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1.
The effect of temperature on the sorption behavior of a synthesized gel structurally close to the fluorine mica mineral, sodium
potassium fluorophologopite, was studied for the heavy metal ions Cd 2+, Hg 2+, and Pb 2+. The synthesized gel was characterized by X-ray powder pattern, energy dispersive spectrometry, infrared spectroscopy, and
thermogravimetric analysis and was found to have the composition Na 0.5K 0.5Mg(AlSi 3O 10)F 2·6H 2O. The effect of temperature on sorption was studied with respect to varying concentrations of metal ions. The overall sorption
capacity of the synthesized gel was found to depend on the number of ion active groups per unit weight of the material. The
data were expressed in terms of distribution coefficients ( K
d). Sorption data followed Freundlich adsorption isotherms. Studies showed that sorption decreased as the concentration of
metal ions increased and increased as the temperature grew, which was evidence that the process was endothermic.
The text was submitted by the authors in English. 相似文献
2.
By precipitation with ammonia of ethanolic solutions containing the appropriate proportions of gallium and aluminium nitrate, following by calcination of the resulting gels at 773 K, mixed Ga 2O 3/Al 2O 3 oxides having Ga:Al ratios of 9:1, 4:1, 1:1, 1:4 and 1:9 were obtained. Powder X‐ray diffraction showed that these mixed metal oxides form a series of solid solutions having the spinel‐type structure; also shown by γ‐Al 2O 3 and γ‐Ga 2O 3. The specific surface area (determined by nitrogen adsorption at 77 K) was found to range from 160 m 2 g ?1 for the mixed oxide having Ga:Al = 9:1 up to 370 m 2 g ?1 for that having Ga:Al = 1:9. High resolution MAS NMR showed that Ga 3+ and Al 3+ ions occur at both tetrahedral and octahedral sites in the spinel‐type structure of the mixed metal oxides, although there is a preferential occupation of tetrahedral sites by Ga 3+ ions. A proportion of penta‐coordinated Al 3+ ions was also found. IR spectra of carbon monoxide adsorbed at 77 K showed that the mixed metal oxides have a considerable Lewis acidity, related mainly to tetrahedrally coordinated metal ions exposed at crystal surfaces. The characteristic infrared absorption band of coordinated (adsorbed) CO appears in the range 2205–2190 cm ?1, and its peak wavenumber is nearly independent of Ga:Al ratio in the mixed gallia‐alumina oxides. 相似文献
3.
A new quinoline-based chemosensor 1 has been designed and synthesised. Its metal ion-binding properties have been documented in organic and aqueous organic solvents. While chemosensor 1 recognises Hg 2+ ions ( K a = 2.15 × 10 4 M ? 1) by exhibiting ratiometric change in emission in CHCl 3/CH 3OH (1:1, v/v), under similar condition both Zn 2+ and Cd 2+ ions are sensed by significant non-ratiometric increase in emission with measurable red shift. In DMSO/H 2O (5:95, v/v), the sensor 1 exhibits a greater selectivity towards Hg 2+ ions ( K a = 9.20 × 10 3 M ? 1) over the other metal ions examined. 相似文献
4.
A series of heterometallic 3d–Gd 3+ complexes based on a lanthanide metalloligand, [M(H 2O) 6][Gd(oda) 3] ? 3 H 2O [M=Cr 3+ ( 1‐Cr )] (H 2oda=2,2′‐oxydiacetic acid), [M(H 2O) 6][MGd(oda) 3] 2 ? 3 H 2O [M=Mn 2+ ( 2‐Mn ), Fe 2+ ( 2‐Fe ) and Co 2+ ( 2‐Co )], and [M 3Gd 2(oda) 6(H 2O) 6] ? 12 H 2O [M=Ni 2+ ( 3‐Ni ), Cu 2+ ( 3‐Cu ), and Zn 2+ ( 3‐Zn )], are reported. Magnetic and heat‐capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of ?Δ Sm between complexes 2‐Co and 1‐Cr . In these two complexes, the 3d metal ions have the same spin ( S=3/2 for Co 2+ and Cr 3+ ions), and the theoretical calculation suggested a larger ?Δ Sm value for 2‐Co (47.8 J K ?1 kg ?1) than 1‐Cr (37.5 J K ?1 kg ?1); however, the significant anisotropy of Co 2+ ions in 2‐Co , which can result in smaller effective spins, gives a smaller value of ?Δ Sm for 2‐Co (32.2 J K ?1 kg ?1) than for 1‐Cr (35.4 J K ?1 kg ?1) at Δ H=9 T. 相似文献
5.
Reduction of Cd 2+ at the dropping mercury electrode in solutions of 1, 3, 5-trihydroxybenzene was carried out in nonbuffer solutions of 0.1 M NaClO 4. The polarogram consists of two waves, the first wave can be taken in quantitative determination of Cd 2+ in solutions containing 3.5 mM 1, 3, 5-trihydroxybenzene in 0.1 M NaClO 4. Mn 2+ produces single well-defined diffusion controlled irreversible wave whose half-wave potential shifts to a more negative value with increasing 1, 3, 5-trihydroxybenzene. Me(II) forms two weak complexes, MX 1 and MX 2 at 25°. The behaviour of this metal ions is summarized. 相似文献
6.
In this work, a hydrophilic task-specific ionic liquid (TSIL) of 1-chloroethyl-3-methylimidazolium chloride functionalized with 8-hydroxyquinoline was used in a dispersive liquid–liquid microextraction method followed by flame atomic absorption spectrometry for the enrichment and determination of trace amounts of cadmium (Cd 2+) ions. The simultaneous chelation and extraction of Cd 2+ ions was carried out by the TSIL. Fine droplets of the water-immiscible TSIL containing target analyte were generated in situ by addition of an anion exchanger potassium hexafluorophosphate (KPF 6) salt to the sample tube. After phase separation by centrifugation for 4 min, the sedimented TSIL was diluted with acidified ethanol for measurement of Cd 2+ content. Some significant parameters influence the preconcentration of Cd 2+ ions such as sample pH, TSIL volume, amount of KPF 6, non-ionic surfactant and salt concentration were investigated. Under the optimal conditions, calibration curve was linear in the range of 5–250 µg L ?1 Cd 2+ with correlation coefficient of 0.9975 and a detection limit of 0.55 µg L ?1. The relative standard deviation for six replicate measurements of 50 µg L ?1 Cd 2+ was 1.5%. The method was successfully applied for the extraction and determination of Cd 2+ ions in water and food samples. 相似文献
7.
Quinoline-based fluorescent probe as a recognition unit was designed and synthesized in this study. The probe R1 displayed excellent selectivity and sensitivity for cadmium ions (Cd 2+) over a wide range of metal ions in acetonitrile-water (MeCN-H 2O) mixed solution. In order to better understand the recognition mechanism between probe and Cd 2+, the density functional theory calculations were performed. Finally, the colorimetric experiment result was observed and conveniently monitored by the naked eye, and a visual detection limit of 4 × 10 ?6 mol L ?1 was achieved. These experimental results indicated the promising potential of the probe to detect Cd 2+ in biological system. Furthermore, the probe R1 was successfully used for the highly sensitive detection of Cd 2+ in living cells. 相似文献
8.
Complexation processes that occur between cadmium(II) hexacyanoferrate(II) (Cd 2[Fe(CN) 6]) and 3 d-metal ions M(II) (M = Mn, Co, Ni, Cu, Zn) in thin gelatin layers with the immobilized cadmium(II) hexacyanoferrates when brought in contact with aqueous solutions of d-metal chlorides are studied. Cd 2+ ions were found to be replaced to some extent by M 2+ ions of the indicated d metals (except for Mn(II)) and form binuclear ( dd)-metal hexacyanoferrates(II). A complete replacement of Cd(II) and formation of M 2[Fe(CN) 6] was observed in none of the cases. 相似文献
9.
Ab initio calculations at the MP2 and CCSD(T) levels of theory have disclosed the conceivable existence of fluorine‐coordinated complexes of HHeF with alkali‐metal ions and molecules M + (M +=Li +–Cs +), M +–OH 2, M +–NH 3 (M +=Li +, Na +), and MX (M=Li, Na; X=F, Cl, Br). All these ligands L induce a shortening of the H? He distance and a lengthening of the He? F distance accompanied by consistent blue‐ and redshifts, respectively, of the H? He and He? F stretching modes. These structural effects are qualitatively similar to those predicted for other investigated complexes of the noble gas hydrides HNgY, but are quantitatively more pronounced. For example, the blueshifts of the H? He stretching mode are exceptionally large, ranging between around 750 and 1000 cm ?1. The interactions of HHeF with the ligands investigated herein also enhance the (HHe) +F ? dipole character and produce large complexation energies of around 20–60 kcal mol ?1. Most of the HHeF–L complexes are indeed so stable that the three‐body dissociation of HHeF into H+He+F, exothermic by around 25–30 kcal mol ?1, becomes endothermic. This effect is, however, accompanied by a strong decrease in the H? He? F bending barrier. The complexation energies, Δ E, and the bending barriers, E*, are, in particular, related by the inverse relationship E*(kcal mol ?1)=6.9exp[?0.041Δ E(kcal mol ?1)]. Therefore the HHeF? L complexes, which are definitely stable with respect to H+He+F+L (Δ E≈25–30 kcal mol ?1), are predicted to have bending barriers of only 0.5–2 kcal mol ?1. Overall, our calculations cast doubt on the conceivable stabilization of HHeF by complexation. 相似文献
10.
A dinitrophenyl hydrazone colorimetric anion sensor (receptor 1 ) was synthesized and its recognition properties towards various anions were investigated by naked eye observation and spectroscopic methods, namely UV‐vis and 1H NMR titrations in DMSO. The addition of AcO ?, F ? and H 2PO 4? to receptor 1 resulted in marked red shift of the charge‐transfer absorbance band (Δ λ=91 nm, 407 nm to 498 nm) concomitant with a 'naked‐eye' detectable colour change from yellow to pink. However, both the colour and spectral changes were reversible by the addition of cations (M II) of 3d 5‐10 as well as Cd II, Hg II, Mg II and Ca II. Subsequently, complementary IMP/INH logic functions based on colour and spectral switching (ON/OFF) were affirmed. The sensor can, thus be utilized as a colorimetric molecular switch modulated by F ?/M II. 相似文献
11.
During an investigation of the insufficiently known system M1O– M2O– X2O 5–H 2O ( M1 = Cd 2+, Sr 2+ and Ba 2+; M2 = Cu 2+, Ni 2+, Co 2+, Zn 2+ and Mg 2+; X = P 5+, As 5+ and V 5+), single crystals of the novel compound dicadmium copper(II) bis[phosphate(V)], Cd 2Cu(PO 4) 2, were obtained. This compound belongs to a small group of compounds adopting a Cu 3(PO 4) 2‐type structure and having the general formula M1 2M2( XO 4) 2 ( M1/ M2 = Cd 2+, Cu 2+, Mg 2+ and Zn 2+; X = As 5+, P 5+ and V 5+). The crystal structure is characterized by the interconnection of infinite [Cu(PO 4) 2] n chains and [Cd 2O 10] n double chains, both extending along the a axis. Exceptional characteristics of this structure are its novel chemical composition and the occurrence of double chains of CdO 6 polyhedra that were not found in related structures. In contrast to the isomorphous compounds, where the M1 cations are coordinated by five O atoms, the Cd atom is coordinated by six. The dissimilarity in the geometry of M1 coordination between Cd 2Cu(PO 4) 2 and the isomorphous compounds is mostly due to the larger ionic radius of the Cd cation in comparison with the Cu, Mg and Zn cations. Sharing a common edge, two CdO 6 polyhedra form Cd 2O 10 dimers. Each such dimer is bonded to another dimer sharing common vertices, forming [Cd 2O 10] n double chains in the [100] direction. The Cu atoms, located on an inversion centre (site symmetry ), form isolated CuO 4 squares interconnected by PO 4 tetrahedra, forming [Cu(PO 4) 2] n chains similar to those found in related structures. Conversely, the [Cd 2O 10] n double chains, which were not found in related structures, are an exclusive feature of this structure. 相似文献
12.
Stability in Methanol and Thermodynamic Transfer Properties of the Cryptates of some Transition Cations and Heavy Metals The nature and stability of the macrocyclic and macrobicyclic complexes of Ag +, Cd 2+, and Pb 2+ (M n+) with 21, 22, 211, 221 and 222 in anhydrous methanol 0.05M in Et 4N +ClO ?4, at 25° (see Scheme) have been determined by potentiometry and spectrophotometry. Binuclear complexes M 2L 2n+ have been observed in all cases, besides the mononuclear ML n+ complexes. The macrobicyclic 1:1 complexes ML n+ exhibit an important ‘cryptate effect’ with M n+=Ag +, Pb 2+ and Cd 2+, but not with Cu 2+ and Zn 2+; their stability is in all cases maximum with 221. The applicability to our results of the recent extrathermodynamic hypothesis involving ML n+ cryptates is examined. 相似文献
13.
The consecutive reactions of (CH 3) 2Si(OC 2H 5) 2 and CH 3Si(OC 2H 5) 3 with methoxide ions were investigated in methanol solutions. The reverse transesterification reactions with ethoxide ions could be neglected in both cases since the concentration of ethoxide in methanol solution was assumed to be low due to the fast equilibrium reaction C 2H 5O ? + CH 3OH ? C 2H 5OH + CH 3O ?. The progress of the reactions was followed by monitoring the formation of ethanol with a Fourier-transform infrared spectrometer. All rate constants were determined at 295 K. The reactions between the dialkoxydimethylsilanes and methoxide ions were assumed to consist of two consecutive steps that can be represented by the net reaction; (CH 3) 2Si(OC 2H 5) 2 + 2CH 3O ? → (CH 3) 2Si(OCH 3) 2 + 2C 2H 5O ?. The two consecutive rate constants were established as 1.93 ± 0.12M ?1s ?1 and 1.00 ± 0.12M ?1s ?1, respectively. The consecutive rate constants for the reactions between the trialkoxymethylsilanes and methoxide ions can be written according to the total reaction; CH 3Si(OC 2H 5) 3 + 3CH 3O ? → CH 3Si(OCH 3) 3 + 3C 2H 5O ?. The three rate constants corresponding to each consecutive step were established as 1.12 ± 0.09 M ?1s ?1, 0.82 ± 0.10 M ?1s ?1, and 0.51 ± 0.06 M ?1s ?1, respectively. © 1995 John Wiley & Sons, Inc. 相似文献
14.
Trifluoromethylsulfonate (triflate) and bis(trifluoromethylsulfonyl)imide (triflimide) salts, well‐known Lewis acid catalysts, present some difficulty in their characterization. By using nitromethane as the solvent, useful electrospray mass spectra in positive and negative ion mode were obtained for salts of metals in oxidation states +2 and +3. In positive mode, addition of a strong Lewis base (triphenylphosphine oxide, TPPO), capable of displacing a triflate (TfO ?) or a triflimide (Tf 2N ?) anion, is necessary for obtaining useful spectra. Under these conditions of solvent and added ligand, the most abundant ions were [M 2+(A ?)(TPPO) 2] + or [M 3+(A ?) 2(TPPO) 2] + with A ? = TfO ? or Tf 2N ?. The MS/MS spectra of these diagnostic ions provide additional analytical information. The breakdown curves, in the form of % dissociated as a function of the ion activation energy, offer a mean for investigating the bonding in these ions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
15.
In this work, we reported a detailed study on the synthesis, structural and magnetic properties of nanocrystalline La0.8Sr0.2MnO3. The synthesized nanoparticles were prepared using a sol–gel method and characterized using X-ray diffraction and high-resolution transmission electron microscope. The average particle size was found in the range from 40 to 45 nm. The magnetization versus temperature M(T) measurements as well as magnetization field dependence M(H) have been investigated using vibrating-sample magnetometer. The magnetization as a function of temperature M(T) indicated a broad second-order magnetic phase transition from ferromagnetic state to paramagnetic state in the Curie temperature region (320–340 K). The magnetocaloric effect of the sample has been estimated and presented a maximum magnetic entropy change |ΔSM|max?=?0.86 J kg?1 K?1 with relative cooling power?=?62.12 J kg?1 at magnetic field (H)?=?2T. Based on the result of magnetocaloric properties, the investigated sample could be considered as a good refrigerant material for near room temperature magnetic refrigeration. 相似文献
16.
AbstractThe green nitrogen-rich coordination compound Cd(SCZ) 2(AFT) 2 ( 1) (AFT =4-amino-3-(5-tetrazolate)-furazan and SCZ?=?semicarbazide) was first synthesized and characterized by EA and Fourier Transform Infrared (FT-IR). The single crystal was cultivated and determined with X-ray diffraction. It revealed that 1 crystallizes in the monoclinic space group P2 1/c. A Cd 2+ ion is coordinated by four N atoms and two O atoms to form a distorted octahedral structure. Among them, two nitrogen atoms are from the two AFT ions and the other four atoms are from two SCZ molecules. The thermal decomposition behavior of 1 was studied with DSC and TG-DTG methods. The apparent activation energy ( E), thermal stability, and safety parameters ( TSADT, TTIT, and Tb) were calculated for 1. Moreover, entropy of activation (Δ S≠), enthalpy of activation (Δ H≠), free energy of activation (Δ G≠), specific heat capacity ( Cp), and impact sensitivity were also discussed in detail. 相似文献
17.
Doubly charged diatomic ions MAr 2+ where M=Mg, Ca, Sr or Ba have been observed by mass spectrometry with an inductively coupled plasma ion source. Abundance ratios are quite high, 0.1 % for MgAr 2+, 0.4 % for CaAr 2+, 0.2 % for SrAr 2+ and 0.1 % for BaAr 2+ relative to the corresponding doubly charged atomic ions M 2+. It is assumed that these molecular ions are formed through reactions of the doubly charged metal ions with neutral argon atoms within the ion source. Bond dissociation energies ( D0) were calculated and agree well with previously published values. The abundance ratios MAr +/M + and MAr 2+/M 2+ generally follow the predicted bond dissociation energies with the exception of MgAr 2+. Mg 2+ should form the strongest bond with Ar [ D0 (MgAr 2+)=124 to 130 kJ mol ?1] but its relative abundance is similar to that of the weakest bound BaAr 2+ ( D0=34 to 42 kJ mol ?1). The relative abundances of the various MAr 2+ ions are higher than those expected from an argon plasma at T=6000 K, indicating that collisions during ion extraction reduce the abundance of the MAr 2+ ions relative to the composition in the source. The corresponding singly charged MAr + ions are also observed but occur at about three orders of magnitude lower intensity than MAr 2+. 相似文献
18.
Na 2Mn 2(1 − x)Cd 2xFe(PO 4) 3 (0 ≤ x ≤ 1) phosphates were prepared by solid state reaction and characterized by powder X-ray diffraction, magnetic susceptibility and Mössbauer spectroscopy. The X-ray diffraction patterns indicated the formation of a continuous solid solution which crystallizes in the alluaudite structural type characterized by the general formula X(2) X(1) M(1) M(2) 2(PO 4) 3. The cation distribution, deduced from a structure refinement of the x = 0, 0.5 and 1 compositions, is ordered in the X(2) sites and disordered in the remaining X(1), M(1) and M(2) sites. The magnetic susceptibility study revealed an antiferromagnetic behaviour of the studied compounds. The 57Fe Mössbauer spectroscopy confirmed the structural results and proved the exclusive presence of Fe 3+ ions. 相似文献
19.
A new cadmium complex of 1,1-diamino-2,2-dinitroethylene (FOX-7) was synthesized and structurally determined. Central Cd 2+ is coordinated by six nitrogens from four NH 3 molecules and two FOX-7 ? anions to form an octahedral structure. The thermal decomposition of Cd(NH 3) 4(FOX-7) 2 was studied with differential scanning calorimeter and TG–DTG methods. The apparent activation energy and pre-exponential constant of the exothermic process are 220.6 kJ M ?1 and 10 17.86 s ?1, respectively. Cd(NH 3) 4(FOX-7) 2 is sensitive. 相似文献
20.
Rigid N‐(substituted)‐2‐aza‐[3]‐ferrocenophanes L1 and L2 were easily synthesized from 1,1 ‐dicarboxyaldehydeferrocene and the corresponding amines. Ligands L1 and L2 were characterized by 1H NMR, 13C NMR and single‐crystal X‐ray crystallography. The coordination abilities of L1 and L2 with metal ions such as Cu 2+, Mg 2+, Ni 2+, Zn 2+, Pb 2+ and Cd 2+ were evaluated by cyclic voltammetry. The electrochemical shift (Δ E1/2) of 125 mV was observed in the presence of Cu 2+ ion, while no significant shift of the Fc/Fc + couple was observed when Mg 2+, Ni 2+, Zn 2+, Pb 2+, Cd 2+ metal ions were added to the solution of L1 in the mixture of MeOH and H 2O. Moreover, the extent of the anodic shift of redox potentials was approximately equal to that induced by Cu 2+ alone when a mixture of Cu 2+, Mg 2+, Ni 2+, Zn 2+, Pb 2+ and Cd 2+ was added to a solution of L1. Ligand L1 was proved to selectively sense Cu 2+ in the presence of large, excessive first‐row transition and late‐transition metal cations. The coordination model was proposed from the results of controlled experiments and quantum calculations. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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