight oxygen atoms located at 2.343A was used as the reference sample to extract the backscattering amplitude and phase shift of the Ce-O bond.One half of the atome locate at the core part with the CeF2-type cubic structures(eight oxyens at 2.343A around Ce),the other half of the atoms are amorphous phase located in the shell part (surface of the nanoparticles) with approximately Ce2O3 structural features (averageed seven oxygens at 2.50A around Ce).

  12. Effects of uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate, and citric acid on tomato plants

    Energy Technology Data Exchange (ETDEWEB)

    Barrios, Ana Cecilia [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Rico, Cyren M. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Trujillo-Reyes, Jesica [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Medina-Velo, Illya A. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Environmental Science and Engineering Ph.D. Program, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Environmental Science and Engineering Ph.D. Program, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States)

    2016-09-01

    Little is known about the physiological and biochemical responses of plants exposed to surface modified nanomaterials. In this study, tomato (Solanum lycopersicum L.) plants were cultivated for 210 days in potting soil amended with uncoated and citric acid coated cerium oxide nanoparticles (nCeO{sub 2}, CA + nCeO{sub 2}) bulk cerium oxide (bCeO{sub 2}), and cerium acetate (CeAc). Millipore water (MPW), and citric acid (CA) were used as controls. Physiological and biochemical parameters were measured. At 500 mg/kg, both the uncoated and CA + nCeO{sub 2} increased shoot length by ~ 9 and ~ 13%, respectively, while bCeO{sub 2} and CeAc decreased shoot length by ~ 48 and ~ 26%, respectively, compared with MPW (p ≤ 0.05). Total chlorophyll, chlo-a, and chlo-b were significantly increased by CA + nCeO{sub 2} at 250 mg/kg, but reduced by bCeO{sub 2} at 62.5 mg/kg, compared with MPW. At 250 and 500 mg/kg, nCeO{sub 2} increased Ce in roots by 10 and 7 times, compared to CA + nCeO{sub 2}, but none of the treatments affected the Ce concentration in above ground tissues. Neither nCeO{sub 2} nor CA + nCeO{sub 2} affected the homeostasis of nutrient elements in roots, stems, and leaves or catalase and ascorbate peroxidase in leaves. CeAc at 62.5 and 125 mg/kg increased B (81%) and Fe (174%) in roots, while at 250 and 500 mg/kg, increased Ca in stems (84% and 86%, respectively). On the other hand, bCeO{sub 2} at 62.5 increased Zn (152%) but reduced P (80%) in stems. Only nCeO{sub 2} at 62.5 mg/kg produced higher total number of tomatoes, compared with control and the rest of the treatments. The surface coating reduced Ce uptake by roots but did not affect its translocation to the aboveground organs. In addition, there was no clear effect of surface coating on fruit production. To our knowledge, this is the first study comparing the effects of coated and uncoated nCeO{sub 2} on tomato plants. - Highlights: • At 500 mg/kg, coated and bare NPs increased stem length by 13 and 9

  13. Microwave synthesis of pure and doped cerium (IV) oxide (CeO2) nanoparticles for methylene blue degradation.

    Science.gov (United States)

    El Rouby, W M A; Farghali, A A; Hamdedein, A

    2016-11-01

    Cerium (IV) oxide (CeO2), samarium (Sm) and gadolinium (Gd) doped CeO2 nanoparticles were prepared using microwave technique. The effect of microwave irradiation time, microwave power and pH of the starting solution on the structure and crystallite size were investigated. The prepared nanoparticles were characterized using X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscope. The photocatalytic activity of the as-prepared CeO2, Sm and Gd doped CeO2 toward degradation of methylene blue (MB) dye was investigated under UV light irradiation. The effect of pH, the amount of catalyst and the dye concentration on the degradation extent were studied. The photocatalytic activity of CeO2 was kinetically enhanced by trivalent cation (Gd and Sm) doping. The results revealed that Gd doped CeO2 nanoparticles exhibit the best catalytic degradation activity on MB under UV irradiation. For clarifying the environmental safety of the by products produced from the degradation process, the pathways of MB degradation were followed using liquid chromatography/mass spectroscopy (LC/MS). The total organic carbon content measurements confirmed the results obtained by LC/MS. Compared to the same nanoparticles prepared by another method, it was found that Gd doped CeO2 prepared by hydrothermal process was able to mineralize MB dye completely under UV light irradiation.

  14. 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)

  15. Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

    Science.gov (United States)

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe res...

  16. EFFECT OF CERIUM ION IMPLANTATION ON THE AQUEOUS CORROSION BEHAVIOR OF ZIRCONIUM

    Institute of Scientific and Technical Information of China (English)

    D.Q. Peng; X.D. Bai; Q.G. Zhou; X.W. Chen; R.H. Yu; X.Y. Liu

    2004-01-01

    In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted by cerium ions with a dosage range from 1 ×1016 to 1 ×1017 ions/cm2 at about 150℃, using MEWA source at an acceler ative voltage of 40kV. The valence of the surface layer was analyzed by X-ray photoelectron spectroscopy (XPS); Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zirconium in a 0.5mol/L H2SO4 solution. It was found that a remarkable decline in the aqueous corrosion behavior of zirconium implanted with cerium ions compared with that of the as-received zirconium. Finally, the mechanism of the corrosion resistance decline of the cerium-implanted zirconium is discussed.

  17. Study on Catalysts with Rhodium Loading on Different Cerium-Zirconium Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The catalysts with Rh loading on different cerium-zirconium mixed oxides were characterized by BET, H2-TPR and OSC. The effects of different cerium-zirconium mixed oxides on catalytic performance and thermal stability of Rh loaded catalyst were studied. The results show that: (1) Rh can enhance cerium-zirconium mixed oxides OSC and catalytic reaction rates; (2) cerium-zirconium mixed oxides with high Ce contents and low Zr contents are more favorable to the stability of catalysts. Moreover, the contents of CeO2 have important effect on catalysts characteristics, and the addition of some rare earth components, such as La, Pr and Nd also have some influences.

  18. Copper-cerium oxides supported on carbon nanomaterial for preferential oxidation of carbon monoxide

    Institute of Scientific and Technical Information of China (English)

    高美怡; 江楠; 赵宇宏; 徐长进; 苏海全; 曾尚红

    2016-01-01

    The CuxO-CeO2/Fe@CNSs, CuxO-CeO2/MWCNTs-Co and CuxO-CeO2/MWCNTs-Ni catalysts were prepared by the im-pregnation method and characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffrac-tion, H2-temperature programmed reduction and N2 adsorption-desorption techniques. It was found that the Fe nanoparticles were encapsulated into the multi-layered carbon nanospheres (CNSs). However, the multi-wall carbon nanotubes (MWCNTS) were generated on the Co/Al2O3 and Ni/Al2O3 precursor. The addition of carbon nanomaterial as supports could improve structural properties and low-temperature activity of the CuO-CeO2 catalyst, and save the used amount of metal catalysts in the temperature range with high selectivity for CO oxidation. The copper-cerium oxides supported on carbon nanomaterial had good resistence to H2O and CO2.

  19. Enhanced hydrogen desorption property of MgH{sub 2} with the addition of cerium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huai-Jun, E-mail: huaijun.lin.489@s.kyushu-u.ac.jp [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Matsuda, Junko [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Li, Hai-Wen [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan); Zhu, Min [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); China–Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510640 (China); Akiba, Etsuo [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan)

    2015-10-05

    Highlights: • Activation energy of MgH{sub 2} desorption is remarkably reduced with the dopant of CeF{sub 4}. • The improvement might be attributed to new Ce–F–Mg species at the CeF{sub 4}/MgH{sub 2} interface. • Easy electron transfer induced from the high valence Ce-cation benefits MgH{sub 2} desorption. - Abstract: Hydrogen desorption property of MgH{sub 2} doped with cerium fluorides with different valences prepared using ball milling has been studied. CeF{sub 4} is catalytically active for hydrogen desorption of MgH{sub 2}. Hydrogen desorption temperature and apparent activation energy of MgH{sub 2} are significantly reduced with dopant of 2 mol% of CeF{sub 4}, which might be attributed to the formation of a new Ce–F–Mg specie at the CeF{sub 4}/MgH{sub 2} interface and the easy electron transfer induced from the high valence Ce-cation. The apparent activation energy of hydrogen desorption of MgH{sub 2} is reduced from ∼160 kJ/mol to ∼110 kJ/mol with the dopant of CeF{sub 4}.

  20. Effect of the phosphorous/cerium ratio in the properties of sintered Ce-monazite

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Teresa [CIEMAT, Materials For Fusion, Avda. Complutense 22, 28040 Madrid (Spain)], E-mail: teresa.hernandez@ciemat.es; Martin, Piedad [CIEMAT, Materials For Fusion, Avda. Complutense 22, 28040 Madrid (Spain)

    2008-10-20

    Three Ce-phosphates were prepared by the precipitation method containing different P/Ce ratio. It has been observed that an excess of phosphorous considerably increases the amount of glassy phase surrounding the monazite grains in the ceramic body and produces the decomposition at high temperatures (over 1400 deg. C). This glassy phase is related with the metaphosphate Ce(PO{sub 3}){sub 3}. On the other hand, an excess of cerium yields the massive precipitation of CeO{sub 2} that appears in the microstructure perfectly distributed into the monazite matrix, but the material remains stable up to 1600 deg. C. In the equimolar composition, an exaggerated grain growth can be observed joined to microcracking. Optical properties and hardness were measured for the three materials and are clearly related with the Ce{sup 3+} presence and the crystalline phase in the material, respectively. The intermediate phases found during heating are discussed and these phases are related to the final characteristics for each material.

  1. Characterization of the alumina film with cerium doped on the iron-aluminide diffusion coating

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Q., E-mail: zhanqin1983@163.com; Yang, H.G.; Zhao, W.W.; Yuan, X.M.; Hu, Y.

    2013-11-15

    An iron-aluminide layer with a thin alumina film on the top as a composite tritium permeation barrier (TPB) coating was characterized under different oxidation conditions. The TPB coating was prepared initially on a China Low Activation Ferritic-Martensitic (CLAM) steel by a pack cementation aluminizing process and then an alumina film was formed on the surface of this iron-aluminide diffusion layer by an oxidizing process. To modify the properties of the FeAl/Al{sub 2}O{sub 3} composite TPB coatings, the rare earth element (cerium) was introduced as a dopant while oxidizing. Characterization showed that a continuous oxide scale with a thickness of about 300–400 nm was formed on the FeAl diffusion layer. The film was mainly composed of Al{sub 2}O{sub 3} doped with a little CeO{sub 2}. In addition, the concentration of α-Al{sub 2}O{sub 3} increased with elevated temperature while oxidizing. The phase transformation behavior of alumina scale on the surface of an iron-aluminide layer was studied in this paper.

  2. STUDY ON ORGANIC LIGHT—RARE—EARTH ADSORBENT—CERIUM BIS(OCTYLPHOSPHATE)

    Institute of Scientific and Technical Information of China (English)

    SuZhengquan; FengHuixia

    1996-01-01

    The tetravalent metal salts of monoalkyl phosphates[M(R-OPO3)2] are a new kind of stationary phases of chromatography-homogeneous bonded phases.The studies on preparation,structure and gas chromatographic efficiency of cerium bis (octylphosphate) (COPP) are reported in this paper. By using chemical analysis,infrared spectra,x-ray diffraction analysis ,the strong evidence that COPP has a layered structure of the α-zirconium phosphate type was demonstrated,the repetitive unit is C8H17OPO3CeO3POC8H17 and there is a little bending or interpenetration of the alkyl chains within the layers.The thermogravimetic analysis of the COPP indicated that it has much more thermalstability than silica-based packings.The thermodynamic parameters ΔH and molecular connectivity indexes x′ for the adsorption of several dozen compounds on the COPP have also been determined by gas chromatographic method,and the fine linearity between them was shown.

  3. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Science.gov (United States)

    Boshui, Chen; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-01

    Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO3, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO3 were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO3 as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO3 were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO3 nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent tribological performances of SA/CeBO3 in rapeseed oil were attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species of B2O3, CeO2 and Fe2O3, and the adsorbates of SA/CeBO3 and rapeseed oil, on the tribo-surfaces.

  4. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  5. Hierarchical porous carbon toward effective cathode in advanced zinc-cerium redox flow battery

    Institute of Scientific and Technical Information of China (English)

    谢志鹏; 杨斌; 蔡定建; 杨亮

    2014-01-01

    Advanced zinc-cerium redox flow battery (ZCRFB) is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity and fast ion diffusion is a hierarchical porous structure, which was synthesized in this work by a method in which both hard template and soft template were used. The structure and the performance of the cathode prepared here were characterized and evaluated by a variety of techniques such as scan-ning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltam-metry (CV), linear sweep voltammetry (LSV), and chronoamperometry (CA). There were mainly three types of pore size within the hierarchical porous carbon:2μm, 80 nm, and 10 nm. The charge capacity of the cell using hierarchical porous carbon (HPC) as posi-tive electrode was obviously larger than that using carbon felt;the former was 665.5 mAh with a coulombic efficiency of 89.0%and an energy efficiency of 79.0%, whereas the latter was 611.1 mAh with a coulombic efficiency of 81.5%and an energy efficiency of 68.6%. In addition, performance of the ZCRFB using HPC as positive electrode showed a good stability over 50 cycles. These results showed that the hierarchical porous carbon was superior over the carbon felt for application in ZCRFB.

  6. Preparation and Visible Light Photocatalytic Activity of Titanium Dioxide Coated Multiwalled Carbon Nanotubes%二氧化钛涂覆多壁碳纳米管的制备及可见光催化活性

    Institute of Scientific and Technical Information of China (English)

    丛野; 秦云; 李轩科; 董志军; 袁观明; 崔正威

    2011-01-01

    以多壁碳纳米管(MWCNTs)为反应性模板,金属钛粉为钛源,采用熔盐法制备碳化钛涂覆的MWCNTs中间体,然后通过控制氧化制备二氧化钛涂覆的MWCNTs复合光催化剂.考察了熔盐反应温度、MWCNTs和钛粉的摩尔比及氧化温度等对产物的结构和形貌的影响.采用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等技术对其进行了系统的表征;以亚甲基蓝(MB)溶液的脱色降解为模型反应,考察了催化剂的可见光(λ>420 nm)催化活性.结果表明:所制备的催化剂基本保持了原始MWCNTs的纤维状形貌,二氧化钛涂层在MWCNTs表面分布均匀.并与MWCNTs之间结合紧密,形成了Ti-O-C键.MWCNTs增强了污染物亚甲基蓝在催化剂表面的吸附,Ti-O-C键的形成使得在二氧化钛价带附近形成了杂质能级,提高了对可见光的吸收和利用.因此所制备的TiO2/MWCNTs复合光催化剂表现出较高的可见光催化活性.%Titanium dioxide coated multiwalled carbon nanotubes (MWCNTs) composite photocatalysts were prepared by the controllable oxidation of titanium carbide coated MWCNTs obtained by the molten salt method using MWCNTs as a reaction template and metal titanium powder as a titanium source. The effects of the molten salt reaction temperature, the molar ratio of MWCNTs to titanium powder, and the oxidation temperature on the structure and morphology of the products were investigated. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM),transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photodegradation of a methylene blue (MB) solution was used to evaluate the photocatalytic activity of the catalyst under visible light irradiation (λ>420 nm). The results suggest that the TiO2 coated MWCNTs keep the similar fibred morphology with the pristine MWCNTs. Uniform and fine

  7. SELECTION OF OXIDES FOR STABILIZATION OF ZIRCONIUM DIOXIDE WHILE OBTAINING THERMAL BARRIER COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2015-01-01

    Full Text Available The paper analyzes selection of oxides and describes in details a majority of oxide systems which are applicable for stabilization of zirconium dioxide while obtaining thermal barrier coatings with maximum amount of tetragonal phase. Methodology of investigation is based on a review of analytical information on the current state of thermal barrier coatings on the basis of zirconium dioxide stabilized by oxides of rare-earth metals. The method used for application of  zirconium dioxide thermal barrier coatings is plasma spraying. Positive results have been also obtained while applying e-beam sputtering, ion-plasma deposition and magnetron sputtering. Nevertheless preferred plasma spraying application for thermal barrier coatings still continues due to its high productivity and versatility that permits to deposit metallic and ceramic materials of the ordered chemical and phase composition.Ytterbium and cerium oxides have been selected as oxides for stabilization of zirconium dioxide in order to obtain thermal barrier coatings. The paper also considers аn oxide system of zirconium dioxide: “hafnium oxide – yttrium oxide”, representing in itself the structure which is similar to zirconium dioxide.

  8. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    OpenAIRE

    2016-01-01

    We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO) reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation ...

  9. Transformation of Cerium Oxide Nanoparticles from a Diesel Fuel Additive during Combustion in a Diesel Engine.

    Science.gov (United States)

    Dale, James G; Cox, Steven S; Vance, Marina E; Marr, Linsey C; Hochella, Michael F

    2017-02-21

    Nanoscale cerium oxide is used as a diesel fuel additive to reduce particulate matter emissions and increase fuel economy, but its fate in the environment has not been established. Cerium oxide released as a result of the combustion of diesel fuel containing the additive Envirox, which utilizes suspended nanoscale cerium oxide to reduce particulate matter emissions and increase fuel economy, was captured from the exhaust stream of a diesel engine and was characterized using a combination of bulk analytical techniques and high resolution transmission electron microscopy. The combustion process induced significant changes in the size and morphology of the particles; ∼15 nm aggregates consisting of 5-7 nm faceted crystals in the fuel additive became 50-300 nm, near-spherical, single crystals in the exhaust. Electron diffraction identified the original cerium oxide particles as cerium(IV) oxide (CeO2, standard FCC structure) with no detectable quantities of Ce(III), whereas in the exhaust the ceria particles had additional electron diffraction reflections indicative of a CeO2 superstructure containing ordered oxygen vacancies. The surfactant coating present on the cerium oxide particles in the additive was lost during combustion, but in roughly 30% of the observed particles in the exhaust, a new surface coating formed, approximately 2-5 nm thick. The results of this study suggest that pristine, laboratory-produced, nanoscale cerium oxide is not a good substitute for the cerium oxide released from fuel-borne catalyst applications and that future toxicity experiments and modeling will require the use/consideration of more realistic materials.

  10. Carbon dioxide absorbent and method of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Robert James; O' Brien, Michael Joseph

    2015-12-29

    In accordance with one aspect, the present invention provides a composition which contains the amino-siloxane structures I, or III, as described herein. The composition is useful for the capture of carbon dioxide from process streams. In addition, the present invention provides methods of preparing the amino-siloxane composition. Another aspect of the present invention provides methods for reducing the amount of carbon dioxide in a process stream employing the amino-siloxane compositions of the invention, as species which react with carbon dioxide to form an adduct with carbon dioxide.

  11. Carbon dioxide absorbent and method of using the same

    Science.gov (United States)

    Perry, Robert James; O'Brien, Michael Joseph

    2014-06-10

    In accordance with one aspect, the present invention provides a composition which contains the amino-siloxane structures I, or III, as described herein. The composition is useful for the capture of carbon dioxide from process streams. In addition, the present invention provides methods of preparing the amino-siloxane composition. Another aspect of the present invention provides methods for reducing the amount of carbon dioxide in a process stream employing the amino-siloxane compositions of the invention, as species which react with carbon dioxide to form an adduct with carbon dioxide.

  12. Preparation and characterization of microporous permeable titanium-based β-lead dioxide electrode%钛基β-二氧化铅微孔渗透电极的制备及表征

    Institute of Scientific and Technical Information of China (English)

    王龙耀; 刘朋; 王岚; 何明阳; 陈群

    2013-01-01

    A microporous permeable titanium-basedβ-PbO2 electrode was prepared using powder-sintered porous titanium plate as substrate through the following steps: (1) pickling with hydrochloric acid; (2) preparing an antimony-doped tin dioxide (ATO) intermediate layer by thermal decomposition; and (3) electrodepositing β-PbO2 coating. The properties of the electrode were characterized. The results showed that the packed structure of particles in porous titanium plate and the honeycomb-like structure after acid picking offer a specific area of 0.53 m2/g and effective stress compensation for adhesive layer. ATO can bond with titanium substrate closely in the form of solid solution, forming a protective layer. The permeable Ti-basedβ-PbO2 electrode features uniform and compact surface and good permeability, and has an oxygen evolution potential of 1.85 V and a service life of 38 h at a current density of 4 A/cm2 in 0.5 mol/L H2SO4 solution.%以多孔钛粉末烧结板为基材,制得钛基β-PbO2微孔渗透电极并对其性能进行表征。主要制备步骤为盐酸侵蚀、热分解涂覆锑掺杂二氧化锡(ATO)中间层及电沉积β-PbO2层。结果表明,多孔钛板自身的粒子堆积结构和酸蚀后的蜂窝状结构为附着层提供了约0.53 m2/g的比表面积和有效的应力补偿。ATO能够以固溶体形式与钛基材紧密结合形成致密的保护层。所得钛基β-PbO2微孔渗透电极表面均匀致密,渗透性能良好。在0.5 mol/L硫酸溶液中,其析氧电位达1.85 V,电流密度4 A/cm2下的电极寿命超过38 h。

  13. Thermopower enhancement by encapsulating cerium in clathrate cages.

    Science.gov (United States)

    Prokofiev, A; Sidorenko, A; Hradil, K; Ikeda, M; Svagera, R; Waas, M; Winkler, H; Neumaier, K; Paschen, S

    2013-12-01

    The increasing worldwide energy consumption calls for the design of more efficient energy systems. Thermoelectrics could be used to convert waste heat back to useful electric energy if only more efficient materials were available. The ideal thermoelectric material combines high electrical conductivity and thermopower with low thermal conductivity. In this regard, the intermetallic type-I clathrates show promise with their exceedingly low lattice thermal conductivities. Here we report the successful incorporation of cerium as a guest atom into the clathrate crystal structure. In many simpler intermetallic compounds, this rare earth element is known to lead, through the Kondo interaction, to strong correlation phenomena including the occurrence of giant thermopowers at low temperatures. Indeed, we observe a 50% enhancement of the thermopower compared with a rare-earth-free reference material. Importantly, this enhancement occurs at high temperatures and we suggest that a rattling-enhanced Kondo interaction underlies this effect.

  14. Effect of Surface Modification on Behaviors of Cerium Oxide Nanopowders

    Institute of Scientific and Technical Information of China (English)

    Li Mei; Shi Zhenxue; Liu Zhaogang; Hu Yanhong; Wang Mitang; Li Hangquan

    2007-01-01

    Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders. A surfactant-sodium dodecyl sulfate(C12H25SO4Na) was used to modify the surface of CeO2 powder particles. The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester, laser particle size analyzer, specific surface area tester, X-ray diffraction tester, and a scanning electron microscope. The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity, and decrease the specific surface area and agglomeration of CeO2 powders. The mechanism of the surface modification of CeO2 powder particles was also discussed.

  15. EPDM composite membranes modified with cerium doped lead zirconate titanate

    Science.gov (United States)

    Zaharescu, T.; Dumitru, A.; Lungulescu, M. E.; Velciu, G.

    2016-01-01

    This study was performed on γ-irradiated ethylene-propylene diene terpolymer (EPDM) loaded with lead zirconate titanate. The inorganic phase has a perovskite structure with general formula Pb(Zr0.65-xCexTi0.35)O3. The three composites with different Ce dopant concentrations revealed the stabilization activity of filler against oxidation proved by chemiluminescence investigation in respect to pristine polymer. The presence of cerium low concentrations in the solid lead zirconate titanate nanoparticles causes significant slowing of oxidation rate during radiation exposure. The improvement in the stabilization feature of filler is correlated with the existence of traps, whose interaction with free radicals assumes medium energy due to their convenient depth.

  16. On the mixed nature of cerium conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Botana, F.J.; Aballe, A.; Bethencourt, M.; Cano, M.J. [Cadiz Univ. (Spain). Dept. de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica; Marcos, M. [Cadiz Univ. (Spain). Dept. de Ingenieria Mecanica y Diseno Industrial

    2002-03-01

    Alternative pretreatments are currently under development in order to avoid the environmental impact produced by using surface finishing processes based on chromates. Some of the environmentally friendly alternatives proposed involve the use of lanthanide based compounds. In this study, conversion coatings on AA5083 (Al-Mg) samples developed using full immersion pretreatments in 500 ppm CeCl{sub 3} aqueous solutions have been investigated. Their microscopic and compositional features have been analyzed using SEM images and EDS spectra. From this analysis it has been determined that this layer over the surface of the samples is of a heterogeneous composition. This coating is formed by an alumina coating covering the aluminum matrix and dispersed cerium-rich islands deposited over the cathodic sites of the alloy. A characterization methodology is proposed based on the utilization of different electrochemical techniques, such as open circuit potential monitoring (OCP), linear polarization (LP) and electrochemical impedance spectroscopy (EIS). (orig.)

  17. Characterization of a zinc-cerium flow battery

    Science.gov (United States)

    Leung, P. K.; Ponce-de-León, C.; Low, C. T. J.; Shah, A. A.; Walsh, F. C.

    The performance of a divided, parallel-plate zinc-cerium redox flow battery using methanesulfonic acid electrolytes was studied. Eight two and three-dimensional electrodes were tested under both constant current density and constant cell voltage discharge. Carbon felt and the three-dimensional platinised titanium mesh electrodes exhibited superior performance over the 2-dimensional electrodes. The charge and discharge characteristics of the redox flow battery were studied under different operating conditions and Zn/Ce reactant, as well as methansulfonic acid concentration. The cell performance improved at higher operating temperatures and faster electrolyte flow velocities. The number of possible cycles increased at reduced states of charge. During 15 min charge/discharge per cycle experiment, 57 cycles were obtained and the zinc reaction was found to be the limiting process during long term operation.

  18. Interplay of spin-orbit and entropic effects in cerium

    Energy Technology Data Exchange (ETDEWEB)

    Lanata, Nicola [Rutgers University; Yao, Yong-Xin [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Ho, Kai-Ming [Ames Laboratory; Kotliar, Gabriel [Rutgers University

    2014-10-01

    We perform first-principles calculations of elemental cerium and compute its pressure-temperature phase diagram, finding good quantitative agreement with the experiments. Our calculations indicate that, while a signature of the volume-collapse transition appears in the free energy already at low temperatures, at higher temperatures this signature is enhanced because of the entropic effects, and originates an actual thermodynamical instability. Furthermore, we find that the catalyst determining this feature is—in all temperature regimes—a pressure-induced effective reduction of the f-level degeneracy due to the spin-orbit coupling. Our analysis suggests also that the lattice vibrations might be crucial in order to capture the behavior of the pressure-temperature transition line at large temperatures.

  19. Cerium intermetallics with TiNiSi-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Janka, Oliver; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ. CNRS (UPR 9048), Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux (ICMCB)

    2016-08-01

    Intermetallic compounds with the equiatomic composition CeTX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals (T) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these CeTX phases and on their physical properties, {sup 119}Sn and {sup 121}Sb Moessbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure-property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch. 2015, 70b, 289; Part II: Z. Naturforsch. 2015, 70b, 695; Part III: Z. Naturforsch. 2016, 71b, 165].

  20. Growth of transition metals on cerium tungstate model catalyst layers

    Science.gov (United States)

    Skála, T.; Tsud, N.; Stetsovych, V.; Mysliveček, J.; Matolín, V.

    2016-10-01

    Two model catalytic metal/oxide systems were investigated by photoelectron spectroscopy and scanning tunneling microscopy. The mixed-oxide support was a cerium tungstate epitaxial thin layer grown in situ on the W(1 1 0) single crystal. Active particles consisted of palladium and platinum 3D islands deposited on the tungstate surface at 300 K. Both metals were found to interact weakly with the oxide support and the original chemical state of both support and metals was mostly preserved. Electronic and morphological changes are discussed during the metal growth and after post-annealing at temperatures up to 700 K. Partial transition-metal coalescence and self-cleaning from the CO and carbon impurities were observed.

  1. The Spin Glass-Kondo Competition in Disordered Cerium Systems

    Science.gov (United States)

    Magalhaes, S. G.; Zimmer, F.; Coqblin, B.

    2013-10-01

    We discuss the competition between the Kondo effect, the spin glass state and a magnetic order observed in disordered Cerium systems. We present firstly the experimental situation of disordered alloys such as CeNi1 - xCux and then the different theoretical approaches based on the Kondo lattice model, with different descriptions of the intersite exchange interaction for the spin glass. After the gaussian approach of the Sherrington-Kirkpatrick model, we discuss the Mattis and the van Hemmen models. Then, we present simple cluster calculations in order to describe the percolative evolution of the clusters from the cluster spin glass to the inhomogeneous ferromagnetic order recently observed in CeNi1 - xCux disordered alloys and finally we discuss the effect of random and transverse magnetic field.

  2. Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

    Science.gov (United States)

    Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

    2015-12-01

    Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

  3. Thermoluminescence and sintering of ultra-pure {alpha} alumina doped with zirconium, thorium, calcium or cerium; Thermoluminescence et frittage de l'alumine {alpha} ultra-pure dopee par le zirconium, le thorium, le calcium, ou le cerium

    Energy Technology Data Exchange (ETDEWEB)

    Ferey, F

    2002-01-01

    Thermoluminescence is a technique of identification of the point defects that appear in a solid consecutively to its fabrication. The synthesis parameters of {alpha}-alumina that will be taken into account here are the atmosphere during thermal treatment (oxidising or reducing), and the effect of the dopants: zirconium, thorium, calcium or cerium. The aim of this work is to correlate the point defects to the reactivity of the powder, especially its sintering. The TL mechanisms of the dosimetric peak of {alpha}-alumina, around 200 deg C, were clarified: the trap is an aggregate of 2 point defects (V{sub al}-V{sub O}), and the recombination centre is Cr{sup 3+}. The sensibilizing effect observed for thorium, or for cerium under reducing atmosphere, is attributed to the presence of a large emission band in the blue-green domain. Chromium is the main impurity at the origin of the E' peak (360 deg C) of {alpha}-alumina. It is acting as trap and also as recombination centre. A mechanism of transfer of energy between Cr{sup 3+} and Ti{sup 4+} is also presented in order to explain the increase of the TL intensity of the E' peak when doping by a tetravalent cation. In the case of doping by calcium, TL allows the revelation of the phase CaAl{sub 12}O{sub 19}. A quenching was observed for {alpha}Al{sub 2}O{sub 3}:Ca and {alpha}Al{sub 2}O{sub 3}:Ce under reducing atmosphere. It is attributed to oxygen vacancies for the doping by calcium, and to the presence of Ce{sup 3+} for the doping by cerium. The alumina prepared under reducing conditions exhibit a perturbation of kinetics during sintering, and also abnormal grain growth in doped samples. This unusual kinetic is explained by a decrease in the concentration of aluminium vacancies under reducing atmosphere, conducting indirectly to a greater segregation of Si{sup 4+} at the grain boundaries, and to the formation of a liquid phase at the surface of grains. This phenomenon is amplified in the case of doping by

  4. CeO2-TiO2复合催化剂催化臭氧化丁二酸性能的研究%Preparation of CeO2-TiO2 and Its Activity in Catalytic Ozonation

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    a series of cerium dioxide doped TiO2 were prepared via incipient wetness impregnation using Ce(NO3)3·6H2O as the precursor. The structure and properties of the catalysts were study by X-ray diffraction. The catalytic activity was evaluated by monitoring the degradation of succinic acid(SA) in the presence of ozone. It was found that increasing the load of cerium dioxide is helpful.%  采用湿式浸渍法制备一系列不同Ce:Ti的CeO2-TiO2复合型催化剂。考察了不同CeO2负载量对纳米TiO2晶相改变和催化臭氧化活性的影响。采用X射线衍射(XRD)对其表征,并测定了不同Ce:Ti下丁二酸的去除率。通过催化臭氧化丁二酸实验,发现改性TiO2能提高催化剂催化臭氧化丁二酸的能力,且随着CeO2负载量的增加催化臭氧化性能提高。并验证催化剂催化臭氧化丁儿的机理为,丁二酸吸附在催化剂表面形成性质更活泼的络合物,最终被臭氧分子所氧化。

  5. CARBON DIOXIDE REDUCTION SYSTEM.

    Science.gov (United States)

    CARBON DIOXIDE , *SPACE FLIGHT, RESPIRATION, REDUCTION(CHEMISTRY), RESPIRATION, AEROSPACE MEDICINE, ELECTROLYSIS, INSTRUMENTATION, ELECTROLYTES, VOLTAGE, MANNED, YTTRIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, NICKEL.

  6. Synthesis of nano-sized ceria (CeO2 particles via a cerium hydroxy carbonate precursor and the effect of reaction temperature on particle morphology

    Directory of Open Access Journals (Sweden)

    Majid Farahmandjou

    2015-06-01

    Full Text Available Cerium oxide (CeO2 or ceria has been shown to be an interesting support material for noble metals in catalysts designed for emission control, mainly due to its oxygen storage capacity. Ceria nanoparticles were prepared by precipitation method. The precursor materials used in this research were cerium nitrate hexahydrate (as a basic material, potassium carbonate and potassium hydroxide (as precipitants. The morphological properties were characterized by high resolution transmission electron microscopy (HRTEM, scanning electron microscopy (SEM and X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and UV-Vis spectrophotometer. XRD results showed face centered cubic CeO2 nanoparticles for annealed nanoparticles at 1000°C. SEM measurement showed that by increasing the calcinations temperature from 200 to 600°C, the crystallite size decreased from 90 to 28 nm. The SEM results showed that the size of the CeO2 nanoparticles decreased with increasing temperature. The particle size of CeO2 was around 25 nm as estimated by XRD technique and direct HRTEM observation. SEM and TEM studies showed that the morphology of the prepared powder was sphere-like with a narrow size distribution. The sharp peaks in FTIR spectrum determined the purity of CeO2 nanoparticles and absorbance peak of UV-Vis spectrum showed the small band gap energy of 3.26 ev.

  7. Effects of cerium nitrate on the growth and physiological characteristics in Cyclocarya paliurusseedlings

    Institute of Scientific and Technical Information of China (English)

    谢寅峰; 李颖; 刘娜娜; 张颖颖; 郭楠; 王涛; 尚绪岚

    2015-01-01

    Field studies were conducted to examine the effects of cerium on the growth and physiological characteristics ofCyclo-carya paliurusseedlings by spraying the foliage with different concentrations of cerium nitrate. Optimal concentrations of cerium ni-trate improved the relative growth yield of seedling height and stems and the soluble protein and sugar content of the leaves. Cerium nitrate also increased the concentration of secondary metabolites including triterpenoids, quercetin and kaempferol, mineral elements K, P, Mg, Mn, Fe and Cu, and the activities of superoxide dismutase (SOD), peroxidase (POX), and phenylalanine ammonia-lyase (PAL) in the leaves. The effects of cerium nitrate on these indices were dose dependent. A concentration of 0.20 mmol/L was optimal to promote the relative growth yield of seedling height, contents of soluble sugar, kaempferol, K, P, Cu, and activities of PAL, SOD, and POX, significantlyincreased by 54.61%, 14.71%, 55.19%, 105.2%, 74.5%, 133.3%, 80.48%, 25.35% and 22.54%, respectively, as compared with the control. However, the maximal increase in relative growth yield of stems, contents of triterpenoid, quercetin, Mg, Mn, and Fe was attained at 1.00 mmol/L treatment, which significantlyincreased by 87.00%, 80.56%, 452.44%, 93.2%, 29.4%, and 133.9%, respectively, compared with control check (CK). Correlation analysis revealed positive relationships between activities of PAL, SOD and contents of triterpenoid, quercetin and kaempferol within a certain concentration range of cerium nitrate. These re-sults suggested that an appropriate concentration of cerium not only was effective in the improvement of physiological function ofC. paliurus, but alsoincreased seedling resistance. Moreover, it stimulated the synthesis of medicinal components in leaves.

  8. 退火温度对溶胶-凝胶法制备TiO2薄膜的结构和光学特性的影响%Effect of annealing temperature on structural and optical properties of sol-gel prepared titanium dioxide thin-films

    Institute of Scientific and Technical Information of China (English)

    张璐; 李国强; 张洪良

    2012-01-01

    Titanium dioxide films were prepared on silica and quartz substrates by sol-gel dip-coating.These films were subsequently thermally annealed at temperatures for 30min;the structural and optical properties of prepared titanium dioxide films were analysed by X-ray diffraction(XRD),scanning electron microscopy(SEM) and UV-visible spectrophotometer,respectively.The ability to degrade methyl orange of these films was also studied.We found that the crystalline phase of the changed gradually from anatase to rutile as annealing temperature increased,and this transition took place at temperatures ranging from 700 to 800℃.During the transition,titanium dioxide films exhibited good,and no cracks were found even after annealing at 800℃.As annealing temperature increased,the absorption peak of titanium dioxide films had a blue-shifted,resulting in the expansion of absorption range in UV area.Titanium dioxide film prepared by this method and annealed at 800℃ for 30min which contained 31.4wt% anatase showed the highest degradation ratio of methyl orange.%采用溶胶-凝胶浸渍提拉法分别在氧化硅和石英衬底上制备TiO2薄膜,并以不同的退火温度保温30min。通过采用X射线衍射仪(XRD)、扫描电镜(SEM)及紫外-可见分光光度计,对TiO2薄膜的结构和光学性能进行了详细分析,并且进行了对甲基橙的降解实验。研究结果表明,随着退火温度的升高,薄膜的晶相由锐钛矿向金红石转变,转变温度在700~800℃之间。在该转变过程中,薄膜结晶程度良好,800℃时薄膜表面平整无开裂;随着热处理温度的升高,TiO2薄膜的吸收峰蓝移,紫外区吸收范围扩大。在800℃退火时,薄膜中所含锐钛矿TiO2为31.4%(质量分数)。此时薄膜表现出最高的甲基橙降解率。

  9. Exposure, Health and Ecological Effects Review of Engineered Nanoscale Cerium and Cerium Oxide Associated with its Use as a Fuel Additive

    Science.gov (United States)

    Advances of nanoscale science have produced nanomaterials with unique physical and chemical properties at commercial levels which are now incorporated into over 1000 products. Nanoscale cerium (di) oxide (CeO(2)) has recently gained a wide range of applications which includes coa...

  10. STUDY ON THE ADSORPTION PROPERTY OF ADSORBENT OF CERIUM-LOADED RED MUD AGAINST FLUORIDE IN WASTEWATER%赤泥负载铈吸附剂对废水中氟的吸附性能研究

    Institute of Scientific and Technical Information of China (English)

    马淞江; 罗道成

    2013-01-01

    将赤泥通过盐酸活化,得到酸活化赤泥,以酸活化赤泥为载体,氧化铈为活性组分,制备了赤泥负载铈吸附剂,在25℃和静态条件下,对赤泥负载铈吸附剂处理含氟废水进行了研究.结果表明,赤泥负载铈吸附剂的制备条件为:盐酸浓度为6 mol/L,赤泥负载铈的反应时间为16h,四水硫酸铈的质量浓度为0.4 g/L,焙烧温度为500℃;在废水pH为6.0,氟的质量浓度为40 mg/L,吸附时间为90 min,按氟与赤泥负载铈吸附剂质量比为1∶100投加赤泥负载铈吸附剂进行处理,氟的去除率可达98%以上.利用Langrnuir吸附等温式对吸附数据进行拟合,得到25℃下的线性方程为(ρe/qe)/(g·L-1)=[0.016 3ρe/(mg· L-1)]+0.050 3,线性相关性R2=0.992 3,吸附剂的饱和吸附量为61.35 mg/g.氟在吸附剂表面的吸附是单分子层吸附.%The acid activated red mud was prepared after red mud was activated by hydrochloric acid. Adsorbent of cerium-loaded red mud was prepared with the acid activated red mud as a carrier, cerium oxide as an active component. Under the condition of 25 ℃ and static state, The treatment of wastewater containing fluoride with the adsorbent of cerium-loaded red mud was studied. The results showed that the preparation conditions of the adsorbent of cerium-oaded red mud were as follows: hydrochloric acid concentration 6 mol/L, reaction time of cerium-loaded red mud 16 h, cerium sulfate four water concentration 0.4 g/L and calcination temperature 500 ℃; the fluoride removing efficiency was above 98% at an adsorption time of 90min, from the wastewater with a pH of 6.0, fluoride concentration of 40 mg/L in the wastewater, and the fluoride mass ratio to the adsorbent of cerium-loaded red mud of 1:100. The adsorption process of the adsorbent of cerium-loaded red mud against the fluoride could be well fitted by Langmuir isotherm equation, its linear equation was (pe/qe)/(g ·L-1)=[0.016 3pe/(mg · L-1)]+0.050 3 (R2=0.992 3). The

  11. Carbon Dioxide Fountain

    Science.gov (United States)

    Kang, Seong-Joo; Ryu, Eun-Hee

    2007-01-01

    This article presents the development of a carbon dioxide fountain. The advantages of the carbon dioxide fountain are that it is odorless and uses consumer chemicals. This experiment also is a nice visual experiment that allows students to see evidence of a gaseous reagent being consumed when a pressure sensor is available. (Contains 3 figures.)…

  12. Carbon Dioxide and Climate.

    Science.gov (United States)

    Brewer, Peter G.

    1978-01-01

    The amount of carbon dioxide in the atmosphere is increasing at a rate that could cause significant warming of the Earth's climate in the not too distant future. Oceanographers are studying the role of the ocean as a source of carbon dioxide and as a sink for the gas. (Author/BB)

  13. Síntese e caracterização de precursores de cério de alta pureza Synthesis and characterization of high purity cerium precursors

    Directory of Open Access Journals (Sweden)

    C. A. S. Queiroz

    2001-03-01

    Full Text Available Neste trabalho são destacadas as técnicas de separação e de purificação de terras raras por precipitação fracionada e troca iônica, além das técnicas usualmente utilizadas no controle analítico destes materiais. A aplicação destas técnicas é mostrada neste trabalho para a obtenção de óxido ou nitrato de cério com pureza > 99%. O principal objetivo é a obtenção de precursores à base de cério para o processamento de cerâmicas de zircônia-céria ou céria contendo terras raras. A disponibilidade de cloretos mistos, matéria-prima para a preparação de terras raras individuais, e o conhecimento das técnicas de separação, purificação e controle analítico de terras raras no IPEN, permite sua obtenção local para uso em pesquisa e desenvolvimento.In this work techniques of fractioned precipitation and ion exchange for separating and purifying rare earth elements are outlined. Other techniques usually utilized in the analytical control of these elements are also briefly discussed. The application of these techniques for the preparation of cerium nitrate or cerium oxide of > 99% purity are demonstrated. The main purpose is to obtain cerium precursors for the processing of zirconia-ceria or ceria-rare earth ceramic materials. The raw material availability in the form of mixed chlorides, and the knowledge of these techniques at IPEN allows for obtaining these precursors in the local market for research and development purposes.

  14. 铁铈复合氧化物催化剂SCR脱硝的改性研究%Study on the modification of iron-cerium mixed oxide catalyst for selective catalytic reduction of NO

    Institute of Scientific and Technical Information of China (English)

    熊志波; 路春美

    2013-01-01

    利用共沉淀法制备了铁铈催化剂,考察添加钛、锆、钨和钼对其SCR脱硝的改性规律.结果表明,钨和钼的添加提高了铁铈催化剂高温脱硝性能,却使其低温活性有所降低;钛的添加对铁铈催化剂脱硝性能具有促进作用,尤其提高了其低温活性,并拓宽了其完全转化温度窗口,为最佳改性物.当钛的物质的量比逐渐由0.10增至0.40,铁铈钛催化剂低温脱硝效率先增大后减小,但其高温脱硝效率逐渐增大至100%,钛的最佳物质的量比为0.15.XRD和N2吸附分析结果表明,钛能优化铁铈催化剂的孔隙结构,增大其比表面积和比孔容,细化其孔径,并与催化剂中铁、铈氧化物形成良好的固溶体,从而提高了铁铈催化剂的SCR脱硝性能.Fe0.8Ce0.05Ti0.15Oz催化剂在150 ~400℃取得了高于90%的NOx转化率.%A series of iron-cerium mixed oxide catalysts modified titanium, zirconium, tungsten and molybdenum were prepared by co-precipitation. The selective catalytic reduction of NOx with NH3(NH3-SCR) activity of the catalysts were carried out in a fixed-bed quartz tube reactor. The research results indicated that the addition of tungsten and molybdenum could increase the high-temperature NH3-SCR activity of the iron-cerium mixed oxide catalysts, but decreased its low-temperature NH3-SCR activity. Titanium could improve the NH3-SCR activity of the iron-cerium mixed oxide catalyst within the range of reaction temperature, especially at low-temperature. Titanium was the most suitable assistant. When increasing the molar fraction of titanium from 0.10 to 0.40, the low-temperature NH3-SCR activity of iron-cerium-titanium mixed oxide catalysts firstly increased and then decreased while the high-temperature activity gradually increased to 100% , and the optimum molar fraction of titanium was 0.15. The results of X-ray diffraction(XRD) and N2 adsorption isotherms showed that the addition of titanium could optimize the pore

  15. Low temperature hydrogen production from ethanol over cerium and nickel based oxyhydrides

    Energy Technology Data Exchange (ETDEWEB)

    Pirez, Cyril; Jalowiecki-Duhamel, L.; Capron, M.; Dumeignil, F. [Univ. des Sciences et Technologies de Lille (France). UCCS Unite de Catalyse et de Chimie du Solide

    2010-07-01

    In theory, hydrogen production from biomass or biomass derived liquids can be a carbon emission free process since all carbon dioxide produced can be recycled back to plants using solar energy. Besides, ethanol is also safe, simple to handle, transport and store, so ethanol lends itself very well to a distributed-production strategy. A very interesting use of hydrogen is based on its conversion into power in fuel cell systems. The wide-spread application of fuel cells becomes closer to reality, so increased attention is focused on hydrogen production technology. Solid oxide fuel cells (SOFCs) are under development as energy production devices, they allow the use of carbon-monoxide resistant nickel anodes and the use of fuels different from hydrogen at the anode, in the so-called direct internal reforming SOFC. However the high operating temperatures undergo catalytic deactivation due to sintering of nickel crystallites and carbon deposition. Hence, worldwide efforts are in progress to discover novel, more active and more stable catalysts. Performing the reaction at lower temperature than 600 C is a challenging goal. C{sub 2}H{sub 5}OH + 3 H{sub 2}O {yields} 2 CO{sub 2} + 6 H{sub 2} (1). Hydrogen production from ethanol steam reforming (H{sub 2}O/C{sub 2}H{sub 5}OH = 3) was investigated over cerium nickel CeNi{sub X}O{sub Y} and (0 < x {<=} 5) mixed oxide catalysts. The influence of different parameters was analysed, such as reaction temperature, Ni content and in-situ pre-treatment in H{sub 2}. While an ethanol conversion of 100 % is reached at 400 C, a stable activity i.e. ethanol conversion, and H{sub 2} selectivity can be obtained at very low temperature (200 C) when the solid is previously in-situ treated in H{sub 2} in a temperature range between 200 C and 300 C. In the present study, we report on H{sub 2} formation activity over CeNi{sub X}O{sub Y} catalysts for reforming of ethanol. The aim of this work was to develop a highly active, selective, stable and

  16. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    Directory of Open Access Journals (Sweden)

    Mirella Gutiérrez-Arzaluz

    2016-05-01

    Full Text Available We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce–Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns.

  17. Mechanism of chlorinating lanthanum oxide and cerium oxide with ammonium chloride

    Institute of Scientific and Technical Information of China (English)

    朱国才; 李赋屏; 肖明贵

    2003-01-01

    Using ammonium chloride(NH4Cl)as a chlorinating agent,the effects of chlorinating temperature,at 300℃ for 90 min,and have no advantage to chlorination of lanthanum and cerium oxides at higher temperature.The thermal decomposition of LaCl3 and CeCl3 is carried out to explore the mechanism of chlorinating lanthanum and cerium oxides.At the same time,the chlorination of lanthanum and cerium oxides is not devoted to the HCl decomposed from NH4Cl,but to NH4Cl directly taking part in the chlorination of La2O3 and CeO2.The lanthanum and cerium oxides in chlorination firstly form intermediate LaOCl and CeOCl,and then transfer to LaCl3 and CeCl3,fither prove the existence of the intermediates LaOCl and CeOCl.Therefore the chlorinating temperature and time should strictly be controlled when the lanthanum oxide and cerium oxide are chlorinated with NH4 Cl.And over-dosage of NH4 Cl should be also applied in the process of chlorination.

  18. Production of cerium zinc molybdate nano pigment by innovative ultrasound assisted approach.

    Science.gov (United States)

    Patel, M A; Bhanvase, B A; Sonawane, S H

    2013-05-01

    Ultrasound assisted synthesis of yellow rare earth cerium zinc molybdate anticorrosion nanopigment is presented. This new class of pigment is eco-friendly alternatives to lead, cadmium and chromium pigment as these pigments contains carcinogenic species like Cr(6+) which is responsible for human disease. The synthesis of nanosized cerium zinc molybdate was carried out using cerium nitrate, sodium zinc molybdate as a precursor materials by conventional and ultrasound assisted chemical precipitation method without addition of emulsification agent. XRD, FTIR and elemental analysis confirm the formation of cerium zinc molybdate nanoparticles. The conductivity results indicate that conventional synthesis takes longer time, while in sonochemical technique (US), reaction completes within short period of time. Improved solute transfer rate, rapid nucleation, and formation of large number of nuclei are attributed to presence of cavitation. Saturation of the Ce(3+) ions reaches earlier in case of sonochemical technique which restricts the growth of particles hence smaller size is obtained. The crystallite size of cerium zinc molybdate was found to be 27nm from XRD analysis.

  19. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents.

    Science.gov (United States)

    Gutiérrez-Arzaluz, Mirella; Noreña-Franco, Luis; Ángel-Cuevas, Saúl; Mugica-Álvarez, Violeta; Torres-Rodríguez, Miguel

    2016-05-24

    We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce-Co/Al₂O₃ membrane, which are employed as catalysts for the catalytic wet oxidation (CWO) reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce-Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns.

  20. Toenail cerium levels and risk of a first acute myocardial infarction: The EURAMIC and heavy metals study

    NARCIS (Netherlands)

    Gomez-Aracena, J.; Riemersma, R.A.; Veer, van 't P.; Kok, F.J.

    2006-01-01

    The association between cerium status and risk of first acute myocardial infarction (AMI) was examined in a case-control study in 10 centres from Europe and Israel. Cerium in toenails was assessed by neutron activation analysis in 684 cases and 724 controls aged 70years or younger. Mean concentratio

  1. 钛白粉-碳酸钙复合填料的制备及在水性油墨中的应用探讨%Preparation of Titanium Dioxide-CaCO3 Composite Filler and Its Application in Waterborne Ink

    Institute of Scientific and Technical Information of China (English)

    张本发

    2016-01-01

    Titanium dioxide is a kind of polymorphic compound,which has the characteristics of small particle size and high whiteness,and its particles are generally 0.1-0.2um.In addition,the color strength of titanium dioxide and light diffusion agent is very strong,when the titanium dioxide dispersed in the media,the ink can make the hiding power is significantly enhanced.In addition,the titanium dioxide,light resistance,alkali resistance and heat resistance is better,so its application to high-quality white ink can be a great use.Today,in the ink industry,titanium dioxide has been widely used.Practice has shown that,in the production of ink,different types of ink products for the quality requirements of titanium dioxide there are some differences.The rutile titanium dioxide is widely used today,its crystal shape,color strength and refractive index,fluorescence is better than other types of titanium dioxide.In addition,the quality of titanium dioxide for the quality of ink equipment will have a certain impact.Titanium dioxide-calcium carbonate composite filler is used in the preparation of a new ink raw materials,it absorbs the titanium dioxide and calcium carbonate material characteristics,and better play the role of titanium dioxide,the quality of the ink can be guaranteed.The preparation of titanium dioxide-calcium carbonate composite filler and its application in water-based ink were discussed in depth,with a view to preparing a higher quality water-based ink.%钛白粉属于一种多晶型化合物,具有颗粒细小、白度较高的特点,其颗粒一般为0.1~0.2um。并且,钛白粉的着色力以及光扩散剂很强,当二氧化钛在介质中分散的时候,可使得油墨的遮盖力得到明显增强。另外,钛白粉的耐光性、耐碱性以及耐热性较好,因此,将其运用到高质量的白色油墨中可得到很大的应用。现今,在油墨行业中,钛白粉得到广泛应用。实践表明,在进行油墨生产时,类

  2. Anti-angiogenic activity of heparin functionalised cerium oxide nanoparticles.

    Science.gov (United States)

    Lord, Megan S; Tsoi, Bonny; Gunawan, Cindy; Teoh, Wey Yang; Amal, Rose; Whitelock, John M

    2013-11-01

    Cerium oxide nanoparticles (nanoceria) are widely reported to be non-cytotoxic and modulate intracellular reactive oxygen species (ROS). In this study, nanoceria (dxRD = 12 nm) were functionalised with either 130 or 880 molecules of unfractionated heparin using the organosilane linker, 3-aminopropyltriethoxysilane. Nanoceria with a low level of heparin functionalisation were found to scavenge intracellular ROS to the same extent as unfunctionalised nanoceria and significantly more than cells exposed to medium only. In contrast, nanoceria with the highest level of heparin functionalisation were not as effective at scavenging intracellular ROS. Nanoceria were localised predominantly in the cytoplasm, while heparin-nanoceria were localised in both the cytoplasm and lysosomes. Together these data demonstrated that the level of nanoceria surface functionalisation with heparin determined the intracellular localisation and ROS scavenging ability of these particles. Additionally, heparin-nanoceria were effective in reducing endothelial cell proliferation indicating that they may find application in the control of angiogenesis in cancer in the future.

  3. Surface modification of promising cerium oxide nanoparticles for nanomedicine applications

    KAUST Repository

    Nanda, Himansu Sekhar

    2016-11-14

    Cerium oxide nanoparticles (CNPs) or nanoceria have emerged as a potential nanomedicine for the treatment of several diseases such as cancer. CNPs have a natural tendency to aggregate or agglomerate in their bare state, which leads to sedimentation in a biological environment. Since the natural biological environment is essentially aqueous, nanoparticle surface modification using suitable biocompatible hydrophilic chemical moieties is highly desirable to create effective aqueous dispersions. In this report, (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl)triethoxysilane was used as a functional, biocompatible organosilane to modify the surface of CNPs to produce promising nanoparticles which open substantial therapeutic avenues. The surface modified nanoparticles were produced in situ via an ammonia-induced ethylene glycol-assisted precipitation method and were characterized using complimentary characterization techniques. The interaction between the functional moiety and the nanoparticle was studied using powerful cross polarization/magic angle sample spinning solid state nuclear magnetic resonance spectroscopy. The surface-modified nanoparticles were extremely small and demonstrated a significant improvement in aqueous dispersibility. Moreover, the existence of a strong ionic coordination between the functional moiety and the surface of the nanoparticle was realised, indicating that the surface modified nanoceria are stable and that the nanoparticles should demonstrate an enhanced circulation time in a biological environment. The surface modification approach should be promising for the production of CNPs for nanomedicine applications. © The Royal Society of Chemistry.

  4. Effect of Impurities and Cerium on Stress Concentration Sensitivity of Al-Li Based Alloys

    Institute of Scientific and Technical Information of China (English)

    孟亮; 田丽

    2002-01-01

    A notch sensitivity factor was derived in order to evaluate the stress concentration sensitivity of Al-Li based alloys. The factor values for the Al-Li alloy sheets containing various contents of impurities and cerium addition were evaluated by determining the mechanical properties. It is found that the impurities Fe, Si, Na and K significantly enhance the stress concentration sensitivity of the alloys 2090 and 8090, whereas cerium addition reduces the stress concentration sensitivity to a certain degree for the high strength alloys. However, an excess amount of cerium addition in the high ductility alloy 1420 can significantly increase the stress concentration sensitivity. As compared with conventional aluminum alloys, the Al-Li based alloys generally show high stress concentration sensitivity. Therefore, a special attention must be paid to this problem in the practical application of Al-Li based alloys.

  5. The role of chemical interactions between thorium, cerium, and lanthanum in lymphocyte toxicity.

    Science.gov (United States)

    Oliveira, Monica S; Duarte, Isabelle M; Paiva, Amanda V; Yunes, Samira N; Almeida, Carlos E; Mattos, Rita C; Sarcinelli, Paula N

    2014-01-01

    Thorium, cerium, and lanthanum are metals present in several types of minerals, the most common of which is monazite. Cerium and lanthanum are elements in the lanthanides series. Thorium, an actinide metal, is a hazardous element due to its radioactive characteristics. There is a lack of information describing the possible chemical interactions among these elements and the effects they may have on humans. Toxicological analyses were performed using cell viability, cell death, and DNA damage assays. Chemical interactions were evaluated based on the Loewe additivity model. The results indicate that thorium and cerium individually have no toxic effects on lymphocytes. However, thorium associated with lanthanum increases the toxicity of this element, thereby reducing the viability of lymphocytes at low concentrations of metals in the mixture.

  6. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Directory of Open Access Journals (Sweden)

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  7. Structure, Morphology and Reducibility of Epitaxial Cerium Oxide Ultrathin Films and Nanostructures

    Directory of Open Access Journals (Sweden)

    Paola Luches

    2015-08-01

    Full Text Available Cerium oxide is a very interesting material that finds applications in many different fields, such as catalysis, energy conversion, and biomedicine. An interesting approach to unravel the complexity of real systems and obtain an improved understanding of cerium oxide-based materials is represented by the study of model systems in the form of epitaxial ultrathin films or nanostructures supported on single crystalline substrates. These materials often show interesting novel properties, induced by spatial confinement and by the interaction with the supporting substrate, and their understanding requires the use of advanced experimental techniques combined with computational modeling. Recent experimental and theoretical studies performed within this field are examined and discussed here, with emphasis on the new perspectives introduced in view of the optimization of cerium oxide-based materials for application in different fields.

  8. Study of phase transitions in cerium in shock-wave experiments

    Directory of Open Access Journals (Sweden)

    Zhernokletov M.V.

    2015-01-01

    Full Text Available Cerium has a complex phase diagram that is explained by the presence of structure phase transitions. Planar gauges were used in various combinations in experiments for determination of sound velocity dependence on pressure in cerium by the technique of PVDF gauge. The data of time dependence on pressure profiles with use of x(t diagrams and the D(u relation for cerium allowed the definition of the Lagrangian velocity of the unloading wave CLagr and the Eulerian velocity CEul by taking into account the compression σ. These results accords with data obtained by using the technique of VISAR and a manganin-based gauge, and calculated pressure dependence of isentropic sound velocity according to the VNIITF EOS. Metallography analysis of post-experimental samples did not find any changes in a phase composition.

  9. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    Energy Technology Data Exchange (ETDEWEB)

    Ding Yuan, Paul Guss, and Sanjoy Mukhopadhyay

    2009-04-01

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detector’s self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  10. Experimental Investigations on the Effects of Cerium Oxide Nanoparticle Fuel Additives on Biodiesel

    Directory of Open Access Journals (Sweden)

    V. Sajith

    2010-01-01

    Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in the nanoparticle form on the major physicochemical properties and the performance of biodiesel. The physicochemical properties of the base fuel and the modified fuel formed by dispersing the catalyst nanoparticles by ultrasonic agitation are measured using ASTM standard test methods. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Comparisons of the performance of the fuel with and without the additive are also presented. The flash point and the viscosity of biodiesel were found to increase with the inclusion of the cerium oxide nanoparticles. The emission levels of hydrocarbon and NOx are appreciably reduced with the addition of cerium oxide nanoparticles.

  11. Exposure of cerium oxide nanoparticles to kidney bean shows disturbance in the plant defense mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanghamitra [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Bandyopadhyay, Susmita [Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Castillo-Michel, Hiram [European Synchrotron Radiation Facility, B.P. 220-38043 Grenoble, Cedex (France); Hernandez-Viezcas, Jose-Angel [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Sahi, Shivendra [Department of Biology, Western Kentucky University, Bowling Green, KY 42101 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States)

    2014-08-15

    Graphical abstract: - Highlights: • Kidney bean roots uptake nCeO{sub 2} primarily without biotransformation. • Cerium reached the root vascular tissues through gaps in the Casparian strip. • On longer exposure to high concentration, roots demonstrate stress response. • In leaves, guaiacol peroxidase plays a major role in ROS scavenging. - Abstract: Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO{sub 2}) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of ∼8 ± 1 nm nCeO{sub 2} (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO{sub 2} exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron μ-XRF mapping, and the chemical forms were identified using μ-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO{sub 2}, although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO{sub 2}/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO{sub 2} exposure in order to maintain cellular homeostasis.

  12. Luminescence properties and decay kinetics of nano ZnO powder doped with cerium ions

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Nihar Ranjan, E-mail: nihar@iitbbs.ac.in [Indian Institute of Technology Bhubaneswar, Bhubaneswar 751013, Orissa (India); Acharya, B.S., E-mail: bsacharya1950@gmail.com [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar 752054, Orissa (India); Singh, Th. Basanta [Luminescence Dating Laboratory, Manipur University, Imphal 795003 (India); Gartia, R.K. [Department of Physics, Manipur University, Imphal 795003 (India)

    2013-04-15

    ZnO nanopowders doped with cerium ions (1.2 and 1.5 at. wt.%) were synthesized through soft solution route using ultrasound. Sonication has been found to be an effective way for doping rare earth ions like cerium into ZnO. This was confirmed from energy dispersive analysis of X-rays (EDAX) measurement. Further, optical absorption and photoluminescence (PL) measurements corroborate this finding. X-ray diffraction (XRD) studies show the increase of crystallite size and unit cell volume with doping of cerium ions. Formation of fibrous structure of ZnO:Ce was observed from the transmission electron microscopy (TEM) measurements. Although the structural measurements indicate Ce{sup 4+} ion occupying substitutional site in ZnO, PL and absorption studies confirmed the presence of Ce{sup 3+} ion in the powder. The coexistence of Ce{sup 3+} and Ce{sup 4+} ions has been explained on the basis of conversion of Ce{sup 3+} to Ce{sup 4+} in the oxidizing environment. Thermoluminescence (TL) and photo-stimulated decay of luminescence (PSDL) decay studies give an idea of various trapping levels present in the band gap of ZnO. These traps release electrons during optical stimulation to give bimolecular kinetics in nano ZnO:Ce powders. -- Highlights: ► Sonication: an effective way of incorporation of cerium ions into ZnO. ► Site dependent characteristic emission of cerium. ► Energy transfer from host lattice to cerium ions. ► Mono and bimolecular kinetics of ZnO:Ce.

  13. Homoleptic cerium(III) and cerium(IV) nitroxide complexes: significant stabilization of the 4+ oxidation state.

    Science.gov (United States)

    Bogart, Justin A; Lewis, Andrew J; Medling, Scott A; Piro, Nicholas A; Carroll, Patrick J; Booth, Corwin H; Schelter, Eric J

    2013-10-07

    Electrochemical experiments performed on the complex Ce(IV)[2-((t)BuNO)py]4, where [2-((t)BuNO)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(n)Bu4N]2[Ce(NO3)6] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with δ symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree through tuning of its ligand-field environment.

  14. Preparation and Performance of Rare Earths Chemical Conversion Film on Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Golden yellow cerium conversion film was obtained on magnesium alloys surface by immersion method and the preparation parameters were established. The influence of different process parameters on the surface morphology and performance of the conversion film were analyzed by means of SEM and electrochemical method. Formation dynamics about cerium conversion film on magnesium alloy in solution containing cerium salt and the anti-corrosion behavior of the conversion film in 3.5% NaCl solution were studied by electrochemical method respectively. The results shows that the conversion film is more compact at room temperature when concentration of cerium sulfate is 10 g·L-1 in the solution; the open circuit potential of the magnesium sample moves up to positive direction about 100 mV, the surface of conversion film becomes even and lustrous, and the adhesion intensity of conversion film increases when adding aluminum nitrate into the solution containing cerium salt. The pH value of the solution and immersion time of the sample in the solution also affect the surface morphology and anti-corrosion property of the conversion film. After covered by rare earths conversion film, the anti-corrosion property of magnesium alloy is obviously improved. Rare earth conversion film has self-repairing capability in corrosion medium.

  15. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Science.gov (United States)

    Kartsonakis, I. A.; Kontogiani, P.; Pappas, G. S.; Kordas, G.

    2013-06-01

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 ± 15 and 221 ± 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  16. Dissociation of outer membrane for Escherichia coli cell caused by cerium nitrate

    Institute of Scientific and Technical Information of China (English)

    陈爱美; 施庆珊; 冯劲; 欧阳友生; 陈仪本; 谭绍早

    2010-01-01

    The biological effect of cerium nitrate on the outer membrane(OM) of Escherichia coli(E.coli) cell was studied,and the antim-icrobial mechanism of rare earth elements was explored.The antimicrobial effect of cerium nitrate on E.coli cell was valued by plate count method,and the morphology change of E.coli cell was observed with scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results showed that the E.coli cell suspension was flocculated when the concentration of Ce(NO3)3?6H2O...

  17. Evaluation of Antiproliferative Potential of Cerium Oxide Nanoparticles on HeLa Human Cervical Tumor Cell

    Directory of Open Access Journals (Sweden)

    Zoriţa Diaconeasa

    2015-05-01

    Full Text Available Cerium oxide nanoparticles (CeO2 nanoparticles as nanomaterials have promising biomedical applications. In this paper, the cytotoxicity induced by CONPs human cervical tumor cells was investigated. Cerium oxide nanoparticles were synthesized using the precipitation method. The nanoparticles were found to inhibit the proliferation of HeLa human cervical tumor cells in a dose dependent manner but did not showed to be cytotoxic as analyzed by MTT assay. The administrated treatment decreased the HeLa cell viability cells from 100% to 65% at the dose of 100 μg/mL.

  18. Cerium: catalytic properties, technological and environmental applications; Cerio: propriedades cataliticas, aplicacoes tecnologicas e ambientais

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Tereza S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica; Hewer, Thiago L.R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Freire, Renato S. [Universidade de Sao Paulo (USP), Cubatao (Brazil). Centro de Capacitacao e Pesquisa em Meio Ambiente]. E-mail: tmartins@if.usp.br

    2007-07-01

    Cerium based-compounds have great importance in a wide range of technological applications, such as: fuel cell devices development; metallurgic processes, petroleum refining; glass and ceramic production. Recently, its catalytic properties have been also explored for environmental applications, especially those to prevent or to control atmospheric and water pollution. Subjects covered in this work include a brief description of the fundaments of cerium catalytic properties and some relevant technological applications. Special attention is given to its photo catalytic activity and its ability to degrade pollutants. Recent results and future prospect about these applications are also evaluated. (author)

  19. Synthesis and characterization of two dimensional metal organic framework of cerium with tetraaza macrocyclic

    Energy Technology Data Exchange (ETDEWEB)

    Bt Safiin, Nurul Atikah; Yarmo, Ambar; Yamin, Bohari M. [School of Chemical Science and Food Technology. Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan (Malaysia)

    2013-11-27

    A two dimensional metal organic framework containing cerium sufate layers and ethylenediaminium between layers was obtained by refluxing the mixture of cerium sulphate and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7, 14-diene bromide. The complex was characterized by infrared spectroscopy and microelemental analysis. X-ray study showed that the complex adopts eleven coordination environments about the central atom. Thermogravimetric study showed the removal of water molecules at about 70°C followed by a gradual mass loss until the whole structure collapsed at about 400°C.

  20. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Kartsonakis, I. A., E-mail: ikartsonakis@ims.demokritos.gr; Kontogiani, P.; Pappas, G. S.; Kordas, G. [NCSR ' DEMOKRITOS' , Sol-Gel Laboratory, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems (Greece)

    2013-06-15

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 {+-} 15 and 221 {+-} 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  1. Feasibility of Substituting Cerium-Rich Metal by La-Pr-Ce Alloy in Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    伏思静; 赵平

    2004-01-01

    In magnesium alloy ZM3, using cheap Lanthanum-praseodymium-cerium (LPC) rare earth as a substitute for rich-cerium rare earth was studied. The experimental results show that when the adding amount of LPC is between 2.53% and 3.33%, the tensile strength increases as the adding amount of LPC increases; when the amount of RE is 2.53% and 3.33%, the average tensile strength is 142.35, 153.65 MPa respectively. The results show that LPC rare earth replacing rich Ce rare earth is feasible for the tensile strength of ZM3.

  2. Synthesis and Characterization of Cerium-Doped Lutetium Aluminum Garnet Phosphors by Nitrate-citrate Sol-Gel Combustion Process

    Institute of Scientific and Technical Information of China (English)

    Li Huili; Liu Xuejian; Zhang Qitu; Huang Liping

    2007-01-01

    Nanosized cerium-doped lutetium aluminum garnet (LuAG:Ce) phosphors were prepared by nitrate-citrate sol-gel combustion process using 1:1 ratio of the citrate:nitrate. The prepared LuAG:Ce phosphors were characterized by XRD, TEM, photoluminescence and radioluminescence spectra excited by UV and X-ray, respectively. The purified crystalline phase of LuAG:Ce was obtained at 900 ℃ by directly crystallizing from amorphous materials. The resultant LuAG:Ce phosphors were uniform and had good dispersivity with an average particle size of about 30 nm. Both photoluminescence and radioluminescence were well-known Ce3+ emissions located in the range of 470~600 nm consisting of two emission bands because of the transition from the lowest 5d excited state (2D) to the 4f ground state of Ce3+, which matched well with the sensitivity curve of the Si-photodiode. There was a little red shift for the emission components from the UV-excited emission spectrum to the X-ray-excited emission spectrum. The fast scintillation decay component of 26 ns satisfies the requirements of fast scintillators.

  3. Effects of Cerium Oxide Nanoparticles on Sorghum Plant Traits

    Science.gov (United States)

    Mu, L.; Chen, Y.; Darnault, C. J. G.; Rauh, B.; Kresovich, S.; Korte, C.

    2015-12-01

    Nanotechnology and nanomaterials are considered as the development of the modern science. However, besides with that wide application, nanoparticles arouse to the side effects on the environment and human health. As the catalyst of ceramics and fuel industry, Cerium (IV) oxide nanoparticles (CeO2 NPs) can be found in the environment following their use and life-cycle. Therefore, it is critical to assess the potential effects that CeO2 NPs found in soils may have on plants. In this study, CeO2 NPs were analyzed for the potential influence on the sorghum [Sorghum bicolor (L.) Moench] (Reg. no. 126) (PI 154844) growth and traits. The objectives of this research were to determine whether CeO2 NPs impact the sorghum germination and growth characteristics. The sorghum was grown in the greenhouse located at Biosystems Research Complex, Clemson University under different CeO2 NPs treatments (0mg; 100mg; 500mg; 1000mg CeO2 NPs/Kg soil) and harvested around each month. At the end of the each growing period, above ground vegetative tissue was air-dried, ground to 2mm particle size and compositional traits estimated using near-infrared spectroscopy. Also, the NPK value of the sorghum tissue was tested by Clemson Agriculture Center. After the first harvest, the result showed that the height of above ground biomass under the nanoparticles stress was higher than that of control group. This difference between the control and the nanoparticles treatments was significant (F>F0.05; LSD). Our results also indicated that some of the compositional traits were impacted by the different treatments, including the presence and/or concentrations of the nanoparticles.

  4. Thermoluminescence of cerium and terbium -doped calcium pyrophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Lozano R, I. B.; Diaz G, J. A. I., E-mail: jesus.roman@nucleares.unam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    The aim of this work is to report the thermoluminescence (Tl) response of Calcium Pyrophosphate phosphor doped with Cerium and Terbium impurities (Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+}). The phosphors were synthesized using the co-precipitation method and annealed at 900 degrees C by two hours for obtain the β phase. The intentional doping with Ce and Tb ions was 1 at.% and 0.1 at.%, whereas in the EDS results the concentration of impurities was 0.39 at.% and 0.05 at.%, respectively. The superficial morphology of phosphor is mainly composed by thin wafers of different size. All samples were exposed to gamma rays from {sup 60}Co in the Gammacell-200 irradiator. The Tl response of the phosphor was measured from Rt up to 350 degrees C and under nitrogen atmosphere in a Harshaw TLD 3500 reader. The glow curves of the Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} powders showed a broad intense Tl peak centered at 165 degrees C and a shoulder at approximate 260 degrees C was observed. A linear Tl response in the range of absorbed dose of 0.2 to 10 Gy was obtained. Tl glow curves were analyzed using the initial rise (IR)and computerized glow curve deconvolution methods to evaluate the kinetics parameters such as activation energy (E), frequency factor (s) and kinetic order (b). (Author)

  5. Variations in Reactivity on Different Crystallographic Orientations of Cerium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, David R [ORNL; Albrecht, Peter M [ORNL; Calaza, Florencia C [ORNL

    2013-01-01

    Cerium oxide is a principal component in many heterogeneous catalytic processes. One of its key characteristics is the ability to provide or remove oxygen in chemical reactions. The different crystallographic faces of ceria present significantly different surface structures and compositions that may alter the catalytic reactivity. The structure and composition determine the number of coordination vacancies surrounding surface atoms, the availability of adsorption sites, the spacing between adsorption sites and the ability to remove O from the surface. To investigate the role of surface orientation on reactivity, CeO2 films were grown with two different orientations. CeO2(100) films were grown ex situ by pulsed laser deposition on Nb-doped SrTiO3(100). CeO2(111) films were grown in situ by thermal deposition of Ce metal onto Ru(0001) in an oxygen atmosphere. The chemical reactivity was characterized by the adsorption and decomposition of various molecules such as alcohols, aldehydes and organic acids. In general the CeO2(100) surface was found to be more active, i.e. molecules adsorbed more readily and reacted to form new products, especially on a fully oxidized substrate. However the CeO2(100) surface was less selective with a greater propensity to produce CO, CO2 and water as products. The differences in chemical reactivity are discussed in light of possible structural terminations of the two surfaces. Recently nanocubes and nano-octahedra have been synthesized that display CeO2(100) and CeO2(111) faces, respectively. These nanoparticles enable us to correlate reactions on high surface area model catalysts at atmospheric pressure with model single crystal films in a UHV environment.

  6. Chemoselective Alternating Copolymerization of Limonene Dioxide and Carbon Dioxide: A New Highly Functional Aliphatic Epoxy Polycarbonate.

    Science.gov (United States)

    Li, Chunliang; Sablong, Rafaël J; Koning, Cor E

    2016-09-12

    The alternating copolymerization of biorenewable limonene dioxide with carbon dioxide (CO2 ) catalyzed by a zinc β-diiminate complex is reported. The chemoselective reaction results in linear amorphous polycarbonates that carry pendent methyloxiranes and exhibit glass transition temperatures (Tg ) up to 135 °C. These polycarbonates can be efficiently modified by thiols or carboxylic acids in combination with lithium hydroxide or tetrabutylphosphonium bromide as catalysts, respectively, without destruction of the main chain. Moreover, polycarbonates bearing pendent cyclic carbonates can be quantitatively prepared by CO2 insertion catalyzed by lithium bromide.

  7. Effect of nano-sized cerium-zirconium oxide solid solution on far-infrared emission properties of tourmaline powders

    Science.gov (United States)

    Guo, Bin; Yang, Liqing; Hu, Weijie; Li, Wenlong; Wang, Haojing

    2015-10-01

    Far-infrared functional nanocomposites were prepared by the co-precipitation method using natural tourmaline (XY3Z6Si6O18(BO3)3V3W, where X is Na+, Ca2+, K+, or vacancy; Y is Mg2+, Fe2+, Mn2+, Al3+, Fe3+, Mn3+, Cr3+, Li+, or Ti4+; Z is Al3+, Mg2+, Cr3+, or V3+; V is O2-, OH-; and W is O2-, OH-, or F-) powders, ammonium cerium(IV) nitrate and zirconium(IV) nitrate pentahydrate as raw materials. The reference sample, tourmaline modified with ammonium cerium(IV) nitrate alone was also prepared by a similar precipitation route. The results of Fourier transform infrared spectroscopy show that tourmaline modified with Ce and Zr has a better far-infrared emission property than tourmaline modified with Ce alone. Through characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the mechanism for oxygen evolution during the heat process in the two composite materials was systematically studied. The XPS spectra show that Fe3+ ratio inside tourmaline modified with Ce alone can be raised by doping Zr. Moreover, it is showed that there is a higher Ce3+ ratio inside the tourmaline modified with Ce and Zr than tourmaline modified with Ce alone. In addition, XRD results indicate the formation of CeO2 and Ce1-xZrxO2 crystallites during the heat treatment and further TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far-infrared emission properties of Ce-Zr doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from much more oxidation of Fe2+ to Fe3+ inside the tourmaline caused by the change in the catalyst redox properties of CeO2 brought about by doping with Zr4+. In all samples, tourmaline modified with 7.14 wt.% Ce and 1.86 wt.% Zr calcined at 800∘C for 5 h has the best far-infrared emission property with the maximum emissivity value of 98%.

  8. Structural and electrochemical studies on the utilization of Cerium (Ce3+ as an additive for nickel hydroxide electrode

    Directory of Open Access Journals (Sweden)

    Marcio Vidotti

    2007-03-01

    Full Text Available This paper describes electrochemical and spectroscopic studies on the utilization of cerium atoms as additives for nickel hydroxide electrodes. Thin films were galvanostatically grown with different amounts of cerium and mixed electrodes were studied by electrochemical measurements and the spectroscopic technique. The electrochromic behavior was investigated by “in situ” experiments , while the amount of species was determined by ICP-OES. The addition of cerium to nickel hydroxide electrodes increases durability, due to modifications in the structural properties, as seen by Raman spectras.

  9. Effects of Cerium on Alloy Elements Distribution in Ferrous Matrix Material

    Institute of Scientific and Technical Information of China (English)

    刘英才; 刘俊友; 尹衍生; 刘国权

    2001-01-01

    The effect of the addition of rare earths in Fe-based high chromium alloy powders on elements distribution in matrix materials and mechanical properties were studied. The results show that the addition of cerium can increase the chromium amount in carbonides and increase the micro-hardness after carbonization and the wear-resistant property of materials.

  10. Growth and characterization of Sm3+ doped cerium oxalate single crystals

    Directory of Open Access Journals (Sweden)

    Minu Mary C

    2016-07-01

    Full Text Available Single crystals of Sm3+ doped cerium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, morphology, nucleation density and quality of the crystals were optimized. Highly transparent single crystals of average size 3 mm × 2 mm × 1 mm with well-defined hexagonal morphology were grown during a time period of two weeks. X-ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c as identical with the pure cerium oxalate. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. The photoluminescence spectrum of the Sm3+ doped cerium oxalate indicated that the Sm3+ ions are optically active in the cerium oxalate matrix. The crystal has a strong and efficient orange red emission with a wavelength peak at 595 nm and hence can be effectively used for optical amplification. Microhardness measurements of the crystal revealed that they belong to the soft material category.

  11. Transient Dynamics of Fluoride-Based High Concentration Erbium/Cerium Co-Doped Fiber Amplifier

    Institute of Scientific and Technical Information of China (English)

    S. S-H. Yam; Y. Akasaka; Y. Kubota; R. Huang; D. L. Harris; J. Pan

    2003-01-01

    We designed and evaluated a fluoride-based high concentration erbium/ cerium co-doped fiber amplifier. It is suitable for Metropolitan Area Networks due to faster transient, flatter (unfiltered) gain, smaller footprint and gain excursion than its silica-based counterpart.

  12. Release of cerium dibutylphosphate corrosion inhibitors from highly filled epoxy coating systems

    NARCIS (Netherlands)

    Soestbergen, M. van; Baukh, V.; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2014-01-01

    Carcinogenic chromates are phased out as corrosion inhibitors in organic coatings, and are replaced by benign alternatives. Cerium-based compounds are excellent corrosion inhibitors in an aqueous environment. However, whether they are effective as corrosion inhibitor in an organic coating also depen

  13. Electroless ternary NiCeP coatings: Preparation and characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Balaraju, J.N., E-mail: jnbalraj@nal.res.in [Surface Engineering Division, CSIR National Aerospace Laboratories, Post Bag No. 1779 Bangalore 560017, Karnataka (India); Chembath, Manju [Surface Engineering Division, CSIR National Aerospace Laboratories, Post Bag No. 1779 Bangalore 560017, Karnataka (India)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Rare earth element (Ce) has been successfully codeposited in NiP matrix. Black-Right-Pointing-Pointer Surface analysis carried out by XPS showed that the Ce is present in +3 and +4 oxidation state. Black-Right-Pointing-Pointer Palladium stability test indicated that the Ce salts in electroless nickel bath has reduced the stability. Black-Right-Pointing-Pointer Cerium codeposition in NiP matrix has increased the microhardness both in as-plated and annealed conditions. Black-Right-Pointing-Pointer Higher thermal stability has been obtained by Ce incorporation. - Abstract: Electroless ternary NiCeP deposits were prepared from alkaline citrate bath containing nickel sulphate, cerium chloride and sodium hypophosphite. Concentration of rare earth cerium was varied from 1 to 2 g/L to obtain ternary deposits containing variable Ce and P contents. The influence of cerium on the deposit properties was analysed. The deposit exhibited a maximum cerium content of 6.2 {+-} 0.1 wt.% when the cerium chloride concentration was 2 g/L. The result of the Pd stability test showed that the stability of the bath was reduced due to Ce salt addition. The microhardness measurements made on both as-plated and heat treated samples exhibited a peak hardness of 1006 {+-} 11 VHN for cerium concentration of 1.5 g/L. The concept of kinetic strength analysis was proved to be applicable only for binary and not for ternary alloys due to multistep deposition mechanism with different kinetic energies. X-ray diffraction (XRD) patterns of as-plated and heat treated samples revealed peaks corresponding to Ni (1 1 1) and nickel phosphide (Ni{sub 3}P). Higher amount of Ce incorporation in NiP matrix increased the crystallisation temperature of the deposit which could be due to the suppression of nickel crystallisation prior to Ni{sub 3}P compound formation and thus increasing the activation energy for the formation of stable phases. Surface compositional analysis

  14. 电化学阻抗谱法研究铈改性TiO2纳米管阵列光电极裂解水产氢动力学%Dynamics Study on the Cerium and Oxidative Cerium Modified TiO2 Nanotube Arrays for Hydrogen Production by Water Splitting Using Electrochemical Impedance Spectrum

    Institute of Scientific and Technical Information of China (English)

    张胜寒; 梁可心; 檀玉

    2012-01-01

    TiO2 nanotube arrays photoelectrodes were prepared by anode oxidation on pure Ti sheet. The donor material glycol (C2H6O2) added in the anode electrolyte significantly reduced the charge transfer impedance of TiO2 nanotubes to promote the photocatalytic water splitting for hydrogen production. TiO2 nanotube arrays electrodes were modified by cerium and oxidative cerium with electrochemical deposition and anodic oxidation. The fiat band potential moves to the negative potential direction after modification. Electrochemical impedance spectrum (EIS) measurement was used to investigate the electron transfer characteristic in photoelectrodes and the interface characteristic in the photoelectrochemical cell (PEC) for hydrogen production. Arcs of EIS and corresponding electrode processes were discussed. Dynamic parameters of the electrodes were calculated by reasonable electrical equivalent circuit fitting. The results indicate that TiO2 nanotube arrays electrode modified by cerium and oxidative cerium could largely decrease the electron transfer resistance which contributes to hydrogen production. The mechanism of the cerium and oxidative cerium acting on TiO2 nanotube arrays to promote charge transfer is discussed.%通过阳极氧化法在纯钛板上制备TiO2纳米管阵列电极.在光电化学电解池阳极中加入供电子物质乙二醇,显著减小了TiO2纳米管的电荷传递阻抗,促进了光电催化裂解水产氢反应.采用阴极电沉积和阳极氧化法制备了单质铈和氧化铈共同改性的TiO2纳米管阵列半导体光阳极,其平带电位向电负方向移动.采用电化学阻抗谱法(EIS)对改性后TiO2纳米管阵列在光电催化裂解水产氢中的电子传输性能以及界面性质进行了表征,确定了各阻抗弧对应的电极过程.采用合理的等效电路模型计算了电极的电子传输动力学参数.结果表明,经铈改性后的TiO2纳米管阵列膜电阻明显减小,

  15. Novel catalytic materials for carbon dioxide reforming of methane under severely deactivating conditions

    Science.gov (United States)

    Stagg-Williams, Susan Michelle

    In recent years, the utilization of carbon dioxide for the reforming of methane (dry reforming) has attracted significant interest due to the industrial advantages over conventional steam reforming. The major obstacle preventing commercialization of this process is the lack of a catalyst capable of operating at the high temperatures and pressures required by industry. This thesis reports the study of the dry reforming reaction over SiO 2 and ZrO2 supported Pt catalysts. It was found that the Pt/ZrO2 catalyst had much higher activity and stability than the Pt/SiO2 catalyst due to the ability of the ZrO2 to adsorb CO2 near the metal particle, facilitating its dissociation. The decomposition of CH4 and the dissociation of CO2 occur via two independent pathways. CH4 decomposition occurs on the metal particle resulting in the formation of H2 and carbon deposition. When Pt is supported on ZrO2, the carbon formed during the decomposition of CH4 can reduce the support to form CO2 creating oxygen vacancies in the support lattice near the metal particle. The adsorption and dissociation of CO2 occurs at the vacancies, forming CO and replenishing the oxygen in the support lattice. This redox mechanism results in a cleaning of the metal particle by oxygen provided by the support. Promoters were added to both the metallic phase and to the support to improve the stability of the catalyst by decreasing carbon deposition. The co-impregnation of Sn and Pt on the ZrO2 resulted in lower activity and stability than the monometallic catalysts. Under oxidizing conditions, segregation of the Pt-Sn alloys occurred, resulting in the formation of tin oxide inhibiting the role of the ZrO2. Catalysts prepared by methods that allow for the controlled placement of Sn on the Pt particle, exhibited high activity and stability under severely deactivating conditions. Promotion of the ZrO2 support with cerium and lanthanum resulted in increased activity and stability of the catalyst. The improved

  16. 4d → 4f resonance in photoabsorption of cerium ion Ce3+ and endohedral cerium in fullerene complex {\\rm{Ce}}@{{{\\rm{C}}}_{82}}^{+}

    Science.gov (United States)

    Schrange-Kashenock, G.

    2016-09-01

    The theoretical investigation of the single-photoionization spectra in the 4d-resonance region (120-150 eV) for the ionic cerium Ce3+ and cerium in the endohedral complex {{Ce}}@{{{{C}}}82}+ (in practice, {{{Ce}}}3+@{{{{C}}}82}2-) is presented. The fullerene cage is modeled by ab initio spherical jellium shell with an accurate account for the real distribution of carbon electron density. The oscillator strengths are calculated within the multiconfiguration Dirac-Fock (MCDF) approach for phototransitions from the outermost shells of the ion Ce3+ with and without the influence of the potential generated by a fullerene cage. It is shown that the integrated oscillator strengths have the main contribution from the Ce3+ 4d → 4f (ten possible from the phototransitions {}2F{7/2,5/2}\\to {}2D{3/2,5/2},{}2F{5/2,7/2},{}2G{5/2,7/2}) resonance photoexcitations. The corresponding precise MCDF values for the oscillator strengths and the transition energies are presented for the first time. It is demonstrated that the resonance {f}4d\\to 4f oscillator strengths are slightly affected by the presence of the cage potential, despite the fact that the spectral levels structure is changed when the effect of this potential is included. The Auger 4d -1 decay from the cerium free ion Ce3+ and the encapsulated endohedral ion Ce3+@ are considered within the two-step model and the corresponding Lorentzian profiles are presented. This model clearly reveals the correspondence of the complex resonance profile in the Ce3+ photoabsorption to the fine structure of ion energy levels. The smoothing of the resonance profile in the photoabsorption of the endohedral system {{Ce}}@{{{{C}}}82}+ compared with the free ion Ce3+ is attributed to increasing the linewidths of the Auger transitions. This increase is estimated from the relevant experiment (Müller et al 2008 Phys. Rev. Lett. 101 133001) to be strong; as at least three times the value for an isolated ion. The presence of the confining fullerene

  17. Effect of cerium substitution on structural and magnetic properties of magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Padalia, Diwakar, E-mail: Padalia.diwakar@gmail.com [Department of Physics, G.B.Pant University of Agriculture & Technology, Pantnagar, Uttrakhand (India); Johri, U.C. [Department of Physics, G.B.Pant University of Agriculture & Technology, Pantnagar, Uttrakhand (India); Zaidi, M.G.H. [Supercritical Fluid Processing Laboratory, Department of Chemistry, G.B.Pant University of Agriculture & Technology, Pantnagar, Uttrakhand (India)

    2016-02-01

    The current work presents the synthesis and properties of cerium doped magnetite (Fe{sub 3}O{sub 4}) nanoparticles synthesized by standard chemical co-precipitation method using NH{sub 4}OH as co-precipitating agent. The effects of cerium ion substitution on structural and magnetic properties of magnetite (Fe{sub 3}O{sub 4}) nanoparticles were reported. These materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The cerium content has a significant influence on structural and magnetic properties. The X-ray diffraction study confirmed the formation of single-phase magnetite with space group Fd3m and crystallite size ranging from 39 to 58 nm. The addition of cerium resulted in a reduction of crystallite size and an increase of cell parameters. FTIR measurements confirmed the formation of different samples and suggested that the reduction of Fe{sup +3} to Fe{sup +2} preferred on a site adjacent to Ce{sup +4}. Magnetic measurements revealed that the saturation magnetization (Ms) and remanence (M{sub r}) decreased while the coercivity (H{sub C}) and squareness (M{sub r}/M{sub S}) increased with increasing cerium content. - Highlights: • There is an increase in cell parameters and strain with Ce-content. • Samples show the presence of secondary phase after 1.0% doping level. • Ce-ions prefer octahedral sites and charge neutrality is accompanied by Fe{sup +3} → Fe{sup +2}. • Magnetization decreases due to weakening of the super exchange interactions. • Squareness and coercivity start to increase with Ce content.

  18. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi [Department of Physics and Astrophysics, University of Delhi (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi (India)

    2015-03-15

    The influence of Cerium doping on the structural and magnetic properties of BiFeO{sub 3} thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi{sub 1−x}Ce{sub x}FeO{sub 3} (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm{sup −1}) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm{sup −1}), shows a minor shift. Sudden evolution of Raman mode at 668 cm{sup −1}, manifested as A{sub 1}-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M{sub s}) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi{sub 0.88}Ce{sub 0.12}FeO{sub 3} thin film found to exhibit better magnetic properties with M{sub s}=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi{sub 1−x}Ce{sub x}FeO{sub 3} thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical

  19. CARBON DIOXIDE SEPARATION BY SELECTIVE PERMEATION.

    Science.gov (United States)

    CARBON DIOXIDE , SEPARATION), (*PERMEABILITY, CARBON DIOXIDE ), POROUS MATERIALS, SILICON COMPOUNDS, RUBBER, SELECTION, ADSORPTION, TEMPERATURE, PRESSURE, POLYMERS, FILMS, PLASTICS, MEMBRANES, HUMIDITY.

  20. Effect of Bi content in precursor solutions on microstructure and ferroelectric properties of bismuth cerium titanate thin films

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Sol-gel derived bismuth cerium titanate (BCT) thin films with different Bi contents in precursor solu- tions were deposited on the Pt/Ti/SiO2/Si substrates. The effect of Bi content in the precursor solutions on the microstructure and ferroelectric properties of the films was investigated. It is found that with Bi content increasing from 90% to 110% of the nominal value in the precursor solutions, the dissipation factor and leakage current density of the BCT films obtained decrease, while the grain sizes, dielectric constant and remanent polarizations (2Pr) increase, and concurrently, a Bi-deficient phase of Bi2Ti2O7 gradually disappears. The film prepared from solution with 110% of the nominal Bi content exhibits pure Bi-layered Aurivillius polycrystalline phase, and the 2Pr value and coercive field value are 67.1 μC/cm2 and 299.7 kV/cm, respectively. Their dielectric constant and the dissipation factor are about 172 and 0.033 at 1 kHz, respectively. Moreover, this film shows no polarization fatigue after 4.46×109 switching cycles.

  1. Cerium oxide nanoparticles/multi-wall carbon nanotubes composites: Facile synthesis and electrochemical performances as supercapacitor electrode materials

    Science.gov (United States)

    Deng, Dongyang; Chen, Nan; Li, Yuxiu; Xing, Xinxin; Liu, Xu; Xiao, Xuechun; Wang, Yude

    2017-02-01

    Cerium oxide nanoparticles/multi-wall carbon nanotubes (MWCNTs) composites are synthesized by a facile hydrothermal method without any surfactant or template. The morphology and microstructure of samples are examined by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS). Electrochemical properties of the MWCNTs, the pure CeO2, and the CeO2/MWCNTs nanocomposites electrodes are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GDC) and electrochemical impedance spectroscopy (EIS) measurements. The CeO2/MWCNTs nanocomposite (at the mole ratio of 1:1) electrode exhibits much larger specific capacitance compared with both the MWCNTs electrode and the pure CeO2 electrode and significantly improves cycling stability compared to the pure CeO2 electrode. The CeO2/MWCNTs nanocomposite (at the mole ratio of 1:1) achieves a specific capacitance of 455.6 F g-1 at the current density of 1 A g-1. Therefore, the as prepared CeO2/MWCNTs nanocomposite is a promising electrode material for high-performance supercapacitors.

  2. Convenient synthesis of substituted pyrroles via a cerium (IV ammonium nitrate (CAN-catalyzed Paal–Knorr reaction

    Directory of Open Access Journals (Sweden)

    Ahmed Kamal

    2016-07-01

    Full Text Available A screening of various cerium salts for promoting the Paal–Knorr pyrrole synthesis revealed the superiority of cerium (IV ammonium nitrate (CAN as a catalyst. Excellent yields of substituted pyrroles were obtained in CAN-catalyzed Paal–Knorr reactions of 1,4-diketones with various amines. The protocol is noteworthy for the mild reaction condition, short reaction times, scalability and easy isolation of products and high yields of the products.

  3. Lipase immobilized on nanostructured cerium oxide thin film coated on transparent conducting oxide electrode for butyrin sensing

    Energy Technology Data Exchange (ETDEWEB)

    Panky, Sreedevi; Thandavan, Kavitha [Centre for Nanotechnology and Advanced Biomaterials (CeNTAB), SASTRA University, Thanjavur 613 401, Tamil Nadu (India); School of Chemical and Biotechnology, SASTRA University, Thanjavur 613 401, Tamil Nadu (India); Sivalingam, Durgajanani [Centre for Nanotechnology and Advanced Biomaterials (CeNTAB), SASTRA University, Thanjavur 613 401, Tamil Nadu (India); School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401, Tamil Nadu (India); Sethuraman, Swaminathan; Krishnan, Uma Maheswari [Centre for Nanotechnology and Advanced Biomaterials (CeNTAB), SASTRA University, Thanjavur 613 401, Tamil Nadu (India); School of Chemical and Biotechnology, SASTRA University, Thanjavur 613 401, Tamil Nadu (India); Jeyaprakash, Beri Gopalakrishnan [Centre for Nanotechnology and Advanced Biomaterials (CeNTAB), SASTRA University, Thanjavur 613 401, Tamil Nadu (India); School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401, Tamil Nadu (India); Rayappan, John Bosco Balaguru, E-mail: rjbosco@ece.sastra.edu [Centre for Nanotechnology and Advanced Biomaterials (CeNTAB), SASTRA University, Thanjavur 613 401, Tamil Nadu (India); School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401, Tamil Nadu (India)

    2013-01-15

    Nanostructured cerium oxide (CeO{sub 2}) thin films were deposited on transparent conducting oxide (TCO) substrate using spray pyrolysis technique with cerium nitrate salt, Ce(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O as precursor. Fluorine doped cadmium oxide (CdO:F) thin film prepared using spray pyrolysis technique acts as the TCO film and hence the bare electrode. The structural, morphological and elemental characterizations of the films were carried out using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) respectively. The diffraction peak positions in XRD confirmed the formation of highly crystalline ceria with cubic structure and FE-SEM images showed uniform adherent films with granular morphology. The band gaps of CeO{sub 2} and TCO were found to be 3.2 eV and 2.6 eV respectively. Lipase enzyme was physisorbed on the surface of CeO{sub 2}/TCO film to form the lipase/nano-CeO{sub 2}/TCO bioelectrode. Sensing studies were carried out using cyclic voltammetry and amperometry, with lipase/nano-CeO{sub 2}/TCO as working electrode and tributyrin as substrate. The mediator-free biosensor with nanointerface exhibited excellent linearity (0.33-1.98 mM) with a lowest detection limit of 2 {mu}M with sharp response time of 5 s and a shelf life of about 6 weeks. -- Graphical abstract: Nanostructured cerium oxide thin films were deposited on transparent conducting oxide (TCO) substrate using spray pyrolysis technique. Fluorine doped cadmium oxide (CdO:F) thin film acts as the TCO film and hence the working electrode. Lipase enzyme was physisorbed on the surface of CeO{sub 2}/TCO film and hence the lipase/nano-CeO{sub 2}/TCO bioelectrode has been fabricated. Sensing studies were carried out using cyclic voltammetry and amperometry with tributyrin as substrate. The mediator-free biosensor with nanointerface exhibited excellent linearity (0.33-1.98 mM) with a lowest detection limit of 2 {mu}M with sharp

  4. Carbon dioxide sensor

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Prabir K. (Worthington, OH); Lee, Inhee (Columbus, OH); Akbar, Sheikh A. (Hilliard, OH)

    2011-11-15

    The present invention generally relates to carbon dioxide (CO.sub.2) sensors. In one embodiment, the present invention relates to a carbon dioxide (CO.sub.2) sensor that incorporates lithium phosphate (Li.sub.3PO.sub.4) as an electrolyte and sensing electrode comprising a combination of lithium carbonate (Li.sub.2CO.sub.3) and barium carbonate (BaCO.sub.3). In another embodiment, the present invention relates to a carbon dioxide (CO.sub.2) sensor has a reduced sensitivity to humidity due to a sensing electrode with a layered structure of lithium carbonate and barium carbonate. In still another embodiment, the present invention relates to a method of producing carbon dioxide (CO.sub.2) sensors having lithium phosphate (Li.sub.3PO.sub.4) as an electrolyte and sensing electrode comprising a combination of lithium carbonate (Li.sub.2CO.sub.3) and barium carbonate (BaCO.sub.3).

  5. Chromatographic separation of cerium(Ⅲ) in L-valine medium using poly[dibenzo-18-crown-6

    Institute of Scientific and Technical Information of China (English)

    SABALE Sandip R; MOHITE Baburao S

    2009-01-01

    A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly[dibenzo-18-crown-6]. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly[dibenzo-18-crown-6] for cerium(Ⅲ) was (0.428±0.01) mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2% ).

  6. Structure Analysis of Oxidation Film of Ignition-Inhibition AZ91D Ma gnesium Alloy Added with Cerium

    Institute of Scientific and Technical Information of China (English)

    黄晓锋; 周宏; 何镇明

    2003-01-01

    The effect of cerium on ignition temperature of AZ91D magnesium alloy was studied. By the addition of cerium of 1%, the ignition temperature is raised by 180 ℃, so the magnesium alloy added with cerium can be melted in air. The burning temperature increases with the increasing of cerium. The structure and chemical compositions of the surface oxide film were investigated by XRD and Auger electron spectrometry(AES). The results of XRD indicate that the oxide film of the surface of ignition-inhibition magnesium alloy can change from loose structure of simple magnesia to compact composite structure consisting of magnesia, cerium oxide, Mg17 A112 and aluminum oxide, which has excellent ignition-inhibition effect. AES depth profile analysis shows that the oxide film can be divided into three layers. The outside layer is mainly made up of magnesia, the middle layer, which consists of cerium oxide, magnesia, and aluminum oxide, is compound and compact. Thermodynamic analysis indicates that the structure of the surface oxide film is accordant to the change of free energy and high vapor pressure of magnesium.

  7. Carbon Dioxide Photodissociation on Iapetus

    Science.gov (United States)

    Palmer, Eric; Brown, R. H.

    2009-09-01

    Carbon dioxide has been detected on Iapetus (Buratti et al., 2005) and is correlated with the dark material, mostly at mid-latitudes on the leading face of Iapetus (Palmer and Brown, in preparation). The average absorption feature of CO2 in the dark region is 24.7%; if it were a thin veneer of CO2 ice, it would be 14 um thick. Estimating the surface area of dark material and extrapolating gives a total CO2 budget of 8 x 107 kg on the surface of Iapetus. Volatile studies indicate that the surface of Iapetus is too hot to have CO2 ice remain on the surface for more than a few hundred years (Palmer and Brown, 2008). It has been suggested that complexing of volatiles, such as in clathrates, fluid or gas inclusions, or adsorption, would increase the stability on the Jovian and Saturnian satellites, increasing their residence times (McCord; et al., 1998; Hibbitts et al., 2001, 2002, 2007). While complexing would increase carbon dioxide's thermal stability, the resident time of CO2 on Iapetus would remain short due to the effect of UV radiation. We calculated the photodissociation rate for CO2 and found that the entire budget of CO2 on Iapetus would be destroyed in less than one Earth year. If we assume a steady-state system on Iapetus (photodissociation equal to photo-generation) approx. 108 kg will be destroyed and produced every Earth year. Unless the complexing mechanism provides some shielding from UV radiation while still allowing the detection of the 4.26-micron CO2 band, then a source of CO2 is required. We suggest that the source of CO2 is photolytic production from water ice and carbonaceous material.

  8. Effects of Cerium Nitrate on Expression of CaM Ⅰ and PMCA Ca2+-ATPase mRNA in Rat Liver

    Institute of Scientific and Technical Information of China (English)

    杨维东; 王艇; 刘洁生; 雷衡毅; 杨燕生

    2001-01-01

    The effect of cerium nitrate on expression of CaM Ⅰ and PMCA1b in rat liver was studied by means of reverse transcription-polymerase chain reaction (RT-PCR). The result shows that neither a high dose (50 mg*kg-1) nor a low dose (1 mg*kg-1) of cerium nitrate induces any alterations of expression of CaM Ⅰ and PMCA 1b mRNA after recurrent intraperitoneal injection of cerium nitrate, which suggests that effect of cerium nitrate on CaM and Ca2+-ATPase might be at posttranscription level.

  9. Instant and supersaturated dissolution of naproxen and sesamin (poorly water-soluble drugs and supplements) nanoparticles prepared by continuous expansion of liquid carbon dioxide solution through long dielectric nozzle

    Science.gov (United States)

    Arita, Toshihiko; Manabe, Noriyoshi; Nakahara, Koichi

    2012-11-01

    Nanoparticles (NPs) of naproxen (a nonsteroidal anti-inflammatory drug, BCS Class 2) and sesamin (a poorly water-soluble lignan) were investigated. By applying a newly developed rapid expansion system of liquid carbon dioxide solutions equipped with a dielectric nozzle, well-separated and fine both naproxen NPs (averaged particle size (APS) = 46.9 nm) and sesamin NPs (APS = 60.2 nm) were obtained without heating, surfactants, and co-solvents. Obtained naproxen and sesamin NPs had large surface/weight ratio, therefore, they showed instant dissolution to water until about ten percent higher than the saturated concentrations. In addition, the technique developed in the study has big advantage on producing especially drug NPs because the NPs produced by the method never includes neither poisonous additives (especially co-solvents and detergents) nor thermally denatured compounds.

  10. Instant and supersaturated dissolution of naproxen and sesamin (poorly water-soluble drugs and supplements) nanoparticles prepared by continuous expansion of liquid carbon dioxide solution through long dielectric nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Arita, Toshihiko, E-mail: tarita@tagen.tohoku.ac.jp [Tohoku University, Institute of Multidisciplinary Research for Advanced Materials (Japan); Manabe, Noriyoshi [Tohoku University, Graduate School of Engineering (Japan); Nakahara, Koichi [Suntory Bussiness Expert Limited, Frontier Center for Value Creation (Japan)

    2012-11-15

    Nanoparticles (NPs) of naproxen (a nonsteroidal anti-inflammatory drug, BCS Class 2) and sesamin (a poorly water-soluble lignan) were investigated. By applying a newly developed rapid expansion system of liquid carbon dioxide solutions equipped with a dielectric nozzle, well-separated and fine both naproxen NPs (averaged particle size (APS) = 46.9 nm) and sesamin NPs (APS = 60.2 nm) were obtained without heating, surfactants, and co-solvents. Obtained naproxen and sesamin NPs had large surface/weight ratio, therefore, they showed instant dissolution to water until about ten percent higher than the saturated concentrations. In addition, the technique developed in the study has big advantage on producing especially drug NPs because the NPs produced by the method never includes neither poisonous additives (especially co-solvents and detergents) nor thermally denatured compounds.

  11. Reduction behavior of cerium(Ⅲ) ions in NaCl-2CsCl melt

    Institute of Scientific and Technical Information of China (English)

    QI Xue; ZHU Hongmin

    2005-01-01

    The cathodic process of cerium(Ⅲ) ions in NaCl-2CsCl melt was studied by cyclic voltammetry and square wave voltammetry with tungsten and gold electrodes at 873 K. The two electroanalytical methods yield similar results. The cathodic process of cerium(Ⅲ) ions consists of two reversible steps: Ce3+ + e-= Ce2+ and Ce2+ + 2e-= Ce. The half wave potentials of Ce3+/Ce2+ and Ce2+/Ce were determined as -2.525 V vs. Cl2/Cl- and -2.975 V vs. Cl2/Cl-, respectively. The diffusion coefficient of Ce3+ was also determined as 5.5 × 10-5 cm2·s-1.

  12. Deposition of cerium contained conversion films on LC4 alloy with square wave pulse method

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; LI Jiuqing; WU Yinshun; ZHANG Pei; HE Jianping

    2004-01-01

    Cerium contained conversion films were deposited on LC4 aluminum alloy using square wave pulse (SWP) in a CeC13 solution with KMnO4 as the oxidant. Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) were adopted to study the composition and the morphology of the film. It is found that the film is composed of Al, Zn, Cu,and small amount of cerium. The polarization curves of the specimens treated with SWP technique measured in 3.5% (mass fraction) NaCl solution reveal that the film thus formed inhibits both the anodic and cathodic process of the corrosion of the specimen. The immersion tests of treated specimens in 3.5% NaCl solution indicate that the corrosion resistance of the SWP treated specimen is better than that of the untreated and is equivalent to or even better than that of the traditionally electrochemically treated specimens.

  13. Color-Fading Spectrophotometric Determination of Cerium with DBC-Arsenazo

    Institute of Scientific and Technical Information of China (English)

    翟庆洲; 张晓霞

    2004-01-01

    In the medium of 0.18~1.08 mol·L-1 sulfuric acid, cerium(Ⅳ) has the color-fading effect on DBC-arsenazo. The apparent molar absorptivity of the color-fading reaction is ε530 nm=1.03×104 L·mol-1·cm-1. Beer′s law is obeyed over the range of 1.20~12.0 μg·ml-1 of Ce (Ⅳ) which shows a linear relationship with the decrease in the absorbance of the colored solution. The effect of thirty-six coexisting ions was studied. The method was applied to the determination of the trace amount of cerium in water samples and has the advantage of high accuracy and good selectivity.

  14. Monte Carlo radiative transfer simulation of a cavity solar reactor for the reduction of cerium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Villafan-Vidales, H.I.; Arancibia-Bulnes, C.A.; Dehesa-Carrasco, U. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Col. Centro, A.P. 34, Temixco, Morelos 62580 (Mexico); Romero-Paredes, H. [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No.186, Col. Vicentina, A.P. 55-534, Mexico D.F 09340 (Mexico)

    2009-01-15

    Radiative heat transfer in a solar thermochemical reactor for the thermal reduction of cerium oxide is simulated with the Monte Carlo method. The directional characteristics and the power distribution of the concentrated solar radiation that enters the cavity is obtained by carrying out a Monte Carlo ray tracing of a paraboloidal concentrator. It is considered that the reactor contains a gas/particle suspension directly exposed to concentrated solar radiation. The suspension is treated as a non-isothermal, non-gray, absorbing, emitting, and anisotropically scattering medium. The transport coefficients of the particles are obtained from Mie-scattering theory by using the optical properties of cerium oxide. From the simulations, the aperture radius and the particle concentration were optimized to match the characteristics of the considered concentrator. (author)

  15. Energy transfer and thermal studies of Pr3+ doped cerium oxalate crystals

    Indian Academy of Sciences (India)

    R Pragash; Gijo Jose; N V Unnikrishnan; C Sudarsanakumar

    2011-07-01

    Energy transfer process at room temperature for cerium (sensitizer) oxalate single crystals doped with different concentrations (10, 13, 15, 17 and 20%) of praseodymium ions (activator) grown by hydro silica gel method has been evaluated. The analysis of energy level diagrams of cerium and praseodymium ions indicates that the energy gap between the sensitizer and the activator ions varies in a small range suggesting a possible energy transfer from the Ce3+ to Pr3+. The emission and absorption spectra of these crystals were recorded. The overlapping of the absorption spectra of Pr3+ and emission spectra of Ce3+ at wavelengths 484 and 478 nm, respectively, strongly supports the possible energy transfer process in this system. From the absorption spectra, oscillator strength, electric dipole moment, branching ratio and Judd–Ofelt parameters of this system were evaluated by least square programming. The quantum efficiency, energy transfer probabilities and thermal properties have been studied.

  16. Thermodynamics of the α -γ transition in cerium studied by an LDA + Gutzwiller method

    Science.gov (United States)

    Tian, Ming-Feng; Song, Hai-Feng; Liu, Hai-Feng; Wang, Cong; Fang, Zhong; Dai, Xi

    2015-03-01

    Utilizing the local-density approximation (LDA) + Gutzwiller method, we have studied the α -γ transition in cerium. Our results indicate that the volume collapse transition between α and γ phases is present at zero temperature with negative pressure. By further providing a newly finite temperature generalization of the LDA + Gutzwiller method (using the mean-field potential approach), the entropy contributed by both electronic quasiparticles and lattice vibration included, we obtain the Gibbs free energy at a given volume and temperature, from which we get the α -γ transition at finite temperature and pressure. Our results indicate that the electronic entropy and lattice vibrational entropy both play important roles in the α -γ transition. We also calculated the equation of state and phase diagram of cerium, finding good agreement with the experiments.

  17. Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

    Science.gov (United States)

    Shabanov, O. M.; Suleymanov, S. I.; Magomedova, A. O.

    2017-01-01

    The electrical conductivity of molten chloride electrolytes of the cerium subgroup lanthanides increases with rising electric field strength and strive to achieve the limiting high voltage values (Wien effect). On exposure of the high-voltage microsecond pulsed fields, the melts are transited into a prolonged non-equilibrium state with increased electrical conductivity and electrolyze current density. During the relaxation processes in non-equilibrium melts, increased electrical conductivity tends to restore the values that are specific to equilibrium systems.

  18. Photocatalytic C-C Bond Cleavage and Amination of Cycloalkanols by Cerium(III) Chloride Complex.

    Science.gov (United States)

    Guo, Jing-Jing; Hu, Anhua; Chen, Yilin; Sun, Jianfeng; Tang, Haoming; Zuo, Zhiwei

    2016-12-05

    A general strategy for the cleavage and amination of C-C bonds of cycloalkanols has been achieved through visible-light-induced photoredox catalysis utilizing a cerium(III) chloride complex. This operationally simple methodology has been successfully applied to a wide array of unstrained cyclic alcohols, and represents the first example of catalytic C-C bond cleavage and functionalization of unstrained secondary cycloalkanols.

  19. CARBON DIOXIDE FIXATION.

    Energy Technology Data Exchange (ETDEWEB)

    FUJITA,E.

    2000-01-12

    Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO{sub 2} conversion. Recent achievements in the efficiency of solar energy conversion and in catalysis suggest that this approach holds a great deal of promise for contributing to future needs for fuels and chemicals.

  20. Chlorine dioxide and hemodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.P. (Dartmouth Coll., Hanover, NH (USA). Dept. of Pharmacology and Toxicology)

    1989-05-01

    Because it has little or no tendency to generate carcinogenic trihalomethanes such as chloroform, chlorine dioxide is an attractive alternative to chlorine for drinking water disinfection. There are, however, concerns about its acute toxicity, and the toxic effects of its by-products, chlorite and chlorate. The human experience with chlorine dioxide in both controlled, prospective studies and in actual use situations in community water supplies have as yet failed to reveal adverse health effects. The EPA has recommended standards of 0.06 mg/L for chlorine dioxide and standards of 0.007 mg/L for chlorite and chlorate in drinking water. Among groups who may be at special risk from oxychlorines in drinking water are patients who must undergro chronic extracorporeal hemodialysis. Although even units for home hemodialysis are supposed to be equipped with devices which effectively remove oxychlorines, there is a always a possibility of operator error or equipment failure. When the equipment is adequately maintained, it is likely that dialysis patients will have more intensive exposures from drinking water than from dialysis fluids despite the much larger volumes of water that are involved in dialysis. This paper discusses a hemodialysis and the standards and effects of oxychlorines. 90 refs., 2 tabs.

  1. Nanoceria and bulk cerium oxide effects on the germination of asplenium adiantum-nigrum spores

    Directory of Open Access Journals (Sweden)

    Aranzazu Gomez-Garay

    2016-12-01

    Full Text Available Aim of study: The effect of cerium oxide engineered nanoparticles on the spore germination of the fern. Asplenium adiantum-nigrum. Area of study: France, Britanny Region, Finistére Department, Plougonvelin, in rocks near the sea. Material and methods: Asplenium spores were cultured in vitro on agar medium with Nano-CeO2 (less than 25 nm particle size and bulk-CeO2. The addition of each nano- and bulk particles ranged from 0 to 3000 mg L-1. Observations on rhizoidal and prothallial cells during first stages of gametophyte development were made. The No-Observed-Adverse-Effect concentration (NOAEC and Lowest-Observed-Adverse-Effect-Concentration (LOEC values for spore germination rate data were analyzed.  Main results: Germination was speeded up by 100 to 2000 mg L-1 nanoceria, while bulk cerium oxide had the same effect for 500 to 200 mg L-1 concentrations. Present results showed cellular damage in the protonema while rhizoid cells seemed not to be affected, as growth and membrane integrity remained. Research highlights: Both nanosized and bulk cerium oxide are toxic for the fern Asplenium adiantum-nigrum, although diverse toxicity patterns were shown for both materials. Diverse toxic effects have been observed: chloroplast membrane damage and lysis, cell wall and membrane disruption which leads to cell lysis; and alterations in morphology and development. Keywords: Nanoparticles; rhizoid; prothallus; chloroplast; fern.

  2. Cerium Biomagnification in a Terrestrial Food Chain: Influence of Particle Size and Growth Stage.

    Science.gov (United States)

    Majumdar, Sanghamitra; Trujillo-Reyes, Jesica; Hernandez-Viezcas, Jose A; White, Jason C; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    2016-07-01

    Mass-flow modeling of engineered nanomaterials (ENMs) indicates that a major fraction of released particles partition into soils and sediments. This has aggravated the risk of contaminating agricultural fields, potentially threatening associated food webs. To assess possible ENM trophic transfer, cerium accumulation from cerium oxide nanoparticles (nano-CeO2) and their bulk equivalent (bulk-CeO2) was investigated in producers and consumers from a terrestrial food chain. Kidney bean plants (Phaseolus vulgaris var. red hawk) grown in soil contaminated with 1000-2000 mg/kg nano-CeO2 or 1000 mg/kg bulk-CeO2 were presented to Mexican bean beetles (Epilachna varivestis), which were then consumed by spined soldier bugs (Podisus maculiventris). Cerium accumulation in plant and insects was independent of particle size. After 36 days of exposure to 1000 mg/kg nano- and bulk-CeO2, roots accumulated 26 and 19 μg/g Ce, respectively, and translocated 1.02 and 1.3 μg/g Ce, respectively, to shoots. The beetle larvae feeding on nano-CeO2 exposed leaves accumulated low levels of Ce since ∼98% of Ce was excreted in contrast to bulk-CeO2. However, in nano-CeO2 exposed adults, Ce in tissues was higher than Ce excreted. Additionally, Ce content in tissues was biomagnified by a factor of 5.3 from the plants to adult beetles and further to bugs.

  3. Controlled Redox Chemistry at Cerium within a Tripodal Nitroxide Ligand Framework.

    Science.gov (United States)

    Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Booth, Corwin H; Schelter, Eric J

    2015-12-01

    Ligand reorganization has been shown to have a profound effect on the outcome of cerium redox chemistry. Through the use of a tethered, tripodal, trianionic nitroxide ligand, [((2-tBuNOH)C6 H4 CH2 )3 N](3-) (TriNOx (3-) ), controlled redox chemistry at cerium was accomplished, and typically reactive complexes of tetravalent cerium were isolated. These included rare cationic complexes [Ce(TriNOx )thf][BAr(F) 4 ], in which Ar(F) =3,5-(CF3 )2 -C6 H3 , and [Ce(TriNOx )py][OTf]. A rare complete Ce-halide series, Ce(TriNOx )X, in which X=F(-) , Cl(-) , Br(-) , I(-) , was also synthesized. The solution chemistry of these complexes was explored through detailed solution-phase electrochemistry and (1) H NMR experiments and showed a unique shift in the ratio of species with inner- and outer-sphere anions with size of the anionic X(-) group. DFT calculations on the series of calculations corroborated the experimental findings.

  4. Cerium, gallium and zinc containing mesoporous bioactive glass coating deposited on titanium alloy

    Science.gov (United States)

    Shruti, S.; Andreatta, F.; Furlani, E.; Marin, E.; Maschio, S.; Fedrizzi, L.

    2016-08-01

    Surface modification is one of the methods for improving the performance of medical implants in biological environment. In this study, cerium, gallium and zinc substituted 80%SiO2-15%CaO-5%P2O5 mesoporous bioactive glass (MBG) in combination with polycaprolactone (PCL) were coated over Ti6Al4 V substrates by dip-coating method in order to obtain an inorganic-organic hybrid coating (MBG-PCL). Structural characterization was performed using XRD, nitrogen adsorption, SEM-EDXS, FTIR. The MBG-PCL coating uniformly covered the substrate with the thickness found to be more than 1 μm. Glass and polymer phases were detected in the coating along with the presence of biologically potent elements cerium, gallium and zinc. In addition, in vitro bioactivity was investigated by soaking the coated samples in simulated body fluid (SBF) for up to 30 days at 37 °C. The apatite-like layer was monitored by FTIR, SEM-EDXS and ICP measurements and it formed in all the samples within 15 days except zinc samples. In this way, an attempt was made to develop a new biomaterial with improved in vitro bioactive response due to bioactive glass coating and good mechanical strength of Ti6Al4 V alloy along with inherent biological properties of cerium, gallium and zinc.

  5. Infrared, thermal and X-ray diffraction analysis of cerium soaps

    Energy Technology Data Exchange (ETDEWEB)

    Mehrotra, K.N. [Agra Univ. (India). Dept. of Chemistry; Chauhan, M. [Agra Univ. (India). Dept. of Chemistry; Shukla, R.K. [R.B.S. Coll., Agra (India)

    1997-03-01

    The physico-chemical characteristics of cerium soaps (Caproate and caprate) in solid state were investigated by IR, thermal and X-ray diffraction measurements. The IR results reveal that the fatty acids exist in dimeric state through hydrogen bonding and soaps possess partial ionic character. The decomposition reaction was found kinetically of zero order with energy of activation 6.7 and 7.3 K cal mol{sup -1} for cerium caproate and caprate, respectively. The X-ray diffraction measurements were used to calculate the long spacings and the results confirm the double layer structure of cerium soaps. (orig.) [Deutsch] Mit Hilfe von IR-, thermischen und Roentgendiffraktionsmessungen wurden die physikalisch-chemischen Eigenschaften von Cerseifen (Capron- und Caprylsaeuresalze)in festem Zustand bestimmt. Die IR-Untersuchungen zeigen, dass die Fettseifen in dimerem Zustand, gebunden durch Wasserstoffbruecken vorliegen und partiell ionischen Charakter haben. Die Zersetzungsreaktion war von einer Kinetik nullter Ordnung, die Aktivierungsenergien lagen bei 6,7 K cal mol{sup -1} fuer Capronsaeuresalze und 7,3 K cal mol{sup -1} fuer Caprylsaeuresalze. Mit Hilfe von Roentgendiffraktionsmessungen wurden die grossen Zwischenraeume bestimmt. Die Ergebnisse lassen auf eine Doppelschichtstruktur der Cerseifen schliessen. (orig.)

  6. Chromium VI adsorption on cerium oxide nanoparticles and morphology changes during the process

    Energy Technology Data Exchange (ETDEWEB)

    Recillas, Sonia; Colon, Joan [Department of Chemical Engineering, Engineering School, Autonomous University of Barcelona, 08193 Bellaterra (Spain); Casals, Eudald; Gonzalez, Edgar [Catalan Institute of Nanotechnology, Autonomous University of Barcelona Campus, 08193 Bellaterra (Spain); Puntes, Victor [Catalan Institute of Nanotechnology, Autonomous University of Barcelona Campus, 08193 Bellaterra (Spain); Catalan Institute of Research and Advanced Studies, Passeig Lluis Companys, 23, 08010 Barcelona (Spain); Sanchez, Antoni, E-mail: antoni.sanchez@uab.cat [Department of Chemical Engineering, Engineering School, Autonomous University of Barcelona, 08193 Bellaterra (Spain); Font, Xavier [Department of Chemical Engineering, Engineering School, Autonomous University of Barcelona, 08193 Bellaterra (Spain)

    2010-12-15

    In this study, suspended cerium oxide nanoparticles stabilized with hexamethylenetetramine were used for the removal of dissolved chromium VI in pure water. Several concentrations of adsorbent and adsorbate were tested, trying to cover a large range of possible real conditions. Results showed that the Freundlich isotherm represented well the adsorption equilibrium reached between nanoparticles and chromium, whereas adsorption kinetics could be modeled by a pseudo-second-order expression. The separation of chromium-cerium nanoparticles from the medium and the desorption of chromium using sodium hydroxide without cerium losses was obtained. Nanoparticles agglomeration and morphological changes during the adsorption-desorption process were observed by TEM. Another remarkable result obtained in this study is the low toxicity in the water treated by nanoparticles measured by the Microtox commercial method. These results can be used to propose this treatment sequence for a clean and simple removal of drinking water or wastewater re-use when a high toxicity heavy metal such as chromium VI is the responsible for water pollution.

  7. Modified semi-coke-supported cerium oxide-doped zinc ferrites for the removal of H{sub 2}S from coal gas

    Energy Technology Data Exchange (ETDEWEB)

    Mi, J.; Guo, T.; Zhu, Y.; Wang, J. [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan (China); Feng, G. [Shanghai Research Institute of Petrochemical Technology SINOPEC, Shanghai (China); Han, L. [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan (China)

    2012-09-15

    Cerium oxide-doped ZnFe{sub 2}O{sub 4} sorbents supported on modified semi-coke (MSC) were prepared to improve the desulfurization efficiency of zinc ferrites. The sulfidation tests of the ZnFe{sub 2}O{sub 4}/MSC sorbents with and without Ce were carried out using a fixed-bed reactor at 450 C. The effect of the CeO{sub 2}/ZnFe{sub 2}O{sub 4} molar ratio of the sorbents on the sulfur capacity was studied. The characteristics of the sorbents were analyzed by X-ray diffraction, N{sub 2} adsorption, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that cerium oxide could greatly improve the desulfurization reactivity of the ZnFe{sub 2}O{sub 4}/MSC sorbents. The molar ratio of Ce to Zn and Fe influences the desulfurization reactivity, and a good sulfur capacity of the sorbent can be obtained with a Ce/Zn/Fe ratio of 4:4:1. It was also found that the addition of CeO{sub 2} could enlarge the surface area and the pore volume, thus improving the dispersion of active components. Ce doping results in an increment of the oxygen adsorbed on the sorbent surface, which facilitates the adsorption of H{sub 2}S. The Ce ions could act as carriers of the oxidation and reduction reactions and the oxygen transfer could be accelerated during the desulfurization process of coal gas. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Effects of Cerium Doping at Ti Sites and Europium Doping at Ba Sites on Dielectric Properties of BaTiO3 Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Two special rare earth elements cerium and europium were chosen to conduct chemical modification of the BaTiO3 structure. The cold-pressing ceramic processing technique was used to prepare barium titanate ceramics doped with Ce at Ti sites and with Eu at Ba sites on the base of formulas Ba(Ti1-xCex)O3(x=0.05, 0.10)(CBT) and(Ba1-yEuy)Ti1-y/8O3(y=0.05, 0.10)(EBT). Associated with structures and microstructures, the effects of cerium and europium doping on dielectric properties of BaTiO3 ceramics were discussed. The CBT ceramics exhibit a pseudo-cubic perovskite structure, while the EBT ceramics exhibit a tetragonal perovskite structure with the exception of the existence of a small percentage of the Eu2Ti2O7 phase. The Curie peak of BaTiO3 shifts towards room temperature at rates of 3 ℃/mol Ce atoms and 10 ℃/mol Eu atoms(Eu≤5%), respectively. Compared with the CBT ceramics, the EBT ceramics show significant advantages, such as a narrow fine grain size distribution(1 μm), a lower porosity and a higher density(5.85 g/cm3), more stable dielectric-temperature dependence(ε'=1600-1800 at t<50 ℃) and a lower dissipation factor(<0.05). The stability of dielectric constant with frequency in BaTiO3 can extend to 107 Hz due to Ce and Eu doping.

  9. Silver Doped Titanium Dioxide Nanomaterials for Enhanced Visible Light Photocatalysis

    OpenAIRE

    Seery, Michael; George, Reena; Pillai, Suresh; Floris, Patrick

    2007-01-01

    This paper presents a systematic study on two different preparation methods for titanium dioxide with silver. The silver can be incorporated by irradiating the reaction mixture during preparation to reduce silver ion to silver metal or by direct calcination of the sol–gel material to decompose silver nitrate to silver. Of the two methods, we found the latter produces a more effective photocatalytic material (6–50% improvement in catalytic efficiency), which is attributed to the fact that the ...

  10. Preparação e caracterização de microfibras de poli(álcool vinílico/dióxido de titânio Preparation and characterization of polyvinyl alcohol/titanium dioxide microfibers

    Directory of Open Access Journals (Sweden)

    Ariadne H. P. de Oliveira

    2013-01-01

    Full Text Available Compósitos de poli(álcool vinílico/dióxido de titânio preparados pela técnica de eletrofiação são potenciais candidatos para aplicações nas quais grande absorbância na região do ultra-violeta e transparência na região do visível são requeridas. A incorporação de semicondutor nas fibras pode ser inferida pela redução da impedância elétrica das fibras fabricadas por eletrofiação, como consequência do aumento na densidade de grãos de semicondutor dispersos nas fibras poliméricas. As propriedades térmicas do compósito polímero/semicondutor são dominadas pela resposta do PVA sendo a influência do dióxido de titânio detectada no espectro de absorção de luz pela maximização da absorbância na faixa de 240 nm a 400 nm. Os resultados indicam que o compósito de PVA/TiO2 pode ser convenientemente aplicado como curativo com proteção adicional contra efeitos de radiação ultravioleta (UVA e UVB na pele humana. Uma aplicação adicional para o compósito PVA/TiO2 foi abordada com o estudo dos processos fotocatalíticos na degradação da rodamina B.Electrospun composites of polyvinyl alcohol/titanium dioxide are potential candidates for applications that require high level of absorbance in the UV and transparency in the visible region. The incorporation of semiconductor particles in the core of fibers can be inferred from the reduction in the electrical impedance of electrospun fibers, as a consequence of the increased density of semiconductor granules along the fiber. The thermal properties of PVA dominate in the complete response of the composite while the influence from titanium dioxide is noted with an increased absorption from 240 nm to 400 nm. The results indicate that the PVA/TiO2 composites can be applied as wound dressing with additional protection against effects of ultraviolet radiation (UVA and UVB on human skin. An additional application studied here was based on the use of PVA/TiO2 nanocomposites as

  11. Optimal Conditions for Preparing Ultra-Fine CeO2 Powders in A Submerged Circulative Impinging Stream Reactor

    Institute of Scientific and Technical Information of China (English)

    Chi Ru'an; Xu Zhigao; Wu Yuanxin; Wang Cunwen

    2007-01-01

    Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3·6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 0.25 and 0.3 mol·L-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g·L-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r·min-1, 80 ℃, 20 min, 5~6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8~2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point group was O5H-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).

  12. Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Röhder, Lena A. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Brandt, Tanja [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); Sigg, Laura [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Behra, Renata, E-mail: Renata.behra@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland)

    2014-07-01

    Highlights: • Phosphate-dispersed CeO₂ NP did not affect photosynthetic yield in C. reinhardtii. • Agglomerated CeO₂ NP slightly decreased photosynthetic yield. • Cerium(III) was shown to affect photosynthetic yield and intracellular ROS level. • Slight effects of CeO₂ NP were caused by dissolved Ce³⁺ ions present in suspensions. • Wild type and cell wall free mutant of C. reinhardtii showed the same sensitivity. - Abstract: Cerium oxide nanoparticles (CeO₂ NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO₂ NP and effects on algae are largely unknown. In this study, the short term effects of CeO₂ NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO₂ NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO₂ NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO₂ NP had a surface charge of ~0 mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO₂ NP at pH 7.5 over 24 h. This effect was exploited to test CeO₂ NP dispersed in phosphate with a mean size of 140 nm and agglomerated in absence of phosphate with a mean size of 2000 nm. The level of dissolved cerium(III) in CeO₂ NP suspensions was very low and between 0.1 and 27 nM in all tested media. Exposure of C. reinhardtii to Ce(NO₃)₃ decreased the photosynthetic yield in a concentration dependent manner with EC₅₀ of 7.5 ± 0.84 μM for wild type and EC₅₀ of 6.3 ± 0.53 μM for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO₃)₃ with effective concentrations similar to those inhibiting photosynthesis. The agglomerated Ce

  13. 水热法从含钛电炉熔分渣中制备纳米片状结构二氧化钛光催化剂%Hydrothermal preparation of nanoflake structured titanium dioxide photocatalysts from electric furnace molten slag

    Institute of Scientific and Technical Information of China (English)

    阙再青; 李克非; 刘洋; 郭敏; 张梅

    2012-01-01

    采用水热法,以氢氧化钠为分离剂,从含钛电炉熔分渣中成功制备出纳米片状结构二氧化钛光催化剂,并探讨了水热反应时间、水热温度以及碱液浓度对分离提取纳米片状结构二氧化钛的影响.随着水热反应时间的延长,水热温度以及氢氧化钠溶液浓度的提高,从含钛电炉熔分渣中分离提取的二氧化钛结晶度越好,微观形貌更趋近于纳米片状结构.水热法处理含钛电炉熔分渣的最佳反应条件是:水热温度高于180℃,水热反应时间大于24h,碱液浓度达到12mol·L^-1.以制备得到的纳米片状结构二氧化钛为光催化剂,在氙灯光照90min后,甲基蓝降解率可达81.1%.%Nanoflake structured titanium dioxide was successfully prepared from electric furnace molten slag by using a hydrotherreal method under the condition of alkaline solution. The effects of hydrothermal temperature, reaction time and sodium hydroxide solution concentration on the titanium extraction and morphology were investigated. Relatively pure and better crystallized nanoflake structured titanium dioxide can be obtained with increasing reaction temperature, time and alkaline solution concentration. The optimum preparing conditions are that the hydrothermal temperature is above 180 ℃ , the reaction time is above 24 h and the concentration of NaOH solution is 12 tool. L^-1. Using the as-prepared TiO2 as a photocatalyst, the degradation rate of methyl blue is above 81.1% under a xenon lamp for 90 min.

  14. Carbon Dioxide Reforming of Methane to Syngas by Thermal Plasma

    Institute of Scientific and Technical Information of China (English)

    孙艳朋; 聂勇; 吴昂山; 姬登祥; 于凤文; 计建炳

    2012-01-01

    Experiments were conducted on syngas preparation from dry reforming of methane by carbon dioxide with a DC arc plasma at atmospheric pressure. In all experiments, nitrogen gas was used as the working gas for thermal plasma to generate a high-temperature jet into a horizontal tube reactor. A mixture of methane and carbon dioxide was fed vertically into the jet. In order to obtain a higher conversion rate of methane and carbon dioxide, chemical energy efficiency and fuel production efficiency, parametric screening studies were conducted, in which the volume ratio of carbon dioxide to methane in fed gases and the total flux of fed gases were taken into account. Results showed that carbon dioxide reforming of methane to syngas by thermal plasma exhibited a larger processing capacity, higher conversion of methane and carbon dioxide and higher chemical energy efficiency and fuel production efficiency. In addition, thermodynamic simulation for the reforming process was conducted. Experimental data agreed well with the thermodynamic results, indicating that high thermal efficiency can be achieved with the thermal plasma reforming process.

  15. Research progress on preparation of monoglycerides by lipase- catalyzed glycerolysis in supercritical carbon dioxide%超临界CO2中脂肪酶催化甘油解制备单甘酯的研究进展

    Institute of Scientific and Technical Information of China (English)

    龚旭; 谷克仁

    2011-01-01

    The development of lipase - catalyzed glycerolysis of oil to synthesize monoglycerides in supercritical carbon dioxide was discussed.The effects of reaction temperature, pressure, water content, substrate ratio and activity of lipase on reaction were analyzed.This method had several advantages, such as lower reaction temperature, better color of the product, no solvent residues and simpler procedures, so it would be a potential method to produce food grade monoglycerides.%论述了超临界CO2条件下脂肪酶催化甘油解制备单甘酯的研究进展,并从反应温度、压力、含水量、底物比例、脂肪酶活性等方面对反应的影响进行了探讨.此法具有反应温度低,产品色泽好,无溶剂残留,操作步骤大大简化等优点,有望成为食品用单甘酯最有潜力的生产方法.

  16. Reaction products of chlorine dioxide.

    OpenAIRE

    Stevens, A A

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxi...

  17. Cyanex 923 as the extractant in a rare earth element impurity analysis of high-purity cerium oxide.

    Science.gov (United States)

    Duan, Taicheng; Li, Hongfei; Kang, JianZhen; Chen, Hangting

    2004-06-01

    In this work, the feasibility of employing Cyanex 923 as an extractant into the non-cerium REE (rare earth elements) impurity analysis of high-purity cerium oxide was investigated. Through investigations on the choice of the extraction medium, the optimium extraction acidity, matrix Ce4+ effect on the non-cerium REE ion extraction, the optimium extractant concentration and suitable extracting time, and oscillation strengh, it was found that when the phase ratio was at 1:1 and the acicidity was about 2% H2SO4, by gently shaking by hand for about 2 min, 10 mL of 30% Cyanex 923 could not extract even for a 20 ng amount of non-cerium REE3+ ions. However, the extraction efficiency for Ce4+ of 100 mg total amount under the same conditions was about 96%, indicating that a 25-fold preconcentration factor could be achieved. Thus, it was concluded that Cyanex 923 could be used in a REE impurity analysis of 99.9999% or so pure cerium oxide for primary sepapation to elimilate matrix-induced interferences encountered in an ICP-MS (inductively coupled plasma mass spectroscopy) determination.

  18. SYNTHESIS OF CATIONIC CERIUM COMPOUNDS [CP2CE(L)2][BPH4] (L = TETRAHYDROFURAN OR TETRAHYDROTHIOPHENE) AND THE CRYSTAL-STRUCTURE OF THE TETRAHYDROTHIOPHENE DERIVATIVE

    NARCIS (Netherlands)

    HEERES, HJ; MEETSMA, A; TEUBEN, JH

    1991-01-01

    Protolysis of the cerium alkyl Cp2*CeCH(SiMe3)2 (1) by triethylammoniumtetraphenylborate provides a useful route to cationic cerium compounds [Cp2*Ce(L)2][BPh4] (2, L = tetrahydrofuran; 3, L = tetrahydrothiophene). The crystal structure of the tetrahydrothiophene derivative was determined by X-ray d

  19. Reactive removal of 2-chloroethyl ethyl sulfide vapors under visible light irradiation by cerium oxide modified highly porous zirconium (hydr) oxide

    Science.gov (United States)

    Mitchell, Joshua K.; Arcibar-Orozco, Javier A.; Bandosz, Teresa J.

    2016-12-01

    Highly porous cerium oxide modified Zr(OH)4 samples were synthesized using a simple one stage urea precipitation method. The amorphicity level of zirconium hydroxide did not change upon addition of cerium oxide particles. A unique aspect of the cerium oxide-modified materials is the presence of both the oxide (CeO2) and hydroxide (Zr(OH)4) phases resulting in a unique microporous structure of the final material. Extensive characterization using various chemical and physical methods revealed significant differences in the surface features. All synthesized materials were microporous and small additions of cerium oxide affected the surface chemistry. These samples were found as effective catalysts for a decontamination of mustard gas surrogate, 2-chloroethyl ethyl sulfide (CEES). Cerium oxide addition significantly decreased the band gap of zirconium hydroxide. Ethyl vinyl sulfide and 1,2-bis (Ethyl thio) ethane were identified as surface reaction products.

  20. 综合性实验-二氧化钛纳米片的制备及其光催化氧活性物种分析∗%A Comprehensive Experiment-Preparation of Titanium Dioxide Nanosheets and Analysis of Photocatalytic Oxygen Active Species

    Institute of Scientific and Technical Information of China (English)

    叶立群; 韩春秋; 马照宇; 刘欣欣; 李珏; 谢海泉; 黄子煊

    2016-01-01

    A comprehensive chemical experiment, preparation of titanium dioxide ( TiO2 ) nanosheets and analysis of photocatalytic oxygen active species, was demonstrated. TiO2 nanosheets photocatalytic material can be prepared through hydrothermal synthesis with HF as surface control agent. It was characterized by X-ray powder diffraction ( XRD ) and transmission electron microscope ( TEM ) . Finally, the photocatalytic activities of oxygen active species ( superoxide radical and hydroxy radical) generation over TiO2 were tested under the full spectrum irradiation with UV-vis spectrometer and fluorescence spectrometer. This experiment connected material preparation, application and mechanism study of nanomaterials. It is beneficial to improve student’s practice ability and comprehensive ability for inorganic chemistry, materials chemistry and physical chemistry, and cultivate their innovative ability.%介绍了一个化学综合性实验:二氧化钛纳米片的制备及其光催化氧活性物种分析。该实验以氢氟酸为表面控制剂,合成二氧化钛纳米片。采用分子探针的方法,分别通过紫外可见光谱和荧光光谱分析光催化过程中的超氧自由基和羟基自由基。本设计实验贯穿纳米材料的合成、应用、机理分析,十分有利于促进学生对纳米技术和催化技术的系统认识以及无机化学、材料化学、物理化学知识的综合运用,激发学生的创新能力。

  1. Regeneration of oxygen from carbon dioxide and water.

    Science.gov (United States)

    Weissbart, J.; Smart, W. H.; Wydeven, T.

    1972-01-01

    In a closed ecological system it is necessary to reclaim most of the oxygen required for breathing from respired carbon dioxide and the remainder from waste water. One of the advanced physicochemical systems being developed for generating oxygen in manned spacecraft is the solid electrolyte-electrolysis system. The solid electrolyte system consists of two basic units, an electrolyzer and a carbon monoxide disproportionator. The electrolyzer can reclaim oxygen from both carbon dioxide and water. Electrolyzer preparation and assembly are discussed together with questions of reactor design and electrolyzer performance data.

  2. Polyacrylic acid-coated cerium oxide nanoparticles: An oxidase mimic applied for colorimetric assay to organophosphorus pesticides.

    Science.gov (United States)

    Zhang, Shi-Xiang; Xue, Shi-Fan; Deng, Jingjing; Zhang, Min; Shi, Guoyue; Zhou, Tianshu

    2016-11-15

    It is important and urgent to develop reliable and highly sensitive methods that can provide on-site and rapid detection of extensively used organophosphorus pesticides (OPs) for their neurotoxicity. In this study, we developed a novel colorimetric assay for the detection of OPs based on polyacrylic acid-coated cerium oxide nanoparticles (PAA-CeO2) as an oxidase mimic and OPs as inhibitors to suppress the activity of acetylcholinesterase (AChE). Firstly, highly dispersed PAA-CeO2 was prepared in aqueous solution, which could catalyze the oxidation of TMB to produce a color reaction from colorless to blue. And the enzyme of AChE was used to catalyze the substrate of acetylthiocholine (ATCh) to produce thiocholine (TCh). As a thiol-containing compound with reducibility, TCh can decrease the oxidation of TMB catalyzed by PAA-CeO2. Upon incubated with OPs, the enzymatic activity of AChE was inhibited to produce less TCh, resulting in more TMB catalytically oxidized by PAA-CeO2 to show an increasing blue color. The two representative OPs, dichlorvos and methyl-paraoxon, were tested using our proposed assay. The novel assay showed notable color change in a concentration-dependent manner, and as low as 8.62 ppb dichlorvos and 26.73 ppb methyl-paraoxon can be readily detected. Therefore, taking advantage of such oxidase-like activity of PAA-CeO2, our proposed colorimetric assay can potentially be a screening tool for the precise and rapid evaluation of the neurotoxicity of a wealth of OPs.

  3. Process for the preparation of pulverulent metallic oxides from aqueous solutions or solid mixtures of metallic nitrates. [UO/sub 3/, ThO/sub 2/, CeO/sub 2/ and PuO/sub 2/]. Procede de preparation d'oxydes metalliques pulverulents a partir de solutions aqueuses ou de melanges solides de nitrates metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Bachelard, R.; Joubert, P.

    1985-05-31

    Oxides of predetermined reactivity adjusted by specific surface for subsequent transformations and/or sintering are prepared by thermal treatment of hydrated uranyl nitrate only or mixed with thorium, cerium and/or plutonium nitrates. In a first step the uranyl nitrate is dehydrated and then calcined in a second step under a controled pressure of water vapor.

  4. Carbon dioxide and climate

    Energy Technology Data Exchange (ETDEWEB)

    1990-10-01

    Scientific and public interest in greenhouse gases, climate warming, and global change virtually exploded in 1988. The Department's focused research on atmospheric CO{sub 2} contributed sound and timely scientific information to the many questions produced by the groundswell of interest and concern. Research projects summarized in this document provided the data base that made timely responses possible, and the contributions from participating scientists are genuinely appreciated. In the past year, the core CO{sub 2} research has continued to improve the scientific knowledge needed to project future atmospheric CO{sub 2} concentrations, to estimate climate sensitivity, and to assess the responses of vegetation to rising concentrations of CO{sub 2} and to climate change. The Carbon Dioxide Research Program's goal is to develop sound scientific information for policy formulation and governmental action in response to changes of atmospheric CO{sub 2}. The Program Summary describes projects funded by the Carbon Dioxide Research Program during FY 1990 and gives a brief overview of objectives, organization, and accomplishments.

  5. Manganese Dioxide with High Specific Surface Area for Alkaline Battery

    Institute of Scientific and Technical Information of China (English)

    HUANG You-ju; LIN Yu-li; LI Wei-shan

    2012-01-01

    The authors reported a facile method for the synthesis of manganese dioxide without any template and catalyst at a low-temperature.The prepared sample was characterized with X-ray diffraction(XRD),scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET) surface analysis,Fourier transform infrared(FTIR) spectrometry,cyclic voltammetry,altemative current(AC) impedance test and battery discharge test.It is found that the prepared sample belongs to α-MnO2 and has a microsphere morphology and a large BET surface area.The electrochemical characterization indicates that the prepared sample displays a larger electrochemical capacitance than the commercial electrolytic manganese dioxides(EMD) in Na2SO4 solution,and exhibits larger discharge capacity than EMD,especially at a high rate discharge condition when it is used as cathode of alkaline Zn/MnO2 battery.

  6. Reaction products of chlorine dioxide.

    Science.gov (United States)

    Stevens, A A

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxide treatment of organic materials are oxidized species, some of which also contain chlorine. The relative amounts of species types may depend on the amount of chlorine dioxide residual maintained and the concentration and nature of the organic material present in the source water. The trend toward lower concentrations of chlorinated by-products with increasing ClO2 concentration, which was observed with phenols, has not been observed with natural humic materials as measured by the organic halogen parameter. Organic halogen concentrations have been shown to increase with increasing chlorine dioxide dose, but are much lower than those observed when chlorine is applied. Aldehydes have been detected as apparent by-products of chlorine dioxide oxidation reactions in a surface water that is a drinking water source. Some other nonchlorinated products of chlorine dioxide treatment may be quinones and epoxides. The extent of formation of these moieties within the macromolecular humic structure is also still unknown. PMID:7151750

  7. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib; Li, Xiang; Zhang, Jinsuo [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210 (United States); Mariani, R. D. [Idaho National Laboratory, Materials and Fuels Complex, Idaho Falls, Idaho 83415 (United States); Unal, Cetin [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)

    2015-12-21

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10{sup −9} m{sup 2}/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions.

  8. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    Science.gov (United States)

    Samin, Adib; Li, Xiang; Zhang, Jinsuo; Mariani, R. D.; Unal, Cetin

    2015-12-01

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10-9 m2/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions.

  9. Catalytic activity of cerium-doped Ru/Al2O3 during ozonation of dimethyl phthalate

    Institute of Scientific and Technical Information of China (English)

    Yunrui ZHOU; Wanpeng ZHU; Xun CHEN

    2008-01-01

    In this paper, factors influencing the mineraliza-tion of dimethyl phthalate (DMP) during catalytic ozona-tion with a cerium-doped Ru/Al2O3 catalyst were studied. The catalytic contribution was calculated through the results of a companrison experiment. It showed that doping cerium significantly enhanced catalytic activity. The total organic carbon (TOC) removal over the doped catalyst at 100 rain reached 75.1%, 61.3% using Ru/Al2O3 catalyst and only 14.0% using ozone alone. Catalytic activity reached the maximum when 0.2% of ruthenium and 1.0% of cerium'were simultaneously loaded onto Al2O3 support. Results of experiments on oxidation by ozone alone, adsorption of the catalyst, Ce ion's and heterogeneous catalytic ozonation confirmed that the contribution of het-erogeneous catalytic ozonation was about 50%, which showed the obvious effect of Ru-Ce/Al2O3 on catalytic activity.

  10. Single crystal fiber growth of cerium doped strontium yttrate, SrY2O4:Ce3+

    Science.gov (United States)

    Philippen, J.; Guguschev, C.; Klimm, D.

    2017-02-01

    First single crystal fibers of cerium doped strontium yttrate were fabricated using the laser-heated pedestal growth technique. Through thermodynamic equilibrium calculations and by high-temperature mass spectrometry suitable growth conditions could be determined. The atmosphere played an important role during crystallization. It affected the composition shift, on the one hand, and the valence state of cerium, on the other hand. These dependencies can be explained by combining X-ray diffraction, elemental analysis, and optical spectroscopy. Crystallization in slightly reducing nitrogen atmosphere proved to be a reasonable choice, because evaporation is suppressed and trivalent cerium is stabilized. Strong green emission that depends on the oxygen fugacity during crystallization could be excited using UV light. Optical properties of SrY2O4:Ce3+ were measured for the first time.

  11. Crystallization behavior of electroless Co-Ni-B alloy plated in magnetic field in presence of cerium

    Institute of Scientific and Technical Information of China (English)

    XUAN Tian-peng; ZHANG Lei; HUANG Qin-hua

    2006-01-01

    The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in general state as well as in magnetic field were studied using potentiometer, plasma emission spectrometer, X-ray diffractometer,transmission electron microscope. The results show that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath.Because of the action of magnetic field and rare earth element cerium, the boron content in alloy decreases, while cobalt and nickel contents increase. As a result, the amorphous Co-Ni-B alloy transforms to the microcrystalline Co-Ni-B-Ce alloy when the plating is in general state, and the Co-Ni-B alloy makes a crystalline transformation because of the action of magnetic field and rare earth element cerium.

  12. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    Science.gov (United States)

    Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

    2015-12-01

    The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce2O3 and CeO2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  13. Implementation of a complex multi-phase equation of state for cerium and its correlation with experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, Frank J [Los Alamos National Laboratory; Jensen, Brian J [Los Alamos National Laboratory; Elkin, Vyacheslav M [VNIITF

    2009-01-01

    The complexity of cerium combined with its interesting material properties makes it a desirable material to examine dynamically. Characteristics such as the softening of the material before the phase change, low pressure solid-solid phase change, predicted low pressure melt boundary, and the solid-solid critical point add complexity to the construction of its equation of state. Currently, we are incorporating a feedback loop between a theoretical understanding of the material and an experimental understanding. Using a model equation of state for cerium we compare calculated wave profiles with experimental wave profiles for a number of front surface impact (cerium impacting a plated window) experiments. Using the calculated release isentrope we predict the temperature of the observed rarefaction shock. These experiments showed that the release state occurs at different magnitudes, thus allowing us to infer where dynamic {gamma} - {alpha} phase boundary is.

  14. Pharmaceutical applications of supercritical carbon dioxide.

    Science.gov (United States)

    Kaiser, C S; Römpp, H; Schmidt, P C

    2001-12-01

    The appearance of a supercritical state was already observed at the beginning of the 19th century. Nevertheless, the industrial extraction of plant and other natural materials started about twenty years ago with the decaffeination of coffee. Today carbon dioxide is the most common gas for supercritical fluid extraction in food and pharmaceutical industry. Since pure supercritical carbon dioxide is a lipophilic solvent, mixtures with organic solvents, especially alcohols, are used to increase the polarity of the extraction fluid; more polar compounds can be extracted in this way. The main fields of interest are the extraction of vegetable oils from plant material in analytical and preparative scale, the preparation of essential oils for food and cosmetic industry and the isolation of substances of pharmaceutical relevance. Progress in research was made by the precise measurement of phase equilibria data by means of different methods. Apart from extraction, supercritical fluid chromatography was introduced in the field of analytics, as well as micro- and nanoparticle formation using supercritical fluids as solvent or antisolvent. This review presents pharmaceutical relevant literature of the last twenty years with special emphasis on extraction of natural materials.

  15. Study on preparation of multi-element modified titanium dioxide and performances thereof%多元改性二氧化钛的制备及其性能研究

    Institute of Scientific and Technical Information of China (English)

    田永淑; 马思源; 侯润欣

    2012-01-01

    Fe-Sm-Yb-TiO2 photocatalysts were synthesized by immersion method.With phenol as degradation target,the influencing factors of catalyst performance and the methods of improving the performance of catalyst were discussed.A preliminary discussion about the mechanism of co-doping improving photocatalytic activity of TiO2 was also made by means of FE-SEM,XRD,and UV-Vis etc..Experiments showed that the most suitable conditions were as follow:when the mass concentration of phenol wastewater was 20 mg/L (normal temperature and pressure), the pH was 7, the dosage of catalyst was 2.5 g/L, the calcining temperature was 550 °C ,and the doping rate of Fe,Sm,and Yb were all 0.5%(mass fraction) ,the degradation rate was up to 90% under the UV light for 4 h.The modified titanium dioxide catalyst also demonstrated fine activity under the visible light.%采用浸渍法制备了铁-钐-镱-二氧化钛改性光催化剂,以苯酚为目标降解物,讨论了影响光催化剂性能的因素和提高光催化剂性能的方法.通过FE-SEM、XRD、UV-Vis等表征手段初步探讨了共掺杂提高二氧化钛光催化活性的机理.实验结果表明:常温、常压下,质量浓度为20 mg/L的苯酚废水(pH=7),当催化剂加入量为2.5 g/L、焙烧温度为550℃、金属(铁、钐、镱)掺杂量各为0.5%(质量分数)时,经4h紫外光照其对苯酚的去除率可达90%以上.改性后的二氧化钛光催化剂在可见光下也能够显示出很好的活性.

  16. The Preparation of Pigment of Iron Black Oxide from the Byproduct of Titanium DioxideFeSO4.H2O%钛白副产硫酸亚铁制备氧化铁黑的研究

    Institute of Scientific and Technical Information of China (English)

    周宏民; 刘跃进; 熊双喜

    2001-01-01

    During the production of titanium pigment, there is a large amount of byproductFeSO4* H2O which contains some impurities, such as Ti, Mn etc. A new technology of preparing iron black oxide from the ferrous sulfate septihydrate was proposed in this paper. The method consists of steps: first purifying the by product FeSO4* H2O, then adding ammonia to form ferrous hydroxide and finally oxidizing ferrous hydroxide into iron black oxide by air under the given conditions. Comparing with the traditional technology, both lower product cost and less waste byproduct were obtained by the method. Some factors affecting the preparing of iron black oxide were tested and the optimal conditions of oxidizing reaction were obtained.%钛白生产中副产大量硫酸亚铁,且含有Ti、Mn等杂质.先将副产硫酸亚铁经净化处理,然后用氨水和空气进行反应生产氧化铁黑,产品质量达到国家标准.与传统工艺相比,生成成本低,减少了三废的排放.对合成氧化铁黑的影响因素也进行了试验研究,得出了较好的合成工艺条件.

  17. Preparation of core-shell Ag@CeO2 nanocomposite by LSPR photothermal induced interface reaction.

    Science.gov (United States)

    Zhong, H X; Wei, Y; Yue, Y Z; Zhang, L H; Liu, Y

    2016-04-01

    The core-shell structure of Ag@CeO2 was prepared by a novel and facile method, which was based on the photothermal effect of localized surface plasmon resonance (LSPR). Nanoparticles (NPs) of Ag were dispersed in a solution containing citric acid, ethylene glycol and cerium nitrate, then under irradiation, Ag NPs generated heat from LSPR and the heat-induced polymerization reaction in the interface between Ag and the sol resulted in cerium gel formation only on the surface of the Ag NPs. After calcination, Ag@CeO2 was successfully obtained, then Ag@CeO2/SiO2 was prepared by loading Ag@CeO2 on SiO2. The resultant catalyst exhibited favorable activity and stability for CO oxidation. The preparation method proposed here should be extendable to other composites with metallic cores and oxide shells in which the metallic nanoparticle possesses LSPR properties.

  18. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

    2009-01-01

    Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

  19. Equivalent Activity Coefficient Phenomenon of Cerium Reacting with Lead or Bismuth in Ag, Cu and Zn Alloy

    Institute of Scientific and Technical Information of China (English)

    薛松柏; 钱乙余; 董健

    2002-01-01

    The relation between contents of cerium and impurity lead or bismuth to their activity coefficient in Ag, Cu and Zn-base alloy was calculated and analyzed by using the ternary system Chou model. The thermodynamic calculation results show that the "equivalent activity coefficient phenomenon" emerges among the activity coefficient of solute in a certain range of cerium (or at a certain point) for the Ce-Pb-X and Ce-Bi-X (X=Ag, Cu or Zn) ternary alloy system. Under this condition, the activity coefficient of solute has nothing to do with its own concentration. The preliminary theoretical analysis to this phenomenon was also made.

  20. Catalytic wet peroxidation of pyridine bearing wastewater by cerium supported SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Subbaramaiah, V. [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India); Srivastava, Vimal Chandra, E-mail: vimalcsr@yahoo.co.in [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India); Mall, Indra Deo [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India)

    2013-03-15

    Highlights: ► Cerium supported SBA-15 (Ce/SBA-15) synthesized by two-step synthesis. ► Characterization of Ce/SBA-15 by FTIR, XRD and BET surface area. ► Catalytic peroxidation of pyridine by Ce/SBA-15. ► Optimization of parameters like catalyst dose, H{sub 2}O{sub 2} dose, initial concentration and temperature. ► Catalyst reusability and leaching study performed. -- Abstract: Cerium supported SBA-15 (Ce/SBA-15) was synthesized by two-step synthesis method in acidic medium. It was further characterized by various characterization techniques such as X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy and N{sub 2} adsorption–desorption pore size distribution analysis. The Ce/SBA-15 showed highly ordered meso-structure with pore diameter ≈ 70–100 A and pore volume ≈ 0.025 cm{sup 3}/g. Ce/SBA-15 was further evaluated as a catalyst for the oxidation of highly toxic and non-biodegradable material, pyridine, by catalytic wet-peroxidation method. The effects of various operating parameters such as catalyst dose (0.5–6 g/l), stoichiometric ratio of H{sub 2}O{sub 2}/pyridine (1–6), initial pyridine concentration (50–800 mg/l) and temperature (313–358 K) have been evaluated and optimized. Ce/SBA-15 showed stable performance during reuse for six cycles with negligible cerium leaching. Kinetic and thermodynamic parameters and operation cost have also been determined.

  1. Fabrication of cerium-doped nonstoichiometric (Ce, Lu, Gd)3+δ(Ga, Al)5-δO12 transparent ceramics

    Institute of Scientific and Technical Information of China (English)

    陈先强; 秦海明; 张烨; 罗朝华; 刘永福; 蒋俊; 江浩川

    2015-01-01

    Cerium-doped nonstoichiometric (Ce,Lu,Gd)3+δ(Ga,Al)5–δO12 (LuGGAG) transparent garnet ceramic samples were fabri-cated via a solid state reaction method in this study. The ceramics were prepared via oxygen sintering followed by hot isostatic press-ing (HIP). The phase and microstructure of the samples were analyzed by X-ray diffraction and scanning electron microscopy (SEM), respectively. The excitation, emission and transmission spectra were also measured. The total optical transmittance of the annealed LuGGAG ceramics with thickness of 3 mm reached 47% at the emission wavelength of 555 nm. The decay time was about 60 ns. Compact microstructure of polycrystalline grains with scale around 5μm were gained according to scanning electron microscopy characterization. The successful preparation of the bulk ceramic material and implementation of the combined oxygen sintering-hot isostatic pressing treatment process provided an important method for the exploration of nonstoichiometric scintillator material.

  2. Spectroscopy of gadolinium gallium garnet doped with cerium under high hydrostatic pressure

    OpenAIRE

    2012-01-01

    Studies of the spectroscopic properties of Ce3+ dopant in bulk Gd3Ga5O12:Ce crystal under pressure are presented. In spite of strong inter-shell 4f ® 5d absorption bands at ambient pressure the cerium luminescence in Gd3Ga5O12 is entirely quenched even at low temperature. It has been shown that applying pressure allows for recovering the 5d ® 4f radiative transitions. Further increase of pressure improves the emission efficiency. This effect is analyzed in terms of two possible phenomen...

  3. ARTICLES: Photoinduced light scattering in cerium-doped barium strontium niobate crystals

    Science.gov (United States)

    Voronov, Valerii V.; Dorosh, I. R.; Kuz'minov, Yu S.; Tkachenko, N. V.

    1980-11-01

    Photoinduced light scattering was observed in cerium-doped (SrxBa1-x)1-y(Nb2O6)y crystals having the composition x = 0.61, y = 0.4993. It was found that this effect is due to holographic amplification of light scattered by crystal defects. An analysis is made of static and dynamic characteristics of self-amplification of scattered light in the crystals. A theoretical model of the process is constructed assuming that the hologram recording process is of the diffusion type. Theoretical results are compared with the experiment.

  4. Photoinduced light scattering in cerium-doped barium strontium niobate crystals

    Science.gov (United States)

    Voronov, V. V.; Dorosh, I. R.; Kuz'minov, Yu. S.; Tkachenko, N. V.

    Photoinduced light scattering was observed in cerium-doped (Srx Ba1-x)1-y(Nb2O6)y crystals having the composition x = 0.61, y = 0.4993. It was found that this effect is due to holographic amplification of light scattered by crystal defects. An analysis is made of static and dynamic characteristics of self-amplification of scattered light in the crystals. A theoretical model of the process is constructed assuming that the hologram recording process is of the diffusion type. Theoretical results are compared with the experiment.

  5. Sequence-specific Hydrolysis of Single-stranded DNA by PNA-Cerium (Ⅳ) Adduct

    Institute of Scientific and Technical Information of China (English)

    He Bai SHEN; Feng WANG; Yong Tao YANG

    2005-01-01

    A novel artificial site specific cleavage reagent, with peptide nucleic acid (PNA) as sequence-recognizing moiety and cerium (Ⅳ) ions as "scissors" for cleaving target DNA, was synthesized. Subsequently, it was employed in the cleavage of target 26-mer single-stranded DNA (ssDNA), which has 10-mer sequence complementary with PNA recognizer in the hybrids,under physiological conditions. Reversed-phase high-performance liquid chromatogram (RPHPLC) experiments indicated that the artificial site specific cleavage reagent could cleave the target DNA specifically.

  6. Trace electrochemical analysis of Europium, Ytterbium, and Cerium at their joint presence in solution

    Directory of Open Access Journals (Sweden)

    Rema Matakova

    2012-03-01

    Full Text Available In the course of several decades at the department of analytical chemistry and chemistry of rare elements there were studied the electrode processes with participation of rare-earth metals (REM in accordance with the long awaiting problem of the development of rare-metal and rare-earth branch of non-ferrous metallurgy of Kazakhstan. With the aim of express and highly sensitive analytical control of raw materials and final product of rare-earth industry there were developed the methods of inversion-voltamperometric determination of low concentrations of europium, ytterbium and cerium under the conditions of their individual and combined presence in the solution.

  7. A nonreciprocal racetrack resonator based on vacuum-annealed magnetooptical cerium-substituted yttrium iron garnet.

    Science.gov (United States)

    Goto, Taichi; Onbasli, Mehmet C; Kim, Dong Hun; Singh, Vivek; Inoue, M; Kimerling, Lionel C; Ross, C A

    2014-08-11

    Vacuum annealed polycrystalline cerium substituted yttrium iron garnet (CeYIG) films deposited by radio frequency magnetron sputtering on non-garnet substrates were used in nonreciprocal racetrack resonators. CeYIG annealed at 800°C for 30 min provided a large Faraday rotation angle, close to the single crystal value. Crystallinity, magnetic properties, refractive indices and absorption coefficients were measured. The resonant transmission peak of the racetrack resonator covered with CeYIG was non-reciprocally shifted by applying an in-plane magnetic field.

  8. APPLICATIONS OF CERIUM BIS (MONOMYRISTY—LPHOSPHATE)ADSORBENT TO REVERSED PHASE LIQUID CHROMATOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    SuZhengquan; FengHuixia; 等

    1996-01-01

    The tetravalent metal salts of monoalkyl phosphates [M(O3POR)2]are a new kind of stationary phases of Chromatography-homogeneous bonded phases.This paper deals with the application of cerium bis(monomyristylphosphate)as support to reversed phase liquid chromatography.The results show that the best mobil phase is CH3CN:H2O=95:5.The good separation to the mixture containing six aromatic hydrocarbons and the determination of naphthalene in a group samples have been achieved.The regression analysis shows that detect limits,linearities and precision for six aromatic hydrocarbons are good.

  9. Relationship between surface area and crystal size of pure and doped cerium oxides

    Institute of Scientific and Technical Information of China (English)

    C.; Bueno-Ferrer; S.; Parres-Esclapez; D.; Lozano-Castelló; A.; Bueno-López

    2010-01-01

    Pure and Zr, La or Pr-doped cerium oxides were characterised by transmission electron microscopy (TEM), N2 adsorption-desorption at -196 oC and X-ray diffraction (XRD). For crystal sizes calculation, the Scherrer and Williamson-Hall equations were compared, and the relationship between surface area and crystal size was critically discussed. It was demonstrated that the Williamson-Hall equation must be used instead of the Scherrer equation to calculate crystal sizes, since the latter equation underestimated ...

  10. High-quality single-crystal growth and unique electronic states in cerium and uranium compounds

    Science.gov (United States)

    Onuki, Yoshichika; Settai, Rikio; Sugiyama, Kiyohiro; Inada, Yoshihiko; Takeuchi, Tetsuya; Haga, Yoshinori; Yamamoto, Etsuji; Harima, Hisatomo; Yamagami, Hiroshi

    2007-03-01

    We have grown many kinds of high-quality single crystals of cerium and uranium compounds and studied the Fermi surface properties via the de Haas-van Alphen experiments and energy band calculations. The quasi-two-dimensional electronic states are clarified in some compounds such as USb2, CeCoIn5, UPtGa5 and most likely UIr. In a ferromagnet CeRh3B2, we have found unique electronic states with quasi-one-dimensional character.

  11. Surface structures of cerium oxide nanocrystalline particles from the size dependence of the lattice parameters

    Science.gov (United States)

    Tsunekawa, S.; Ito, S.; Kawazoe, Y.

    2004-10-01

    Cerium oxide nanocrystalline particles are synthesized and monodispersed in the size range from 2 to 8nm in diameter. The dependence of the lattice parameters on particle size is obtained by x-ray and electron diffraction analyses. The size dependence well coincides with the estimation based on the assumption that the surface is composed of one layer of Ce2O3 and the inside consists of CeO2. The effect of particle size on lattice parameters is discussed from the differences in the fabrication method and the surface structure.

  12. Nanostructured composite materials of cerium oxide and barium cerate

    Science.gov (United States)

    Medvedev, D. A.; Pikalova, E. Yu.; Demin, A. K.; Khrustov, V. R.; Nikolaenko, I. V.; Nikonov, A. V.; Malkov, V. B.; Antonov, B. D.

    2013-02-01

    Nanosized powders with a composition of (1- x)Ce0.8Sm0.2O2-δ- xBace0.8Sm0.2O3-δ ( x = 0, 0.3, and 1) were obtained by self-ignition combustion synthesis (SICS) from the appropriate nitrates and various organic fuels (glycine, glycerol, citric acid, and a mixture of citric acid and ethylene glycol). The most finely dispersed powders formed when the concentration of the perovskite phase in the system decreased or when glycerol or citric acid-enthyleneglycol mixture was used as a fuel during SICS. A procedure for the preparation of powders and nanostructured ceramics was developed and their electric properties were studied.

  13. DC electrical conductivity study of cerium doped conducting glass systems

    Science.gov (United States)

    Barde, R. V.; Waghuley, S. A.

    2013-06-01

    The glass samples of composition 60V2O5-5P2O5-(35-x)B2O3-xCeO2, (1 ≤ x ≤ 5) were prepared by the conventional melt quench method. The samples were characterized by X-ray diffraction and thermo gravimetric-differential thermal analysis. The glass transition temperature and crystallization temperature determined from TG-DTA analysis. The DC electrical conductivity has been carried out in the temperature range 303-473 K. The maximum conductivity and minimum activation energy were found to be 0.039 Scm-1 and 0.15 eV at 473 K for x=1, respectively.

  14. Uranium dioxide electrolysis

    Science.gov (United States)

    Willit, James L.; Ackerman, John P.; Williamson, Mark A.

    2009-12-29

    This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

  15. Forecasting carbon dioxide emissions.

    Science.gov (United States)

    Zhao, Xiaobing; Du, Ding

    2015-09-01

    This study extends the literature on forecasting carbon dioxide (CO2) emissions by applying the reduced-form econometrics approach of Schmalensee et al. (1998) to a more recent sample period, the post-1997 period. Using the post-1997 period is motivated by the observation that the strengthening pace of global climate policy may have been accelerated since 1997. Based on our parameter estimates, we project 25% reduction in CO2 emissions by 2050 according to an economic and population growth scenario that is more consistent with recent global trends. Our forecasts are conservative due to that we do not have sufficient data to fully take into account recent developments in the global economy.

  16. 外胶凝法制备高温气冷堆UO2核芯的湿法工艺%Wet Process of External Gelation of Uranium for Preparation of Uranium Dioxide Kernel of High Temperature Gas-cooled Reactors

    Institute of Scientific and Technical Information of China (English)

    周湘文; 郝少昌; 赵兴宇; 马景陶; 王阳; 邓长生

    2012-01-01

    为制备高温气冷堆用燃料致密UO2核芯,对传统的溶胶-凝胶法进行优化和改进.主要对改进后的外胶凝工艺的湿法部分进行介绍,包括U3O8粉的溶解即欠酸硝酸铀酰(ADUN)溶液的制备、胶液的制备、胶液的分散和胶凝及凝胶球的陈化、洗涤和干燥等,并对湿法过程的机理进行了探讨.采用这一工艺,所得重铀酸铵微球的球形度好、尺寸分布均匀且具有良好空隙结构,经过后续的干法工艺如焙烧、还原和烧结,可制备出合格的高温气冷堆用燃料致密UO2核芯.%In order to prepare the dense uranium dioxide (UO2) kernel for high temperature gas-cooled reactors (HTGR) fuel, the conventional sol-gel processes are optimized and modified. The wet process of modified external gelation of uranium (EGU) is introduced, which includes the dissolution of U3Og, i.e. the preparation of acid-deficiency uranyl nitrate, preparation of broth solution, casting and gelation of broth solution and aging, washing and drying of the gelled spheres, and etc. The mechanism of wet process of EGU is also discussed. With the optimized wet process, the ammonium diuranate (ADU) microspheres with good sphericity, uniform diameter and perfect porous structure are prepared. After the subsequent treatments of dry processes such as calcination, reduction and sintering, the eligible dense UO2 kernels for HTGR fuel are manufactured.

  17. Surface Modification of Nanometer TiO2 and Effect of Preparing TiO2/P(St-co-DVB) Composites by Dispersion Polymerization

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; FENG Yaqing; LI Xianggao; XIE Jianyu; LI Gang

    2006-01-01

    Surface modification of nanometer titanium dioxide particles and effect of preparing TiO2/P (St-co-DVB) composites by dispersion polymerization are described. To introduce vinyl group onto the surface of titanium dioxide particles, the titanium dioxide particles were surface-modified with a silicane coupling agent, methacryloylpropyltrimethoxysilicane. Polymer encapsulation in the presence of either modified-titanium dioxide particles or unmodified-titanium dioxide particles was carried out by dispersion polymerization of styrene, divinylbenzene in ethanol medium with polyvinylpyrrolidone as stabilizer, and 2, 2'-azobis(isobutyronitrile) as initiator. The modified-titanium dioxide was analyzed with Fourier-transform infrared spectroscopy( FTIR), UV-Vis spectrophotometer, thermogravimetric analysis and transmission microscope. The polymer encapsulation of modified-titanium dioxide and unmodified-titanium dioxide particles was confirmed with FTIR and transmission electron microscope. Results show that compared with unmodified-titanium dioxide, modified-titanium dioxide is more suitable for preparing inorganic core/organic shell composites.

  18. Scintillation and Luminescence Properties of Undoped and Cerium-doped LiGdCl4 and NaGdCl4

    Energy Technology Data Exchange (ETDEWEB)

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith D.; Bizarri, Gregory; Weber, Marvin J.; Derenzo, Stephen E.

    2008-10-05

    We report the scintillation properties of the undoped and cerium-doped variations of LiGdCl4 and NaGdCl4. Powder samples of these materials exhibit significant scintillation under X-rays. The samples were synthesized by solid-state methods from a 1:1 molar ratio of lithium or sodium chloride and gadolinium chloride. Cerium trichloride was used as the dopant. The physical, optical, and scintillation properties of these materials were analyzed by powder X-ray diffraction, photoluminescence, X-ray excited luminescence, and pulsed X-ray luminosity measurements. Increases in light yields are observed as the concentration of cerium increases. The highest light yields occurred at 20 percent cerium doping for both compounds. At larger concentrations neither compound formed, indicating a breakdown of the lattice with the addition of large amounts of cerium cations. At 20 percent cerium, LiGdCl4 and NaGdCl4 display scintillation light 3.6 times and 2.2 times the light yield of the reference material, YAlO3:Ce3+, respectively. Both emit in the ranges of 340 ? 350 nm and 365 - 370 nm and display multiexponential decays with cerium-like decay components at 33 ns (LiGdCl4:Ce) and 26 ns (NaGdCl4:Ce).

  19. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution; Caracterizacao da microestrutura e da atividade catalitica de oxido de cerio obtido por solucao coloidal

    Energy Technology Data Exchange (ETDEWEB)

    Senisse, C.A.L.; Bergmann, C.P.; Alves, A.K., E-mail: carolinasenisse@hotmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alege, RS (Brazil). Lab. de Materiais Ceramicos

    2012-07-01

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  20. Effects of cerium oxide supplementation to laying hen diets on performance, egg quality, some antioxidant enzymes in serum and lipid oxidation in egg yolk.

    Science.gov (United States)

    Bölükbaşı, S C; Al-Sagan, A A; Ürüşan, H; Erhan, M K; Durmuş, O; Kurt, N

    2016-08-01

    This study was conducted to determine the effects of dietary cerium oxide levels (0, 100, 200, 300 or 400 mg/kg) on the laying performance, egg quality, some blood serum parameters and egg lipid peroxidation of laying hen. In total, one hundred and twenty 22-week-old brown Lohman LSL laying hens were randomly assigned to five groups equally (n = 24). Each treatment was replicated six times. Dietary supplementation of cerium oxide had no significant effect on feed intake and egg weight. The addition of cerium oxide to the laying hens' feed improved feed conversion ratio and increased (p laying hens feed led to a significant (p laying hen diets. It was also observed that serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration decreased significantly with supplementation of cerium oxide in diets. Inclusion of cerium oxide resulted in a significant reduction in thiobarbituric acid reactive substance (TBARS) values in egg yolk in this study. It can be concluded that the addition of cerium oxide had positive effects on egg production, feed conversion ratio and egg shelf life. Based on the results of this study, it could be advised to supplement laying hens feed with cerium oxide as feed additives.