摘要:

A unified expression is derived for the computation of column height or number of non-ideal stages for backmixed liquid-liquid contactors in terms of both diffusion and backflow models, assuming linear equilibria. By substitution of the appropriate values of the roots of the characteristic equations, solutions are obtainable for backmixing in both phases, in one or other phase, or for no backmixing in either (i.e., plug flow). An extension of the method to non-linear equilibrium is also described, in which the equilibrium curve is approximated by straight line segments. Scale-up of an extractor can be effected within minutes using a program written on this basis for a HP-41CV calculator.

ISSN:0736-6299    

DOI:10.1080/07366298308918421

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The extraction properties of poly-(diphenylphosphinylmethyl) arenes in which the fragments of different methyl substituted aromatic compounds serve as hard bridges connecting the P=0 functional groups was studied. The extraction of trivalent transplutonium elements and rare earth elements, uranium (VI), plutonium (IV) by chloroform solutions of these reagents as function of HNO3, and ligands concentration was investigated. The selectivity of reagents was found to depend only on mutual arrangement of P=0 groups in the bridge regardless of their number. Conformational analysis of the reagents described have been used to establish their structure and cause of their selectivity with respect to one or another element.

ISSN:0736-6299    

DOI:10.1080/07366298308918422

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

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 and1,2-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).

ISSN:0736-6299    

DOI:10.1080/07366298308918423

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The extraction of uranium(VI) with 5,8-diethyl-7-hydroxydodecan-6-one oxime (LIX 63; HR) has been studied from the viewpoint of solvent effects. The distribution constant of LIX 63 (KDR) determined between organic solvents and the aqueous phase In creased In the order: n-heptane < n-hexane < kerosene < carbon tetrachloride < chlorobenzene < toluene < chloroform. The extracted species was found to be UO2R2, whose extraction equilibrium constant was evaluated as log Kex= −2.11±0.14 independent of solvent types. This reaction was first-order in metal and second-order in extractant and inverse first-order in hydrogen ion. The apparent rate constant has been found to vary inversely with the square of the KDR value in accordance with the view that the rate-determining step is ascribed to the reaction of UO2R+with the second ligand in the aqueous phase.

ISSN:0736-6299    

DOI:10.1080/07366298308918424

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The solvent extraction of europium(III) into solutions of thenoyltrifluoroacetone and benzoic acid in cyclohexane, carbon tetrachloride, benzene, chloroform, pentachloroethane, and tetrachloroethane has been measured at 25°C. It has been found that the extracted species involve two types of adducts, EuA3· HB and EuA3· 2HB where A denotes the TTA anion and HB the benzoic acid monomer. The magnitude of the adduct formation constants in different solvents has been correlated with the dimerization constants of benzoic acid in the solvents.

ISSN:0736-6299    

DOI:10.1080/07366298308918425

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The mechanism of the extraction of copper (II), nickel (II), cobalt (II) and thorium (IV) from aqueous buffer media with 4-dinitrobenzoyl1-2, 4-dihydro-5-methyl-2-phenyl-311-pyrazol-3-one (DMPP) in benzene has been investigated. The values of log K*where K*refers to the extraction equilibrium Mn++-nHL ⇌ MDn+ nH+are Cu(II)& lpar; + 0.3), Co(II) (−6.65), Ni(II) (−5.04) and Th(IV) ( + 6.1). Solid complexes synthesized have the composition CuL2· 2H2O, NiL2· 2H2O and ThL4respectively (L = anion of the ligand). DMPP seems to be superior to the corresponding 4-benzoyland 4-nitrobenzoyl derivatives of 2,4-dihydro-5-methyl-2-phenyl1-3 H-pyrazol1-3-one (MPP) and also better than thenoyltrifluoroacetone, the popularly employed fluorinated β-dike tone in the system investigated.

ISSN:0736-6299    

DOI:10.1080/07366298308918426

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The extraction of Pu(IV) by Aliquat-336 from aqueous nitric acid containing oxalic acid was studied with a view to exploring the feasibility of recovery of Pu(IV) from Pu(IV) oxalate precipitation effluents. Distribution ratio data were obtained as a function of concentration of nitric acid, oxalic acid and Aliquat-336. The data obtained revealed that Pu(IV) can be extracted almost quantitatively by 20% Aliquate-336 in xylene from aqueous medium containing oxalic acid up to 0.25 M provided the nitric acid concentration is ≥ 4 M. These data suggest that Pu(IV) can be recovered directly from nitric acid - oxalic acid waste generated in Pu-oxalate precipitation by Aliquat-336 extraction.

ISSN:0736-6299    

DOI:10.1080/07366298308918427

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Ion-exchange properties of a new type of hydrous titanium dioxide with a fibrous form, which was obtained from potassium dititanate (K2O(TiO2)2), have been studied. The pH titration curve snowed that this material behaved as a bifunctional ion-exchanger. Distribution coefficients of some divalent metal ions on this material were measured as a function of pH and the selectivity series were found to be Ba > Sr > Ca > Mg for alkaline earth metal ions and Cu > Zn > Mn > Co > Ni for divalent transition metal ions. Large separation factors were obtained between some metal ion pairs and the mutual separations such as Cu from Sr, Ca, Mg, Co and Ni, and Mg from Ba and Zn have been achieved on columns of this material.

ISSN:0736-6299    

DOI:10.1080/07366298308918428

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The ion exchange behavior of 4 low rank coals has been investigated. Their total carboxyl group contents ranged from 1.52 meq/g for a subbituminous coal to 2.78 meq/g for a lignite. The coverage of the carboxyl groups by metal cations varied from 30% to 60% (on an equivalent basis) for the raw coals. For all raw coals, Ca2+was the predominant metal cation. The equilibrium ion exchange behavior of metal cations for H+was found to be a linear function of pH regardless of the cation concentration in solution. Thus, the extent of exchange is a function of available hydrogen ions. From equilibrium ion exchange measurements, the following cation exchange selectivity pattern for a subbituminous coal was determined:

ISSN:0736-6299    

DOI:10.1080/07366298308918429

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The kinetics of ion exchange in a subbituminous coal have been investigated. The rate determining step in the exchange processes was determined to be intraparticle diffusion for particle sizes of 9,500 × 4,000 μm, 425 × 250 μm and 180 × 125 μm. The kinetics of exchange for the 180 × 125 μm particles was very rapid and approached film diffusion control. A relatively simple mathematical model developed by Helfferich (1) describe adequately ion exchange kinetics. The model was effective in predicting the extent of exchange as a function of time and the time required to reach complete exchange. Interdiffusion coefficients at 298 K obtained from the model for exchange of H for Na+, Mg2+and Ca2+ranged from 2.0 × 1010−6to 2.6 × 10−8cm2/s with the values decreasing in the order:

ISSN:0736-6299    

DOI:10.1080/07366298308918430

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor