EXTRACTION OF PHOSPHORIC ACID FROM NITRATE SOLUTIONS WITH ISOAMYL ALCOHOL

The extraction of phosphoric acid with isoamyl alcohol from aqueous solutions relevant to and produced by leaching of phosphatic iron ore by nitric acid has been studied. The results indicate that the extraction of phosphoric acid is not temperature dependent in the range 25–40°C, and that it increases with increasing the concentration of HNO₃ or H₂SO₄. The salting-out effect of the different nitrate salts on the extraction of phosphoric acid is found to be in the order of Mg²⁺> Ca²⁺ > Na+> NH+₄ K+. The presence of Fe³⁺ and Al³⁺ may reduce the extraction of phosphoric acid. Phosphoric acid can be extracted selectively against the different nitrate salts but nitric acid is coextracted. The excess coextraction of nitric acid from the aqueous phase will result in the precipitation of some phosphate complexes of Fe, Al, Ca, etc. Some tests of the continuous multistage extraction were also performed and a flowsheet for the recovery of the phosphoric acid is suggested.     

Application of Single-Ion Activity Coefficients to Determine the Solvent Extraction Mechanism for Components of High-Level Nuclear Waste

Abstract

The TRUEX solvent extraction process is being developed to remove and concentrate transuranic (TRU) elements from high-level and TRU radioactive wastes that are currently stored at U.S. Department of Energy sites. Phosphoric acid is one of the chemical species of concern in the application of solvent extraction processes for removal of actinides, for instance at the Hanford site, where bismuth phosphate was used to recover plutonium.

The mechanism of phosphoric acid extraction with TRUEX-NPH solvent at 25°C was determined from phosphoric acid distribution ratios, which were measured by using a phosphoric acid radiotracer and a variety of aqueous phases containing different concentrations of nitric acid and nitrate. A model was developed for predicting phosphoric acid distribution ratios as a function of the thermodynamic activities of nitrate ion, and hydrogen ion. The Generic TRUEX Model (GTM) was used to calculate these activities based on the Bromley method. The derived model supports extraction by CMIO and TBP in TRUEX-NPH solvent of a phosphoric acid-nitric acid complex and a CMPO-phosphoric acid complex.     

A CHEMICAL MODEL OF THE SOLVENT EXTRACTION SYSTEM: NITRIC ACID- URANYL NITRATE- WATER - TRI-n-BUTYL PHOSPHATE (TBP) - DILUENT

ABSTRACT

A mathematical model founded on the equilibrium constants expressions has been developed for the simultaneous extraction of nitric acid and uranyl nitrate with TBP in alkane diluents. The model uses chemical activities of nitric acid and uranyl nitrate in the aqueous phase and the stoichiometric concentrations of their TBP solvates in the organic phase. The apparent formation constants of the species (TBP)₂, (TBP)₂HNo₃, TBPHNO₃, and UO₂(NO)₃ 2TBP, present in the organic phase, have been established. The model fits well the distribution results over the whole concentration range of the extraction isotherms, and extractant concentrations 5–10% TBP. The starting data are the chemical activities of nitric acid and uranyl nitrate in the aqueous phase and their stoichiometric concentrations in the organic phase.     

Extraction and Stripping Behavior of Iron (III) from Phosphoric Acid Medium by D2EHPA Alone and Its Mixtures with TBP/TOPO

In the present study an attempt has been made to understand the extraction and stripping behavior of iron (III) with D2EHPA alone and its mixture with TBP or TOPO in phosphoric acid medium. Effect of variables such as concentrations of iron (III), phosphoric acid, and phosphate in the aqueous phase, D2EHPA, TBP, and TOPO concentrations in the organic phase and temperature on the extraction process has been studied. The extraction of iron (III) decreased with increase in phosphoric acid concentration. The increase in D2EHPA concentration increased the extraction of iron (III). The presence of TOPO or TBP with D2EHPA showed antagonism. The increase in temperature decreased the extraction of iron (III) with D2EHPA alone and its mixture with either TOPO or TBP showing the exothermic nature of the extraction reaction. The stripping of iron (III) by various reagents followed the order: oxalic acid > phosphoric acid > hydrochloric acid > sulphuric acid > mixture of sulphuric and hydrofluoric acids > ascorbic acid > citric acid irrespective of extraction systems. Higher temperature favors the stripping. The effect of diluents on iron (III) extraction has also been studied. The mechanism of extraction has been explained in the light of the results obtained.     

A STUDY OF COMPLEXES YIELDED BY HNO3 Fe(III)AND Eu(III) EXTRACTION FROM NITRATE MEDIA WITH ACIDIC Zr(IV) AND Hf( IV) DI-2-ETHILHEXYLPHOSPHATES

Possible reasons for significant enhancement of solvent extraction of some metals with dialkylphos-phoric acids in the presence of Zr(IV) and Hf(IV) are critically discussed, taking into consideration both the literature and the autors'data on the structure of acidic salts formed by these acids with Zr(IV) and Hf(IV). The chemistry of extraction of nitric acid, FeUII) and Eu ( I I I ) with Zr(IV) and Hf(IV) salts of di-2-ethy1hexy1 phosphoric acid (HX) has been studied using IR and ³¹P NMR spectroscopy. Nitric acid is extracted by these salts due to interaction with their acceptor sites that results in the formation of a new polymeric extractant with bidentate anions of two types, (X-H-X)- and (X-H-N0₃)_. Protons of these groups can be exchanged with metal cations extracted, e.g., with Fe(III) or Eu(I 11 ), heteropolynuc1 ear complexes with non-equivalent (chelating and bridge) N0₃ anions being formed during the extraction. The composition and structure of coordination polyhedrons formed around Zr(IV), Hf(IV), Fe(III) and Eu(III) have been determined. The reasons for a higher extraction ability of the salts studied for Fe(III) and Eu(III) versus D2EHPA itself are described.     

THE EXTRACTION OF Eu(III) FROM ACIDIC MEDIA BY OCTYL(PHENYL)-N,N-DIISOBUTYL CARBAMOYLMETHYLPHOSPHINE OXIDE.

The extraction behavior of Eu(III) from nitric and hydrochloric acid By solutions of CMPO with and without TBP has been studied using mesitylene and dodecane as diluents. Compared to CMPO alone, the CMPO-TBP mixture shows a slight enhancement in the extraction of Eu(III) from nitric acid above 2M and lower DEu’ s from low acidity. The distribution ratios measured for Eu(III) between HN03 and CMPO-TBP in dodecane are higher than the corresponding values in mesitylene.Extractant dependency studies in the presence and absence of TBP show that at low HN03 concentrations, the extractant dependency curve obtained in the presence of TBP lies below the curve obtained in the absence of TBP. At high acidity, the opposite is observed. The extraction of Eu(III) from hydrochloric acid by CMPO-TBP in dodecane is much lower than from nitric acid. A comparison between CMPO and D2EHPA for Eu(III) extraction has been carried out.     

Nitric Acid Extraction into the TODGA/TBP Solvent

The tridentate diglycolamide ligand N,N,N′,N′-tetraoctyl diglycolamide (TODGA) shows many interesting properties and is a very good extractant for the minor actinides (MAs) and lanthanides but, due to its low loading capacity, requires a phase modifier when used in a solvent extraction process. Consequently, applications of TODGA in conjunction with tri-butyl phosphate (TBP) in novel DIAMEX and SANEX processes for recovering MAs have been reported. However, TODGA and TBP also extract nitric acid and this has a significant influence on process performance. Here new distribution data for the extraction of nitric acid into solvent phases containing TODGA and TBP have been collected and modeled using an equilibrium-based approach accounting for nitric acid activities in the aqueous phase. Models for the extraction of nitric acid using the individual extractants were obtained using a variety of complexes and these were then combined to give the extraction of the mixed TODGA and TBP solvent. Using this approach, the nitric acid extraction of the mixed TODGA/TBP system can be reliably reproduced indicating that no significant synergistic or antagonistic complexes are formed in solution.     

THE EXTRACTION OF Am(III) FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE - TRI-n-BUTYL PHOSPHATE MIXTURES

Abstract

The extraction behavior of Am(III) from nitric acid by octy1(phenyl)-N,N-diisobutylcarbamoyl methyphosphine oxides, OØD[IB]CMPO, in the presence of tributylphosphate, TBP, has been studied using diethylbenzene, decalin, and normal aliphatic hydrocarbon diluents. Relative to ØD[IB]CMPO alone, mixtures of TBP and OØD[IB]CMPO show a slight enhancement in the extraction of Am(III) from nitric acid solution above 2 M and a moderate decrease in extraction for lower acid concentrations. The net effect of TBP addition to OØD[IB]CMPO (as well as other selected carbamoyl methylphosphoryl extractants) is a relative insensitivity of the distribution ratio of Am(III) to HNO₃ concentration in the range of 0.5 M to 6 M and facilitated stripping of Am(III) with dilute acid. Since a continuous variation study of Am(III) extraction using mixtures of ØOD[IB]CMPO and TBP at a fixed total concentration revealed no evidence of a mixed complex, the TBP appears to be behaving primarily as a phase modifier

The most significant benefit gained from addition of TBP to ØD[IB]CMPO is the increased metal ion loading capacity and extractant compatibility with alicyclic and aliphatic diluents. The use of TBP to overcome phase compatibility with other bifunctional extractants of the carbamoylmethylphosphoryl type and the use of other phase modifiers with ØD[IB]CMPO have also been investigated.     

Thermodynamical and catalytic aspects of zinc separation from aqueous solution

The present research work examines extraction mechanism of zinc by D2EHPA (Di-2-ethyl hexyl phosphoric acid) and comprehensively studies the main effective parameters on the process. Results of thermodynamic experiments showed that zinc extraction by D2EHPA was endothermic and spontaneous, and thermodynamic parameters including entropy and enthalpy were+27.37 J·mol^-1·K^-1 and 25.21 kJ·mol^-1, respectively. Gibbs free energy was varied between -7.21 kJ·mol^-1 and -8.41 kJ·mol^-1 with the variation of temperature from 20℃ to 70℃. Solution ionic strength was increased by addition of potassium and lithium sulfate solution while addition of calcium sulfate decreased ionic strength whereby zinc extraction efficiency was also decreased. TBP showed positive synergism at concentration of 5% (v/v) and negative synergism effect at concentrations of 2% and 10%. Simultaneous addition of both TBP and salt caused extraction efficiency to drop significantly and lower both TBP and ionic strength efficiency. Results showed that a continuous addition of TBP tends to effectively improve the zinc extraction efficiency. Experiments in the presence of catalyst Ni-Raney demonstrated that zinc extraction kinetic increases remarkably and due to easy recycling of the catalyst, we can propose a novel idea in solvent extraction field.     

复合萃取剂在微分散萃取湿法磷酸中的应用

本文采用名义孔径为20μm的烧结网作为分散介质,以水/磷酸/TBP+异丙醚和水/磷酸/TBP+煤油作为体系,研究了相比、磷酸质量分数、流量对萃取率及单级效率的影响。实验结果表明:水/磷酸/TBP+异丙醚体系的萃取率与单级效率优于水/磷酸/TBP+煤油体系。相比对萃取率及单级效率的影响较大;磷酸质量分数对萃取率的影响较大,对单级效率的影响较小;而流量对二者的影响均较小。以TBP+异丙醚为复合萃取剂,在流量为1000mL/min,磷酸质量分数为50%,相比为4∶1时,萃取率可达44.40%,单级效率83.32%,反萃率80.21%。     

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.     

乳化液膜法脱除磷酸中镉的研究

镉是磷酸中的有害杂质之一,其对环境的污染和对人体的毒害日趋严重,所以必须控制磷酸中镉等有害杂质的含量。用乳化液膜法除去磷酸中的镉,采用单因素实验法,重点考察了表面活性剂Span-80,T151,T154及用量、萃取剂TBP,P204及用量、萃取时间对脱除磷酸中镉的影响。结果显示：表面活性剂T154用量为2.0 mL及萃取剂P204用量为2.0 mL时,乳化液膜具有较好的稳定性,且萃取时间为15 min时,从磷酸中除镉的效果最优。     

Extraction of some mineral acids by high molecular weight quaternary ammonium chloride

The distribution equilibria of hydrochloric, nitric, perchloric, sulphuric and phosphoric acids between aqueous solutions and a solution of tricaprylmethyl-ammonium chloride in organic solvent have been investigated. The organic phases have been studied by infra-red and nuclear magnetic resonance spectroscopy. As a result, it is found that at low aqueous acidity the extraction of these acids is governed by the ion exchange reaction, forming the mono-quaternary ammonium salts of monobasic acids and the mono-, di- (and tri-) quaternary ammonium salts of di- (and tri-) basic acids, and at higher acidity by the formation of the adducts to quaternary ammonium salts with additional acids.     

二（2-乙基己基）磷酸/磷酸三丁酯复合萃取剂协萃对氨基苯甲酸

为强化两性官能团化合物的萃取分离性能,以对氨基苯甲酸（PABA）为被分离溶质,二（2-乙基己基）磷酸（D2EHPA）/磷酸三丁酯（TBP）/正庚烷的混合物为萃取剂进行了萃取平衡特性的研究,考察了溶液的pH值、D2EHPA浓度、TBP浓度对于萃取平衡的影响,建立了复合萃取剂协同萃取PABA的萃取平衡分配系数的表达式.结果表明,D2EHPA/TBP/正庚烷复合萃取剂萃取PABA具有明显的协萃效应,协萃机理为D2EHPA及TBP分别与PABA的Lewis碱性官能团（—NH2）和Lewis酸性官能团（—COOH）缔合形成亲油性更强的萃合物,且D2EHPA与TBP的浓度差异越小,协萃效应越明显.根据萃取平衡分配系数表达式拟合求取了表观萃取平衡常数,复合萃取剂的值远大于D2EHPA、TBP单独作为萃取剂的值,进一步证明了本文提出的协萃机理.     

液膜法提取单质金的迁移机理及其应用

本文研究了用磺化煤油作稀释剂时磷酸三丁酯从王水溶液中萃取Ａｕ的萃合比，证明了溶液中ＨＮＯ或ＮＯ＾－３在酸度小于３．０ｍｏｌ／ｄｍ６３时对ＴＢＰ萃取Ａｕ的萃合比没有影响，分析了液膜选择性迁移Ａｕ的机理；研究了以ＴＢＰ为载体的乳状液膜以王水为介质的含Ａｕ，Ｃｕ，Ｎｉ的电镀废水中的选择性回收Ａｕ，内水相得到纯度９９．９５的黑色粉末单质Ａｕ，一级回收率为９９．９％。．     

A New Approach to Simulation of Extraction Equilibria in the PUREX Process

A new approach to simulation of interphase equilibrium at extraction of actinides in various valent states, some fission products, and admixed acids from nitric acid media in the presence of salting out agents by diluted TBP has been developed. It is based on a set of simultaneous chemical reactions, including salvation, hydrolysis, complexing, etc., characterized by apparent concentration constants. A software package was created for simulation of spent fuel component distribution in multistage countercurrent extraction processes.     

反应萃取法制备熔盐级硝酸钾工艺探讨

反应萃取法是一种低成本、高效制备熔盐级硝酸钾的方法。研究了氯化钾和硝酸结晶萃取制备熔盐级硝酸钾的工艺,通过参数优化,得到了实验室条件下最佳的反应结晶条件：HNO₃与KCl物质的量比为（1.4~1.5）∶1,冷却结晶温度为5~10 ℃,冷却结晶时间为60 min,并通过重结晶获得了纯度大于99.4%的熔盐级硝酸钾。母液中的硝酸在萃取温度为30 ℃、磷酸三丁酯（TBP）体积分数为30%、油水相比为5∶1时能被磷酸三丁酯TBP和磺化煤油组成的萃取体系有效萃取。     

磷酸三丁酯和异丁基十二烷基亚砜萃取铀(VI)的研究

研究了以甲苯作稀释剂时 ,磷酸三丁酯 (TBP)和异丁基十二烷基亚砜 (BDSO)萃取铀 (VI)的机理。考察了硝酸浓度、温度对分配比的影响 ,求得萃取反应的热力学函数。考察了萃取剂浓度对协萃系数的影响 ,发现TBP和BDSO具有协萃效应 ,最大协萃系数在TBP :BDSO =1:1处     

Adsorption off Lauryl Sulfate from Electrolyte Solutions on Cobalt Hydroxide

Abstract

The adsorption of lauryl sulfate on cobalt(II) hydroxide from solutions of inorganic salts has been found to change as follows: without salt ≥ chloride ≥ bromide ≥ nitrate ≥ sulfate ≥ phosphate Adsorption in the presence of acids increases in the following series: without acid ≥ hydrochloric ≥ sulfuric ≥ phosphoric, and is higher than in the presence of salts. The surface concentration of lauryl sulfate adsorbed from a suspension without electrolyte is about 0.9 (μmol/ m². The surface coverage of hydroxide by lauryl sulfate is about 1/5 of a monolayer, but it decreases in the presence of electrolyte. The law of mass action was applied to characterize the effect of solution composition on the adsorption of lauryl sulfate on cobalt(II) hydroxide.