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1.
The decomposition of Li 2S 2O 6·2 H 2O, Na 2S 2O 6·2 H 2O, and MgS 2O 6·7 H 2O has been studied using TG and DTG. Both sodium and lithium dithionates dehydrate in one step. Magnesium dithionate dehydrates in three separate steps. All three of the dithionates undergo further decomposition and lose sulfur dioxide to give stable sulfates. Kinetic parameters are presented for these reactions. 相似文献
2.
Hydrated strontium borate, SrB 4O 7·3H 2O, has been synthesized and characterized by XRD, FT-IR, DTA-TG and chemical analysis. The molar enthalpy of solution of SrB 4O 7·3H 2O in 1 mol dm −3 HCl(aq) was measured to be (21.15 ± 0.29) kJ mol −1. With incorporation of the previously determined enthalpies of solution of Sr(OH) 2·8H 2O(s) in [HCl(aq) + H 3BO 3(aq)] and H 3BO 3 in HCl(aq), and the enthalpies of formation of H 2O(l), Sr(OH) 2·8H 2O(s) and H 3BO 3(s), the enthalpy of formation of SrB 4O 7·3H 2O was found to be −(4286.7 ± 3.3) kJ mol −1. 相似文献
3.
The linear attenuation coefficients in aqueous solutions of some chlorides and sulphates, viz. MgCl 2·6H 2O, CaCl 2, SrCl 2·6H 2O, BaCl 2·2H 2O, Na 2SO 4, K 2SO 4 and MgSO 4·7H 2O were determined at 81, 356, 511, 662, 1173 and 1332 keV by the γ-ray transmission method in a good geometry setup. From the precision measured densities of these solutions, mass attenuation coefficients were then obtained which varied systematically with the corresponding changes in the concentrations (g/cm 3) of these solutions. A comparison between experimental and theoretical values of attenuation coefficients has shown that the study has potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form. 相似文献
4.
By using the “ simultaneous Q-DTA, Q-TG measuring technique” elaborated recently, conditions near to the requirements of thermodynamics can be created, thus the “normalized” course of curves taken by this method, their characteristic temperatures or the values measured for the enthalpy change can be considered to be near to the theoretical values. For testing this new method, CuSO4·5H2O, MnSO4·5H2O, Mg(NO3)2·6H2O and Na2SO4·10H2O have been investigated. These model substances can be prepared in stoichiometric composition free of impurities, their decomposition mechanism is well-known, thus the effect of the altered experimental conditions by the simultaneous Q-DTA, Q-TG method on the course of their dehydration can be calculated. 相似文献
5.
The FT infrared spectrum in the 4000–400 cm −1 range of SO 3 vapors, matrix isolated in argon and in water doped argon solid layers, is reported. Vibrational bands are assigned to pure SO 3 monomeric and polymeric species and to SO 3H 2O complexes, on the basis of theoretical B3LYP and MP2 calculations employing the aug-cc-pVTZ basis sets. The spectroscopic evidence suggests that in addition to the monomer, both the dimeric and the cyclic trimeric (SO 3) n complexes are the only other SO 3 forms present in the matrix. The spectra also indicate the presence of the 1:1 and the 1:2 SO 3·H 2O complexes as well as traces of H 2S 2O 7 and water complexed H 2SO 4, but no evidence for a stable 2:1 SO 3H 2O complex was found. The occurrence of the various species is discussed in the light of their calculated energies. 相似文献
6.
In order to utilize the brine resources in China, the solid-liquid equilibria in quaternary system Li +, K +//SO 42-, B 4O 72--H 2O at 288 K was studied by the isothermal solution equilibrium method. Solubilities and densities of solutions were determined experimentally. According to the experimental data, the equilibrium phase diagrams, density-composition diagram and corresponding water content diagram of the quaternary system were plotted. Double salt KLiSO 4 was found in the reciprocal quaternary system Li +, K +//SO 42-, B 4O 72--H 2O at 288 K. The quaternary system has three invariant points, seven univariant curves and five fields of crystallization. The five crystallization regions correspond to Li 2B 4O 7·3H 2O, Li 2SO 4·H 2O, K 2B 4O 7·4H 2O, K 2SO 4 and KLiSO 4, respectively. The crystallization field of salt Li 2B 4O 7·3H 2O is the largest, whereas that of Li 2SO 4·H 2O is the smallest. The experimental results show that Li 2SO 4·H 2O has a strong salting-out effect on other salts. 相似文献
7.
Different from the traditional pyrometallurgical recovery process of Li and Co from spent lithium-ion batteries, a new recovery method for Li and Co was established by converting LiCoO 2 into water-soluble metal sulfates by roasting a mixture of LiCoO 2 and NaHSO 4·H 2O. The evolution law of the mixture with increased roasting temperature was investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), in situ X-ray diffraction(XRD), XRD, and X-ray photoelectron spectroscopy(XPS). The results show that the phase transition of LiCoO 2 mixed with NaHSO 4·H 2O with increased temperature proceeded as follows:LiCoO 2, NaHSO 4·H 2O→LiCoO 2, NaHSO 4→Li 1-xCoO 2, LiNaSO 4, Na 2S 2O 7, Na 2SO 4→Li 1-xCoO 2, Co 3O 4, LiNaSO 4, Na 2SO 4→Co 3O 4, LiNaSO 4. The reaction mechanism of this roasting process may be as follows:LiCoO 2+NaHSO 4·H 2O→1/2Li 2SO 4+ 1/2Na 2SO 4+1/3Co 3O 4+1/12O 2+3/2H 2O, Li 2SO 4+Na 2SO 4=2LiNaSO 4. 相似文献
8.
This work presents chemical modeling of solubilities of metal sulfates in aqueous solutions of sulfuric acid at high temperatures. Calculations were compared with experimental solubility measurements of hematite (Fe 2O 3) in aqueous ternary and quaternary systems of H 2SO 4, MgSO 4 and Al 2(SO 4) 3 at high temperatures. A hybrid model of ion-association and electrolyte non-random two liquid (ENRTL) theory was employed to fit solubility data in three ternary systems H 2SO 4–MgSO 4–H 2O, H 2SO 4–Al 2(SO 4) 3–H 2O at 235–270 °C and H 2SO 4–Fe 2(SO 4) 3–H 2O at 150–270 °C. Employing the Aspen Plus™ property program, the electrolyte NRTL local composition model was used for calculating activity coefficients of the ions Al 3+, Mg 2+ Fe 3+ and SO 42−, HSO 4−, OH −, H 3O +, respectively, as well as molecular species. The solid phases were hydronium alunite (H 3O)Al 3(SO 4) 2(OH) 6, hematite Fe 2O 3 and magnesium sulfate monohydrate (MgSO 4)·H 2O which were employed as constraint precipitation solids in calculating the metal sulfate solubilities. A correlation for the equilibrium constants of the association reactions of complex species versus temperature was implemented. Based on the maximum-likelihood principle, the binary interaction energy parameters for the ionic species as well as the coefficients for equilibrium constants of the reactions were obtained simultaneously using the solubility data of the ternary systems. Following that, the solubilities of metal sulfates in the quaternary systems H 2SO 4–Fe 2(SO 4) 3–MgSO 4–H 2O, H 2SO 4–Fe 2(SO 4) 3–Al 2(SO 4) 3–H 2O at 250 °C and H 2SO 4–Al 2(SO 4) 3–MgSO 4–H 2O at 230–270 °C were predicted. The calculated results were in excellent agreement with the experimental data. 相似文献
9.
A new family of heteropolytungstate complexes (NH 4) 21[Ln(H 2O) 5{Ni(H 2O)} 2As 4W 40O 140]· xH 2O(Ln=Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na 27[NaAs 4W 40O 140]·60H 2O with NiCl 2·6H 2O and Ln(NO 3) 3· xH 2O at pH≈4.5. The crystal structures of (NH 4) 21[Gd(H 2O) 5{Ni(H 2O)} 2As 4W 40O 140]·51H 2O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P2 1/ n with a=19.754(3), b=24.298(4), c=39.350(6) Å, β=100.612(3)°, V=18564(5) Å 3, Z=2, R1( wR2)=0.0544(0.0691). The central site S1 and two opposite sites S2 of the big cyclic ligand [As 4W 40O 140] 28− are occupied by one Ln 3+and two Ni 2+, respectively, each site supply four O d coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni 2+and Ln 3+. Polyanion [Ln(H 2O) 5{Ni(H 2O)} 2As 4W 40O 140] 21− has C2v symmetry. IR and UV–vis spectra of [NaAs 4W 40O 140] 27− of the title compounds are discussed. 相似文献
10.
We report the crystal and molecular structures of the complex of 18-C-6 with H 3O +BF 4− (I) and the complex of 18-C-6 with BF 3OH 2·H 2O (II). The different modes of appearance of the “BF 3” species as BF 3, BF 3OH 2, BF 3OH 2·H 2O and BF 4−, as well as their structurally significant intermolecular and intramolecular interactions, are discussed. In complex I the oxonium ion is bound at the centre of the 18-C-6 macrocycle. The oxonium oxygen is located practically equidistant (2.68–2.73 Å) from the six macrocyclic ethereal oxygens. The BF 4− counter-ion is positioned 7.3 Å away from the oxonium ion in the same general plane of the crown ether. This anion is not involved in any direct intermolecular contacts, a fact that may explain why it is spherically disordered. In complex II there is no guest molecule (or ion) present in the “cavity” of the macrocycle, but there are two hydrogen-bonded systems of BF 3OH 2·H 2O that are interacting with the crown ether on either side of the general macrocyclic plane. Complex II features three types of hydrogen bonds—the O(water)-HO(crown) bonds (2.83 and 2.85 Å), the O(water)H-O(BF 3) bond (2.49 Å) and the O(BF 3)-HO(crown) bond (2.65 Å). The strong intermolecular O(crown)O(water)O(BF 3) and O(crown)O(BF 3) interactions stabilize the normally unstable BF 3OH 2·H 2O species. 相似文献
11.
Potassium cobalt hexacyanoferrate(II), K 2CoFe(CN) 6 · 1.4H 2O, loses its water when heated up to 170°C, and the anhydrous compound begins to decompose above 230°C. The cyanide groups are evaporated off in the temperature range 230–350°C, and the solid products thus formed are K 2CO 3, Fe 2O 3, Co 3O 4 and CoFe 2O 4. In the range 550–900°C, the cobalt-containing compounds become CoO, and K 2CO 3 probably partly decomposes to K 2O, so that the product mixture at 900°C is K 2CO 3/K 2O, Fe 2O 3 and CoO. Above this temperature, K 2CO 3 decomposes to K 2O. 相似文献
12.
Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA ( N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C 5H 6N 2O 2)(C 4H 5NO 4) 2−(H 2O) 2]·H 2O, [Ni(C 5H 6N 2O 2)(C 5H 7NO 4) 2−(H 2O) 2]·H 2O and [Ni(C 5H 6N 2O 2)(C 6H 8N 2O 5) 2−(H 2O) 2]·1.5H 2O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy ( E*), enthalpy (Δ H*), entropy (Δ S*) and free energy change of decomposition (Δ G*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate. 相似文献
13.
A series of chromium(III) complexes [Cr(bipy)(HC 2O 4) 2]Cl·3H 2O (1), [Cr(phen)(HC 2O 4) 2]Cl·3H 2O (2), [Cr(phen) 2(C 2O 4)]ClO 4 (3), [Cr 2(bipy) 4(C 2O 4)](SO 4)·(bipy) 0.5·H 2O (4) and [Mn(phen) 2(H 2O) 2] 2[Cr(phen)(C 2O 4) 2] 3ClO 4·14H 2O (5) were synthesized (bipy=4,4′-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3–5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1–3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed. 相似文献
14.
The compounds K 4Ti(O 2) 4·2H 2O, K 3Ta(O 2) 2F 4 and K 2V 2O 3(O 2) 2F 2 undergo photolysis in the solid state. The photolysis kinetics obey the parabolic rate equation p = kt1/2 and indicate a monoexcitation process for the photolysis. These features are similar to those reported previously for peroxo complexes. The mechanism of evolution of oxygen reported earlier appears to be the same in all these solids. 相似文献
15.
Phase behavior of the extraction system, Cyanex 923–heptane/H 2SO 4–H 2O has been studied. The third phase appeared at different aqueous H 2SO 4 concentration with varying initial Cyanex 923 concentration and temperature affects its appearance. Almost all of H 2SO 4 and H 2O are extracted into the middle phase. The H 2SO 4 concentration in the third phase increases with the increasing aqueous acid concentration ( CH2SO4,b) while the water content first increases and then reaches a constant value at CH2SO4,b=11.3 mol l −1. In the region of CH2SO4,b higher than 5.2 mol l −1, the composition of the middle phase is only related to the equilibrium concentration of H 2SO 4 in the bottom phase. H 2SO 4 and H 2O are transferred into the middle phase mainly by their coordination with Cyanex 923 when CH2SO4,b is less than 11.3 mol l −1. When CH2SO4,b is higher than 11.3 mol l −1, excess H 2SO 4 is solubilized into the polar layer of the aggregates. In the region considered, the extracted complex changes from C923 · H 2SO 4 to C923 · H 2SO 4 · H 2O and then to C923 · (H 2SO 4) 2 · H 2O. 相似文献
16.
Thermal decomposition taking place in solid state complex, NiC 2O 4·2H 2O, has been investigated in air by means of TG–DTG/DTA, DSC, XRD. TG–DTG/DTA curves showed that the decomposition proceeds through two well-defined steps with DTA peaks closely corresponding to the weight loss obtained. XRD showed that the final decomposition product of NiC 2O 4·2H 2O was NiO. Kinetics analysis of NiC 2O 4·2H 2O decomposition steps was performed under non-isothermal conditions. The activation energies were calculated through Friedman and Flynn–Wall–Ozawa (FWO) methods, and the most possible kinetic model function has been estimated through the multiple-linear regression method. The activation energies for the two decomposition steps of NiC 2O 4·2H 2O were 171.1 ± 4.2 and 174.4 ± 8.1 kJ/mol, respectively. 相似文献
17.
In this paper, we summarise our recent research interest in the hydrothermal synthesis and structural characterisation of multi-dimensional coordination polymers. The use of N-(phosphonomethyl)iminodiacetic acid (also referred to as H 4pmida) in the literature as a versatile chelating organic ligand is briefly reviewed. This molecule plays an important role in the formation of centrosymmetric dimeric [V 2O 2(pmida) 2] 4− anionic units, which were first used by us as building blocks to construct novel coordination polymers. Starting with [V 2O 2(pmida) 2] 4− in solution, we have isolated [M 2V 2O 2(pmida) 2(H 2O) 10] species (where M 2+ = Mn 2+, Co 2+ or Cd 2+) via the hydrothermal synthetic approach, which were then employed for the construction of [CdVO(pmida)(4,4′-bpy)(H 2O) 2]·(4,4′-bpy) 0.5·(H 2O), [CoVO(pmida)(4,4′-bpy)(H 2O) 2]·(4,4′-bpy) 0.5, [Co(H 2O) 6][CoV 2O 2(pmida) 2(pyr)(H 2O) 2]·2(H 2O) and [Cd 2V 2O 2(pmida) 2(pyr) 2(H 2O) 4]·4(H 2O) by the inclusion of bridging organic ligands in the reactive mixtures, such as pyrazine (pyr) and 4,4′-bipyridine (4,4′-bpy). These materials can contain channel systems, and exhibit magnetic behaviour, not only due to the V 4+ centres but also to the transition metal centres which establish the links between neighbouring dimeric [V 2O 2(pmida) 2] 4− anionic units. A closely related anionic moiety, [Ge 2(pmida) 2(OH) 2] 2−, was engineered to allow the study of such crystalline hybrid materials using one- and two-dimensional high-resolution solid-state NMR. 相似文献
18.
The effects of calcination temperature and doping with K 2O on solid–solid interactions and physicochemical properties of NiO/Fe 2O 3 system were investigated using TG, DTA and XRD techniques. The amounts of potassium, expressed as mol% K 2O were 0.62, 1.23, 2.44 and 4.26. The pure and variously doped mixed solids were thermally treated at 300, 500, 750, 900 and 1000 °C. The catalytic activity was determined for each solid in H 2O 2 decomposition reaction at 30–50 °C. The results obtained showed that the doping process much affected the degree of crystallinity of both NiO and Fe 2O 3 phases detected for all solids calcined at 300 and 500 °C. Fe 2O 3 interacted readily with NiO at temperature starting from 700 °C producing crystalline NiFe 2O 4 phase. The degree of reaction propagation increased with increasing calcination temperature. The completion of this reaction required a prolonged heating at temperature >900 °C. K 2O-doping stimulates the ferrite formation to an extent proportional to its amount added. The stimulation effect of potassium was evidenced by following up the change in the peak height of certain diffraction lines characteristic NiO, Fe 2O 3, NiFe 2O 4 phases located at “d” spacing 2.08, 2.69 and 2.95 Å, respectively. The change of peak height of the diffraction lines at 2.95 Å as a function of firing temperature of pure and doped mixed solids enabled the calculation of the activation energy (Δ E) of the ferrite formation. The computed Δ E values were 120, 80, 49, 36 and 25 kJ mol −1 for pure and variously doped solids, respectively. The decrease in Δ E value of NiFe 2O 4 formation as a function of dopant added was not only attributed to an effective increase in the mobility of reacting cations but also to the formation of potassium ferrite. The calcination temperature and doping with K 2O much affected the catalytic activity of the system under investigation. 相似文献
19.
TiO 2 nanoparticles and H 2Ti 2O 5·H 2O, Na 2Ti 2O 4(OH) 2 nanotubes were synthesized by solvothermal method and their applications in the degradation of active Brilliant-blue (KN-R) solution were investigated. The experimental results revealed that the synthesized TiO 2 nanoparticles had a good crystallinity and a narrow size distribution (about 4–5 nm); the obtained H 2Ti 2O 5·H 2O, Na 2Ti 2O 4(OH) 2 were tubelike products with an average diameter of 20–30 and 200–300 nm length. The three catalysts we synthesized had some hydroxyl groups and the maximum absorption boundaries of the samples were all red-shifted, which indicated the samples had a promising prospect in photocatalysis. The results of the photocatalytic experiments indicated that the photocatalytic activity of the samples was: TiO2 > H2Ti2O5·H2O > Na2Ti2O4(OH)2, which was in good accordance with the fact of FTIR and UV–vis absorption spectra. The formation mechanism of these nanostructures was also discussed. 相似文献
20.
二苯并型环状碘鎓盐(结构通式如1)是一类人工合成的化合物,近30年的研究表明,某些二苯并型环状碘鎓盐具有抑菌、降血压,抗辐射及抗心律失常 [1-4]等生理活性. 相似文献
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