THIRD PHASE FORMATION IN NITRIC ACID EXTRACTION BYn-OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYL-METHYLPHOSPHINE OXIDE

ABSTRACT

The third phase formation was studied as a function of n-octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and tri-M-butyl phosphate (TBP) concentrations and temperature in the extraction of nitric acid. The concentration fractions of CMPO and TBP in the second and the third phases were determined by gas chromatography. Both CMPO and TBP were found to be enriched in the third phase. The concentrations of nitric acid in the second and the third phases relatively agreed with the calculated concentrations based on the extraction equilibrium constants of nitric acid by CMPO and TBP. The extraction of Np with the third phase formation was also discussed.     

STUDY OF MICELLAR EXTRACTION IN THE SYSTEM (2-ETHYLHEXYL) PHOSPHONIC ACID MONO-(2-ETHYLHEXYL) ESTER - Co (II) - SURFACTANT

ABSTRACT

The equilibrium and kinetics of the extraction of cobalt (II) by P507 in Teric N9 micelles have been studied. The structure of the (2-ethylhexyl) phosphonic acid mono-(2-ethylhexyl) ester (known as P507), in Teric N9 micelles have been investigated using interfacial tension and fluorescence quenching measurements. It has been found that there is an interaction between these two components and mixed micelles are formed

The complex of Co²⁺ with P507 in Teric N9 aqueous solution has been shown to have a 1:3 stoichiometry and the equilibrium constant has been obtained by slope analysis. The rate of complex formation in the micelle media is very fast with the reaction going to completion in less than 0.2 seconds.     

EXTRACTION STUDIES ON THE SYSTEM BETWEEN BIS(2-ETHYLHEXYL) PHOSPHORIC ACID AND CHROMIUM(III) IN SEVERAL AQUEOUS SOLUTIONS

The extraction of chromium(III) by carboxylic acids and acidic organophosphorus compounds has been investigated. In general, chromium(III) was not extracted by carboxylic acids but the organophosphorus compound, di-2-ethylhexyl phosphoric acid, was found to be particularly adequate for the extraction. The partition of chromium(III) in nitrate medium and solutions of di-2-ethylhexyl phosphoric acid in Shellsol-T was studied using a tracer of 51cr. Distribution measurements of the metal ion in a wide range of pH and organophosphoric acid concentrations have been performed. The experimental data treated by a graphical method have been explained assuming the presence in the organic phase of the species Cr(DEHP)₃(H₂O)²(HDEHP). Equilibrium constants for the different extraction reactions are given. The extraction of the monomeric species was found to be independent of Ac^?or SO⁼ ₄ions presence.     

LIQUID - LIQUID EXTRACTION OF GALLIUM(m) FROM ACIDIC NITRATE MEDIA WITH BIS(2-ETHYLHEXYL) PHOSPHINIC ACID IN TOLUENE

ABSTRACT

The distribution equilibria of gallium(III) between bis(2-ethylhexyl) phosphinic acid dissolved in toluene and acidic aqueous nitrate media has been investigated as a function of the concentration of extractant in organic phase and concentration of hydrogen ion and gallium(III) ion in aqueous phase. The extraction characteristics of bis(2-ethythexyl) phosphinic acid are compared with that of bis(2-ethylhexyl) phosphoric acid to get further information. The stoichometry of the extracted species is determined on the basis of slope analysis and IR spectra. Gallium is extracted by a cation exchange mechanism as GaRs₃ by bis(2-ethylhexyl) phosphinic acid and as GaRs₃-HR by bis(2-ethylhexyl) phosphoric acid. Temperature dependence of the extraction equilibrium is examined by temperature variation method. Both extraction processes are endothermic in nature and increase in temperature is favorable.     

LIQUID - LIQUID DISTRBUTION EQUILIBRIUM IN THE TERNARY SYSTEM : CITRIC ACID - 2-BUTANOL - WATER 298.15 K

Partition of citric acid, 2-butanol and water between the aqueous and alcoholic phases is reported. Distribution of citric acid is expressed in terms of, H₃Cit (2-BuOH)₅, complex formation in the organic phase. Detailed thermodynamic analysis of the investigated system is presented.     

DISTRIBUTION DATA FOR THE SYSTEM Th(NO3)4:UO2(NO3)2:HNO3/30 % TBP IN DODECANE

Abstract

Distribution data for the systems Th(NO₃)₄:HNO₃/30 % TBP in dodecane and Th(NO₃)₄:UO₂(NO₃)₂:HNO₃/30 % TBP in dodecane have been evaluated experimentally. By means of these data a caleulationa1 model has been derived which makes it possible to determine data in the investigated range. A method is also described for the evaluation of distribution data at very low thorium concentrations.     

BaO－TiO_2系中Ba_2Ti_9O_（20）相形成的研究

研究了ＢａＯ－ＴｉＯ_２系中Ｂａ_２Ｔｉ_９Ｏ_（２０）相的形成规律。结果表明：ＢａＯ－ＴｉＯ_２系中，不加任何添加剂可以合成Ｂａ_２Ｔｉ_９Ｏ_（２０）相；在ＢａＯ－ＴｉＯ_２系中Ｂａ：Ｔｉ＝２：９附近存在一个很窄的单相Ｂａ_２Ｔｉ_９Ｏ_（２０）区；烧结阶段Ｂａ_２Ｔｉ_９Ｏ_（２０）相的最终合成并不依赖于预烧阶段部分此相的形成；通氧烧结对Ｂａ_２Ｔｉ_９Ｏ_（２０）相的形成影响不大，但可以抑制钛的变价。实验还发现，Ｂａ_２Ｔｉ_９Ｏ_（２０）陶瓷化学计量比的偏离将导致微波下介电常数的下降。     

EFFECT OF NITRIC ACID EXTRACTION ON PHASE BEHAVIOR,MICROSTRUCTURE AND INTERACTIONS BETWEEN PRIMARY AGGREGATES IN THE SYSTEM DIMETHYLDIBUTYLTETRADECYLMALONAMIDE (DMDBTDMA) / n-DODECANE / WATER: A PHASE ANALYSIS AND SMALL ANGLE X-RAY SCATTERING (SAXS) CHARACTERISATION STUDY

ABSTRACT

Among the different problems to be solved when designing a liquid-liquid solvent extraction process, third phase formation. i.e. the splitting of the organic phase into two layers when extracting high concentration of solutes, like nitric acid or metallic nitrates (here trivalent f ions), is one of the most important to address. In some conditions the formation of a “third phase” is observed with dimethyldibutyltetradecylmalonamide (DMDBTDMA), a potential extractant used in the DIAMEX process

We have investigated the phase behavior of the system DMDBTDMA / n-dodecane / water / HNO₃, in the acceptable concentration limits for the DIAMEX process.     

KINETICS AND MECHANISM OF THE INTERFACIAL MASS TRANSFER OF Zn2+, Co2+, Ni2+ IN THE SYSTEM: BIS(2-ETHYLHEXYL)PHOSPHORIC ACID,n-DODECANE - KNO3, WATER

ABSTRACT

The mass transfer rate of Zn(II), Co(II) and Ni(II) between aqueous nitrate solutions and n-dodecane solutions of the organic soluble ligand HDEHP has been investigated using a forced convection, constant interfacial area stirred cell. The distribution ratios necessary to evaluate the kinetic experiments have been determined and the equilibrium constants which describe the heterogeneous complex formation reaction between Zn²⁺, Co²⁺, Ni²⁺ and HDEHP have been evaluated. The results have been interpreted according to two limiting models: 1) the mass transfer rate is controlled by slow reversible interfacial reactions, 2) the mass transfer is controlled by interfacial film diffusion. Both models are adequate to Interpret the experimental data. The conclusion Is reached that, if interfacial chemical reactions are rate controlling, rate constants of interfacial complex formation reactions independent of the nature of the cation are obtained. This result supports a reaction mechanism which is rate controlled by the microscopic diffusion of the cation through a viscous and structured layer of interfacial water adjacent to the liquid interface     

PHASE EQUILIBRIA IN THE H2/CH4 SYSTEM AT TEMPERATURES FROM 92.3 TO 180.0 K AND PRESSURES TO 140 MPa*

Experimental measurements of liquid-vapor phase equilibria in the system H₂/CH₄ are reported for ten temperatures in the range 92.3 to 180 K, and pressures to 140 MPa. The mixture critical line and the pressure-temperature trace of the three-phase region solid-liquid-vapor have been located. The three-phase region and the critical line intersect at T = 91.5 K and P = 147 MPa to form an upper critical end point. Experimental results have been compared with predictions of three equations of state, Peng-Robinson, Reclich-Kwong and Deiters, and with calculations based on statistical mechanical perturbation theory.     

PHASE EQUILIBRIA IN THE H2/CH4 SYSTEM AT TEMPERATURES FROM 92.3 TO 180.0 K AND PRESSURES TO 140 MPa*

Experimental measurements of liquid-vapor phase equilibria in the system H₂/CH₄ are reported for ten temperatures in the range 92.3 to 180 K, and pressures to 140 MPa. The mixture critical line and the pressure-temperature trace of the three-phase region solid-liquid-vapor have been located. The three-phase region and the critical line intersect at T = 91.5 K and P = 147 MPa to form an upper critical end point. Experimental results have been compared with predictions of three equations of state, Peng-Robinson, Reclich-Kwong and Deiters, and with calculations based on statistical mechanical perturbation theory.     

Pb(Zn_(1/3)Nb_(2/3))O_3-Pb(Fe_(2/3)W_(1/3))O_3二元系陶瓷的介电性质和钙钛矿相的形成机制

制备 Pb(Zn_(1/3)Nb_(2/3))O_3(PZN)基陶瓷电容器,最主要的问题是形成有害于介电性质的焦录石相。实验表明,固相反应法很难合成钙钛矿结构的 PZN 陶瓷,于1000经固相反应的产物是含立方焦录石的混合物,在 PZN 中添加0.53mol 的 PFW,试样中的钙钛矿相超过97%。通过对 Pb(Fe_(2/3)W_(1/3))O_3(PFW)结晶化学和烧结机理的分析,证明在 PZN 中添加 PFW 能减少或抑制焦录石的形成。本文报导了 PZN-PFW 二元系陶瓷的相关系和介电性质,探讨了钙钛矿相的形成机理。     

288K下Li~ ,K~ //CO_3~(2-),B_4O_7~(2-)-H_2O四元体系的相平衡

引　言众所周知 ,我国严重缺乏可溶性固体钾矿资源 ,可利用的钾矿产资源主要为液态 ,如盐湖卤水等 .我国是一个多盐湖国家 ,盐湖总数逾千个 ,仅西藏湖区面积大于 1km2 的盐湖就有 2 0 0多个 .在西藏盐湖中 ,扎布耶盐湖卤水以Li、B、K含量高而闻名于世 .该湖卤水主要成分为Li 、     

翁泉沟硼镁铁矿的硫酸法加工(Ⅱ)──H_3BO_3-MgSO_4-MgC1_2-H_2O体系相图及其应用

测定了25℃、100℃H_3BO_3-MgSO_4-MgCl_2-H_2O体系的溶解度并绘成相图.根据相图，H_3BO_3-MgSO_4溶液可以MgCl_2为盐析剂，在100℃下蒸发析出一水硫酸镁，其母液冷至25℃析出H_3BO_3，硼酸母液循环用作盐析剂，使H_3BO_3和MgSO_4完全分离．文中并讨论了MgCl_2的最适用量.     

Pb(Ni1/3Nb2/3)O3-PbTiO3系统准同型相界附近的介电、热释电和压电性能

用两步合成法制备了（１－ｘ）Ｐｂ（Ｎｉ１／３Ｎｂ２／３）Ｏ３－ｘＰｂＴｉＯ３系陶瓷,ｘ分别为０．２８,０．３０．０．３２,０．３４,０．３６,０．３８和０．４０,研究了试样的相组成以及介电,热释电和压电性能。ＸＲＤ结果分析表明：准同型要界在ＰｂＴｉＯ３摩尔分数ｘ＝０．３４￣０．３８处,组成在准同型相界附近的试样具有最大的介电常数,热释电系数和压电系数。介电性能测试结果还表明,组成在准同型相界附近的     

PREPARATION OF (Ni/W)-γ-Al2O3 MICROSPHERES AND THEIR APPLICATION IN ADSORPTION DESULFURIZATION FOR MODEL GASOLINE

A kind of desulfurization adsorbent, (Ni/W)-γ-Al₂O₃ microsphere, was prepared by a new method of in situ chemical reduction. The adsorbent consists of active components (transition metals Ni and W) and a carrier (γ-Al₂O₃). Ni and W in γ-Al₂O₃ microspheres are fine in size and can be distributed homogeneously on the surface and inside of the γ-Al₂O₃ carrier. The desulfurization of the adsorbent made by the in situ chemical reduction method was carried out in model gasoline. Its desulfurization capacity increases 23% in comparison with that made by the conventional impregnation method. The composition and configuration of adsorbents were analyzed by scanning electron microscopy (SEM), electron energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The in situ chemical reduction method offers a new and promising method for preparation of desulfurization adsorbents containing active components.