Liquid-Liquid Equilibria for Water + Nitromethane + (1-Propanol,or + Acetone,or + p-Dioxane) Ternary Systems at 303.15 K

Abstract

Liquid-liquid equilibria, distribution coefficients, and selectivities of ternary systems of the type: (water + K + nitromethane), where Kis 1-propanol, acetone, or p-dioxane, have been determined at (303.15 ± 0.05) K, in order to evaluate the suitability of nitromethane for extracting preferentially the second components from their aqueous solutions. The line data were satisfactorily correlated by the Othmer and obias method, and the plait point coordinates for the three systems were estimated. The experimental data were compared with values calculated using the NRTL and UNIQUAC models, and with those predicted by the UNIFAC group contribution method. This last method predicts qualitative and quantitative behaviour which are in disagreement with experimental results, while the values calculated using the other two models are in agreement but only when the concentration of component K is low. The three ternary systems studied have distribution coefficients higher than unity, and high selectivities. Therefore, nitromethane could be considered as a potential solvent for the extraction of K from its aqueous solutions     

Vapor-Liquid Equilibria in the Systems Ethyl 1,1-Dimethylethyl Ether + Cyclohexane and + Benzene at 94.00 kPa

Abstract

Consistent vapor-liquid equilibria for the binary systems of ETBE with benzene and cyclohexane at 94.00 kPa have been measured. Both systems show slightly positive deviation from ideal behavior and do no present azeotropic behavior. The activity coefficients and boiling points of the solutions were correlated with its mole fractions by the Redlich-Kister, Wohl, Wilson, UNIQUAC, NRTL, and Wisniak -Tamir equations. The data were also compared with UNIFAC predictions.     

Phase Equilibria in the Systems Oxolane + Vinyl Acetate,Oxolane + Ethyl 1,1-Dimethylethyl Ether and Vinyl Acetate + Ethyl 1,1-Dimethylethyl Ether

Abstract

Vapor-liquid equilibrium at 94kPa has been determined for the binary systems oxolane (THF) + vinyl acetate, oxolane + ethyl 1,1-dimethylethyl ether (ETBE) and vinyl acetate + ethyl 1,1-dimethylethyl ether. The three systems present slight to moderate positive deviations from ideal behavior and, to a first approximation, can be considered to behave like regular solutions. An azeotrope is present in the system vinyl acetate + ETBE that boils at 340.40 K and contains 49.8% mol vinyl acetate. The activity coefficients of the systems were correlated reasonable well with its composition by the Wohl, Wilson, UNIQUAC and NRTL models. The boiling points of the binary systems were correlated with the Wisniak-Tamir equation.     

Isobaric Phase Equilibria in the Binary Systems Ethyl 1,1-Dimethylethyl Ether + 1-hexene and + Cyclohexene at 94.00 kPa

Abstract

Consistent vapor-liquid equilibrium has been determined for the binary systems 1-hexene + ethyl 1,1-dimethylethyl ether (ETBE) and ethyl 1,1-dimethylethyl ether + cyclohexene at 94.00 kPa. The two systems present slight positive deviations from ideal behavior, can be considered to behave like regular solutions and do not present azeotropic behavior. Pure component vapor pressures are also reported for 1-hexene and cyclohexene. The phase equilibrium of the systems was correlated well by the Wilson, UNIQUAC, and NRTL models and reasonably predicted by the UNIFAC group contribution method. The boiling points of the binary systems were correlated with the Wisniak-Tamir equation.     

Syntheses,structures and photochromic properties of two tetrazolylazo-based K+ and Cd2+ complexes

A 5,5′-azotetrazole (H₂AT)-based K⁺ complex of [K₃(AT)_1.5(H₂O)₄] (1) and another 5-azotetrazolyl salicylic acid (H₃ASA)-based Cd²⁺ complex [Cd(H₂ASA)₂(H₂O)₂] (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complex 1 shows a 3-D structure formed by two μ_7- and μ_8-bridging trans-AT^2? ligands and μ_2-bridging waters linking three kinds of K⁺ ions. Complex 2 features a 1-D chain structure in which each trans-enol H₂ASA^? anion is a μ_2-bridging ligand with one N(tetrazole) atom and one O(carboxyl) coordinating to two different Cd²⁺ ions. The photochromic and photoluminescent properties for aqueous solutions of 1 and 2 were investigated.     

Dielectric constant and dielectric relaxation in aqueous solutions of K<Subscript>2</Subscript>[PdCl<Subscript>4</Subscript>] and K<Subscript>2</Subscript>[PtCl<Subscript>4</Subscript>]

The MW-dielectric properties of aqueous solutions of K₂[PtCl₄] (I) and K₂[PdCl₄] (II) were studied at 298 and 313 K in the frequency range (12–25 GHz) corresponding to the maximum dielectric constant dispersion for water and aqueous solutions of these salts. The low-frequency conductivities were measured. The static dielectric constant, the dielectric relaxation time, and the enthalpy of activation of the dielectric relaxation of the solutions were determined. Compared to pure water, in solutions of salts I and II, the orientational mobility of water molecules is increased and the network of H-bonds is violated more strongly than that of most other ions with hydrophilic hydration. It was demonstrated for the first time that dielectric spectroscopy can be used for analyzing complexation processes in systems containing aqua and hydroxo chloride complexes of metals.     

Preparation of a fluorescent sensor based on BODIPY-functionalized hydroxyapatite nanoparticles and spectroscopic study of the Cd2+ and Zn2+ complex formation

A new fluorescent chemosensor 1, which based on hydroxyapatite (HA) nanoparticles covalently functionalized with a difluoroboron dipyrromethene, has been prepared by nucleophilic substitution of the fluorescent dye 3-chloro-4,4-difluoro-8-(4-tolyl)-5-[bis(pyridine2-ylmethyl)amino]-4-bora-3a,4a-diaza-s-indacene (2) with surface-modified HA nanoparticles. The HA particles were prepared by using SiO₂ as templates (THA) with 3-(aminopropyl)triethoxysilane (THA-APTES). Substitution of the electron-withdrawing chlorine in 2 by an electron-donating amino group of HA changes the properties of the nanoparticles 1 and the corresponding fluorescent dye 2. Absorption and emission maxima of 1 in ethanol are red-shifted by 75 and 30?nm, respectively, in comparison with those of 2. In contrast to no selectivity of dye 2 for Cd²⁺ or Zn²⁺ in EtOH/H₂O (95/5?V/V) solutions, the nanofluorescent probe 1 forms 1?:?1 complexes with Cd²⁺ or Zn²⁺, producing an instant color change along with large hypsochromic shifts in the absorption and fluorescence spectra by 70 and 35?nm, respectively, and large cation-induced fluorescence amplifications.     

Limited Solubility and Critical Exponents for Some Indole + Hydrocarbon Systems

Abstract

The solubility of indole n-octane, n-decane and n-dodecane has been measured at several temperatures. The three systems exhibit limited solubilities with upper critical solution temperatures. The critical exponents of the three systems, evaluated from the experimental data, are found to be the same within the limits of experimental error: β = 0.50 ± 0.4.     

1H NMR Relaxation Studies on Glycerine-Water and Dioxan-Water with Paramagnetic Ions

Abstract

The Proton magnetic Resonance (PMR) spin-lattice and spin-spin relaxation times (T ₁ and T ₂) were measured in highly viscous (glycerine - water) and less viscous (dioxan-water) systems at different temperatures. The values of relaxation times increase with increasing the temperature. This result is interpreted as due to the combined effect of viscosity and temperature in these solutions. The relaxation times were also measured in these solutions containing paramagnetic ions(PMI). The results indicate that the possibility of an anti-parallel bonding of the paramagnetic ions is higher in highly viscous solutions as compared to low viscous systems and the association in the above mixtures appears to be weak.     

[2+2]-Photocycloaddition von Cyclohexen an 2-Acetyl-5,5-dimethyl-1,3-cyclohexandion und 3-Acetyl-1,5,5-trimethyl-2,4-pyrrolidindion

Summary Irradiation of solutions of excess cyclohexene and 2-acetyl-5,5-dimethyl-1,3-cyclohexanedione (1), and 3-acetyl-1,5,5-trimethyl-2,4-pyrrolidinedione (4) results mainly in the formation of 1,5-diones2 and5. These originate from intermediate cycloadducts of cyclohexene and theexo-enols of the cyclic 1,3-diketones. The yields decrease with increasing polarity of the solvent. In solution2 and5 are in equilibrium with the cyclic hemiacetales3 and6.

     

Phase Equilibria in the Systems Ethyl 1,1-Dimethylethyl Ether + Benzene + 2,2,4-Trimethylpentane and Benzene + 2,2,4-Trimethylpentane at 94.00 kPa

Abstract

Consistent vapor-liquid equilibria data at 94.00 kPa have been determined for the ternary system ethyl 1,1-dimethylethyl ether + benzene + 2,2,4-trimethylpentane and for its constituent binary benzene + 2,2,4-trimethylpentane, in the temperature range 343 to 370 K. The systems exhibit slight positive deviations from ideal behavior and the system benzene + 2,2,4-trimethylpentane presents an azeotrope. The VLE data have been correlated with the mole fraction using the Redlich-Kister, Wilson, NRTL, UNIQUAC, and Tamir relations. These models, in addition to UNIFAC, allow good prediction of the VLE properties of the ternary system from those of the pertinent binary systems.     

Excess Molar Volume of 1-propanol+Aniline, +N-methylaniline, +N,N-dimethylaniline

Abstract

Densities of the systems, 1-Propanol(P)+aniline(A), 1-Propanol(P)+N-Methylaniline (NMA) and 1-Propanol(P)+N,N-Dimethylaniline(DMA) have been measured from 21°C to 50°C at an interval of 5°C. The excess molar volumes, V ^E, of the systems, P+A and P +NMA have been found to be negative for the whole range of composition. V^E of the system P+DMA has also been found to be negative, except in DMA-rich region where small positive excess volume is observed. The negative excess volume has been explained primarily in terms of strong specific interaction and size difference of unlike molecules. The magnitude of the negative excess volumes of these systems is of the order, P+A > P + NMA > P + DMA, which has been strongly influenced by steric effect due to CH₃ group attached to N-atom of NMA and DMA. In the highly rich region of DMA in P+DMA system the small positive excess volume is accounted for by the steric effect and breaking up of H-bond of 1-Propanol.     

1-丁基-3-甲基咪唑六氟磷酸盐+水+醇体系的相行为

在298.15 K, 常压下研究了1-丁基-3-甲基咪唑六氟磷酸盐([bmim][PF₆])+水+甲醇、[bmim][PF₆]+水+乙醇、[bmim][PF₆]+水+2-丙醇、[bmim][PF₆]+水+1-丙醇三元体系的相行为. 结果表明, 对于含甲醇、乙醇和2-丙醇的体系, 醇在水+醇溶液中摩尔分数分别为0.55-1.00、0.40-0.75 和0.35-0.50 时, 醇的水溶液与[bmim][PF₆]可以互溶. 而水+1-丙醇体系没有此类现象. 这说明, 这类三元系的相行为不但取决于醇分子的大小, 而且取决于其结构.     

Synthetic Hydroxyapatites as Inorganic Cation-Exchangers; Exchange Characteristics for Pb2+ and Sn2+ Ions in Acidic Solution

Abstract

The cation-exchange characteristics between Pb²⁺ ions of aqueous solutions containing counter-anions (F^?, C1^?) and Ca²⁺ ions of synthetic hydroxyapatite samples have been investigated in detail under the conditions of low pH values (3.0, 4.0 and 5.0) by a normal batch method. Even at the low pH value of 3.0 the apatite structure in a solution containing F^? or C1^? ions was maintained via a concurrent ion-exchange effect of Pb²⁺ ions together with F^? or C1^?ions, which are known to be exchangeable with OH- ions of the apatite. Moreover, it was found that Ca²⁺ ions in the apatite sample can easily be exchanged for Pb²⁺ ions almost without distinction between MI and M2 sites, assisted by the loosening effect of protons even at room temperature. Next, it was found that the hydroxyapatite samples are transformed into amorphous states by the reactions between Ca ²⁺ ions in the samples and Sn ²⁺ ions in the SnC1₂ acidic aqueous solutions with pH of 3.0 or below with a molar ratio of Sn²⁺/Ca²⁺ -1.0. The existence of hydroxyapatite as amorphism in acidic aqueous solutions such as SnC1₂ is quite interesting, because in general the hydroxyapatite has been found to be dissolved in acidic aqueous solutions. Moreover, the obtained amorphism are found to be stable up to at least 500 to 6OO°C but to be unstable in alkaline solutions. The characteristics of Sn²⁺ ions are found to have been found to form crystalline Pb ²⁺ apatite even in be quite different from those of homologous Pb²⁺ ions which have been found to form crystalline pb²⁺ apatite even in such an acidic atmosphere.     

Determination of Gallium By Liquid-Liquid Extraction-Flame Atomic Absorption Spectrometry In Bayer Process Aluminate Solutions

Abstract

The described flame-atomic absorption determination of gallium involves the extraction of 8-hydroxyauinoline-Ga complex and the extraction of galhum as an ion association complex from strong hydrochloric acid into Methyl Isobutyl Ketone (MIBK). Both of the examined extraction systems were found to be workable for gallium determination in aqueous solutions. A comparison of mentioned extraction systems showed that only the second one can be applied for gallium determination in low concentration in aluminate solutions (strong alkaline). Finally, an analytical scheme for gallium determination in aluminate solutions is recommended (extraction of Ga from hydrochloric acid solutions, 3.0-50M, through matrix matched calibration curve). the proposed procedure was found to be simple, selective and accurate.     

Studies on Synthetic Inorganic Ion Exchangers-III Quantitative Separations of Mg2+ -Pb2+, Zn2+ - Pb2+ Cu2+ - Pb2+, Al3+ - Pb2+, Zn2+ - Cd2+, and Mg2+ - Cd2+ on Lead Antimonate Columns

Abstract

A new inorganic ion exchanger, lead antimonate has been synthesized having an Pb:Sb ratio of 1:5 and cation exchange capacity of 1.46 mequiv./g. It is fairly stable in water and dilute solutions of acids, bases and salts. Ion distribution studies on twenty metal ions have been determined on this gel at pH 1,2,3 and 5. The following mixtures have been separated: Mg²⁺ - Pb²⁺, Zn²⁺ - Pb²⁺, Zn²⁺ - Pb²⁺, Cu²⁺ - Pb²⁺, Al³⁺ - Pb²⁺, Zn²⁺ - Cd²⁺ and Mg²⁺ - Cd²⁺. Mg²⁺ and Al³⁺ were removed with 0.4 M ammonium nitrate, Cu²⁺ and Zn²⁺ with 0.4 M ammonium nitrate + 0.1M nitric acid (1:1), Pb²⁺ with 0.5M nitric acid and Cd²⁺ with 0.25M nitric acid. A tentative structure of this material is proposed on the basis of chemical analysis, pH titrations, thermogravimetry and IR spectrophotometry.     

Phase equilibria in systems based on Tl4SnSe3 and Tl4SnSe4 ternary compounds

Phase equilibria in the Tl₄SnSe₃-Tl (I), Tl₄SnSe₃-Sn (II), Tl₄SnSe₄-SnSe (III), Tl₄SnSe{ia4}-TlSe (IV), and Tl₄SnSe₃-Tl₄SnSe₄ (V) systems have been studied by differential thermal analysis and power X-ray diffraction. Systems I–V have been found to have eutectic interactions. In systems I and II, width regions of solid solutions based on the ternary compound Tl₄SnSe₃ are formed.     

Phase Equilibria in the Ternary System Methyl 1,1-Dimethylethyl Ether + Benzene + Toluene

Abstract

Consistent vapor-liquid equilibrium data at 94kPa have been determined for the ternary system methyl 1,1-dimethylethyl ether (MTBE) + benzene + toluene. The results indicate that the system deviates positively from ideality and that no azeotrope is present. The ternary activity coefficients of the system have been correlated with the composition using the Redlich-Kister, Wilson, NRTL, UNIQUAC, and UNIFAC, models. It is shown that most of the models allow a very good prediction of the phase equilibrium of the ternary system using the pertinent parameters of the binary systems. In addition, the Wisniak-Tamir relations were used for correlating bubble-point temperatures.     

Thin Layer Ionophoresis of D-Block Metal Ions in Aqueous Solutions of Complex Forming Acids and Their Sodium Salts: Specific Separation of Pd2+ and Pt4+ from Numerous Metal Ions

Abstract

Thin layer ionophoresis of d-block metal ions was studied at 100 volts for 3 h. Aqueous solutions of citric, tartaric and oxalic acids and their sodium salts were chosen as background electrolyte. The mechanism of migration is explained in terms of precipitation and adsorption. There is no significant heating during ionophoresis. Pd²⁺ and Pt⁴⁺ were separated from numerous metal ions.     

Excess Molar Volumes of n-Pentanol + Cumene,n-Pentanol + 1,4-Dioxane and Cumene + 1,4-Dioxane at Different Temperatures

Abstract

Molar excess volumes (V^E ) and partial molar excess volumes ( ^VE ) are reported for non-electrolyte binary mixtures of n-pentanol + cumene, n-pentanol + 1,4-dioxane and cumene + 1,4-dioxane at four temperatures and over the whole concentration range. In these systems, the n-pentanol is a highly polar molecule with association in its pure state, while the others two show little polarity without association in their pure states. The results of V^E are discussed in terms of the interactions between components. The Prigogine–Flory–Patterson model of solution thermodynamics has been used to predict V^E . This work shows the importance of the three contributions δV _int, δV _p? and δV_F to V^E .