吡啶从硝酸介质中萃取铀(Ⅵ)的研究

研究了新萃取剂吡啶从硝酸介质中萃取铀的机理。考察水相硝酸浓度、萃取剂浓度、盐析剂硝酸钠以及振荡时间和温度对萃取分配比的影响，确定了萃合物的组成。求得萃取硝酸铀酰过程的平衡常数及反应的热力学函数。同时研究了相比的影响，以及稀释剂的影响。发现吡啶萃取能力在不同稀释剂中由弱到强的顺序为：四氯化碳、氯仿、苯、甲苯、环己烷、煤油。     

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     

DCH-18-C-6/乙酸乙酯萃取体系萃取分离铀(Ⅵ)的研究

以二苯并-18-冠醚-6(DCH-18-C-6)作为萃取剂,采用溶剂萃取法萃取分离溶液中的铀(Ⅵ),研究了稀释剂、盐析剂、介质酸度等条件对萃取率的影响,确定了乙酸乙酯为稀释剂,0.1 mol/L的KH2PO4为盐析剂、水杨酸为酸性介质的溶剂萃取体系。该萃取体系在选定的条件下,对1×10-4mol/L的铀酰离子一次萃取率可达82.5%。     

新试剂DBPMP用于铀的萃取光度法测定研究

本文将新型螯合萃取剂DBPMP用于铀的萃取光度法研究。提出了一种选择性好,灵敏度高的测定方法。铀浓度在0～5.0mg/25ml范围内符合比尔定律。将本法用于矿石中铀的测定,结果满意。     

腐植酸对叔胺萃取铀的影响

简要叙述了腐植酸的主要性能,论述了腐植酸对叔胺-煤油溶液萃取铀和反萃取铀过程的影响。腐植酸与腐植酸铀酰盐对叔胺-煤油溶液萃取铀将降低萃取效率,并形成乳化。在反萃取铀过程中,实践表明,采用腐植酸脱除剂Na2CO3作为反萃取剂进行反萃取,可以有效把叔胺-煤油溶液中负载的铀、腐植酸铀酰盐以及腐植酸反萃取下来,铀的反萃取率达98%以上,腐植酸的脱除率达99%以上;且两相之间无乳化膜。     

P507从盐酸介质中萃取铑(Ⅲ)的研究

本文对P507（2-乙基已基膦酸单酯）从盐酸介质中萃取铑的可能性作了研究,在适宜的条件下，氨化后的P507对铑的水合阳离子萃取，萃取率可达99％以上，反萃取率可达99．9％以上。     

单级萃取—反萃取同时分离回收磷酸中铀和稀土

使用单级萃取－反萃取工艺，从湿法磷酸（ＷＰＡ）中回收铀和稀土的新工艺，既简单又易于控制，因为它只涉及酸性介质。该工艺是基于用二（２－乙基己基）磷酸（ＤＥＰＡ）和磷酸三丁酯（ＴＢＰ）和磷酸三丁酯（ＴＢＰ），从湿法磷酸中萃取铀和稀土。发现ＤＥＰＡ是唯一有效的，它稳定并且易于反萃取。其它的有机磷酸酯易水解，并且很难反萃取。用含有酸性氟化物的介质，对稀土和铀进行反萃取。对于铀来说，以六价（Ｕ＾６＋）形成被     

MNA-TBP从盐酸介质中萃取Ir(Ⅳ)

对ＭＮＡ－ＴＢＰ从盐酸介质中萃取Ｉｒ（Ⅳ）作了研究．结果表明：ＭＮＡ－ＴＢＰ对Ｉｒ（Ⅳ）萃取有协同效应．当ＭＮＡ和ＴＢＰ在正辛烷中的浓度各为０．４５ｍｏｌ／Ｌ，待萃液中ＨＣｌ总浓度为４ｍｏｌ／Ｌ，铱浓度为１７３．１３μｇ／ｍｌ，相比为１时，协萃系数Ｒ为２．３３，协萃合物的组成为（ＭＮＡＨ）＋．ＩｒＣｌ＄２－６．（ＨＴＢＰ）＋．     

Extraction of Lanthanides with Diamides of Dipicolinic Acid from Nitric Acid Solutions. I

Abstract

Three ortho-, meta-, and para-derivates of ethyl(tolyl)diamides of dipicolinic acid were synthesized and tested on their extraction performance from nitric acids solutions. Extraction of americium and lanthanides (Ln) by these compounds as a function of nitric acid concentration was studied. Distribution ratios of studied metals were determined using ICP-OES method and radiotracer ²⁴¹Am. Am/Ln separation differs among studied diamides, and the best separation was found for N,N′-diethyl-N,N′-di(ortho)tolyl-diamide.     

The Extraction of Uranium(VI) from Mineral Acid Solutions by Di-4-octylphenylphosphoric Acid (DOPPA)

Abstract

The extraction of uranium(VI) from sulfuric, hydrochloric, nitric, and perchloric acid was studied using dioctylphenylphosphoric acid (DOPPA) in heptane as extractant. At low aqueous acid concentration, an ion-exchange mechanism was generally observed and the extracted species was of the type UO₂A₄H₂. Deviation from this behavior was observed at higher acid concentrations. From perchloric acid solutions, after an initial decrease, the extraction coefficient increased after 3 to 4 N acid. Some of the explanations offered in the literature for this behavior in the case of di-2-ethylhexylphosphoric acid (DEHPA) have been critically examined. Extraction of mineral acids, particularly HCI and HNO₃, was also observed with DOPPA but to a lesser extent than with DEHPA.     

Rapid Solvent Extraction of Uranium(VI) with N-Phenylbenzohydroxamic Acid

Abstract

A rapid method for the simultaneous solvent extraction and spectrophotometric determination of macro-amounts of hexavalent uranium with N-phenyl-benzohydroxamic acid is described. The intense blood-red colored complex thus extracted from chloroform at pH ～ 4 absorbs at around 510 nm. A clean-cut separation from many commonly occurring metal ions is easily accomplished. Effects of acidity, reagent concentration, and diverse ions on the visible absorption of the extracted complex have also been investigated.     

Solvent Extraction of Uranium (VI) from Chloride Solutions using Cyphos IL-101

The solvent extraction of uranium (VI) from chloride solutions by Cyphos IL-101 in xylene has been studied. Distribution coefficients were found to increase with aqueous chloride concentration and extractant concentration. The enthalpy of extraction is endothermic with ΔH = +24 ± 2 kJ·mol^?1. Based upon slope analysis, an anion exchange extraction mechanism is proposed, with formation of a UO₂Cl₄ ^2- complex in association with 4 Cyphos IL-101 ligands. The extraction kinetics were fast, with complete equilibration occurring within 30 seconds. An isotherm for uranium extraction from 1.0 mol·L^?1 chloride solution by 0.1 mol·L^?1 Cyphos IL-101 in xylene shows that 45 mmol·L^?1 uranium can be loaded into the organic phase in equilibrium with 2.1 mmol·L^?1 in the aqueous phase. The absorption spectrum of the uranium loaded solvent between 350 and 550 nm is indicative of the UO₂Cl₄ ^2- complex with only chlorides present in the inner coordination sphere, unlike the more strongly hydrogen bonded Alamine 336 extracted uranium complex. Subject to the same experimental conditions, distribution coefficients for Cyphos IL-101 were significantly greater than for Alamine 336 or Aliquat 336.     

The Solvent Extraction of Uranium(VI) by N-m-Tolyl-o-methoxybenzohydroxamic Acid

Abstract

A simple and rapid spectrophotometric determination of uranium(VI) is described. The uranium(VI) N-m-tolyl-o-methoxybenzohydroxamic acid complex is extracted with chloroform at pH 5.3 to 5.5 from aqueous solution. Maximum absorption of orange-red extract occurs at 510 nm. The colored complex obeys Beer's law over the range 0.3 to 20 ppm of uranium. The effect of acidity, reagent concentration, and diverse ions on the visible absorption of extracted complex has been studied.     

Adsorption of Uranium(VI) and Zirconium(IV) from Acid Solutions on Silica Gel

Abstract

Adsorption of uranium(VI) and zirconium(IV) from aqueous solutions on silica gel was investigated by the batch equilibration method. The influence of shaking time and concentrations of nitric acid (i.e., pH of solution) and metal ions in solution were studied. Adsorption of uranium(VI) and zirconium(IV) increases with an increase of pH (decrease of nitric acid concentration) and ion concentrations. The adsorption mechanism of uranium(VI) and zirconium(IV) from aqueous solutions on silica gel is proposed. It is shown that zirconium(IV) and uranium(VI) can be separated if the concentration of nitric acid in solution is higher than 0.01 mol/dm³.     

Extraction of Nitric Acid into Alcohol: Kerosene Mixtures

Abstract

Nitric acid extraction from 0.1 mol/L – 5 mol/L nitric acid into varied volume fractions (5%–100%) of long-chain aliphatic alcohols (1-hexanol, 1-octanol, 2-ethylhexanol, 1-decanol) in alkanes (different kerosenes, n-dodecane, isooctane) was measured. At equal molar alcohol concentration, 1-hexanol, 1-octanol, and 1-decanol extract equal amounts of nitric acid. The amount of nitric acid extracted into 2-ethylhexanol is approxmately half compared to 1-octanol. The alkane does not influence nitric acid extraction. Extraction can accurately be calculated taking into account the formation of a species (HNO₃)(ROH)₂. Due to the change in diluent properties with alcohol volume fraction, conditional equilibrium constants must be used.     

Extraction of U(VI), Th(IV), and Lanthanides(III) from Nitric Acid Solutions with CMPO-Functionalized Ionic Liquid in Molecular Diluents

The extraction of microquantities of U(VI), Th(IV), and lanthanides(III) from nitric acid solutions with CMPO-functionalized ionic liquid 1-[3[[(diphenylphosphinyl)acetyl]amino]propyl]-3-tetradecyl-1H-imidazol-3-ium hexafluorophosphate, CMPO-FIL(I) in molecular organic diluents has been studied. The effect of HNO₃ concentration in the aqueous phase and that of extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes was determined. CMPO-FIL(I) demonstrates greater extraction ability towards Ln(III) than its neutral CMPO analog, diphenylphosphorylacetic acid N-nonylamide. This inner synergistic effect increases with a decreasing organic diluent polarity. The partition of CMPO-FIL(I) between the equilibrium organic and aqueous phases is the dominant factor governing the extractability of Ln(III) ions in the extraction system.