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1.
In this paper, we have reported the preparation of low cost γ-Al2O3 membrane on a macroporous clay support by dip-coating method. For the synthesis of γ-Al2O3 top layer on the support, a stable boehmite sol is prepared using aluminium chloride salt as a starting material by sol–gel route. The structural properties of the composite membrane as well as γ-Al2O3 powder is carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption–desorption isotherm data, Fourier transform infrared analysis (FTIR) and dynamic light scattering (DLS) analysis. The mean particle size of the boehmite sol used for coating is found to be 30.9 nm. The pore size distribution of the γ-Al2O3–clay composite membrane is found to be in the range of 5.4–13.6 nm. Separation performance of the membrane in terms of flux and rejection of single salts solution such as MgCl2 and AlCl3 as a function of pH, salt concentration and applied pressure is also studied. The rejection and flux behavior are found to be strongly dependent on electrostatic interaction between the charged molecules and γ-Al2O3–clay composite membrane. The intrinsic rejection has been determined by calculating the concentration at membrane surface (Cm) using Speigler–Kedem model. It is found that the observed rejection shows anomalous trend with increase in applied pressure and the intrinsic rejection increases with increase in applied pressure, a trend typical of the separation of electrolyte through charged membranes. At acidic pH, both the salt solution shows higher rejection. With increase in the salt concentration, observed rejection of salt decreases due to the enhanced concentration polarization. The maximum rejection of MgCl2 and AlCl3 is found to be 72% and 88%, respectively for salt concentration of 3000 ppm.  相似文献   

2.
Five new diorganotin(IV) complexes of the types {(Me2Sn)24-(C8H3NO6)](μ3-O)}n (1), {(Me2Sn)23-(C8H8O4)](μ3-O)}n (2), {(Me2Sn)24-(C8H10O4)](μ3-O)}n (3) {(Me2Sn)24-(C8H10O4)](μ3-O)}n (4) and {(Me2Sn)24-(C10H14O4)](μ3-O)}n (5) have been synthesized by reactions of 5-nitroisophthalic acid, meso-cis-4-cyclohexene-1,2-dicarboxylic, meso-cis-1,4-cyclohexanedicarboxylic acid, meso-cis-1,3-cyclohexanedicarboxylic acid and chiral cis-(1R,3S)-(+)-camphoric acid with trimethyltin chloride under hydrothermal condition. All complexes were characterized by elemental analysis, IR, 1H NMR, 13C NMR, 119Sn NMR and X-ray crystallography. The structural analyses show that complex 1 has a 1D infinite polymeric chain in which 5-nitroisophthalic acid acts as a tetradentate ligand coordinating to dimethyltin(IV) ions, complexes 2, 3 and 4 possess 2D polymeric structures in which dicarboxylate acid act as tridentate or tetradentate ligands coordinating to dimethyltin(IV) ions, complex 5 possesses a irregular 3D framework in which chiral cis-(1R,3S)-(+)-camphoric acid acts as a tetradentate ligand coordinating to dimethyltin(IV) ions.  相似文献   

3.
Mesoporous YSZ–γ-Al2O3 membranes were coated on α-Al2O3 (Ø2 mm) tube by dipping the α-Al2O3 support tube into mixed sol consists of nano-size YSZ and bohemite particles followed by drying and calcination at 600 °C. Addition of bohemite in YSZ sol helped a good adhesion and uniform coating of the membrane film onto α-Al2O3 support. The quality of the mesoporous YSZ–γ-Al2O3 membranes was evaluated by the gas permeability experiments. The number of defects was minimized when the γ-Al2O3 content became more than 40%. Addition of γ-Al2O3 inhibited the crystal growth of YSZ, sintering shrinkage and distortion stress. Increase of calcination temperature and time results in the increase of pore size and N2 permeance. A hydrogen perm-selective membrane was prepared by filling palladium into the nano-pores of YSZ–γ-Al2O3 layer by vacuum-assisted electroless plating. Crystal growth of palladium was observed by thermal annealing of the membrane at 600 °C for 40 h. The Pd–YSZ–γ-Al2O3 composite membrane revealed improved thermal stability allowing long-term operation at elevated temperature (>500 °C). This has been attributed to the improved fracture toughness of YSZ–γ-Al2O3 layer and matching of thermal expansion coefficient between palladium and YSZ. Although fracture of the membrane did not occur, decline of H2 flux was observed when the membrane was exposed in 600 °C. This has been attributed to the agglomeration of palladium particles by crystal growth and dense packing into the pore networks of YSZ–γ-Al2O3 by elevation of temperature.  相似文献   

4.
A series of α-Fe2O3/FeOOH nanostructures with different morphologies have successfully been synthesized based on K4[Fe(CN)6] at 140 °C by a novel hydrothermal method. The morphology and phase of α-Fe2O3/FeOOH can be controlled by adjusting the reaction time. UV–vis absorption spectrum, X-ray powder diffraction, and transmission electron microscopy analyses were used to characterize the resulting products. A detailed, rational mechanism is proposed for the formation of α-Fe2O3/FeOOH nanostructures. The potential applications of the as-synthesized α-Fe2O3/FeOOH nanoparticles with different morphologies on photocatalytic decomposition of salicylic acid were also investigated.  相似文献   

5.
Variation of the phases of Nd2NiO4+δ with the excess oxygen concentration δ has been examined at room temperature in the range 0.067≤δ≤0.224 using the X-ray powder diffraction technique. The phases observed at room temperature are orthorhombic-I (0.21<δ≤0.224), orthorhombic-IV (0.175<δ≤0.21), orthorhombic-II (0.15<δ≤0.175), orthorhombic-II+quasi-tetragonal-I (0.10<δ≤0.15), and quasi-tetragonal-I (0.067<δ≤0.10).  相似文献   

6.
Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. BaZr0.1Ce0.7Y0.2O3−δ (BZCY7) electrolyte based PCMFCs with stable Ba0.5Sr0.5Zn0.2Fe0.8O3−δ (BSZF) perovskite cathode were investigated. Using thin membrane BZCY7 electrolyte (about 15 μm in thickness) synthesized by a modified Pechini method on NiO-BZCY7 anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.015 V, a maximum power density of 486 mW cm−2, and a low polarization resistance of the electrodes of 0.08 Ω cm2 was achieved at 700 °C. The results have indicated that BZCY7 proton-conducting electrolyte with BSZF cathode is a promising material system for the next generation solid oxide fuel cells.  相似文献   

7.
The reactions of P4S3 with As4S3 and of P4Se3 with As4Se3 in the molten state yields molecules of the type P m As4–m S3 and P m As4–m Se3, respectively. A method was developed to separate the different components by the HPLC technique, and to determine their concentrations. The identification of the isomers in the HPLC pattern was achieved with the aid of the LC-MS method. In the selenium system, the distribution of the different species is statistical. In the system P4S3-As4S3, the formation of PAs3S3 with one phosphorus atom in the apical position is favoured.
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8.
The Taylor dispersion (peak-broadening) method is used to measure ternary mutual diffusion coefficients at 25°C for fifteen different compositions of the system KCl–LaCl 3 -water at ionic strengths from 0.02 to 0.24 mol-dm–3. The diffusion coefficients are evaluated by least-squares analysis of the refractive index profiles across the dispersed solute peaks. Diffusing LaCl 3 is found to cotransport significant amounts of KCl. Monte Carlo simulations are used to estimate the precision of ternary diffusion coefficients determined by the dispersion method. Tracer diffusion coefficients are also reported for La 3+ ions in aqueous KCl solutions and for K+ ions in aqueous LaCl 3 solutions.  相似文献   

9.
CrCl3(thf)3 is a common starting material in the synthesis of organometallic and coordination compounds of Cr. Deposited as an irregular solid with no possibility of recrystallization, it is not a purity guaranteed chemical, causing problems in some cases. In this work, we disclose a well-defined form of the THF adduct of CrCl3 ([CrCl2(μ-Cl)(thf)2]2), a crystalline solid, that enables structure determination by X-ray crystallography. The EA data and XRD pattern of the bulk agreed with the revealed structure. Moreover, its preparation procedure is facile: evacuation of CrCl3·6H2O at 100 °C, treatment with 6 equivalents of Me3SiCl in a minimal amount of THF, and crystallization from CH2Cl2. The ethylene tetramerization catalyst [iPrN{P(C6H4-p-Si(nBu)3)2}2CrCl2]+[B(C6F5)4] prepared using well-defined [CrCl2(μ-Cl)(thf)2]2 as a starting material exhibited a reliably high activity (6600 kg/g-Cr/h; 1-octene selectivity at 40 °C, 75%), while that of the one prepared using the impure CrCl3(thf)3 was inconsistent and relatively low (~3000 kg/g-Cr/h). By using well-defined [CrCl2(μ-Cl)(thf)2]2 as a Cr source, single crystals of [(CH3CN)4CrCl2]+[B(C6F5)4] and [{Et(Cl)Al(N(iPr)2)2}Cr(μ-Cl)]2 were obtained, allowing structure determination by X-ray crystallography, which had been unsuccessful when the previously known CrCl3(thf)3 was used as the Cr source.  相似文献   

10.
The bulk superconducting YCa2Cu3O7−δ compounds are prepared at an ordinary pressure of oxygen by conventional solid-state reaction method. The formation of sample is tested by means of XRD and is studied for their ac susceptibility below room temperature up to 77.5 K. The samples are found single-phase orthorhombic structure and found superconducting at 83.5 K. It is shown that the analysis is consistent with published data on YBa2Cu3O7−δ oxide superconductor.  相似文献   

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