RECOVERY OF URANIUM FROM ACID MEDIA BY MACROPOROUS BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The extraction of uranium from various acid media such as nitric acid, sulphuric acid, hydrochloric acid, phosphoric acid and perchloric acid by a macroporous bifunctional phosphinic acid resin (MPBPA) has been studied. The distribution coefficients for the extraction of uranium by the MPBPA resin are compared with the corresponding values reported in literature for the conventional sulphonic acid resin. The results clearly indicate the suitability of the MPBPA resin to recover uranium from different types of acid solutions of widely ranging acidities.     

EXTRACTION OF ACTINIDES BY BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The extraction of U(VI), Am( III), Pu( IV), Np( IV) and ThIV) by bifunctional phosphinic acid resin of various cross linkages is reported as function of nitric acid concentration. From the comparison of the distribution coefficient values it is suggested that the recovery of these actinide elements from waste solutions as we II as their mutual separations is possible by using phosphinic acid resin.     

EXTRACTION CHEMISTRY OF COBALT AND NICKEL BY DI(1-METHYLHEPTYL)PHOSPHINIC ACID

The fundamental characteristics and mechanism of extraction of cobalt (II) and nickel(II) by di-(1-methylheptyl) phosphinic acid (DMHPA) were studied. The extraction ability of cobalt(II), nickel (II) and various metals by DMHPA decreases in the order Fe(III) > Zn ? Pb(II) > Mn(II) > Cu(II) > Co(II) > Mg > Ca > Ni(II). The difference of the pH_½ values for nickel and cobalt reaches 2.06 pH units, which is apparently greater than those from extraction by di(2-ethylhexyl)phosphoric acid (DEHPA)and 2-ethyl-hexyl ester 2-ethylhexylphosphonic acid(DHEHPA).The slope analysis and IR spectroscopy reveal that the stoichiometrics of cobalt and nickel extracted species are Co(HA₂)₂ and Ni(HA₂)₂(H₂O)₂ respectively. As demonstrated by the study of the electronic spectroscopy the structure of the extracted complexes were shown as tetrahedral and octahedral configuration respectively. Furthermore, the coordination field parameters of the complexes were calculated.     

KINETICS OF PHENOL EXTRACTION FROM AQUEOUS PHASE BY SULFURIC ACID SALTS OF TRIOCTYLAMINE

The kinetics of the extraction of phenol from the aqueous phase by sulfuric acid salts of trioctylamine (TOA salts) in kerosene and the stripping of phenol from the organic phase by sodium hydroxide solution were studied using a constant interfacial area cell. Measurements of the extraction and stripping rates were made by measuring the time-dependent phenol concentrations in the aqueous phase. It is found that the extraction rate of phenol is strongly dependent on the initial concentration of phenol in the aqueous phase and on the initial concentration of TOA salts in the organic solvent. However, the effect of the total sulfate concentration and the acidic concentration on the extraction rate are not significant. The stripping rate is only a function of the initial concentration of phenol in the TOA salt-organic phase. By analyzing the experimental data, it was recognized that the extraction of phenol occurs at the interface, rather than in the bulk of the solution. The diffusion resistance, rather than the resistance of chemical reaction, is the rate-controlling step for the phenol extraction. Based on the experimental data, simple expressions of the extraction rate and stripping rate of phenol were obtained.     

COBALT-NICKEL SEPARATION BY SOLVENT EXTRACTION WITH BIS(2,4,4 TRIMETHYLPENTYL)PHOSPHINIC ACID

Abstract

The use of an organophosphinic acid to separate cobalt from nickel by solvent extraction is described. Comparative data indicate that the phosphinic acid is superior to analagous phosphoric and phosphonic acids in terms of cobalt-nickel selectivity and the ability to reject calcium. Important reagent properties, such as low aqueous solubility and hydrolytic stability, are discussed. The results of continuous, counter-current, mini-plant tests demonstrate the recovery of high purity cobalt from concentrated nickel sulphate solutions.     

EXTRACTION OF DIVALENT METALS WITH BIS(2,4,4 TRIMETHYLPENTY) PHOSPHINIC ACID

The extraction of Cd(II), Cu(II) and Zn(II) from 0.1 mol dm^minus3 aqueous nitrate solutions with bis(2,4,4-trimethylpentyl)phosphinic acid (HBTMPP) dissolved in Isopar-H has been studied with relation to the total extractant concentration, the equilibrium pH and the total metal concentration in the aqueous phase.

The stoichiometry of the extracted species and their equilibrium constants have been determined by graphical and numerical methods and appear to be CdA₂ (HA)₂ and CdA₂ (HA)₃ for Cd(II), CuA₂(HA)₂ for Cu(II) and ZnAzHA and ZnAz(HA)₂ for Zn(II). The extraction efficiency follows the order Zn(II)<Cu(II)<Cd(II)     

EXTRACTION AND SEPARATION OF HEAVY RARE EARTH(III) WITH EXTRACTION RESIN CONTAINING DI(2,4,4-TRIMETHYL PENTYL) PHOSPHINIC ACID (CYANEX 272)

ABSTRACT

Extraction resins, of the type of Levextrel, (which is a collective term for styrene/divinylbenzene based copolymers of predominantly macroporous structure that contain a selective extractant) are important for the recovery and separation of metal ions, as they combine features of solvent extraction and ion exchange resins. This paper presents the results of the adsorption of heavy rare earth ions (Ho(III), Er(III), Tm(III), Yb(III), Lu(III) and Y(II1)) from hydrochloric acid solutions at 0.2 mol/L ionic strength and 50°C by the extraction resin containing di (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272) and the chromatographic separation of (Er(III), Tm(III) and Yb(III)). Technological separation products, with purity and yield of Tm₂O3 >99.97%, >80%; Er₂O₃ >99.9%, >94% and Yb₂O₃ >99.8%, >80% respectively, have been obtained from a feed having the composition Tm₂O₃ 60%, Er₂O₃ 10%, and Yb₂O₃ 3%, the others 27%.

The distribution coefficients, extraction equilibrium constants and separation factors have been determined as a function of acidity, loading of the resin and rare earths, flow rates and column ratios. The resolutions and efficiencies of separation of Er/Tm/Yb each other have been calculated. The stoichiometry of the extraction of rare earth ions has been suggested as well.     

大孔树脂在高纯过氧化氢生产中的应用

研究了抗氧化性较好的大孔吸附树脂和大孔阴阳离子交换树脂生产高纯过氧化氢的方法。通过实验选择了D990 4作为脱除有机物的树脂 ,在 8BV/h的流速下 ,总有机碳 (TOC)净化度为 88.7%。通过电感耦合等离子直读光谱仪 (ICP)分析离子含量的变化 ,考察了大孔阴阳离子交换树脂的净化效果。在 8BV/h的流速下 ,ICP检出物总净化率达 98.5 % ,总P去除率大于 99.9% ,可满足电子工业的需要。     

REACTION KINETICS OF POLYSTYRENE-BASED PHOSPHINIC ACID ION EXCHANGE/REDOX RESINS WITH METAL IONS

ABSTRACT

The ion exchange/redox kinetics displayed by the phosphinic acid polymer with aqueous solutions of silver and mercury is presented as a function of reaction temperature (6° to 45° C) and solution pH (0 to 5). The network variables studied include the crosslink level and macroporosity. At each pH, increasing the temperature leads to a more rapid approach to equilibrium. The amount complexed at equilibrium is lowest at pH Q relative to the higher pH solutions due to increased H⁺ competition for ligating sites. Metal ion reduction, rather than ion exchange, is the dominant component at equilibrium. Matrix rigidity and macroporosity do not affect Ag(I) kinetics. The rate of Hg(II) sorption is much faster than for Ag(I). Macroporosity is an important variable with mercury: macroporous resins complex more than twice the amount found with gels at 15 minutes contact. It is proposed that Ag kinetics are limited by a slow redox reaction while the Hg kinetics are diffusion-limited due to a fast redox reaction. Differences in reactivity arise from the reaction stoichiometry     

溶剂萃取法分离提取衣康酸

研究了溶剂萃取法提取衣康酸的工艺 .首先进行了萃取剂的选择 .研究了萃取剂浓度、pH值、萃取温度在不同萃取体系中对萃取衣康酸的影响 .并在实验基础上建立了相应萃取分配的数学模型     

草酸与乙醛酸的萃取分离

以草酸和乙醛酸的稀溶液为分离对象 ,采用三辛胺 (TOA)为萃取反应剂、正辛醇为稀释剂 ,研究了单溶质、双溶质有机酸的萃取分离特性 ,测定了溶液pH值、萃取反应剂的浓度等因素对双溶质有机酸萃取的影响 ,提出了萃取的化学反应发生在有机相中的假定 ,建立了TOA萃取草酸的数学模型 .实验结果表明 ,草酸与TOA的萃合物有 1∶1和 1∶2两种形式 .在本实验的条件范围内 ,草酸的分配系数较乙醛酸大 ,且随溶液pH值的增大而下降 ,草酸对乙醛酸的分离系数随pH值的增大而减小 .随萃取反应剂浓度的增大 ,两酸的分配系数皆随之增大 ,分离系数也随之增大 ,而且对于高浓度的萃取反应剂在较高的溶液pH值下草酸仍具有较大的分离系数 .采用单溶质萃取反应平衡常数及纯稀释剂中双溶质的分配系数预测双溶质萃取的结果 ,预测值与实验值相当接近     

乙醇酸与乙醛酸的萃取分离

以乙醇酸和乙醛酸的稀溶液为分离对象,采用三烷基氧磷 (TRPO)为萃取剂、甲基异丁基酮 (MiBK)为稀释剂,研究了单、双溶质有机酸的萃取分离特性,测定了TRPO、有机酸的浓度等因素对单、双溶质有机酸萃取平衡的影响,在适当假定的基础上,建立了描述TRPO萃取乙醇酸、乙醛酸单、双溶质特性的数学模型.结果表明,随TRPO浓度的增大,分离系数β_{（glycolic /glyoxylic）}由小于1逐渐增大至大于1,乙醇酸与TRPO的萃合物有1∶1和1∶2两种形式,采用单溶质萃取反应平衡常数预测双溶质萃取的结果,预测值与实验值相当接近.同时,还对三烷基胺、磷酸三丁酯等萃取剂分离乙醇酸和乙醛酸的特性进行了讨论.     

三辛胺萃取草酸的机理

选择草酸稀溶液为萃取对象 ,采用三辛胺 (TOA)为络合剂 ,正辛醇为稀释剂 ,开展了TOA萃取草酸的机理研究 .以红外谱图为分析手段 ,通过测定络合剂及被萃溶质的浓度对萃合物组成的影响 ,得到其萃合物以 1∶1和 1∶2 (酸 :碱 )两种形式存在于有机相中 ;并通过萃取平衡实验 ,获得了TOA萃取草酸的平衡特性 ,进一步验证了萃合物组成 .以此为基础建立了草酸与TOA两种萃合比情况下的数学模型 ,拟合求得了K₁₁及K₁₂ ,其中 1∶2萃合物的化学萃取平衡常数远远小于 1∶1的相应值     

PURIFICATION OF HYDROCHLORIC ACID BY ISOOCTANE EXTRACTION

ABSTRACT

Removal of organic compounds from hydrocloric acid can be performed by a solvent extraction process followed by a solvent regeneration step by adsorption with sepiolite. The extraction study includes the analysis of the influence of the operating conditions, the determination of the solute distribution coefficient for isooctane and the effect of temperature on the extraction. The adsorption isotherms were calculated to check the technical viability of the method. The obtained efficiency of extraction is close to 90 wt%, whereas that of the solvent regeneration recovery is over 67 wt%     

PPO改性线性酚醛树脂的热降解动力学研究

以聚苯醚(PPO)改性线性酚醛树脂.采用热重分析法研究了不同升温速率下PPO改性酚醛树脂的热降解过程,通过非模型拟合法中的Flynn-Wall-Ozawa法、Friedman法和Kissinger法计算了降解过程的热降解活化能.结果表明,该树脂的热降解活化能随转化率的提高呈现先升高后降低再升高的态势,转化率为10%时,...     

DILUENT EFFECT ON THE EXTRACTION OF URANIUM(VI) FROM HYDROCHLORIC ACID SOLUTIONS BY TRIOCTYLMETHYLAMMONIUM CHLORIDE

ABSTRACT

The extraction of uranium(VI) from hydrochloric acid solutions by trioctylmethylammonium chloride (TOMAC) has been examined using various diluents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m-xylene, nitrobenzene, carbon tetrachloride, chloroform and 1,2-dichloroethane. It was found that by assuming a regular solution, the distribution coefficient and the enthalpy change associated with the metal extraction can be expressed in terms of the solubility parameter of TOMAC, diluent and the complex formed in the organic phase and their molar volumes. Additionally an empirical relation holds between distribution coefficient and the viscosity of diluent. Further results for the extraction of divalent manganese, cobalt, copper, zinc and cadmium from hydrochloric acid solutions by TOMAC are investigated in comparison with those of uranium(VI).     

液膜法从海水中提取溴的动力学研究

本文报导了利用液膜技术从海水中提取溴的动力学的部分研究工作，在不同组分的液膜、不同组分的内相条件下，分别测定了对溴分离，浓缩的反应速率常数，并给出了该反应的简化传质速率方程。     

用DTA研究环氧树脂固化反应动力学

本文用DTA和FIR研究双酚A二缩水甘油醚型环氧树脂与2-乙基-4-甲基咪唑固化反应动力学,探讨了固化反应的机理。结果表明,此固化反应是分步进行的。第一步是加成反应,第二步是催化聚合反应,由此确定适宜采用分段固化工艺。通过DTA曲线推得固化工艺温度,并计算固化反应各步活化能：E1＝36．8kJ．mol-1,E2＝53．gkJ·mol-1。