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71.
Mohamad Sh. Ramadan Nabila M. El-Mallah Sherif M. Abd-Elmenem 《Journal of Dispersion Science and Technology》2013,34(8):1110-1120
AbstractThe interaction between anionic dyes [Reactive Orange 122 (R.O 122), Reactive Blue 19 (R.B 19), Reactive Violet 5 (R.V 5) and Acid Green 20 (A.G 20)] with cationic surfactant cetyltrimethylammoniun bromide (CTAB) has been investigated by spectrophotometry and conductance technique. The used dyes are characterized by tautomeric behavior which affects the mechanism of the interaction. Various parameters such as dye structure, surfactant composition, solvent composition, temperature and pH of the medium were studied. The spectral data were applied for calculating the binding constant between dye and surfactant (Kb), fraction of micellization (?mic), and standard free energy change of binding (ΔG°b) in 0,10,20 and 30 v/v % acetonitile (AN). Conductance technique was constructed to estimate the ion pairing constant (Ka) at different temperatures and v/v % AN. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) for ion pair formation were evaluated. The role of hydrophobic and electrostatic effect on dye-surfactant interaction was discussed. 相似文献
72.
M. Lachica E. Barahona 《International journal of environmental analytical chemistry》2013,93(1-4):219-221
Abstract The effect of using solution matrices in calibration standards different from those employed for the extraction steps in the determination of Cd, Cr, Cu, Ni and Zn were tested. Cu and Zn are little affected by matrix effects but, if the extractant is ammonium acetate, the use of other matrices may result in too high Cd, Cr and Ni values. 相似文献
73.
The effect of laser irradiation on the optical properties of thermally evaporated Se100?x Te x (x=8, 12, 16) chalcogenide thin films has been studied. The result shows that the irradiation causes a shift in the optical gap. The results have been analyzed on the basis of laser irradiation-induced defects in the film. The width of the tail of localized state in the band gap has been evaluated using the Urbach edge method. As the irradiation time increases, the values of the optical energy gap for all compositions decrease, while tail energy width increases. It is also observed that the optical energy gap decreases with increasing Te content in the alloy. These changes are a consequence of an increment in disorder produced by laser irradiation in the amorphous structure of thin film. 相似文献
74.
Considering the diffusion reaction at solid interfaces, the ignition temperature of compounds fabricated by self-propagating high-temperature synthesis (SHS) is modelled with the help of size-dependent activation energy. As reactant size decreases, ignition temperature also decreases. This is because of increased contact areas between the reactants and the lowered diffusion barrier, both of which must be calculated specifically for reactants in nanoscale. The model predictions and experimental results are consistent for some metallic compounds. 相似文献
75.
An unusual substitution reaction of an aromatic sulfonic group based on 3-carbonyl-4-phenolsulfonic acid was discovered in a diazo-coupling process.The reaction occurred under mild reaction conditions (pH 8.0-9.0.0-5 C,solvent:water) within a short reaction time(1h).A plausible substitution reaction mechanism by phenol-ketone resonance was proposed. 相似文献
76.
《Physics and Chemistry of Liquids》2012,50(5):529-545
Abstract Attention is focussed here on a variety of cylindrically symmetric inhomogeneous electron liquids. These include separable potentials in which a general variation along the (z) axis of cylindrical symmetry is combined with isotropic harmonic confinement in the (x, y) plane. in this case, an explicit differential equation is derived for the Slater sum along the z axis by projecting out of the (off-diagonal) canonical density matrix the states with zero angular momentum about the axis of symmetry. Some attention is then given to the calculation of the Slater sum for a hydrogen-like atom in a uniform electric field of arbitrary strength. the model of a separable potential with harmonic confinement, though no longer exact, is shown to lead directly to a (now approximate) equation for the Slater sum along the z axis for the Stark effect in hydrogen. Finally some further progress is shown to be possible in the extreme high field limit. 相似文献
77.
78.
A new and green method for the synthesis of α,β-unsaturated arylsulfones had been achieved through the condensation of aromatic aldehydes,chloroacetonitrile,benzenesulfinic acid sodium salt in the presence of l-butyl-3-methyl imidazolium hydroxide([bmim]OH) in EtOH under reflux.The ionic liquid was recovered and recycled for subsequent reactions.The advantages of this protocol were non-toxic,easy work-up and good yields. 相似文献
79.
80.
《Journal of Coordination Chemistry》2012,65(21):3473-3483
Two Co(II) coordination polymers, [CoL(npa)]·2H2O (1) and [CoL(Hnpa)2] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H2npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound 1 was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting a μ2-bridging mode and connecting two Co2+ cations to generate a 26-membered Co2L2 loop. The npa2? link adjacent Co2L2 loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound 2 was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa? adopt a μ1-η0?:?η1 coordination to connect adjacent Co2+ cations into a 2-D polymeric layer. The μ2-bridging L ligands connect adjacent 2-D [Co(Hnpa)]n polymeric layers into a 3-D NaCl-like framework. The Co2+ cations and the L ligands in compounds 1 and 2 exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing 1 and 2 and the thermal stabilities of 1 and 2 were investigated. 相似文献