Einfluss Organischer Lösungsmittel auf die Extraktion von Thorium(IV) und Uran(VI) mit Substituierten Sekundären,Tertiären und Quartären Ammoniumnitraten aus Salpetersauren Lösungen

The influence of ethanol on the distribution of thorium(IV) and uranium(VI) between solutions of nitric acid and solutions of Amberlite LA-2, Trilaurylamine and Aliquat 336-nitrate has been investigated. Increasing amounts of nitric acid and ethanol in the aqueous phase cause an increase of the acid concentration in the organic phase. This concentration can be calculated by a given formula for Amberlite LA-2. The distribution of acid and ethanol is discussed. The distribution ratios of thorium(IV) and uranium(VI) are changed by adding ethanol to the liquid-liquid-system. This can be explained by the shift of the equilibrium of the metal nitrate complexes and by the enhanced extraction of acid.      

Distribution ratio, distribution constant and partition coefficient. Countercurrent chromatography retention of benzoic acid

There is some confusion in chromatography between terms such as solute distribution ratio, distribution constant and partition coefficient. These terms are very precisely defined in the field of liquid-liquid systems and liquid-liquid extraction as well as in the field of chromatography with sometimes conflicting definitions. Countercurrent chromatography (CCC) is a chromatographic technique in which the stationary phase is a support-free liquid. Since the mobile phase is also liquid, biphasic liquid systems are used. This work focuses on the exact meaning of the terms since there are consequences on experimental results. The retention volumes of solutes in CCC are linearly related to their distribution ratios. The partition coefficient that should be termed (IUPAC recommendation) distribution constant is linked to a single definite species. Using benzoic acid that can dimerize in heptane and ionize in aqueous phase and an 18 mL hydrodynamic CCC column, the role and relationships between parameters and the consequences on experimental peak position and shape are discussed. If the heptane/water distribution constant (marginally accepted to be called partition coefficient) of benzoic acid is 0.2 at 20 °C and can be tabulated in books, its CCC measured distribution ratio or distribution coefficient can change between zero (basic aqueous mobile phase) and more than 25 (acidic aqueous mobile phase and elevated concentration). Benzoic acid distribution ratio and partition coefficient coincide only when both dimerization and ionization are quenched, i.e. at very low concentration and pH 2. It is possible to quench dimerization adding butanol in the heptane/water system. However, butanol additions also affect the partition coefficient of benzoic acid greatly by increasing it.     

N，N′-二甲基-N，N′-二辛基-3-氧戊二酰胺从盐酸介质中萃取三价镧系金属的研究

以煤油/辛醇(7:3,V/V)为稀释剂,研究N,N′-二甲基-N,N′-二辛基-3-氧戊二酰胺(DMDODGA)从盐酸介质中萃取三价镧系金属的性能及反应机理;考察了水相盐酸浓度、萃取剂浓度及温度对其萃取性能的影响。结果表明分配比在所研究酸度范围内随盐酸浓度的增加先增大后减小;随萃取剂浓度的增加而增大;萃合物的组成为MCl3.2DMDODGA(M=Sm,Gd,Dy)或MCl3.DMDODGA(M=Er,Lu)。萃取过程为放热反应,升高温度不利于萃取。同时计算出了萃取反应的平衡常数及热力学函数。萃合物的红外光谱表明羰基氧、醚氧均与镧系离子配位。     

Distribution coefficients and cation-exchange selectives of elements with AG50W-X8 resins in perchloric acid

Cation-exchange distribution coefficients with AG50W-X8, a sulphonated polystyrene resin, aie presented for 44 cations in perchloric acid solutions of concentrations varying from 0.1 to 4.0M. The cations are arbitrarily arranged in a table according to their distribution coefficients in 1.OM perchloric acid. Some possible separations are discussed and elution curves are presented for the separation of the ion pairs Zn-Pb, Tl(I)-Bi, Mg-Al and Co(II)-Fe(III). Selectivity sequences for uni-, bi-, ter- and quadrivalent cations are given in which the cations are ordered on the basis of the average numerical value of their distribution coefficients over the straight part of the curve obtained by plotting the logarithm of the distribution coefficient against the logarithm of [H(+)].     

二(2-乙基己基)磷酸与酒石酸衍生物复合萃取拆分扁桃酸外消旋体

本文研究了扁桃酸对映体在含二(2-乙基己基)磷酸(D2EHPA)与酒石酸衍生物复合手性选择剂的正辛醇-水两相体系中的萃取分配行为,考察了酒石酸衍生物的种类和初始浓度、D2EHPA的初始浓度、扁桃酸的初始浓度、萃取温度对分配系数和分离因子的影响.结果显示,复合手性选择剂能提高分配系数和分离因子,D2EHPA与D-酒石酸衍生物的复合手性选择剂与L-扁桃酸对映体比与D-扁桃酸对映体形成更稳定的非对映体复合物;且D2EHPA与二对甲基苯甲酰酒石酸(DTTA)的复合手性选择剂的手性选择性大于D2EHPA与二苯甲酰酒石酸(DBTA)的复合手性选择剂;同时,扁桃酸的初始浓度、萃取温度对分配系数和分离因子的影响较大.     

Mass transfer of weak acid in nanometer-sized pores of octadecylsilyl-silica gel

The sorption of bromophenol blue or anthracene-9-carboxylic acid as a weak acid into single octadecylsilyl (ODS)-silica gel microparticles in a solution was analyzed by microcapillary injection-manipulation and absorption microspectroscopy. The distribution ratio and the sorption rate were highly dependent on the pH of the solution. These results are discussed in terms of the acid dissociation/association, distribution between the ODS and solution phases, and intraparticle diffusion of the weak acid in the nanometer-sized pores of the ODS-silica gel.     

钼(Ⅵ)和钨(Ⅵ)的阴离子交换性能研究——含有机溶剂体系

本文在含有机溶剂的盐酸体系和络合剂-盐酸体系中,研究了铜和钨在强碱性阴离子交换树脂ZerolitEF上的阴离子交换行为.探讨了影响钼和钨在树脂相和溶液相间分配的主要因素及其机理,为大量钼中痕量钨的分离和浓集提供了依据.     

Effects of acid rain on soil humic compounds

The modifications induced by acid rain on the solubility, molecular configuration and molecular weight distribution of humic (HA) and fulvic (FA) acids were studied. A natural soil was subjected to simulated acid rain until a soil pH of 4 was obtained; HA and FA acids were then extracted and characterised. The results obtained were compared both with those of natural soil and with those of a soil subjected to acid rain. Elute analysis indicates the continuous release of soluble organic compounds as a consequence of acid rain simulation, although no relationship was found with the process of soil acidification. The yields of HA and FA show that HA values are the same while FA amount is higher in the natural soil; in acid soils their water solubility increases. The molecular weight distribution shows that HA consist of a mixture of compounds of different molecular weights; they are molecules for the most part larger than 100 kDa and their distribution is not changed by soil acidification. FA can be considered to form a much more homogeneous system; in natural soil, the molecules are larger than 50 kDa, while in acidified soil they are for the most part smaller than 3 kDa.     

Die Verteilung von Uran(IV) zwischen unverdünntem Tri-n-butylphosphat und wäßrigen Salpetersäurelösungen

The distribution ratios of U(IV) in small concentrations between aqueous nitric acid and undiluted tri-n-butylphosphate phases were determined. U(IV) can well be extracted from aqueous nitric acid solutions. The ratio of distribution increases up to nitric acid concentrations 8n in the aqueous equilibrium phase, passes through a maximum between 8n to 9n and decreases again. Some factors of possible importance for the shape of the curve are being discussed briefly.     

Studies on the separation of Pu,Am and Cm with solid and liquid anion exchanges

Systematic studies are carried out on the distribution of Pu(IV), Am(III) and Cm(III) from nitric acid media using solid (Dowex) and liquid (TCMA) anion exchangers. The distribution of these elements from nitric acid-organic solvent mixtures is also investigated. In view of the given results, convenient procedures for interseparation of the mentioned elements are recommended.     

Einfluss Organischer Lösungsmittel auf die Extraktion von Thorium(IV) und Uran(VI) mit Substituierten Sekundären,Tertiären und Quartären Ammoniumnitraten aus Salpetersauren Lösungen

The influence of methanol on the distribution of thorium(IV) and uranium(VI) between aqueous solutions of nitric acid and solutions of Amberlite LA-2, trilaurylamine and Aliquat-336-nitrate has been investigated. The amount of acid in the organic phase increases with increasing concentration of nitric acid and methanol in the aqueous phase. The concentration of acid in the organic phase can be calculated by a given formula for Amberlite LA-2. The distribution of methanol is discussed. The distribution of thorium(IV) and uranium(VI) changes, when methanol is added. This is explained by the shift of the equilibrium of the metal complex and by the enhanced extraction of acid.     

Extraction of uranium(VI) from nitric acid medium by 1.1M tri-n-butylphosphate in ionic liquid diluent

Summary A systematic study on the extraction of U(VI) from nitric acid medium by tri-n-butylphosphate (TBP) dissolved in a non-traditional diluent namely 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆) ionic liquid (IL) is reported. The results are compared with those obtained using TBP/n-dodecane (DD). The distribution ratio for the extraction of U(VI) from nitric acid by 1.1M TBP/bmimPF₆ increases with increasing nitric acid concentration. The U(VI) distribution ratios are comparable in the nitric acid concentration range of 0.01M to 4M, to the ratios measured using 1.1M TBP/DD. In contrast to the extraction behavior of TBP/DD, the D values continued to increase with the increase in the concentration of nitric acid above 4.0M. The stoichiometry of uranyl solvate extracted by 1.1M TBP/IL is similar to that of TBP/DD system, wherein two molecules of TBP are associated with one molecule of uranyl nitrate in the organic phase. Ionic liquid alone also extracts uranium from nitric acid, albeit to a small extent. The exothermic enthalpy accompanying the extraction of U(VI) in TBP/bmimPF₆ decreases with increasing nitric acid and with TBP concentrations.     

Compositional heterogeneity in pectic polysaccharides: NMR studies and statistical analysis

Pectins are a class of heterogeneous polysaccharides used in the food industry as a result of their ability to form gels. They are primarily composed of a (1ŕ4)-α-D-galactopyranosyluronic acid backbone where the carboxylic acid group is methyl esterified at a level which depends on the source of the pectin and processing conditions used to isolate the material. Of considerable interest is the distribution of the free acid and methyl ester groups along this polymer chain. NMR spectroscopy, coupled with statistical analysis, is a powerful technique for the study of sequence distribution of monomers. Experimental conditions (temperature, pD) are reported which are appropriate for the analysis of pectic polysaccharides. Results are presented from a study of sequence distribution in native, modified, and fractionated pectins using ¹H and ¹³C solution NMR methods. The triad sequence information was examined using Bernoullian and Markovian probability models in conjunction with continuous Gaussian distribution and discrete models. Intermolecular heterogeneity in pectins results in triad frequencies which reflect the distribution of acid and ester monomers for native and base saponified pectins. Fractionation of pectin through physicochemical methods and subsequent spectroscopic analysis provide insight into this heterogeneity. Segregation into discrete polymer populations shows a structural diversity best approximated by a 3-component statistical model.     

On the acidity of saponite materials: a combined HRTEM, FTIR, and solid-state NMR study

Acid clays were prepared by exchanging a synthetic saponite in HCl solutions of different concentration (0.01 and 1M, respectively). A combined experimental approach (XRD, HRTEM, N2 physisorption, solid-state MAS NMR, and TGA) was used to investigate on the structural, morphological, and textural features of the samples treated under mild and strong acid conditions. FTIR spectroscopy of adsorbed probe molecules with different basicity (e.g., CO and NH3) was used to monitor the surface acid properties and acid site distribution. XRD and SS-MAS NMR indicated that the activation under mild acid conditions does not alter the clay structure, while a deep modification of the saponite framework occurred after ion exchange in 1 M HCl solution. The presence of porous amorphous silica phase after treatment under strong acid conditions was confirmed by TEM inspection augmented by SS-MAS NMR and FTIR spectroscopy. N2 and Ar physisorption measurements suggested that cavitation phenomena occurred in saponite structure. N2 physisorption confirmed that the porosity and surface area of the samples are strongly modified upon strong acid treatment. FTIR spectroscopy of adsorbed NH3 pointed out that the H-exchange in mild conditions increased the number of surface Br?nsted acid sites. Conversely, these sites are significantly depleted after treatment under strong acid conditions. The use of CO as a FTIR probe molecule, which is applied for the first time to study synthetic acid clays, allowed to monitor distribution and strength of Br?nsted acid sites, whose acidity is similar to that of strong acid zeolites. The Al-OH sites with medium acidity are also found in acid-activated saponites. The distribution of strong and medium acid sites is strictly dependent on the acid conditions adopted.     

Adsorption behaviour of metal ions on hydroximate resins

Some new chelating ion-exchange resins containing a hydroxamic acid moiety attached to a divinylbenzene styrene (DVBS) copolymer, i.e. glycine hydroximate in DVBS (GH-DVBS). anthranilic acid hydroximate in DVBS (AAHDVBS), malonic acid dihydroximate in DVBS (MAH-DVBS) and iminodiacetic acid dihydroximate in DVBS (IDAAH-DVBS). have been synthesized and their various physicochemical characteristics studied. The degree of retention of metal ions by the resins at equilibrium has been determined in terms of the molar distribution coefficient (k(d)). In general, the resins having a dihydroximate moiety are found to be more efficient compared to monohydroximate resins. However, it is of interest to note that the monohydroximate derivative of amino acid (GH-DVBS) showed better metal retention capability than the dihydroximate of carboxylic acid (MAH-DVBS). The selectivity of the resins for transition and highly charged metal ions is quite high compared to that for alkaline earth metals. All the synthesized resins can be utilized for the separation of a mixture of metal ions because the differences in the distribution coefficient values are large enough to permit good separations on columns. However, the GH-DVBS resin was tried for the separation of copper cobalt and copper nickel mixtures at pH 5.5 using the column mode of operation.     

Die Extraktion von Uran(IV) aus wäßrig-organischen Salpetersäurelösungen mit dem Nitrat des sekundären Amins Amberlite LA-1

The distribution of U(IV) between methanolic, ethanolic and acetonic aqueous nitric acid solutions and the nitrate of the secondary amine Amberlite LA-1 in cyclohexane was investigated. The distribution of the excess acid and the alcohol (acetone) was also investigated. The U(IV) distribution data were correlated with 1) the content of nitric acid and U(IV)-hexanitratocomplex in the mixed aqueous-organic phase and 2) with the concentration of excess acid and methanol (acetone) in the organic phase. These correlations indicate that the extraction of U(IV) is mainly determined by 1) the shift of the complex equilibrium from the side of cationic species to that of neutral and anionic complexes and 2) the competition between these metal complexes and the acid as solvating partners for the extractant molecules. Spectrophotometric investigations show that in the organic phase uranium is present as a hexanitrato complex.     

The adsorption behaviour of99Mo(VI),238U(VI),95Zr(IV) and95Nb(V) on alumina

The distribution of Mo(VI) and the interfering radiocontaminants U(VI), Zr(IV) and Nb(V) have been investigated between chromatographic alumina and aqueous hydrochloric acid solutions of concentrations ranging from 0.5M to 11M. At low acidities (less than 1M HCl) the distribution coefficients increase with the decrease of acid concentration, while in the region of 2–4M they increase with the increase of the acid concentration. Above 4M HCl, the increase inK _D continues with the acid concentration for both Zr(IV) and Nb(V), but constant values are reached for U(VI) and Mo(VI).     

Separation studies of molybdenum(VI) and rhenium(VII) using TPPO as an extractant

A simple, rapid and reproducible method for the extractive separation of molybdenum(VI) and rhenium(VII) is proposed using triphenylphosphine oxide (TPPO) dissolved in toluene as an extractant. The extractions are carried out from the hydrochloric and hydrobromic acid medium. The extraction of molybdenum is quantitative from 2.54-3.10 M hydrochloric acid and from 3.76-3.98 M hydrobromic acid, and that of rhenium is from 6.78-7.91 M hydrochloric acid. The probable nature of the extractable species is established using log distribution ratio-log concentration plots. The method permits mutual separation of molybdenum(VI) and rhenium(VII) and is applicable for the analysis of alloys and pharmaceutical sample. The detection limits for molybdenum(VI) and rhenium(VII) are 0.8 ppm and 4 ppm respectively.     

Comparison of ligands for the recovery of trace aluminium(III) by anion-exchange

The preconcentration of aluminium(III) traces in the form of anionic complexes on an anion-exchanger is described. The ligands used to form anionic complexes are hydroxide, sulphosalicylic acid, chromotropic acid and 2-(4-sulphophenyl)-1,8-dihydroxynaphthalene-3,6-disulphonic acid. Recoveries were evaluated under different conditions and in the presence of potential interferences (surfactants, inorganic salts, organic anions). The experimental behaviour is compared with that which can be predicted from the computed distribution of the different species. The results show that chromotropic acid is superior for the recovery and preconcentration of Al(III).     

氨基酸在乙醇/磷酸氢二钾双水相体系中分配行为

研究了5种结构和性质各异的氨基酸(谷氨酸,半胱氨酸,苯丙氨酸,赖氨酸,精氨酸)在亲水性有机溶剂乙醇和磷酸盐溶液形成的乙醇/K2HPO4双水相体系中的分配行为及其影响因素。当双水相体系中乙醇的质量分数从22%增加到30%时,半胱氨酸和苯丙氨酸的分配系数明显增大,其它三种氨基酸的分配系数变化幅度不大;当磷酸盐的质量分数从14%增加到22%时,氨基酸的分配系数的变化均不明显;双水相体系的pH值对氨基酸的分配系数影响较大,当pH增加时,5种氨基酸的分配系数均增加,但是当pH约为9.5时,苯丙氨酸、半胱氨酸的分配系数接近相等但与其它3种氨基酸的分配系数相差较多,当pH为6.0~8.0时,苯丙氨酸的分配系数远远大于另外4种氨基酸。氨基酸的支链结构中含有非极性基团将导致其分配系数的增加。