摘要:

The solvent extraction of zinc(II) and cadmium(II) from nitrate media by several different carboxylic acids (HA) was investigated. The acids used included a series of alkanoic acids of differing steric complexity (quantified by measurement of their steric parameters, Es), as well as two examples of 2-bromoalkanoic acids.

ISSN:0736-6299    

DOI:10.1080/07366299408918197

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The solvent extraction of the trivalent lanthanides and yttrium from nitrate media by 0.5M solutions of four different 2-bromoalkanoic acids (HA) in xylene was studied. The extraction of these metals was found to take place in a pH range about one pH unit more acidic than with the parent alkanoic acids. The order of selectivity towards the individual lanthanides and yttrium was found to depend markedly on the structure of the 2-bromoalkanoic acid. Thus, for the most sterically hindered compound used (2-bromo-2-ethylhexanoic acid) the pH0 5values decrease more or less continuously from lanthanum to lutetium, although the overall difference is quite small (pH0 5LUpH0 5LU= 0,30 pH unit). With this extractant the behaviour of yttrium most closely resembles that of the light lanthanide, neodymium. For the least sterically hindered extractant used (2-bromodecanoic acid) the pH0 5LUvalues decreased only in the interval from lanthanum to praseodymium, following which the values increase more or less continuously through to lutetium, with the overall change representing a small selectivity towards lanthanum (pH0 5LUpH0 5LU= -0.12 pH unit). With 2-bromodecanoic acid and analogous compounds of low steric hindrance (2-bromo-3-cyclohexylpropanoic and 2-bromo-3,5,5-trimethylhexanoic acids), the extraction of yttrium was found to be less than that of any of the lanthanides.

ISSN:0736-6299    

DOI:10.1080/07366299408918198

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A novel sulfur-containing solvent extraction reagent, 3,3-diethylthietane (DETE) was synthesized and its extraction mechanism of platinum (IV) from aqueous hydrochloric acid solution was investigated at 30 °C in terms of the equilibrium distribution and extraction kinetics as well as its aqueous distribution and inter-facial adsorption equilibrium. Toluene was used as a diluent. It was elucidated that platinum(IV) is extracted as a solvated complex of the type, PtCl4-4DETE. DETE was found to have no inter-facial activity and the aqueous partition coefficient as high as 8.17xl0-4. Extraction rate was measured by using a vigorously stirred cell. It was of the first order with respect to DETE while it is 0th and inversely first order with respect to chloride ion in its low and high concentration region; this result was interpreted in terms of the classical hetero-phase homogeneous reaction model.

ISSN:0736-6299    

DOI:10.1080/07366299408918199

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Interfacial activity of decyl pyridinemonocarboxylates with or without the presence of decanol was studied in systems containing an excess of modifier and a constant ratio of extractant to modifier used in comparable amounts. The importance of appropriate procedures for reprocessing the interfacial tension data has been demonstrated for the estimation of the absolute and relative interfacial concentrations of extractant molecules at the interface. Decyl isonicotiniate has the highest interfacial activity when compared to that of decyl nicotiniate and decyl picoliniate. When alcohol is used in a large excess then the interface is mainly occupied by its molecules. In systems containing comparable amounts of decyl picoliniate and decanol, the co-adsorption of these two compounds occurs with mole fractions at the interface close to 0.4 and 0.6 for decyl picoliniate and decanol, respectively. It should, however, be pointed out that the determination of the mole fractions of these two compounds at the interface was possible only in a very limited region of concentrations corresponding to a domain of interfaci al tension ranging from 26 to 29 mN m-1a to whom the correspondence should be sent

ISSN:0736-6299    

DOI:10.1080/07366299408918200

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Interfacial tension isotherms were measured and interpreted for model bis-hydroxyoximes. The rate of copper extraction from sulphate solutions was determined.

ISSN:0736-6299    

DOI:10.1080/07366299408918201

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of copper(D) from concentrated chloride ion solutions by various pyridinecarboxylic acid esters is investigated. It is shown that the efficiency of the extraction is strongly dependent on the water activity (aw) and total concentration (σ) of ionic or molecular species dissolved in the aqueous phase. For decyl nicotinate, decyl isonicotinate, decyl picolinate and ACORGA CLX-50 (all denoted EXT) in toluene, the distribution of copper(II) can be satisfactorily represented by the formation of CuCl2(EXT)2in the organic phase on the condition of taking into account the existence of CuClx(2-X)complexes (x = 1 to 4) in the aqueous phase. The apparent extraction constant KeX and stability constants |βi of the variousCuOx(2-X)complexes are estimated for two aqueous media corresponding to awandσ= 0.835 and a = 8.0 mol.L-1, and aw= 0.617 and σ = 12.0 mol.L-1, respectively. On the other hand, in the case of ACORGA CLX-50 in kerosene, more complex phenomena influencing the activity coefficient of the extractant seem to occur.

ISSN:0736-6299    

DOI:10.1080/07366299408918202

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of p-, m- and o-nitrophenols with various ketones and esters was studied. The distribution constants of phenols between water and organic solvents were determined. The concentration constants of extraction of mononitrophenols were found to increase with reduced length of one of the alkyl radicals. So, the extraction constants decrease in the following series: acetates > propionates > other aliphatic esters and methyl n-alkyl ketones > di-n-alkyl ketones > diisoalkyl ketones. The extraction constants for cyclic ketones are the highest. This effect was explained in terms of decisive interference of steric hindrances in the constants of formation of hydrated solvates, the main species of p- and m-nitrophenols complexes extracted.

ISSN:0736-6299    

DOI:10.1080/07366299408918203

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Extraction systems containing diisopropyl ether ( IPE) and high initial hydrochloric acid concentration ( higher than 7.1 mol/L) are very sensitive to temperature changes. Small changes ( a few degrees centigrade) in working temperature may cause changes not only of the phase volume but also of the number of phases. Results of investigation of the temperature effect over the interval of 15 to 40°C on the volume and number of equilibrated phases in the system hydrochloric acid - water - IPE -iso-pentyl alcohol as well on the distribution of hydrochloric acid are given. The observed effect of temperature is compared to that in systems containing n-pentyl or n-hexyl alcohol as a component of mixed solvent.

ISSN:0736-6299    

DOI:10.1080/07366299408918204

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Extraction of perchloric acid using a nitrobenzene solution of dibenzo-lB-crown-6 ( DB18C6) has been investigated. It has been found that perchloric acid is extracted in a dissociated form of protonized crown cation HL+org ( L means crown) and anion C104org If the concentration of acid in the organic phase increases, partial association to neutral particle HL.CIO4org and/or dimmer ( HL+)2org takes place. The extraction constants, the protonization constant of DB18C6 in nitrobenzene, and the association constant of the ions HL++org and Clo4org In nitrobenzene have been determined.

ISSN:0736-6299    

DOI:10.1080/07366299408918205

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Jet plates with elevated rims around their openings are assumed to improve the performance of pulsed extraction columns. A comparison with conventional plates was carried out in a pilot-plant size column with the system of water, toluene and acetone. Hold-up, drop size, backmixing and axial concentration profiles in both phases were measured simultaneously. Mass transfer coefficients were evaluated from measured data by minimising the deviations of measured concentration profiles from model prediction using standard and open-end stagewise backflow models. Equations from the literature for prediction of drop size, hold-up and backmixing coefficients were modified by recalculating the empirical coefficients from recent data to enable quantification of trends and replacement of missing values. The transfer coefficents correlated against actual velocity of the dispersed phase rised to a power between 0.6 and 1, the influences of pulsation velocity, drop size and actual velocity of the continuous phase being by an order of magnitude smaller. The magnitude of the transfer coefficients was comparable to those measured earlier under similar conditions in a reciprocating plate extraction column where, however, the mentioned additional influences were more important.

ISSN:0736-6299    

DOI:10.1080/07366299408918206

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor