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941.
Hongjuan Liu Shuibo Xie Ju Liao Tianrun Yan Yingjiu Liu Xinhai Tang 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1349-1360
A novel graphene oxide/bentonite composite (GO/bentonite) was synthesized and then characterized through powder X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and energy dispersive spectroscopy. Adsorption achieved equilibrium within 10 min. Moreover, U(VI) adsorption on GO/bentonite was highly dependent on solution pH and independent of ionic strength. These characteristics suggested that inner-sphere surface complexes of U(VI) formed on GO/bentonite. The adsorption of U(VI) from aqueous solution on GO/bentonite was fitted to the pseudo-second-order and Freundlich isotherm models. The maximum sorption capacity of GO/bentonite was 234.19 mg g?1 under neutral pH at 303 K. GO/bentonite is a potentially powerful adsorbent for the efficient removal of U(VI) from aqueous solutions. 相似文献
942.
Abdullah Abdul Samat Abdul Azim Jais Mahendra Rao Somalu Nafisah Osman Andanastuti Muchtar Kean Long Lim 《Journal of Sol-Gel Science and Technology》2018,86(3):617-630
The electrical conductivity and electrochemical performance of a La0.6Sr0.4CoO3-δ (LSC) cathode produced by a modified citrate-EDTA sol-gel method assisted with activated carbon are characterized for a proton-conducting solid oxide fuel cell (H+??SOFC) application at intermediate temperature. Thermogravimetric analysis revealed that the decomposition of the unrequired intermediate compounds in the precalcined powder was completed at 800?°C. A single LSC perovskite phase was formed at a calcination temperature of 900?°C, as confirmed by X-ray diffraction analysis. The particle size, crystallite size, and BET-specific surface area of the powder are 219–221?nm, 18?nm, and 9.87?m2?g?1, respectively. The high index value of the extent of agglomeration (5.53) showed that the powder was barely agglomerated. Bulk LSC sintered at 1200?°C for 2?h showed the highest direct-current electrical conductivity (σd.c) compared to that of bulk LSC sintered at 1000?°C and 1100?°C. The value of σd.c was affected by the density and porosity of the sintered samples. The area specific resistance (ASR) of screen-printed LSC working on a proton conductor of BaCe0.54Zr0.36Y0.1O2.95 (BCZY) decreased from 5.0?Ω?cm2–0.06?Ω?cm2 as the temperature increased from 500?°C to 800?°C with an activation energy of 1.079?eV. Overall, in this work, the LSC material produced with the aid of activated carbon meet the requirements for the application as a cathode in an intermediate temperature H+-SOFC. 相似文献
943.
Alina Ponomareva Valeri Babushok Elizaveta Simonenko Nikolai Simonenko Vladimir Sevast’janov Olga Shilova Irina Kruchinina 《Journal of Sol-Gel Science and Technology》2018,87(1):74-82
Powders of Sm0.6Sr0.4CoO3-δ and La0.6Sr0.4CoO3-δ were synthesized using wet chemical technique. Structural and surface properties of synthesized materials were studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), IR spectroscopy, and scanning electron microscopy (SEM). The influence of pH on the phase state, chemical composition, morphology, and fractal dimension of the synthesized powders were investigated. It was found that the change of pH has the influence on phase composition of synthesized powders. The increase of solution pH allows one to obtain homogeneous samples at lower temperatures down to 900–950?°C. 相似文献
944.
Hongliang Xu Shiping Sun Sanying Jiang Hailong Wang Rui Zhang Qinfu Liu 《Journal of Sol-Gel Science and Technology》2018,87(3):676-684
Kaolinite/TiO2 composites were prepared by using sol-gel method and raw kaolin, pretreated kaolinite and tetrabutyl titanate as the main raw materials. X-ray diffractometer, field-emission scanning electron microscope and infrared spectrometer analysis were carried out to characterize the phase composition and microstructure of the samples. The photocatalytic performance of the kaolinite/TiO2 composites were evaluated by degrading the methylene blue (MB) and phenol aqueous solution, respectively. The results show that intercalation and exfoliation reduced the size and thickness of kaolinite particles. Acid treatment improved the distribution and the loading quantity of TiO2 grains. When the kaolinite/TiO2 composites were calcined at 500?°C, the tetragonal structure of anatase particles of 30–100?nm in size were obtained, but the exfoliated kaolinite crystals were damaged. The degradation rate of MB increased gradually with the extension of photocatalytic reaction time and the enhancement of photocatalyst dosage. The adsorption performance of acid-treated kaolinite/TiO2 composite (AKT) was nearly the same as that of raw kaolin/TiO2 composite (RKT), but that of the exfoliated kaolinite/TiO2 composite (EKT) was the most excellent. The photocatalytic performance of AKT and EKT were better than that of RKT, and AKT exhibited the optimum property. Under a certain photocatalyst dosage and photocatalysis time, the absorption rate and the degradation rate decreased gradually with the enhancement of initial concentration of MB. Similar result was also acquired for the degradation of phenol. Both the acid treating and the exfoliating to kaolinite enhanced the photocatalytic performance of the kaolinite/TiO2 composite photocatalysts, but acid treatment may be more helpful to the preparation of high performance kaolinite/TiO2 composite photocatalyst. 相似文献
945.
Lijuan Wang Hua Lv Binjie Li Yanbao Zhao Lei Sun 《Journal of Sol-Gel Science and Technology》2018,88(3):654-659
Flower-like ceria (CeO2) architectures consisting of well aligned nanosheets were first synthesized by a glycol solvothermal method. The size of CeO2 architectures is about 5?μm in width and 10?μm in length, with the nanosheets thickness below 100?nm. Subsequently, the adsorbed Ag ions on the surface of CeO2 were in situ reduced to form Ag nanoparticles (NPs), leading to the fabrication of Ag/CeO2 hybrid architectures (HAs). The formed Ag NPs with sizes of 20–40?nm were uniformly loaded on the surface of the CeO2 sheets. The antibacterial properties of Ag/CeO2 HAs against Gram-negative E. coli and Gram-positive S. aureus were evaluated by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and a filter paper inhibition zone method. The results demonstrated that Ag/CeO2 HAs displayed excellent antibacterial activity toward S. aureus and E. coli, which were attributed to the synergistic antibacterial effect between Ag NPs and CeO2 in HAs. Here, CeO2 nanoflowers as a new substrate could restrict Ag NPs aggregations and improve their antibacterial activities. Therefore, the resulted Ag/CeO2 HAs would be considered as a promising antibacterial agent. 相似文献
946.
Baowen Wang Heyu Li Ning Ding Qiuwan Shen Haibo Zhao Chuguang Zheng 《Journal of Thermal Analysis and Calorimetry》2018,132(1):17-27
Chemical looping combustion (CLC) by direct use of coal as fuel is promising with its prominent advantages, but insufficient conversion of coal in the CLC system is a great limitation. In this research, in order to explore the limiting factor inherent for coal conversion in the CLC system, from the perspective of chemical structure of coal, reaction of a selected Chinese typical coal (designated as LZ) with Fe2O3 was systematically investigated. Thermogravimetric investigation of LZ coal reaction with Fe2O3 at the oxygen excess number Φ = 1.0 indicated that after dehydration, there existed three discernible reaction stages as observed, which were attributed to the combined reactions of Fe2O3 with the primary and secondary gaseous products evolved from LZ coal. Meanwhile, the Fe2O3 provided should be controlled around Φ = 1.0 aiming at effective conversion of LZ coal and simultaneous proper utilization of Fe2O3. And then, both gaseous Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy analysis of the gaseous and solid products formed from reaction of LZ coal with Fe2O3 at Φ = 1.0 indicated that full conversion of LZ coal was not reached with a little unconverted CO occurring, though partial Fe2O3 was over reduced to lower valence of oxides than Fe3O4. Furthermore, in order to explore the insufficient conversion of LZ coal at the molecular scale, X-ray photoelectron spectroscopy analysis revealed the distribution and evolution of the carbon functional groups involved in LZ coal after its reaction with Fe2O3 and further found that effective conversion of the aromatic/aliphatic C=C/C–H groups in LZ coal was the rate-limited step at the molecular scale with the relative content of these groups still dominated around 59% after LZ coal reaction with Fe2O3. Finally, solid IR (infrared) analysis and quantitative evaluation of the solid products of LZ coal reaction with Fe2O3 indicated that the length of aliphatic C–H groups decreased due to its partial disintegration, while the aromatization of the residual char was aggravated with the higher relative IR intensity ratio of the aromatic C=C groups, which reduced the reactivity of LZ residual char and hindered the full conversion of LZ coal. 相似文献
947.
Eva Kuzielová Matúš Žemlička Jiří Másilko Martin T. Palou 《Journal of Thermal Analysis and Calorimetry》2018,133(1):63-76
Stability of Dyckerhoff cement Class G partially substituted (15 mass%) by metakaolin (MK), silica fume (SF) and ground granulated blast-furnace slag (BFS) was investigated after 7 days of curing under standard and two different autoclaving conditions. Mercury intrusion porosimetry, X-ray diffraction analysis and combined thermogravimetric–differential scanning calorimetry were used to evaluate pore structure development, compressive strength and their dependence on the type of additives in relation to the particular phase composition. Hydrothermal curing led to the formation of α-C2SH and jaffeite, mostly in the case of referential samples and compositions with addition of slowly reacting BFS. Whilst modest hydrothermal curing (0.6 MPa, 165 °C) favoured formation of α-C2SH, larger amounts of jaffeite were determined after curing at the highest used pressure and temperature (2.0 MPa, 220 °C). Undesired transformation of primary hydration products was prevented especially by addition of highly reactive and very fine SF. Particular composition attained the best pore structure characteristics and compressive strength after curing at 0.6 MPa and 165 °C. Formation of more stable phases with C/S ratio close to 1 was proved by wollastonite formation during DSC analyses. More severe conditions of curing, however, led to the significant deterioration of microstructure and strength of corresponding sample, probably due to the formation of trabzonite, killalaite and zoisite. Considering the values of hydraulic permeability coefficient and compressive strength, replacement of cement by MK improved significantly the properties of cement when compared with the referential as well as with other blended compositions under the mentioned curing conditions. 相似文献
948.
Titanium and its alloys are used in production of implants such as knee and hip prostheses due to their superior properties. Ti–Nb–Zr ternary alloys are preferred over other metallic implant materials due to the presence of non-toxic elements, high corrosion resistance, good biocompatibility, and proper mechanical properties. The aim of this work is to investigate the effect of zirconium addition on α → β phase transformation, microstructure, and mechanical behavior of Ti–16Nb alloy. In doing so, Ti–16Nb–xZr (x: 0, 5, 10, 15 mass%) alloys are produced by powder injection molding, which offers advantages such as low cost, net shape, and easy production of complicated parts for implant fabrication. X-ray diffraction analysis and scanning electron microscope images showed that zirconium behaves as a β stabilizer and according to differential thermal analysis, and it decreases α to β transition temperature approximately 30 °C. It is also revealed that increasing zirconium content caused finer microstructure and hardness of the alloy was raised from 336 HV0.5 to 412 HV0.5 while elastic modulus remains approximately steady between 103 and 110 GPa. It is concluded that Ti–Nb–Zr alloys have been found to be a good alternative to known metallic implant materials. 相似文献
949.
Basavarajeshwari M. Baraker Blaise Lobo 《Journal of Thermal Analysis and Calorimetry》2018,132(2):879-893
Core/shell composites of CuC2O4·2H2O@AP and ZnC2O4·2H2O@AP were prepared from metal oxalates on suspended AP particles in ethanol. CuO and ZnO nano-metal oxides as the nano-catalysts were made from CuC2O4·2H2O and ZnC2O4·2H2O simultaneously by thermal decomposition of AP. The particle size of CuO nano-particles was very finer, and the ZnO particles showed a considerable growth during formation. The kinetic triplet of activation energy, frequency factor, and model of thermal decomposition of pure AP, CuC2O4·2H2O@AP, and ZnC2O4·2H2O@AP composites were estimated by applying three model-free (FWO, KAS, and Starink) and model-fitting (Starink) methods. Based on the thermal analysis, the CuC2O4@AP composite has better catalytic performance and the thermal decomposition temperature of AP decreased to about 126.44 °C. 相似文献
950.
Yunyun Yang Xilei Cao Hang Luo Xufu Cai 《Journal of Thermal Analysis and Calorimetry》2018,132(3):1557-1566
Lipid nanoparticles, both solid lipid nanoparticles and nanostructured lipid carriers (NLC), containing tacrolimus (FK) were obtained by solvent diffusion method associated with ultrasonication using stearic acid (SA) or beeswax as solid lipid. The oleic acid was used as liquid lipid in the NLC. Lipid nanoparticles were characterized by determining the drug loading, particle size, polydispersity index (PDI) and zeta potential (ZP). Analysis by differential scanning calorimetry and X-ray diffraction were performed. Lipid nanoparticles presented nano-sized from 139 to 275 nm. The PDI results show the particles present from 0.3 to 0.5, and ZP was higher than |25| mV. Drug loading ranged of 2.3–3.2%. SA nanoparticles presented better ZP, average size and distribution. However, beeswax nanoparticles showed higher drug loading. Results suggest there are no incompatibilities between FK and the raw materials. Polymorphic modifications were not observed. The results presented show that lipid nanoparticles using both lipids were successfully obtained and may represent promising delivery system of FK in topical formulations. 相似文献