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1.
Liu Wenjun  F. Hui  J. Lédion  Wu Xingwu 《Ionics》2009,15(3):337-343
This paper investigated the respective applications of zinc and copper ions as inhibitors in the recycling water. The results show when their concentrations are not less than 0.5 mg L−1, the treated water is clear as usual. However, their scaling on the tube wall still lasts. In the solution of zinc ion, the weight of precipitation on the tube wall always increases stably; but in the solution of copper ion, that increases less stably; besides, when the concentration of copper ion is beyond 2 mg L−1, the increase of precipitation weight on the tube wall has become small. All of which showed different scaling mechanisms. For the solution of zinc ion, the scaling on the tube wall increases stably because of the homogeneous germs. However, in the solution of copper ion, the different types of copper ion germs will be adsorbed selectively by the tube wall because of heterogeneous germs, or the part of having been adsorbed germs onto the tube wall will be washed out.  相似文献   

2.
A new preparation method for CuInS2 and CuInSe2 nanoparticles synthesis is described without using any organic solvent. Heating Cu, In, and S/Se precursors dissolved in water for 30 min in a microwave oven in the presence of mercapto-acetic acid leads to monodispersed chalcopyrite nanoparticles. No precipitation of these nanoparticles is observed after several months at room temperature. These new materials have been thoroughly characterized to confirm their compositions, sizes, and structure without any filtration. Transmission electron microscopy (TEM) confirmed particle sizes below 5 nm. Energy dispersive X-ray analysis (EDXA) confirmed the chemical composition of these samples. X-ray diffraction (XRD) showed a chalcopyrite-type structure with crystallite size of about 2 nm. No difference has been observed between batch and continuous synthesis processes. Cu x InS2 and Cu x InSe2 nanoparticles, with x < 1, have been also synthesized and identified. Simulation using a commercial software confirmed the difference between copper poor (Cu x InS2) and copper rich (CuInS2) chalcopyrite structures. Conventional spray deposition techniques have been used to form relatively thin films on solid substrates.  相似文献   

3.
Transverse flow transversely excited (TFTE) CO2 lasers are easily scalable to multikilowatt level. The laser power can be scaled up by increasing the volumetric gas flow and discharge volume. It was observed in a TFTE CW CO2 laser having single row of pins as an anode and tubular cathode that the laser power was not increasing when the discharge volume and the gas volumetric flow were increased by increasing the electrode separation keeping the gas flow velocity constant. The discharge voltage too remained almost constant with the change of electrode separation at the same gas flow velocity. This necessitated revision of the scaling laws for designing this type of high power CO2 laser. Experimental results of laser performance for different electrode separations are discussed and the modifications in the scaling laws are presented.  相似文献   

4.
The rates of graphite gasification in interaction with high-temperature gas flows were compared. Carbon dioxide and a mixture of water vapor and argon taken in a 1:1 molar ratio were used as reagents. The reactor was a tube furnace; its temperature was varied from 1250 to 1400 K. The rates of graphite gasification in CO2 and water vapor-argon mixture flows were approximately equal at 1250–1300 K, whereas, at 1350–1400 K, the water vapor-argon mixture exhibited higher reactivity than CO2. The data obtained were approximated by Arrhenius dependences; the activation energy was found to be 153 kJ/mol for CO2 and 248 kJ/mol for H2O-Ar.  相似文献   

5.
Based on the chemical model of coal, slit micropores with different pore sizes are established and structures are optimized in the software of materials studio. As the temperature rises, absolute adsorption capacities of H2O are slightly affected, while absolute adsorption capacities of CO2 and CH4 gradually decrease. As the fugacity rises, excess adsorption curves of CO2 experience increase-decrease-gentle three stages, while the curves of CH4 gradually decrease. With the increase of pore size, adsorption capacities of H2O increase, while adsorption capacities of CO2 and CH4 gradually decrease. H2O firstly adsorbs on the oxygen-containing functional group, so the walls of pore are the preferential area for H2O, while CO2 and CH4 choose to adsorb on–C–C–, therefore the walls are the primary area for CO2 and CH4. Strong potential in micropores and hydrogen bond among water molecules will promote the water adsorption, while the adsorptions of CO2 and CH4 are only induced by the Van der Waals interaction, but the difference between adsorption density and bulk density of CO2 and CH4 decides the change of excess adsorption capacity.  相似文献   

6.
The magnetic and thermodynamic properties of the complete Ln2/3Cu3Ti4O12 series were investigated. Here Ln stands for the lanthanides La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. All the samples investigated crystallize in the space group Im[`3]Im\bar{3} with lattice constants that follow the lanthanide contraction. The lattice constant of the Ce compound reveals the presence of Ce4+ leading to the composition Ce1/2Cu3Ti4O12. From magnetic susceptibility and electron-spin resonance experiments it can be concluded that the copper ions always carry a spin S = 1/2 and order antiferromagnetically close to 25 K. The Curie-Weiss temperatures can approximately be calculated assuming a two-sublattice model corresponding to the copper and lanthanide ions, respectively. It seems that the magnetic moments of the heavy rare earths are weakly coupled to the copper spins, while for the light lanthanides no such coupling was found. The 4f moments remain paramagnetic down to the lowest temperatures, with the exception of the Tm compound, which indicates enhanced Van-Vleck magnetism due to a non-magnetic singlet ground state of the crystal-field split 4f manifold. From specific-heat measurements we accurately determined the antiferromagnetic ordering temperature and obtained information on the crystal-field states of the rare-earth ions.  相似文献   

7.
Polycrystalline samples of intercalated compounds Cu x HfSe2 have been synthesized for the first time and their electrical resistivity has been measured at both direct current and alternating current (with a frequency ranging from 200 Hz to 150 kHz) in the temperature range 80–300 K. It has been shown that the intercalation of copper atoms between three-layer Se-Hf-Se blocks leads to an increase in the electrical resistivity of the samples, as well as to a more pronounced activated character of the temperature dependence of the electrical resistivity. A time dependence of the electrical resistivity of the Cu x HfSe2 samples at room temperature, which is associated with the presence of copper ions in the sample, has been determined.  相似文献   

8.
The optical technology based on Mach-Zehnder interferometry was successfully applied to a high-pressure liquid CO2 and water system to measure CO2 solution density. Experiments were carried out at a pressure range of from 5.0 to 12.5 MPa, temperatures from 273.25 to 284.15 K, and CO2 mass fraction in solution up to 0.061. CO2 solution density data were obtained from two sets of experiments. These data were calculated through the fringe shifts induced by density changes inside of the high-pressure vessel, which were directly recorded during the experiments, and a modified version of Lorentz-Lorenz formulation. The experimental results indicated that the density ratio of CO2 solution to that of pure water at the same pressure and temperature is monotonically linear with the CO2 concentration in the solution. The slope of this linear function, calculated by the experimental data fitting, is 0.275.  相似文献   

9.
Optical properties (photoluminescence and absorption) of Eu(bta)3(B) n (B = H2O or 1,10-phenanthroline) polycrystalline powders and fluoroacrylate polymers (FAPs) impregnated with these compounds using supercritical CO2 (SC CO2) were investigated. It was established that impregnation of Eu(bta)3phen into the FAPs using an SC CO2 solution was difficult to achieve. The type of B (ancillary ligand) and the polymer matrix were shown to influence the temperature quenching of photoluminescence of Eu3+ ions in the range 25–100°C. A comparative analysis of quantum yields (λex = 300 and 380 nm) and photoluminescence decay times (λex = 337.1 nm) for Eu(bta)3B n and for Eu(bta)3B n -doped FAPs was performed.  相似文献   

10.
A Cu2+-doped single crystal of catena-trans-bis(N-(2-hydroxyethyl)-ethylenediamine) zinc(II)-tetra-m-cyanopaladate(II) [ZnPd(CN)4(C4H12N2O2)] complex has been investigated by electron paramagnetic resonance (EPR) technique at room temperature. EPR spectra indicate that Cu2+ ions substitute for magnetically equivalent Zn2+ ions and form octahedral complexes in [ZnPd(CN)4(C4H12N2O2)] hosts. The crystal field affecting the Cu2+ ion is nearly axial. The optical absorption studies show two bands at 322 nm (30864 cm−1) and 634 nm (15337 cm−1) which confirm the axial symmetry. The spin Hamiltonian parameters and the relevant wave function are determined.  相似文献   

11.
Novel multifunctional ceria based materials may show an improved performance in catalytic processes involving CO2 activation and reforming of hydrocarbons. Towards a more detailed understanding of the underlying surface chemistry, we have investigated CO2 activation on single crystal based ceria and magnesia/ceria model catalysts. All model systems are prepared starting from well-ordered and fully stoichiometric CeO2(111) films on a Cu(111) substrate. Samples with different structure, oxidation state and compositions are generated, including CeO2-x/Cu(111) (reduced), MgO/CeO2-x/Cu(111) (reduced), mixed MgO-CeO2/Cu(111) (stoichiometric), and mixed MgO-CeO2-x/Cu(111) (reduced). The morphology of the model surfaces is characterized by means of scanning tunneling microscopy (STM), whereas the electronic structure and reactivity is probed by X-ray photoelectron spectroscopy (XPS). The experimental approach allows us to compare the reactivity of samples containing different types of Ce3+, Ce4+, and Mg2+ ions towards CO2 at a sample temperature of 300 K. Briefly, we detect the formation of two CO2-derived species, namely carbonate (CO3 2-) and carboxylate (CO2 -) groups, on the surfaces of all investigated samples after exposure to CO2 at 300 K. In parallel to formation of the carbonate species, slow partial reoxidation of reduced CeO2-x/Cu(111) occurs at large doses of CO2. The reoxidation of the reduced ceria is largely suppressed on MgO-containing samples. The tendency for reoxidation of Ce3+ to Ce4+ by CO2 decreases with increasing degree of intermixing between MgO and CeO2-x. Additionally, we have studied the stability of the formed carbonate species as a function of annealing temperature.  相似文献   

12.
Synchrotron small angle X-ray scattering (SAXS) was performed to investigate the effect of dissolved CO2 in toluene on the conformation of polystyrene (PS) in the solution. It has been found that the second virial coefficientA 2 and the radius of gyrationR g decrease with the increasing antisolvent CO2 pressure. The scattering intensity of PS chain followedI(h)h −α under different antisolvent pressures (0, 0.6, 1.5, 2.4, 3.3, and 4.2 MPa), suggesting that the PS chain has self-similar structure behavior or a fractal structure in the presence of antisolvent CO2. All this reveals a large effect of antisolvent pressure or the solubility of CO2 in the solution on PS structure. The fractal dimensions increase with the increasing antisolvent pressure, indicating that the polymer chain changes from a swollen coil into a rather dense globule in the course of adding antisolvent CO2.  相似文献   

13.
We present the results of analysis of the errors introduced by hot-band transitions 1110-0111, 0310-0111, 1200-1201 of the CO2 molecule and the absorption lines of the H2O and NO2 molecules in determination of the temperature and partial pressure of CO2, included in the gas mixture CO2: N2:H2O: NO2 at atmospheric pressure, by multiple-frequency laser probing using a CO2 laser tunable over the lines of the 0001-[1000,0200]I,II ground-state laser transitions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 810–815, November–December, 2007.  相似文献   

14.
Terbium doped Y2O3 planar waveguides were fabricated by sol–gel process and dip-coating using yttrium acetate as precursor. Two different doping modes were compared, i.e. introduction in the sol of dispersed Tb3+ions from dissolved Tb(NO3)3, or of nanoparticles of Tb2O3 or [Y2O3:50% Tb] from an alcoholic suspension. The chemical and nanostructural properties were analyzed by infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The Tb3+ fluorescence properties were studied as a function of temperature and atmosphere of the thermal treatments, and of the Tb3+ concentration. The fluorescence properties are discussed in relation to the quenching mechanisms induced by Tb4+ transformation, residual OH groups, and crystallites size and structure. Optical propagation losses of the Tb doped Y2O3 planar waveguides related to the doping modes and Tb3+ concentration are presented. Doping sol–gel films by nanoparticles is shown to be a valuable alternative to the conventional doping from dissolved terbium salt. PACS 81.21.Fw; 84.40.Az; 78.67.Bf  相似文献   

15.
Sodium silicate glasses doped with CuO and mixed with different contents of Bi2O3 (ranging from 4 to 16 mol%) were prepared. D.C. conductivity studies over a range of temperature from 225 to 325 K have been carried out. The conductivity is observed to decrease linearly with increase of Bi2O3 concentration. The results are analyzed using optical absorption, ESR, and IR spectral data. The spectroscopic studies have indicated that there is a gradual reduction divalent copper ions to monovalent ions with increase of Bi2O3 concentration. These studies have also indicated that such Cu+ ions participate in the glasses network forming and increase the polymerization of the glass network. The analysis of the results of D.C. conductivity indicated that in temperature region T > θ D/2, the small polaron hoping model is valid, and the conduction is predicted to be adiabatic type. The analysis of the results has further revealed that there is a gradual change over of conduction mechanism from ionic to electronic with increase of Bi2O3 concentration. The low temperature part of D.C. conductivity is explained using variable range hopping (VRH) model.  相似文献   

16.
A comparative analysis of the copper and iron ions bonds exchange energies was conducted for various variants of orderings and distributions of iron ions among crystallographic positions in ludwigite Cu2FeBO5. Analysis showed that the exchange bonds of iron ions play a key role in the formation of magnetic order. The magnetic ordering strongly depends on the distribution of iron ions among the positions. In the case when the Fe3+ is in the same position as in Fe3BO5, the most favorable magnetic structure is similar to the magnetic structure of ludwigite Fe3BO5. In other cases, the type of magnetic ordering is different.  相似文献   

17.
Experimental results on the interaction of Mo atoms with various oxygen-containing molecules (NO, O2, N2O, and CO2) at high temperatures (>1200 K) are presented, which are in close agreement with measurements at moderate and low temperatures. It is demonstrated that the height of the activation barrier is additionally increased for spin-forbidden reactions and that an increase in the heat of reaction causes an increase in the rate constant for a given type of reaction. For the reactions of Mo atoms with O2 and N2O, interpolated temperature dependences of the rate constants, based on the high-temperature measurements conducted in the present work and the published low-temperature data, are proposed.  相似文献   

18.
Electrical, resonant, and magnetic properties of intercalated copper chromium disulfide CuCrS2 are studied. It is established that CuCrS2 is an antiferromagnetic semiconductor with Néel temperature TN=40.7 K and an effective magnetic moment of 4.3µB. Anomalies in the electrical, magnetic, and resonant properties of CuCrS2 are found at Tc=110 K, which suggest an electron transition accompanied by alteration of the valences of the 3d-metal ions.  相似文献   

19.
The routine methods for stable oxygen and hydrogen isotope analysis of water involve water–CO2 gas equilibration and water reduction on hot metal (e.g. Zn, Cr, U) and subsequent mass spectrometric analysis of the evolved gases of CO2 and H2 for 18O/16O and 2H/1H ratios, respectively. Precise determination of the isotopic composition of water in brines with application of these standard methods is still problematic and technically often impossible due to detrimental influence of dissolved salts. The new method of brine desalination presented in this study overcomes the problem of the isotope salt effects encountered during the application of the routine techniques for the determination of the isotopic composition of high saline waters. The procedure combines two technical steps: (i) the chemical precipitation of Mg and Ca ions as insoluble non-hydroscopic fluorides, and (ii) the vacuum distillation of water from solution–precipitate mixture. The application of simple vacuum distillation allows full extraction of water and dehydration of remaining salts in a temperature range from 300 to 350?°C without hydrogen and oxygen isotope fractionation. The precision and accuracy of δ18O and δ2H determination of saline waters and brines with prior application of AgF desalination procedure is comparable with that usually obtained for fresh waters.  相似文献   

20.
The magnetic susceptibility and specific heat of single crystals of the Ba2Fe2GeO7 barium ferrigermanate are investigated. It is revealed that the temperature dependence of the magnetic susceptibility exhibits a kink at a temperature T = 8.5 K. The number of nonequivalent positions of Fe3+ ions and their occupancies are determined using Mössbauer spectroscopy. It is shown that the Fe3+ ions located in tetrahedral positions T2 are ordered incompletely, which is inconsistent with the results obtained previously. An assumption is made regarding the possible ground magnetic state of the Ba2Fe2GeO7 compound.  相似文献   

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