KINETICS OF SOLVENT EXTRACTION OF LANTHANIDE COMPLEXES OF MACROCYCLIC DIAMINODICARBOXYLIC ACIDS

Studies of the kinetics of extraction of La(III), Eu(III), and Lu(III) complexes of 1,7-diaza-4,10,13-trioxacyclopentadecane-N,N′-diacetic acid (DAPDA) and l,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N′-diacetic acid (DACDA) have been carried out at pH 5.5 and 7.5. Thenoyltrifluoroacetone (TTA) was employed as the extractant in chloroform. The rates of extraction were found to be influenced by the nature of the extracted species. For the binary species, Ln(TTA),, the rates were governed by the dissociation rates of their macrocyclic complexes in the aqueous phase and were relatively slow. For some cases where extractions involved predominantly ternary species, Ln(DAPDA/ DACDA)TTA, the rates were relatively fast and independent of the aqueous macrocyclic complex dissociation rates. The significance of the rates of solvent extraction were discussed.     

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).     

AN EXTRACTION STUDY OF LANTHANIDE CHLORO COMPLEXES THE AD0GEN-464C1 - LiCl SYSTEM

The distribution of lanthanides and yttrium between o-xylene solutions of Adogen-464Cl and aqueous solutions of LiCl was investigated over a broad range of LiCl and extractant concentrations. It has been found that stability constants of inner sphere lantha-nide chloro complexes decrease across the series, whereas the equilibrium constants for the transfer of the negatively charged chloro complexes increase with increasing lanthanide atomic number.     

不对称五氮齿镉和铟大环配合物的激发态性能研究

本文研究了不对称五氮齿镉和铟大环配合的的激发态性能及其光稳定性。结果表明：它们的三重态能量在１２０ｋＪ／ｍｏｌ左右,最低激发三重态敏化产生单重态氧的量子产率在０．６￣０．９,它们的分子一阶超极化率在￣１０＾－２８ｅｓｕ,在光照的条件下,配合物Ⅰ相当稳定,而配合Ⅱ则形成不稳定化合物导致光褪色。     

AN EXTRACTION STUDY OF LANTHANIDE NITRATO COMPLEXES THE ADOGEN-464NO3- NH4NO3SYSTEM.

ABSTRACT

Extraction of lanthanides and yttrium was studied in the interval of ammonium nitrate concentrations from 1 to 10M, and of Adogen-464 nitrate concentrations from 0·00039 to 0·39M. From the aqueous phase separation factor and from the published stability constant for Eu, stability constants for 1:1 complexes of La, Nd, Gd, Ho, Tm, Lu and Y have been determined, at 1M ammonium nitrate concentration. It was found that stability constant decreases from 2·7 for La to 2·3 for Lu. It has been shown that in the interval of Adogen-464 nitrate concentrations employed, lanthanides from La to Nd appear in the organic phase as 1:5 complexes, whereas lanthanides heavier than Nd appear also as 1:4 complexes. Relative values (with regard to lanthanum) of Gibbs energy, enthalpy (from the temperature effect) and entropy for formation of 1:5 complexes,and the position of yttrium within lanthanides have been determined. It is concluded from the experimental data that the extracted 1:4 and 1:5 complexes are of the inner sphere type, with nitrate ions acting as bidentate ligands, and that the contribution from covalency to bonding is the same in the aquo ion and in the 1:5 nitrato complex.     

INFLUENCE OF THE AMINE NATURE ON THE COMPOSITION OF PALLADIUM COMPLEXES IN SOLVENT EXTRACTION SYSTEMS

ABSTRACT

The extraction of palladium chloro complexes by di-n-octylamine and diamines of various structure as function of the composition of the aqueous and organic phases has been studied. The compositions of the extracted species are indicated and the mechanisms of their distribution are described. It was shown that from 1 to 3 M HC1 solutions. complexes such as (R₂NH₂)₂PdCl₄ solvated by molecules of dioctvlamine chloride are extracted. With increasing the initial concentrations of palladium or decreasing acidity of the aqueous phase, a direct coordination takes place, first of one and then two molecules of amine to atom of palladium with the formation of extracted compounds such as HC1 solutions by salts of amines, diamines and QAB ionic associates such as (AmH)₂PdCl₄, (AmH)₂)PdCl₄ and (R₄N)₂PdCl₄, respectively, are recovered into the organic phase. In systems containing trioctylamine, tetraoctylalkylenediamines (n = 4, 6) and QAB. ionic associates containing the dimeric complex anion, Pd₂Cl₆ ^2-, are also formed. When primary (n-octylaniline - OA) and secondary amines are used as extractants the formation of dimeric species in the organic phase is not observed.

The extraction of palladium from weakly acidic and neutral solutions can proceed through a combination of anion-exchange and coordination mechanisms with the formation of (AmH)[Pd(Am)Cl₃] in systems with primary and secondary amines, and through a coordination mechanism with the formation of complexes such as Pd(Am)₂Cl₂ in systems with primary, secondary and tertiary amines. When palladium is extracted by diamines with a short hydrocarbon chain (n=2) the formation of coordination compounds also takes place.     

活性稀释剂种类对环氧树脂体系性能的影响研究

采用丁基缩水甘油醚(660)、乙二醇二缩水甘油醚(669)和苯基缩水甘油醚(690)三种活性稀释剂对环氧树脂/甲基四氢邻苯二甲酸酐(MeTHPA)固化体系进行改性,研究了稀释剂对树脂胶液粘度及其固化物力学性能和电性能的影响。结果表明,当加入669和690稀释剂后,体系的介电性能基本不变,耐电弧性能提高,而660的加入会降低体系的介质损耗,对耐电弧性能影响很小。其中,当690的添加量为3%时,耐电弧达到94s,比纯树脂提高了22%;当添加量为3%～12%时,树脂固化物的拉伸强度稳定在45～55MPa之间。     

活性稀释剂含量对环氧树脂体系阻尼性能的影响

将活性稀释剂乙二醇二缩水甘油醚669加入Epon828/T403体系中,研究其对体系粘度及阻尼性能的影响。结果表明,669能显著降低双酚A型环氧树脂的粘度,改善其加工性能。随着669含量的增加,体系损耗峰的高度先升高后降低,而宽度持续增加,玻璃化转变温度明显降低。且当669质量分数为20%时,体系阻尼性能达到最优。此外,随着测试频率的增大,tanδ-T频向高温移动,tanδ峰值增大。     

THE THERMODYNAMICS OF EXTRACTION OF SOME LANTHANIDE AND OTHER IONS BY DINONYLNAPHTHALENESULPHONIC ACID

The thermodynamics of extraction of some lanthanide ions and bismuth, aluminium, calcium and zinc ions from perchloric acid into solutions of dinonylnaphthalenesulphonic acid have been studied. Extraction of the trivalent ions is dominated by the entropy of complexing. Electrostriction of large complex micelles by the complexed ion is postulated in order to account for the entropy effect. In the case of divalent ions, the enthalpy of dehydration of the ion is more important. A strategy for improving the separation factors is proposed.     

活性稀释剂对T700/BMI复合材料力学性能的影响

本文采用苯乙烯作改性BMI树脂的活性稀释剂以降低树脂粘度,并对该树脂体系进行了DSC测试和IR光谱分析。实验表明,加入苯乙烯后,树脂体系的反应活性极大提高,固化温度降低。实验还研究了苯乙烯的用量对T700/BMI复合材料力学性能的影响,结果表明,随着苯乙烯用量的增加,T700/BMI复合材料的拉伸强度、弯曲强度及层间剪切强度逐渐增大,但苯乙烯用量超过15%(W%)时,拉伸强度呈下降趋势,而弯曲强度和层间剪切强度则继续增大,直到苯乙烯用量超过25%(W%)时,才呈下降趋势。因此,苯乙烯的用量控制在15%～25%(W%)较为合适。     

THE THERMODYNAMICS OF EXTRACTION OF SOME LANTHANIDE AND OTHER IONS BY 2-ETHYLHEXYLHYDROGEN-P-PHENYLPHOSPHONATE.

The thermodynamics of extraction of some lanthanide ions and bismuth, aluminium, calcium and zinc ions from perchloric acid into solutions of 2-ethylhexylhydrogen-p-phenylphosphonate have been studied. The extractions have been compared with those that employ dinonylnaphthalenesulphonic acid and factors that are responsible for the greater selectivity of the phosphonate have been elucidated. Charge density of the cation has a major influence on the mechanism of the reaction and in turn upon the thermodynamic parameters.     

稀释气体对化学气相沉积SiC涂层生长行为的影响

以CH3SiCl3-H2为反应气体,采用Ar和H2作为稀释气体。在1100℃、负压条件下,由化学气相沉积制备了SiC涂层,研究了稀释气体对涂层沉积速率、形貌以及晶体结构的影响。以Ar为稀释气体时,随着稀释气体流量的增加沉积速率迅速减小;用Ar作稀释气体制备的SiC涂层相对粗糙,随着Ar流量的增加,晶粒簇之间的空隙较大,涂层变得疏松。XRD分析表明：当稀释气体Ar流量超过200ml／min时,涂层中除了β-SiC外,还逐渐出现了少量的α-SiC。以H2为稀释气体时,当H2流量增加到400ml／min时,涂层的沉积速率迅速增大;以H2为稀释气体制备的SiC涂层致密、光滑,沉积的SiC涂层全部是β-SiC,且具有非常强的(111)晶面取向,涂层中无α-SiC出现。     

EXTRACTION OF LIGHT LANTHANIDE NITRATES BY TRI-n-BUTYL PHOSPHATE

The distribution of La, Pr, Nd, Eu, Gd and Tb nitrates between water and tributyl phosphate was investigated over a broad range of concentrations. It has been found that the distribution constant varies only slightly with the lanthanide atomic number, whereas the activity coefficients of the salts in concentrated organic solutions change considerably with both the lanthanide atomic number and concentration. Distribution ratios and separation factors for a number of binary mixtures were determined as a function of the composition at constant total concentration in each phase.     

RADIOLYSIS OF DIISODECYL PHOSPHORIC ACID AND ITS EFFECT ON THE EXTRACTION OF NEPTUNIUM

Radiolysis of diisodecyl phosphoric acid (DIDPA) in n-dodecane containing tributyl phosphate (TBP) was examined by analyzing concentrations of acidic extractants and H₃PO₄, and its effect on the extraction of neptuniua was studied froi the aspect of the extraction rate. For the solvent containing 0.5 fi DIDPA and 0.1 1 TBP Irradiated in the absence of HNO₃, G-values for degradation of DIDPA and for production of dibutyl phosphoric acid (DBP)were found to be 0.47 and 0.14, respectively. For the solvent irradiated in stationary contact with 0.5 M HNO3, G-value for DIDPA degradation was found to be 0.78, which ras 1.7 tines larger than the value for the solvent irradiated in the absence of HNO₃.     

EXTRACTION MECHANISM OF PALLADIUM WITH DIDODECYLMONOTHIOPHOSPHORIC ACID IN HEPTANE DILUENT

ABSTRACT

Kinetic study of the extraction of palladium(D) with didodecylmonothiophosphoric acid in n-heptane diluent was carried out using a stirred transfer cell to clarify the extraction mechanism. The effect of surfactants on the kinetics of palladium extraction was also investigated, to elucidate the role of surfactants used in liquid surfactant membranes. Moreover, the interfacial tension between the organic and aqueous phases was measured to elucidate the adsorption equilibrium of the surfactants. It was found that the interfacial activity of each surfactant is higher than that of the extractant. In the kinetic study of palladium extraction, the experimental results of the extraction rate was analyzed by the interfacial reaction model, taking into account of the adsorption of the surfactant and extractant. The rate-determining step of palladium extraction was the complex formation between four chloro-palladium complexes and the extractant at the interface, and the extraction rate constants of each palladium species were obtained. The extraction rate of palladium in n-heptane diluent was much faster than that in toluene. Additionally, it was suggested that there was particular interaction between the surfactant and extractant at the interface. The effect of the surfactant on the extraction rate was explained by taking into account the adsorption of the surfactant at the interface.     

EQUILIBRIUM OF SOLVENT EXTRACTION OF LANTHANIDE IONS WITH DIDODECYLPHOSPHORIC ACID

Measurement of the extraction equilibrium of europium by didodecylphosphoric acid dissolved in toluene diluent vas carried out at 303 K. From vapor-phase osmometry, it was found that the extractant (HR) is apt to diaerize in toluene diluent. It vas clarified that the lanthanide ion (Ln³⁺) is extracted according to the following equation.

The extraction equilibrium constant of the metal vas obtained.

The extraction equilibria of three lanthanide ions, that is, samarium, europium and gadolinium by the extractant from mixed solution of the metals were also measured. The extraction equilibrium constants of respective metals were obtained. The separation factor between samarium and europium vas found to be improved compared vith the extractions by 2-ethyIhexylphosphonic acid mono-2-ethylhexyl ester and di (2-ethylheiyl)phosphoric acid.     

EFFECT OF BORIC ACID ON THE EXTRACTION OF BASTNASITE LEACHING LIQUOR BY CYANEX 923

The effect of boric acid on the extraction of bastnasite leaching liquor by Cyanex 923 was studied. Boric acid wasnt extracted alone by Cyanex 923 and didnt influence the cerium(IV) extraction. But it can enhance the extraction of hydrofluoric acid evidently and came into organic phase in form of (HF)(H3BO3).(Cyanex 923).     

EXTRACTION OF URANYL IONS BY SYNERGISTIC MIXTURES OF THENOYLTRIFLUOROACETONE AND MACROCYCLIC DONORS

A linear polyether, 1, 13-bis[8-qulnoly]-l,4,7,10,13-pentaoxa-trldecane (K-5) and an aza-crown ether, 4,13-didodecyl-1,7,10,16-tetraoxadiazacyclooctadecane (K22DD) when combined with thenoyltrlfluoroacetone (HTTA) have been shown to exhibit a synergistic effect on the extraction of uranyl ion. The effects of the addition to the organic phase of K-5, K22DD, and tert-butylcyclohexyl-15-crown-5 (15-C-5) on the extraction of UO₂ ⁺² by HTTA in chloroform from 0.5 M NaNO₃ at 25°C have been measured. The results indicate the extraction is enhanced by the formation of an adduct, UO₂(TTA)₂S for K-5 and K22DD. No enhancement of the extraction was seen with the crown ether. The organic phase stability constants for both K-5 and K22DD were evaluated and found to be similar in magnitude. These results suggest that the major factor in the formation of the synergistic adduct is the presence of the nitrogen atom in the synergist.     

DILUENT AND EXTRACTANT EFFECTS ON THE ENTHALPY OF EXTRACTION OF URANIUM(VI) AND AMERICIUM(III) NITRATES BY TRIALKYL PHOSPHATES

ABSTRACT

The effect of various diluents such as n-hexane, n-heptane n-octane, isooctane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-hexadecane, cyclohexane, benzene, toluene, p-xylene, mesitylene and o-dichlorobenzene on the enthalpy of extraction of uranyl nitrate by tri-n-amyl phosphate (TAP) over the temperature range 283 K - 333 K has been studied. The results indicate that the enthalpy of extraction does not vary significantly with the diluents studied. Also enthalpies of extraction of uranyl nitrate and americium(III) nitrate by neutral organo phosphorous extractants such as tri-n-butyl phosphate (TBP), tri-n-amyl phosphate (TAP), tri-sec-butyl phosphate (TsBP), tri-isoamyl phosphate )TiAP) and tri-n-hexyl phosphate (THP) have been studied. An attempt has been made to explain the trends, on the basis of the nature of the solvate formed and the different terms which contribute to the overall enthalpy change.