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41.
A.?H.?Naik N.?V.?Thakkar S.?R.?DharwadkarEmail author K.?D.?Singh Mudher V.?Venugopal 《Journal of Thermal Analysis and Calorimetry》2004,78(3):707-713
Sodium zirconium phosphate [NaZr2P3O12], a potential ceramic matrix for fixation of high level nuclear waste, was synthesized by heating the mixture of sodium carbonate [Na2CO3], zirconyl nitrate hydrate [ZrO(NO3)2·5H2O] and ammonium dihydrogen phosphate [NH4H2PO4] in air, in a resistance heated furnace and a microwave heating system respectively in the temperature range 450 to 650°C. The mixture heated for 1 h in a resistance furnace at 450°C yielded a poorly crystalline NaZr2P3O12 [NZP]. Increasing the temperature to 650°C produced a highly crystalline product. The same mixture heated in a microwave oven at 450°C for 1 h however, yielded the most crystalline NZP.In an alternate method, the mixture of sodium dihydrogen phosphate (NaH2PO4), zirconium dioxide (ZrO2) and diammonium hydrogen phosphate [(NH4)2HPO4] heated in resistance furnace at 650°C for the same period did not react in air. It also did not yield the pure product at 450°C when heated in microwave assembly for 1 h.The authors thank the Board of Research in Nuclear Sciences (BRNS) of the Department of Atomic Energy (DAE) for the financial support for this work under the project No. 2000/37/19/BRNS/1959 dtd09-02-02. 相似文献
42.
43.
Preparation and Characterization of Nanotitanium Dioxide Coating Film Doped with Fe^3+ Ions on Porous Ceramic 总被引:2,自引:0,他引:2
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 Fe^3+ ions was prepared by sol-gel processing. The influences of the process conditions of coating nanophotocatalytic material- Fe^3+-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 Fe^3+ 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 Fe^3+ 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 rain. 相似文献
44.
Žaneta Mesíková Petra Šulcová M. Trojan 《Journal of Thermal Analysis and Calorimetry》2006,84(3):733-736
Synthesis of the green
spinel pigment Co0.46Zn0.55(Ti0.064Cr0.91)2O4 by a novel two-step method of preparation have
been investigated. Inorganic pigments are almost always prepared by a solid
state reaction. It is classical ceramic method which used oxides, hydroxides
or carbonates as precursors. The reaction is performed at temperature higher
than 1300°C and an agent of mineralization is usually present. The presented
novel method of preparation decreases the calcining temperature necessary
for reaching of bright and clear hue of the pigments prepared. Main attention
was focused on the influence of two types of titanium raw materials on the
temperature region of the spinel structure formation and on the colour properties
of the pigments. The mixture of precursors with TiO2
gives a one-phase system when calcining at 1100°C but the colour properties
are more interesting at 1150°C. Thermal stability of this pigment is limited
by temperature 1300°C. This temperature is connected with partial oxidation
of Cr(III) to Cr(VI). Thermal analysis provided the first information about
the temperature region of the pigment formation and determined the thermal
stability of pigment. 相似文献
45.
Mesoporous amorphous MnO<Subscript>2</Subscript> as electrode material for supercapacitor 总被引:1,自引:0,他引:1
Mao-Wen Xu Dan-Dan Zhao Shu-Juan Bao Hu-Lin Li 《Journal of Solid State Electrochemistry》2007,11(8):1101-1107
A kind of novel mesoporous, electrochemical active material, amorphous MnO2 has been synthesized by an improved reduction reaction and using supramolecular as template. The synthesized sample was characterized
physically by thermogravimetric analysis, X-ray diffraction, transmission electron microscope (TEM), and Brunauer–Emmett–Teller
(BET) surface area measurement, respectively. Electrochemical characterization was performed using cyclic voltammetry and
chronopotentiometry in 2 mol/l KOH aqueous solution electrolyte. The results of BET and TEM analysis indicated that supramolecular
template plays an important role in the process of big specific surface area mesoporous material forming. After sintering
at 200 °C, the sample still remained an amorphous structure, and its specific capacitance reached 298.7 F/g and presented
a very stable capacitance after 500 cycles. In addition, the electrochemical process, such as ion transfer and electrical
condition, was also investigated with electrochemical impedance spectroscopy. 相似文献
46.
The carbon ceramic electrode prepared with sol-gel technique is modified by a thin film of chlorogenic acid (CGA). By immersing the carbon ceramic electrode in aqueous solution of chlorogenic acid at less than 2 s a thin film of chlorogenic acid adsorbed strongly and irreversibly on the surface of electrode. The cyclic voltammetry of the resulting modified CCE prepared at optimum conditions shows a well-defined stable reversible redox couple due to hydroquinone/quinone system in both acidic and basic solutions. The modified electrode showed excellent electrocatalytic activity toward NADH oxidation and it also showed a high analytical performance for amperometric detection of NADH. The catalytic rate constant of the modified carbon ceramic electrode for the oxidation of NADH is determined by cyclic voltammetry measurement. Under the optimised conditions the calibration curve is linear in the concentration range 1-120 μm. The detection limit (S/N = 3) and sensitivity are 0.2 μM and 25 nA μM−1.The results of six successive measurement-regeneration cycles show relative standard deviations of 2.5% for electrolyte solution containing 1 mM NADH, indicating that the electrode renewal gives a good reproducible and antifouling surface. The advantages of this amperometric detector are: high sensitivity, excellent catalytic activity, short response time t < 2 s, remarkable long-term stability, simplicity of preparation at short time and good reproducibility. 相似文献
47.
A copper hexacyanoferrate modified ceramic carbon electrode (CuHCF/CCE) had been prepared by two-step sol-gel technique and characterized using electrochemical methods. The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V (vs. SCE) in 0.050 mol·dm^-3 HOAc-NaOAc buffer containing 0.30 mol·dm^-3 KCl. The charge transfer coefficient (a) and charge transfer rate constant (ks) for the modified electrode were calculated. The electrocatalytic activity of this modified electrode to hydrazine was also investigated, and chronoamperometry was exploited to conveniently determine the diffusion coefficient (D) of hydrazine in solution and the catalytic rate constant (kcat). Finally, hydrazine was determined with amperometry using the resulting modified electrode. The calibration plot for hydrazine determination was linear in 3.0 × 10^-6--7.5 × 10^-4 mol·dm^-3 with the detection limit of 8.0 × 10^-7 molodm^-3. This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods, such as renewable surface, good long-term stability, excellent catalytic activity and short response time to hydrazine. 相似文献
48.
H. J. Cortes C. D. Pfeiffer B. E. Richter T. S. Stevens 《Journal of separation science》1987,10(8):446-448
Porous ceramic bed supports for fused silica packed capillary columns utilized in liquid chromatography were prepared by polymerizing solutions containing potassium silicate in-situ within a column to create a mechanically stable, rugged, and easily constructed termination. The effect of the bed support length on efficiency, and comparisons to glass wool bed supports, were considered in terms of column efficiencies and hydrodynamic variables. Results obtained indicate better performance for the ceramic bed support. 相似文献
49.
50.
Voltammetry of immobilized microparticles was used to study the electrochemistry of the raw pigments that produce the metallic lustre on ceramics after a successful firing. To study this influence of the mixture components on the reduction properties to achieve the metallic lustre, 14 mixtures of illitic clay, Fe2O3, HgS, CuO and AgNO3 were prepared and studied in different media. Iron oxide improves the yield of the reduction of the metals and cinnabar helps a closer reduction of silver to copper reduction and prevents the Ag? Cu alloying because of the formation of silver–mercury adducts. The presence of one of the metals influences the peak position of the other metal. The use of vinegar as diluting agent is not casual, because in this media the reduction of silver takes place at a potential closer to the copper. This electroanalytical technique allowed to distinguish between powders of different composition and offered some information about the role of the components in the reduction of copper and silver and the selection of vinegar to prepare the raw pigment suspensions. 相似文献