共查询到20条相似文献,搜索用时 0 毫秒
1.
E. H. Lee J. K. Lim D. Y. Chung H. B. Yang J. H. Yoo K. W. Kim 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):339-346
This study was carried out to investigate the characteristics of an oxidative-dissolution of fission products (FP) when uranium
(U) is dissolved in a Na2CO3–H2O2 carbonate solution. Simulated FP-oxides which contained 12 components were added to the solution to examine their dissolution
behaviors. It was found that H2O2 was an effective oxidant to minimize the dissolution of FP. For the 0.5 M Na2CO3–0.5 M H2O2 solution, such elements as Re, Te, Cs, and MoO2 were dissolved with yields of 98 ± 2%, 98 ± 2%, 93 ± 2%, and 26 ± 3%, respectively, for 2 h. Among these components, Re,
Te, and Cs were completely dissolved within 10–20 min without regard to the concentrations of Na2CO3, and H2O2 due to their high solubility in the carbonate solution with and without H2O2. However, MoO2 was very slowly dissolved and its yield was 29 ± 3% for 4 h. The pH of the dissolved solution revealed the greatest influence
on the dissolution yields of the FP, exhibiting the most effective pH condition in the range of 10–12 in order to create a
considerable suppression of the co-dissolution of FP during the oxidative-dissolution of U. 相似文献
2.
Eil-Hee Lee Jae-Gwan Lim Dong-Yong Chung Han-Beom Yang Kwang-Wook Kim 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(2):387-395
The removal of Cs and Re (as a surrogate for Tc) by selective precipitation from the simulated fission products which were
co-dissolved with uranium during the oxidative dissolution of spent fuel in a Na2CO3–H2O2 solution was investigated in this study. The precipitations of Cs and Re were examined by introducing sodium tetraphenylborate
(NaTPB) and tetraphenylohosponium chloride (TPPCl), respectively. The precipitation of Cs by NaTPB and that of Re by TPPCl
each took place within 5 min, and an increase in temperature up to 50 °C and a stirring speed up to 1000 rpm hardly affected
their precipitation rates. The most important factor in the precipitation with NaTPB and TPPCl was found to be a pH of the
solution after precipitation. Since Mo tends to co-precipitate with Cs or Re at a lower pH, an effective precipitation with
NaTPB and TPPCl was done at pH of above 9 without the co-precipitation of Mo. More than 99% of Cs and Re were precipitated
when the initial concentration ratio of NaTPB to Cs was above 1 and when that of TPPCl to Re was above 1. The precipitation
of Cs and Re was never affected by the concentration of Na2CO3 and H2O2, even though they were raised up to 1.5 and 1.0 M, respectively. Precipitation yields of Cs and Re in a Na2CO3–H2O2 solution were found to be dependent on the concentration ratios of [NaTBP]/[Cs] and [TPPCl]/[Re]. 相似文献
3.
Magdalena Leśniak Marcin Gajek Janusz Partyka Maciej Sitarz 《Journal of Thermal Analysis and Calorimetry》2017,130(1):165-176
In this work, the structure and thermal properties of aluminosilicate fritted glazes in SiO2–Al2O3–CaO–MgO–Na2O–K2O–ZnO system with (4.0 mol%) and without addition of ZnO were examined by GIXRD, FTIR, MAS-NMR and thermal methods (DTA, DIL). It has been found that the all experimental glazes are amorphous material (transparent glazes). On the base of spectroscopic investigations, it was found that zinc ions exist in the network glazes in the octahedral coordination—Zn2+ ions play a network modifier role in structure of glazes. An analysis of the data obtained from thermal tests showed that addition of ZnO into chemical composition results in decrease in glass transition temperature value (T g) for all glazes (DTA, DIL). The coefficient of thermal expansion (α) is decreased as the whole measurement range for one series of fritted glazes. 相似文献
4.
L. N. Ignat’eva N. N. Savchenko Yu. V. Marchenko G. A. Zverev V. M. Buznik 《Russian Journal of Inorganic Chemistry》2018,63(11):1389-1394
Glasses of the MnNbOF5–BaF2–InF3 system were prepared. The structure, thermal behavior, and crystallization of these glasses were studied by IR and Raman spectroscopy, differential scanning calorimetry (DSC), X-ray powder diffraction, and microscopy. The \(\rm{NbO}_2\rm{F}_4^{3-}\) and \(\rm{InF}_6^{3-}\) ions form a mixed glass network. Glass crystallization occurs in one or two steps depending on the component ratio. The major crystal phases are Ba3In2F12 and BaNbOF5. The obtainability of transparent crystal-glass samples in MnNbOF5–BaF2–InF3 glasses via heat treatment is shown. 相似文献
5.
Magdalena Leśniak Marcin Gajek Janusz Partyka Maciej Sitarz 《Journal of Thermal Analysis and Calorimetry》2017,128(3):1343-1351
Thermal properties of raw aluminosilicate ceramic glazes in the multicomponent system of SiO2–Al2O3–CaO–K2O–Na2O–ZnO modified by ZnO addition were studied by differential thermal analysis (DTA), dilatometry (DIL), hot-stage microscopy (HSM), X-ray diffraction and fourier transform infrared spectroscopy (FTIR). Using the method of differential thermal analysis, the ways in which zinc oxides affect the temperature of transition (T g), crystallisation (T c) were determined. An analysis of the DTA data obtained during thermal tests showed that an increase in ZnO content results in decreasing the T g value. Also, the influence of ZnO on characteristic temperatures and viscosity of glazes was checked. The introduction of zinc oxide (ZnO) into the glaze composition contributes to the decrease in viscosity of such glazes. An increasing ZnO content in the glazes also causes the reduction in softening (T s), half-sphere (T half-sphere) and fusion (T fusion) temperatures. The mid-infrared spectroscopy showed that the thermal properties of glazes in SiO2–Al2O3–CaO–K2O–Na2O–ZnO system modified by addition of ZnO can be associated with the depolymerising influence of zinc ions on the structure of the tested glazes. 相似文献
6.
Dong-Yong Chung Heui-Seung Seo Jae-Won Lee Han-Beom Yang Eil-Hee Lee Kwang-Wook Kim 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(1):123-129
A feasibility and basic study to find a possibility to develop such a process for recovering U alone from spent fuel by using
the methods of an oxidative leaching and a precipitation of U in high alkaline carbonate media was newly suggested with the
characteristics of a highly enhanced proliferation-resistance and more environmental friendliness. This study has focused
on the examination of an oxidative leaching of uranium from SIMFUEL powders contained 16 elements (U, Ce, Gd, La, Nd, Pr,
Sm, Eu, Y, Mo, Pd, Ru, Zr, Ba, Sr, and Te) using a Na2CO3 solution with hydrogen peroxide. U3O8 was dissolved more rapidly than UO2 in a carbonate solution. However, in the presence of H2O2, we can find out that the leaching rates of the reduced SIMFUEL powder are faster than the oxidized SIMFUEL powder. In carbonate
solutions with hydrogen peroxide, uranium oxides were dissolved in the form of uranyl peroxo-carbonato complexes. UO2(O2)
x
(CO3)
y
2−2x−2y
, where x/y has 1/2, 2/1. 相似文献
7.
A. B. Shishmakov Yu. V. Mikushina O. V. Koryakova L. A. Petrov 《Russian Journal of Inorganic Chemistry》2017,62(11):1435-1440
How the specific surface area and the amorphous-to-crystalline titania phase ratio in TiO2–SiO2 (14 mol % TiO2) xerogels change during the fivefold repeated cycles comprising the hydrogen peroxide treatment of the xerogel followed by drying and calcining of the binary material, was traced by the BET method, X-ray powder diffraction, and IR spectroscopy. 相似文献
8.
Poonam Sharma Praveen Kumar Anjana Solanki Rohit Shrivastav Sahab Dass Vibha R. Satsangi 《Journal of Solid State Electrochemistry》2012,16(4):1305-1312
A visible-light sensitive bilayered photoanode of Fe–TiO2/Zn–Fe2O3 has been developed by spray pyrolytically depositing Zn–Fe2O3 layers onto predeposited Fe–TiO2 thin film on ITO substrate. Fe–TiO2/Zn–Fe2O3 photoelectrodes were characterized by XRD, Raman, AFM, UV-vis absorption spectroscopy. Photoelectrochemical properties of
bilayered Fe–TiO2/Zn–Fe2O3 photoelectrode were studied by Mott–Schottky curves and I–V characteristics. Bilayered Fe–TiO2/Zn–Fe2O3 photoelectrode was observed to possess much higher separation efficiency of photogenerated charge carriers and could generate
nine times better photocurrent density than pure Fe–TiO2. Solar to hydrogen conversion efficiency exhibited by this electrode was 0.77%. 相似文献
9.
V. Ya. Kavun N. F. Uvarov A. B. Slobodyuk A. S. Ulikhin I. A. Telin V. K. Goncharuk 《Russian Journal of Electrochemistry》2017,53(8):884-892
Ionic mobility and electrical conductivity of solid solutions with fluorite structure, obtained with solid-state approach in PbF2–SbF3 and PbF2–SnF2–SbF3 systems, are studied by 19F NMR and electrochemical impedance spectroscopy methods. The 19F NMR spectra parameters, types of ion motions in the fluoride sublattice, and the ionic conductivity magnitude are shown to be determined by the temperature and fluoride concentration in the solid solutions. The solid solution specific conductivity in the PbF2–SbF3 and PbF2–SnF2–SbF3 systems at 420–450 K is as high as ~10–2 S/cm, which allows accounting the solid solutions as a base for preparation of functional materials. 相似文献
10.
P. Mošner K. Vosejpková L. Koudelka L. Beneš 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1129-1135
The effect of TeO2 additions on the thermal behaviour of zinc borophosphate glasses were studied in the compositional series (100 − x)[0.5ZnO–0.1B2O3–0.4P2O5]–xTeO2 by differential scanning calorimetry, thermodilatometry and heating microscopy thermal analysis. The addition of TeO2 to the starting borophosphate glass resulted in a linear increase of glass transition temperature and dilatometric softening
temperature, whereas the thermal expansion coefficient decreased. Most of glasses crystallize under heating within the temperature
range of 440–640 °C. The crystallization temperature steeply decreases with increasing TeO2 content. The lowest tendency towards crystallization was observed for the glasses containing 50 and 60 mol% TeO2. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were Zn2P2O7, BPO4 and α-TeO2. Annealing of the powdered 50ZnO–10B2O3–40P2O5 glass leads at first to the formation of an unknown crystalline phase, which is gradually transformed to Zn2P2O7 and BPO4 during subsequent heating. 相似文献
11.
By the DFT/B3LYP method the equilibrium structures of oxygen complexes with water are calculated in various geometric conformations with symmetries C 2v and C s . By the MRCI/CASSCF method potential energy surface cross-sections of the 1.3[O2–H2O] complexation reaction are constructed. With taking into account the spin-orbit coupling, the forbidden transition moments a 1Δ g –X 3Σ g ?, b 1Σ g +–a 1Δ g , c 1Σ u ?–a 1Δ g , A 3Σ u +–X 3Σ g ? of the complexes are calculated and changes in their intensities at different geometric configurations of the complex are revealed. 相似文献
12.
K. S. Kislitsina N. A. Shchadneva R. I. Khusnutdinov 《Russian Journal of Organic Chemistry》2018,54(7):992-995
The system hydrogen peroxide–hexafluoroacetone sesquihydrate effectively oxidizes adamantane in the presence of VO(acac)2 to afford 64% of adamantan-1-ol in tert-butyl alcohol or 76% of adamantan-2-one in a mixture of acetic acid with pyridine. 相似文献
13.
T. V. Belysheva E. Yu. Spiridonova V. F. Gromov G. N. Gerasimov L. I. Trakhtenberg 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2116-2121
The sensor properties of In2O3 · SnO2 polycrystalline films having different compositions were studied in the detection of 2% hydrogen in air over the temperature
range 330–530°C. Films containing 19% In2O3 were most sensitive to hydrogen. The temperature dependence of the sensitivity of sensors passed a maximum, the position
of which depended on the composition of the film. The temperature at which sensor sensitivity was maximum decreased as the
content of indium oxide increased. This temperature was 485°C for the SnO2 film and 425°C for the In2O3 film. The response and relaxation times of sensors also decreased as the amount of In2O3 in the composite metal oxide film increased. Possible mechanisms of the sensor sensitivity of the films are discussed. 相似文献
14.
A series of MoO3/ZrO2–Al2O3 catalysts was prepared and investigated in the sulfur-resistant methanation aimed at production of synthetic natural gas. Different methods including impregnation, deposition precipitation, and co-precipitation were used for preparing ZrO2–Al2O3 composite supports. These composite supports and their corresponding Mo-based catalysts were investigated in the sulfur-resistant methanation, and characterized by N2 adsorption–desorption, XRD and H2-TPR. The results indicated that adding ZrO2 promoted MoO3dispersion and decreased the interaction between Mo species and support in the MoO3/ZrO2–Al2O3 catalysts. The co-precipitation method was favorable for obtaining smaller ZrO2 particle size and improving textural properties of support, such as better MoO3 dispersion and increased concentration of Mo6+ species in octahedral coordination to oxygen. It was found that the MoO3/ZrO2–Al2O3 catalyst with ZrO2Al2O3 composite support prepared by co-precipitation method exhibited the best catalytic activity. The ZrO2 content in the ZrO2Al2O3 composite support was further optimized. The MoO3/ZrO2–Al2O3 with 15 wt % ZrO2 loading exhibited the highest sulfur-resistant CO methanation activity, and excess ZrO2 reduced the specific surface area and enhanced the interaction between Mo species and support. The N2 adsorption-desorption results indicated that the presence of ZrO2 in excessive amounts decreased the specific surface area since some amounts of ZrO2 form aggregates on the surface of the support. The XRD and H2-TPR results showed that with the increasing ZrO2 content, ZrO2 particle size increased. These led to the formation of coordinated tetrahedrally Mo6+(T) species and crystalline MoO3, and this development was unfavorable for improving the sulfur-resistant methanation performance of MoO3/ZrO2–Al2O3 catalyst. 相似文献
15.
A. I. Klyndyuk E. A. Tugova O. N. Karpov E. A. Chizhova M. V. Tomkovich V. M. Kononovich 《Russian Journal of General Chemistry》2016,86(10):2282-2287
The sequence of phases appearance during the formation of Bi1–xNdxFeO3 solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO3 or NdFeO3) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi1–xNdxFeO3 as the final product, due to the prevalence of various interphase contacts in the starting reaction zone. 相似文献
16.
L. G. Bruk A. V. Ustyugov E. A. Katsman L. D. Iskhakova I. V. Oshanina O. P. Tkachenko L. M. Kustov O. N. Temkin 《Kinetics and Catalysis》2017,58(2):179-190
A systematic study of the kinetics of the low-temperature oxidation of carbon monoxide with oxygen on a PdCl2–CuCl2/γ-Al2O3 supported catalyst was carried out over a wide range of the partial pressures of oxygen, water, and CO in order to test hypotheses on the reaction mechanism. It was shown that, as the temperature was increased from 20 to 38°C, rate of formation of CO2 decreased and the apparent activation energy was about–40 kJ/mol. The hypotheses of different degrees of complexity concerning the reaction mechanism were formulated based on physicochemical data and a Langmuir–Hinshelwood model. Mechanisms in which carbon dioxide is formed on the interaction of the surface Pd(I) and Pd(II) complexes that include carbon monoxide and water with the surface complex of Cu(I) that coordinates oxygen were recognized as the most probable. 相似文献
17.
In this study, mechanical activation process was used for intimate mixing as well as producing finely ground particles, increased surface area and improved chemical reactivity of milled materials for producing SrTiO3 from commercially pure strontium carbonate and TiO2 as a contributive process. Characterization of milled powder mixture by X-ray diffraction analysis showed that disappearing, decreasing and/or shifting of the patterns occurred with mechanical activation that means amorphization was taken place. Amorphization was also demonstrated by FT-IR analysis where shift of band centers as well as the decrement of transmittance related to CO3 was observed. Advantage of amorphization was established with high-temperature XRD analysis which showed 1300 °C was not enough for non-activated mixture to form SrTiO3, whereas structure only composed of SrTiO3 at 1000 °C for activated ones. The reason for this phenomenon was investigated by DTA-TG analysis, and it was based on energy accumulation originated from mechanical activation that corresponds to peak temperature shifting to the lower temperatures and CO2 liberation at mechanical activation step arising from local temperature rising at the vial during high-energy milling that was understood from peak temperature, and area decrement of endothermic peak corresponds to decomposition of SrCO3. 相似文献
18.
E. M. Glebov V. F. Plyusnin V. P. Grivin A. B. Venediktov S. V. Korenev 《Russian Chemical Bulletin》2007,56(12):2357-2363
Photochemistry of the PtBr6
2− complex in aqueous solution was studied by steady-state and laser flash photolysis (308 nm). The multistep photoaquation
of the complex occurs in the nano-and microsecond time intervals without the formation of intermediate platinum(III) complexes.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2277–2283, December, 2007. 相似文献
19.
V. V. Popov A. P. Menushenkov A. A. Yastrebtsev N. A. Tsarenko L. A. Arzhatkina I. V. Shchetinin M. V. Zheleznyi K. V. Ponkratov 《Russian Journal of Inorganic Chemistry》2017,62(9):1147-1154
The crystal and local structures of the complex oxides (1–x)ZrO2 ? xY2O3 (YSZ) (x = 0.08–0.40) prepared by precipitation from solutions of metal salts followed by heat treatment in air were comprehensively studied by X-ray diffraction and Raman spectroscopy. Despite the same crystal structure type of the YSZ powders (cubic system, space group \(Fm\overline 3 m\) (225)), there are differences in the local structure of the samples. Comparison of the Raman spectra recorded at different laser excitation wavelengths provided the conclusion that the peaks observed in the Raman spectra of the YSZ samples with high yttrium content (x = 0.18–0.40) are likely to be due to luminescence of the powders. 相似文献
20.
L. M. Delitsyn 《Doklady Chemistry》2017,477(1):265-270
The system LaPO4–SiO2–NaF–Nb2O5–Fe2O3 is characterized by immiscibility fields in the liquid state region. Addition of iron expands fields of immiscibility of melts and decreases the temperature of their coexistence. A fraction of 87–90% of niobium is extracted into iron silicate melt, and 92–98% of lanthanum is extracted into phosphate salt melt. 相似文献