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1.
Uv and visible absorption spectra and the molar conductance curve of NiBr2 in acetonitrile solution have been determined at 25°C. Equilibrium concentrations and formation constants of the consecutive NiBr+, NiBr02, and NiBr?3, complexes have been calculated from the spectrophotometric results making use of the isosbestic points found in an auxiliary study of three-component solutions with variable Br?:Ni(II) mole ratio. The existence of NiBr+ in the form of the [NiBrL5]+ pseudooctahedral complex, and that of NiBr?3 in the form of the [NiBr3L]? pseudotetrahedral complex is inferred, while the nature of NiBr02 remains unclear. 相似文献
2.
《Electrochimica acta》1985,30(5):603-612
Visible absorption spectra and the molar conductance curve at NiCl2 dissolved in dimethylformamide (DMF) have been determined at 25°C. Absorption spectra of ternary system Ni(ClO4)2 + Et4NCl + DMF and NiCl2 + chlorobenzene + DMF have also been determined at 25°C. It has been found that at lower concentrations of NiCl2 monochloride nickel complex NiCl(DMF)+5 and outer-sphere ion-pair {NiCl(DMF)+5Cl−}0 coexist in the solution. The presence of pseudotetrahedral complex NiCl3DMF− and the existence of coordinative disproportionation equilibrium have been established in the more concentrated solutions of NiCl2. The formation constant of outer-sphere ion-pair equal to (1.33 ± 0.2) × 102 has been derived from the conductometric data. The equilibrium constant of disproportionation reaction equal to (3.89 ± 0.2) × 102 has been determined on the basis of the absorption spectra of NiCl2 in DMF. 相似文献
3.
Visible absorption spectra of the CuCl+ and CuCl02 complexes in dimethyl sulphoxide (DMSO) are derived from an auxiliary study of the Cu(ClO4)2 + Et4NCl mixed solutions of variable chloride concentration. The second step association equilibrium CuCl+ + Cl? ? CuCl02 is then shown, from the visible absorption spectra, to predominate over a broad concentration range in the solutions of CuCl2 in DMSO. Accordingly, the second step association constant is derived from the molar conductivity curve of CuCl2 using the Shedlovsky's method, while the first step association constant is estimated from the conductometric data of the most dilute solutions: K01 = (16.5 ± 1.5)104, K02 = (8 ± 0.2)102 at 25°C. The results are compared with those earlier obtained for NiCl2 and CoCl2 in DMSO solution, non-conformation of the association constants to the Irving-Williams series being pointed out. 相似文献
4.
Visible absorption spectra and the molar conductance curve for CoCl2 in dimethyl sulphoxide (DMSO) have been determined and are analyzed in terms of the nature of ionization equilibria set up in the respective solutions. Auxiliary absorption spectra determinations of the CoCl2 + Et4NCl and Co (ClO4)2 +Et4NCl mixed solutions indicate consecutive formation of the CoCl(DMSO)+5, CoCl3DMSOt-, and CoCl2t-4 complex ions, in addition to the Co(DMSO)2+6 parent cation. Coordinative disproportionation producing the CoCl3DMSOt- complex anion is shown to predominate in the more concentrated solution of CoCl2 in DMSO. Consecutive stability constants of the chloro-complexes of cobalt(II) are derived. 相似文献
5.
《Electrochimica acta》1986,31(2):185-192
Visible absorption spectra and the molar conductance curve of CoBr2 dissolved in N,N-dimethylformamide (DMF) have been determined at 25°C. Absorption spectra of ternary systems Co(ClO4)2 + Et4NBr + DMF and CoBr2 + chlorobenzene + DMF have also been determined at 25°C. The results indicate the formation of the CoBr(DMF)+5. CoBr3DMF− complex electrolyte controlling the electrolytic properties of the solution. The stability constants of the individual bromo-complexes of cobalt(II) have been calculated. 相似文献
6.
The visible absorption spectra and the molar conductance curves of solutions of NiI2, NiBr2, Ni(BF4)2, Ni(ClO4)2 and Ni(CF3COO)2 DMSO at 25°C have been determined. The results indicate a weak association which is only of the outer-sphere type, in each case involving the Ni(DMSO)2 +6 complex. The conductance data are analysed using the Lee-Wheaton conductance equation for unsymmetrical electrolytes. The first-step association constants (K1) and the limiting ionic conductances, λ0, for the Ni(DMSO)2 +6 cation as well as for the BF?4 and CF3COO? anions are obtained. A linear relation between log K1 and the reciprocal of the anionic radius is observed. On the basis of this relation, the relative contribution of the outer-sphere association for solutions of NiCl2 in DMSO is estimated. 相似文献
7.
A comparative study was conducted to assess the performance of 1 N solutions of hydrochloric acid, ferrous chloride and ferric chloride solutions to dissolve the 74% Ni-4% Cu-20% S nickel sulphide matte anodes. The essential variables considered here were: temperature (25° and 75° C), oxygen and controlled potential. The relative aggressiveness as estimated by the potentiokinetic polarization curves and dissolution experiments with open circuit can be arranged in the following sequence: Fe3+>Fe2+>H+. At +400 mV versus SCE, the aggressiveness reversed in the following sequence: H+>Fe2+>Fe3+. The experimental values of dissolution rates with open circuit and at constant potential were higher than those calculated from the dissolution current densities (potentiokinetic polarization curves), and from the amount of charge passed (at +400 mV versus SCE).Attack by intergranular dissolution and pitting was observed throughout these experiments. The formation of -NiS by the reaction Ni3S2 Ni2++2-NiS+ 2e was confirmed by X-ray analysis. The above results are interpreted in the light of the possible electrochemical mechanisms. 相似文献
8.
A 3 M ferrous chloride solution of pH 1.5 and operated at 72° C was found suitable to electro-oxidize nickel sulphide concentrates containing the following constituents in wt.%: nickel 20, iron 8, magnesium 10, silicon 8, sulphur 11 and copper 0.83.The percentages of dissolution for 16 A h at current passed (current density 20–120 mAcm–2 with respect to graphite) were in the ranges: Ni 90–70; Cu 70–50 and Mg 20–15. The changes in mol % of the final (mainly elemental) sulphur to initial sulphide-sulphur were in the range of 50 to 25. On the other hand the mole ratio of initial to final iron decreases, and this relates to the precipitation of hydroxides. Corresponding to these changes, the X-ray diffraction patterns detected the presence of elemental sulphur and hydrated oxides of iron and magnesium. The anolyte pH and electrode potential were followed during the electro-oxidation experiments.Experiments were carried out to establish the feasibility of separating copper from nickel chloride-copper chloride mixtures at 75° C. It was possible to separate copper whose concentration was 5 gl–1 or above while that of nickel was 75 gl–1. The cathodic polarization curves for copper, nickel and hydrogen discharge from their individual and binary mixtures were used to predict the conditions required to avoid copper-nickel alloy deposition, and the efficiencies of deposition. 相似文献
9.
Influence of tetrabutyl-, tetrapentyl- and tetraisopentylammonium ions on the reduction of nickel(II) in thiocyanate solutions at the dropping mercury electrode has been investigated. These tetraalkylammonium ions, at their low concentrations, inhibit the reduction of nickel(II). However, at their high concentrations, the strong inhibiting effect disappers with the formation of a new wave corresponding to the reduction of a negatively charged nickel(II) thiocyanate complex, which is stabilized by the formation of ion pair with tetraalkylammonium cation. The variation of the reduction current with tetraalkalylammonium concentration was explained by taking into consideration both the change of the total charge of nickel(II) thocyanate complex involved in the reduction process and the simultaneous adsorption of tetraalkylammonium and thiocyanate ions on the mercury electrode. 相似文献
10.
Upper (UCST) and lower (LCST) critical solution temperatures have been measured for poly(α-methyl styrene) in four solvents. The extent of solvent—polymer interaction was found to be reflected in the miscibility range exhibited by these systems. The data could be described by theoretical curves derived using the Patterson—Delmas theory, if an arbitrary selection of the reference temperature was made for each quasi-binary system. Curves showing the relative contributions of the cohesive energy and free volume contribution to the polymer—solvent interaction parameter were also derived from this theory; these illustrated that while the free volume factors predominated at the LCST, the cohesive energy contribution could still play a significant role. 相似文献
11.
Recep Ali Kumbasar 《Journal of Industrial and Engineering Chemistry》2012,18(1):145-151
The selective transport of cobalt (II) from ammoniacal solutions containing nickel (II) and cobalt (II) by emulsion liquid membranes (ELMs) using 8-hydroxyquinoline (8-HQ) as extractant has been presented. Membrane solution consists of a diluent (kerosene), a surfactant (ECA 4360J), and an extractant (8-HQ). Very dilute sulphuric solution buffered at pH 5.0 has been used as a stripping solution. The ammoniacal feed solution pH was adjusted to 9.0 with hydrochloric acid. The important variables governing the permeation of cobalt (II) have been studied. These variables are membrane composition, pH of the feed solution, cobalt (II) and nickel (II) concentrations of the feed solution, stirring speed, surfactant concentration, extractant concentration, complexing agent concentration and pH of the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively transport 95.0% of cobalt (II) from ammoniacal feed solution containing Co2+ and Ni2+ ions. The separation factors of cobalt (II) with respect to nickel (II), based on initial feed concentration, have experimentally found to be of as high as 31 for equimolar Co(II)–Ni(II) feed solution. 相似文献
12.
David W O'Connell Colin Birkinshaw Thomas F O'Dwyer 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(11):1820-1828
A series of adsorption studies was carried out on a glycidyl methacrylate‐ modified cellulose material functionalised with imidazole (Cellulose‐g‐GMA‐Imidazole) to assess its capacity in the removal of Ni(II) ions from aqueous solution. The study sought to establish the effect of a number of parameters on the removal of Ni(II) from solution by the Cellulose‐g‐GMA‐Imidazole. In particular, the influence of initial metal concentration, contact time, solution temperature and pH were assessed. The studies indicated a Ni(II) uptake on the Cellulose‐g‐GMA‐Imidazole sorbent of approximately 48 mg g?1 of nickel from aqueous solution. The adsorption process fitted the Langmuir model of adsorption and the binding process was mildly endothermic. The kinetics of the adsorption process indicated that nickel uptake occurred within 400 min and that pseudo‐second order kinetics best describe the overall adsorption process. Nickel(II) adsorption, recovery and re‐adsorption studies indicated that at highly acidic pH values the adsorbent material becomes unstable, but in the range pH 3–6, the adsorbent is stable and shows limited but significant Ni(II) recovery and re‐adsorption capability. Copyright © 2006 Society of Chemical Industry 相似文献
13.
In this paper, a one-pot and easy-to-handle method at room temperature without additional chemicals for the modification of graphene oxide (GO) with surfactant is found. Removal of nickel (II) ions from aqueous solutions by GO and surfactant (sodium dodecyl sulphate) modified graphene oxide (SDS-GO) was studied spectrophotometrically at room temperature as a function of time, initial concentration and pH. Adsorption capacity of the adsorbent was increased dramatically (from 20.19 to 55.16 mg/g found by Langmuir model) due to the functionalization of the surface by SDS. The driving force of the adsorption of Ni(II) ions is electrostatic attraction and Ni(II) ions adsorbed on the GO surface chemically besides ion exchange. 相似文献
14.
K Ranganathan 《Carbon》2003,41(5):1087-1092
Activated carbons were developed from Casurina equisetifolia leaves, by chemically treating with sulfuric acid (1:1) or zinc chloride (25%), at low (425 °C) and high (825 °C) temperatures. The resulting powdered activated carbons were applied for removing mercuric ions from aqueous solution at different agitation times and mercuric ion concentrations. The equilibrium data fitted well the Langmuir adsorption isotherm. The Langmuir adsorption capacities were 12.3 and 20.3 mg g−1 for low temperature carbons and 43.9 and 38.5 mg g−1 for high temperature carbons impregnated with H2SO4 and ZnCl2, respectively. Studies of the effects of carbon dosage, NaCl concentrations and solution pH values were carried out for the more effective, high temperature carbons. Increasing NaCl concentration resulted in a significant decrease in the adsorption efficiency. Adsorption was high from solutions with low and neutral pH values and lower for solutions with alkaline pH values for the high temperature carbons. 相似文献
15.
Based on the polymerization data presented in part I of this series, a kinetic mechanism for the polymerization of butadiene in toluene initiated with nickel(II) stearate–diethyl aluminum chloride was proposed. Expressions for the conversion, the degree of polymerization, and the cis content were derived. Those models were then used to correlate the experimental data from which the rate constants were estimated. A quantitative discussion of various aspects of the polymerization is also presented. 相似文献
16.
The polymerization of butadiene with nickel (II) stearate–Et2AlCl catalyst has been studied in a batch reactor. The rate of polymerization is first order with respect to monomer and increases with the addition of water. In this system, no appreciable termination reaction has been found and the chain transfer to monomer dictates the molecular weight distribution of the polymer products. Molecular weight increases with conversion and water content. The cis-1,4 content was found to be a function of the extent of polymerization. 相似文献
17.
18.
Iminodiacetic acid functionalized polyglycidyl methacrylate grafted-carbon fibers (PGMA-IDA/CFs) were prepared for Ni(II) removal from aqueous solutions. The effects of solution pH value, temperature and adsorption time were investigated. The maximum adsorption capacity of Ni(II) on PGMA-IDA/CFs is 0.923 mmol·L?1 · g?1 at pH 5.2 and 50 °C. Kinetic data indicate that the adsorption process matches the pseudo-second-order model and Elovich kinetic model. Thermodynamic data suggest that the adsorption process is endothermic spontaneous reaction. 相似文献
19.
20.
At high ionic strength the ion pair (NiPy2+4, nX?) or complex (NiPy4X2), n = 0, 1, 2; X? = Cl?, Br?, SCN?, N?3, F?, NO?3, ClO?4; is adsorbed at the surface of mercury electrode. Under specified conditions in chloride, bromide, and thiocyanates solutions the electroreduction is preceded by a crystallization of a complex on the electrode surface. The inductive role of specifically coadsorbed Cl? ions is discussed. 相似文献