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1.
The interaction between two similar plane double-layers for Al 2(SO 4) 3 type asymmetric electrolytes was investigated with the aid of λ parameter method. The interaction energies for the system at positive surface potential were expanded in the power series at low and high potential, respectively. The high potential formula can be applied to 0.2 ≤ ye < y 0 ≤ 20. This almost covers with the bounds of all potential, and that the calculative method is relative simple. The accurate numeral results and V′? ξd curves were given for y 0 ≤ 20. When y 0 ≥ 5, V′ hardly change with y 0. The interaction energies between two similar plane parallel double layers for the different type electrolytes at y 0 = 1 were compared. The present results are also fit for Mg 3(PO 4) 2 type electrolytes at negative surface potential. 相似文献
2.
Isopiestic results are reported for the quaternary system H 2O–NaCl–Na 2SO 4–MgSO 4. The excess free energies for mixing the double salt Na 2 Mg(SO 4) 2 with NaCl are fairly large and negative, as also are the free energies for mixing the three salts to form the quaternary aqueous system. 相似文献
3.
Summary The atomic arrangements within the structures of NH 4Ag 2(AsS 2) 3 [ a=9.557(2), b=7.414(2), c=16.29(1) Å; =91.30(5)°; space group P2 1/n; R( F)=0.042] and (NH 4) 5Ag 16(AsS 4) 7 [ a=64.49(6), b=6.471(2), c=12.806(4) Å; =95.47(5)°; space group Cc; R( F)=0.073] were determined from single crystal X-ray data. In these two compounds the coordination spheres of the Ag atoms are quite different. In NH 4Ag 2(AsS 2) 3, the Ag atoms exhibit a [2+2]- and a [3+1]-coordination to S atoms up to 3.3 Å and with Ag atom neighbours at 2.93 Å and 3.05 Å respectively. In (NH 4) 5Ag 16(AsS 4) 7, the Ag atoms are — with one exception- [4] coordinated (Ag-S<3.3 Å) and the distances to further Ag atom neighbours are greater than 3.1 Å. NH 4Ag 2(AsS 2) 3 represents an ordered cyclo-thioarsenate(III) with three-membered As 3S 6 rings, (NH 4) 5Ag 16(AsS 4) 7 a neso-thioarsenate(V) with two split Ag atom positions. Both compounds were synthesized under moderate hydrothermal conditions.
Synthesen und Kristallstrukturen von NH4Ag2(AsS2)3 und (NH4)5Ag16(AsS4)7 mit einer Diskussion über (NH4)Sx Polyeder Zusammenfassung Die Atomanordnungen in den Strukturen von NH4Ag2(AsS2)3 [a=9.557(2),b=7.414(2),c=16.29(1) Å; =91.30(5)°; Raumgruppe P21/n;R(F)=0.042] und (NH4)5Ag16(AsS4)7 [a=64.49(6),b=6.471(2),c=12.806(4) Å; =95.47(5)°; Raumgruppe Cc;R(F)=0.073] wurden anhand von röntgenographischen Einkristalldaten bestimmt. In diesen beiden Verbindungen sind die Koordinationsverhältnisse um die Ag-Atome sehr unterschiedlich. In NH4Ag2(AsS2)3 besitzen die Ag-Atome bis 3.3 Å eine [2+2]- und [3+1]-Koordination durch S-Atome mit weiteren Ag-Atomen bei 2.93 Å und 3.05 Å. In (NH4)5Ag16(AsS4)7 sind die Ag-Atome mit einer Ausnahme [4]-koordiniert (Ag-S < 3.3 Å), und die Abstände zu weiteren Ag-Atomen sind größer als 3.1 Å. NH4Ag2(AsS2)3 stellt ein geordnetes Cyclothioarsenat(III) mit dreigliedrigen As3S6-Ringen dar, (NH4)5Ag16(AsS4)7 ein Nesothioarsenat (V) mit zwei aufgespaltenen Ag-Positionen. Beide Verbindungen wurden unter mäßigen Hydrothermalbedingungen synthetisiert. 相似文献
4.
The compound, (NH 4)[VO(O 2) 2(NH 3)], thermally decomposes to ammonium metavanadate, which then decomposes to vanadium pentoxide. Using a heating rate of 5 deg·min –1, the first decomposition step occurs between 74° and 102°C. The transformation degree dependence of the activation energy ( -E) is shown to follow a decreasing convex form, indicating that the first decomposition step is a complex reaction with a change in the limiting stage of the reaction. Infrared spectra indicated that the decomposition proceeds via the gradual reduction of the ratio of the (NH 4) 2O to V 2O 5 units from the original 11 ratio in ammonium metavanadate, which may be written as (NH 4) 2O·V 2O 5, to V 2O 5.The assistance of Professor A. M. Heyns (University of Pretoria) and Professor K. L. Range (University of Regensburg) is gratefully acknowledged as well as the financial assistance of the University of Pretoria and the FRD. 相似文献
5.
Gases released during the conversion of NH 4Zr 2(PO 4) 3 to HZr 2(PO 4) 3 were identified using an apparatus in which gases released from a sample placed in a thermogravimetric analyzer were directly introduced to a gas cell of an IR spectrometer. Such acidic gases as N 2O and NO were detected besides the basic NH 3 gas, and their formation mechanism was discussed.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
6.
A series of Zr(SO 4) 2/SiO 2 solid acid catalysts with different Zr(SO 4) 2 loadings were prepared by water-soluble-impregnation method at room temperature. Then, the prepared catalysts were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectrum, X-ray diffraction, adsorption/desorption of N 2, and temperature-programmed desorption of NH 3. The results showed that the active component Zr(SO 4) 2 was successfully adhered to the mesoporous SiO 2, and the acid amount of Zr(SO 4) 2/SiO 2 increased with the increasing of the Zr(SO 4) 2 loadings. Finally, the wheat stalk was used as raw material and depolymerized over Zr(SO 4) 2/SiO 2 to produce ethyl levulinate (EL). The reaction mixture was separated and purified by filtration and vacuum distillation. The kinetic characteristics and the reaction pathway were also studied. A comparative study showed that 20 wt.% Zr(SO 4) 2/SiO 2 exhibited higher catalytic activity. When reaction temperature, time, catalyst dosage and Zr(SO 4) 2 loadings were 190 °C, 50 min, 20 wt.% and 30 wt.%, the EL yield reached a maximum of 17.14%. The relative content of EL exceeded 90% after three steps of distillation. 相似文献
7.
The incorporation mechanism of Cs + ions from CsNO 3 into NH 4Zr 2(PO 4) 3 was studied on a mixture of CsNO 3 and NH 4Zr 2(PO 4) 3 by powder X-ray diffraction analysis and by monitoring off-gases released from the mixture upon heating with a thermogravimetry
analyzer connected to an infrared spectrometer. With increasing temperature, the decomposition of CsNO 3 first started, followed by the conversion of NH 4Zr 2(PO 4) 3 to HZr 2(PO 4) 3 with the release of NH 3. At around 500°C, the Cs Zr 2(PO 4) 3 phase started to appear as a result of the H +/Cs + ion exchange. No Cs + ion loss was observed at thermal treatment temperatures of 900°C and lower. 相似文献
8.
The thermal decomposition of [Co(NH 3) 6] 2(C 2O 4) 3·4H 2O was studied under isothermal conditions in flowing air and argon. Dissociation of the above complex occurs in three stages. The kinetics of the particular stages thermal decomposition have been evaluated. The R N and/or A M models were selected as those best fitting the experimental TG curves. The activation energies, E, and lnA were calculated with a conventional procedure and by a new method suggested by Koga et al. [10, 11]. Comparison of the results have showed that the Arrhenius parameters values estimated by the use of both methods are very close. The calculated activation energies were in air: 96 kJ mol –1 (R 1.575, stage I); 101 kJ mol –1 ( Ain1.725 stage II); 185 kJ mol –1 ( A
2.9, stage III) and in argon: 66 kJ mol –1 ( A
1.25, stage I); 87 kJ mol –1 ( A
1.825, stage II); 133 kJ mol –1 ( A
2.525, stage III). 相似文献
9.
The leaching of V(V) from soil by two phosphate reagents, viz. (NH 4) 2HPO 4 and Na 3PO 4 has been studied. (NH 4) 2HPO 4 (1 M) and Na 3PO 4 (0.01 M) were efficient enough to extract all V(V) species from samples. The results were compared with that extracted by Na 2CO 3. Statistical evaluations show that the proposed method is similar to the established method utilizing Na 2CO 3.The method was applied in the analysis of soil samples from contaminated area of the vanadium mine where many grazing cattle died.Validation of the method was also done by comparing the sum of V(IV) and V(V) and the total vanadium obtained from the samples by an independent method. It was found that the sum of V(V) and V(IV) is in good agreement with the total content of vanadium in all samples after HF-H 2SO 4-HClO 4 digestion. From the results of the investigation, it follows that the use of phosphate fertilizers in V(V)-rich soil may enhance the mobility and availability of V(V) to plants. The plants, in turn, are consumed by animals that may die depending on the level of poisoning. 相似文献
10.
Fe 2O(SO 4) 2 is a secondary product of the decomposition of FeSO 4⋅H 2O. Part I of this study presents results on the synthesis of Fe 2O(SO 4) 2 in gaseous environment containing either low or high concentration of oxygen. In this paper the existence of differences
between the structures of Fe 2O(SO 4) 2 and Fe 2(SO 4) 3 is proved on the basis of a detailed thermal study of Fe 2O(SO 4) 2 upon dynamic heating (differential thermal analysis) and upon isothermal heating (thermal-analytic balance) in various gaseous
environments as well as by presenting kinetic data on the processes of decomposition of both compounds.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
The synthesis and thermal decomposition of Na 2(SO 4) 2·2H 2O in both air and nitrogen are described. The synthesis was performed by two different procedures, but in both cases the same product was obtained, corresponding to the general formula given above. The crystals obtained were investigated by methods of X-ray powder diffraction, and chemical and thermal analysis. The differences in thermal decomposition in air and nitrogen are discussed. 相似文献
12.
Ce(SO 4) 2‐mediated nitration of N, N‐dialkylanilines with NaNO 2 using water as the solvent has been achieved in good to excellent yields. The nitrating reaction proceeded smoothly at ambient temperature. 相似文献
13.
A simple and efficient synthesis of 3,4-dihydropyrimidinones or thiones is described, using silica-supported ceric sulfate [Ce(SO 4) 2-SiO 2] as a heterogeneous catalyst from an aldehyde, 1,3-dicarbonyl compound, and urea or thiourea at 110 °C under solvent-free conditions. Compared with the classical Biginelli reaction, this new method consistently has better yields, short reaction time, easy separation, and tolerance toward various functional groups. 相似文献
14.
The thermal decomposition of tribochemically activated Al 2(SO 4) 3· xH 2O was studied by TG, DTA and EMF methods. For some of the intermediate solids, X-ray diffraction and IR-spectroscopy were applied to learn more about the reaction mechanism. Thermal and EMF studies confirmed that, even after mechanical activation of Al 2(SO 4) 3· xH 2O, Al 2O(SO 4) 2 is formed as an intermediate. Isothermal kinetic experiments demonstrated that the thermochemical sulphurization of inactivated Al 2(SO 4) 3· xH 2O has an activation energy of 102.2 kJ·mol ?1 in the temperature range 850–890 K. The activation energy for activated Al 2(SO 4) 3· xH 2O in the range 850–890 K is 55.0 kJ·mol ?1. The time of thermal decomposition is almost halved when Al 2(SO 4) 3· xH 2O is activated mechanically. The results permit conclusions concerning the efficiency of the tribochemical activation of Al 2(SO 4) 3· xH 2O and the chemical and kinetic mechanisms of the desulphurization process. 相似文献
15.
The data on the thermal decomposition of FeSO4?H2O upon various regimes of heating and gaseous environment prove the formation of intermediate products of the types Fe2O(SO4)2 and FeOHSO4, their stability and amount being determined mainly by temperature and oxygen-reduction potential. This communication aims at presenting results on the synthesis and characterization of Fe2O(SO4)2. The synthesis was carried out using a laboratory thermal equipment operating under isothermal conditions in the temperature range 713–813 K in a gaseous environment either poor in oxygen or containing 100% oxygen. The experimental conditions under which Fe2O(SO4)2 is stable are established. The effect of three basic parameters on the synthesis of Fe2O(SO4)2 is clarified: the oxygen partial pressure, the ratio PH2O/PO2 and the temperature and the mode of heating. Mössbauer spectroscopy and X-ray diffraction data for Fe2O(SO4)2 are presented. 相似文献
16.
KAl(SO 4) 2·12H 2O was found to catalyze efficiently a one-pot three-component cyclocondensation of isatoic anhydride and primary amines or ammonia sources such as (NH 4) 2CO 3, NH 4OAc and NH 4Cl with aromatic aldehydes under mild conditions to afford the corresponding mono- and disubstituted 2,3-dihydroquinazolin-4(1 H)-ones in good yields. 相似文献
17.
The crystal structure of the new phase Cu 7(OH) 6(TeO 3) 2(SO 4) 2 [ a=7.389 (1), b=7.638 (1), c=7.662 (2) Å, =75.17 (1), =75.90 (1), =84.19 (1)°; Z=1] was determined by direct methods and Fourier summations from X-ray intensities, and was refined in space group P
-C
i
1
to R=0.039. As usual, the Cu(II) atoms are coordinated to four O atoms forming approximately a square with average Cu-O=1.96 (3) Å; one or two more distant O neighbours complete the coordination. The shape of the TeO 3 group is a rather clear-cut trigonal pyramid. A disorder was found for the SO 4 tetrahedra. The compound was synthesized under hydrothermal conditions [500 (10) K, saturation vapour pressure]. Herrn Prof. Dr.K. Komarek zum 60. Geburtstag gewidmet. 相似文献
19.
Osmotic coefficients of water have been measured isopiestically for the entire region of homogeneous ternary solutions for the Rb 2SO 4- (NH 4) 2SO 4-H 2O system at 25°C. One might expect that water isoactivity lines should be straight since this system involves a continuous series of solid solutions. The related systems (K 2SO 4-Rb 2SO 4-H 2O and (K 2SO 4- (NH 4) 2 SO 4-H 2O) obey the linearity of water isoactivity lines rule. Contrary to expectations, the (Rb 2SO 4-(NH 4) 2-SO 4-H 2O appears to be the first water–salt system containing continuous solid solutions in which the mentioned rule is not obeyed. 相似文献
20.
Raman and FTIR spectra of guanidinium zinc sulphate [C(NH 2) 3] 2Zn(SO 4) 2 are recorded and the spectral bands assignment is carried out in terms of the fundamental modes of vibration of the guanidinium cations and sulphate anions. The analysis of the spectrum reveals distorted SO 42− tetrahedra with distinct S–O bonds. The distortion of the sulphate tetrahedra is attributed to Zn–O–S–O–Zn bridging in the structure as well as hydrogen bonding. The CN 3 group is planar which is expressed in the twofold symmetry along the C–N (1) vector. Spectral studies also reveal the presence of hydrogen bonds in the sample. The vibrational frequencies of [C(NH 2) 3] 2 and HC(NH 2) 3 are computed using Gaussian 03 with HF/6-31G* as basis set. 相似文献
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