Cyanex 923-H2SO4体系萃取第3相的形成和应用

三相体系;Cyanex 923-H2SO4体系萃取第3相的形成和应用     

Comments on the electronic properties of cyclopropane,cyclobutane, and cyclohexane

Spectral quantities of cyclopropane, cyclobutane, cyclohexane, and of several derivatives, have been calculated by a semiempirical all-valence electron SCF-CI MO method. In cyclopropane, HOMO is practically localized in the carbon-frame, and LVMO is purely so. In cyclobutane, these two MO's are based on C-H bonds, while cyclohexane holds an intermediate position. Despite the overall similarity-experimental and computed-of the spectra of these molecules, assignments are non-parallel. Like cyclopropane, cyclobutane can extend conjugation, but to a diminished degree; cyclohexane behaves in this respect like an acyclic alkane. An interpretation of this gradation, in terms of the nature of high-lying MO's, is proposed.     

Three-phase extraction study of cyanex 923-n-heptane/H(2)SO(4) system

Phase behavior of the extraction system, Cyanex 923–heptane/H₂SO₄–H₂O has been studied. The third phase appeared at different aqueous H₂SO₄ concentration with varying initial Cyanex 923 concentration and temperature affects its appearance. Almost all of H₂SO₄ and H₂O are extracted into the middle phase. The H₂SO₄ concentration in the third phase increases with the increasing aqueous acid concentration (C_H2SO4,b) while the water content first increases and then reaches a constant value at C_H2SO4,b=11.3 mol l⁻¹. In the region of C_H2SO4,b higher than 5.2 mol l⁻¹, the composition of the middle phase is only related to the equilibrium concentration of H₂SO₄ in the bottom phase. H₂SO₄ and H₂O are transferred into the middle phase mainly by their coordination with Cyanex 923 when C_H2SO4,b is less than 11.3 mol l⁻¹. When C_H2SO4,b is higher than 11.3 mol l⁻¹, excess H₂SO₄ is solubilized into the polar layer of the aggregates. In the region considered, the extracted complex changes from C923 · H₂SO₄ to C923 · H₂SO₄ · H₂O and then to C923 · (H₂SO₄)₂ · H₂O.     

Kinetic modelling of cadmium removal from phosphoric acid by non-dispersive solvent extraction

In this work it is reported that the kinetic modelling of the separation of cadmium from phosphoric acid by non-dispersive solvent extraction. Using Cyanex 302 as selective extractant, the extraction step was carried out in a hollow fibre module containing polypropylene fibres, whereas the concentration step required a ceramic module with tubular channels due to the high acidity of the backextraction agent. Application of the methodology previously reported by the authors led to the development of a kinetic model with three design parameters, i.e., equilibrium constant of the extraction reaction (K'_e = 6 × 10³ mol⁻²/l⁻²), membrane mass transport coefficient of the extraction module K_me=8.33×10⁻⁸ m/s) and of the backextraction module (K_ms=3.33×10⁻⁸ m/s), that described satisfactorily the behaviour of the separation-concentration system. Thus, in this work a new application of the non-dispersive solvent extraction technology is presented, characterising at the same time the behaviour and parameters of a new type of contactor, i.e., a tubular ceramic module.     

Cyanex301的纯化及其特性

研究了用Ｃｙａｎｅｘ３０１［ＴＭ］铵盐在苯中重结晶以纯化Ｃｙａｎｅｘ３０１的方法，该法收率６２．４％，产品纯度＞９９％。测定了经纯化后产品的红外光谱，研究了纯化产品在－水正庚烷体系中的分配平衡及其在正庚烷中的缔合，浓度在０．２～１．０ｍｏ１／Ｌ范围，Ｃｙａｎｅｘ３０１主要以二聚形式存在。     

Enhancement of dielectric and electro-optical parameters of a newly prepared ferroelectric liquid crystal mixture by dispersing nano-sized copper oxide

ABSTRACT

Here, we present the effect of copper (II) oxide nanoparticles (nCuO) on dielectric and electro-optical parameters of a newly prepared ferroelectric liquid crystal (FLC) mixture, namely W302. The FLC mixture, comprising of pyrimidine compounds, was characterised through dielectric spectroscopy, differential scanning calorimetry (DSC), polarising optical microscopy (POM) and other electro-optical methods. The material parameters such as spontaneous polarisation, rotational viscosity, response time and tilt angle of W302 were found to be 14 nC/cm², 240 mPa.s, 150 µs and 28^?, respectively. The phase transition temperatures of W302 were observed through DSC and further confirmed by the dependence of dielectric loss factor in homogeneously aligned FLC sample with temperature. We also demonstrate the observance of a low-frequency dielectric relaxation mode due to the unwinding of the helix, called as partially unwound helical mode (p-UHM) along with Goldstone mode. The behaviour of p-UHM has been systematically studied with temperature and applied bias field. Further, dispersion of nCuO into host W302 has shown a significant increase in dielectric permittivity. Also, the p-UHM relaxation peak in the dielectric regime has disappeared with the incorporation of nCuO. These studies would be useful to fabricate better electro-optical devices for display, switching and beam steering applications. The formulation and characterization of a ferroelectric liquid crystal (FLC) mixture W302 composed of pyrimidine compounds is presented. Then, we observed the effect of copper (II) oxide nanoparticles (nCuO) on dielectric and electro-optical parameters of a newly prepared and characterized FLC mixture.     

P204-Cyanex 923混合溶剂萃取铟

磷酸;P204-Cyanex 923混合溶剂萃取铟     

Preparation and Characterization of Ceramic Hollow Microspheres for Heavy Metal Ion Removal in Wastewater

Ceramic hollow microspheres (CHMSs) were prepared to use as supports for the removal of heavy metal ions from industrial waste-water. A water extraction sol–gel technique was used to prepare porous CHMS by extracting water from an emulsion of LUDOX (silica colloid; SiO₂, Aldrich Co.) and 2-ethyl-1-hexanol. Experiments were conducted to control pore size, wall thickness, and separation yield by examining the ratio of precursors (LUDOX and 2-ethyl-1-hexanol), catalyst (NH₄OH), sintering temperature, surfactant (SPAN 80), extractant (n-butanol), stirring speed, and concentration of precursor (LUDOX). The results revealed that the optimum conditions were 20 ml of a 10 wt% solution of LUDOX, 10 ml of NH₄OH, a sintering temperature of 500°C, 0.4 ml of SPAN 80, 200 ml of n-butanol, and a stirring speed of 730 rpm/100 ml of 2-ethyl-1-hexanol. CHMSs were impregnated in Cyanex 272 and examined for their ability to remove heavy metal ions from a solution. Based on an experiment involving the removal of metal ions using CHMSs that were prepared under optimum conditions, Zn ion was removed at a level of 0.354 mmol/g at pH 4, which was about twice the adsorption capacity of CHMSs prepared by Wilcox (Mater. Res. Soc. Symp. Proc.346, 201 (1994)).     

Continuous Transport of Zn(II) by Ammonium Chloride Media via Supported Liquid Membrane System

With the gradual depletion of traditional zinc resources, the full use of various non-traditional zinc-containing resources has received intensive attention. However, the efficient recovery of zinc ions with low concentrations remains challenging. Here efficient and continuous recovery of zinc ions in ammoniacal chloride media by a flat supported liquid membrane system is achieved, using Cyanex923 and TBP mixed extractant as the membrane phase. This article discusses the synergistic effect between Aliquat336, Cyanex923 and TBP, the effects of feed pH, total ammonia concentration, Cl⁻ concentration and temperature on Zn(II) transport.     

Comparison of the force field in various pyrochlore families. II. Phases presenting structural defects

A previous study of various A₂B₂O₆O′ pyrochlore families by vibrational spectroscopy allowed the analysis of the ir and Raman spectra and the force fields of pyrochlore phases presenting structural defects. The spectra of the following compounds were compared: (i) ideal pyrochlore Cd₂Ta₂O₇, (ii) lacunary Tl₂Ta₂O₆, (iii) nonstoichiometric Pb_1.5Ta₂O_6.5, and (iv) Pb_2.3Ta₂O_7.3 exhibiting regular shear planes. If the tridimensional network of TaO₆ octahedra is not modified and the perturbations concern only the A₄O′ tetrahedra network, a slight modification of the vibrational spectra and a weak decrease in the TaO stretching and OTaO bending force constants are observed. But, if the octahedra network is perturbed, large modifications appear on the spectra, revealing unambiguously the existence of new types of bonds created by the defects in the structure. The Raman intense lines observed in the low frequency range in lead compounds is also discussed.