摘要:

A new process for the extraction and recovery of strontium from acidic waste streams is described. In this process, called SREX (for Strontium Extraction), strontium is extracted from acidic ( ≥ 1 M HNO3) solution using a 0.20M solution of di-t-butylcyclohexano-18-crown-6 in 1-octanol. Extracted strontium is readily stripped from the organic phase using either water or dilute (<0.05 M) HNO3. Tests of the process on a synthetic dissolved sludge waste solution show that only strontium, barium, and technetium are appreciably extracted by the crown ether. Prolonged exposure of the process solvent to nitric acid at elevated temperatures or to ≤ 50 Wh/L γ radiation from a60Co source produces essentially no deterioration in its performance. Benchtop batch countercurrent extraction experiments show that 99.7% of the strontium initially present in a feed solution can be removed in only three extraction stages.

ISSN:0736-6299    

DOI:10.1080/07366299108918039

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The extraction equilibrium of Ti(IV) was studied between aqueous nitric acid solutions (0.1-6M) and n-heptane solutions of di(2-ethylhexyl(phosphoric acid. The kinetics of the extraction and stripping reaction was also examined in a dispersion system using a stirred vessel. With increasing the acid concentration, the distribution ratio of Ti(IV) decreases and goes through a minimum. It was shown that the extraction of Ti(IV) from low acidic media in the concentration range 0.1-2M is a cation exchange reaction. For the higher acid solutions, the equilibrium distribution increases with the concentration of nitrate as well as nitric acid. This suggests that the extraction takes place by solvation reaction at high acidities. Furthermore, rate equations of the Ti(IV) extraction were obtained for the forward and backward reactions of the cation exchange. It was shown that a good agreement exists between the extraction constants from the equilibrium data and the two rate equations.

ISSN:0736-6299    

DOI:10.1080/07366299108918040

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The separation of Pd(II) from Pt(II), Ir(III) and Rh(III) with trioctylphosphine oxide (TOPO) in heptane using centrifugal partition chromatography (CPC) has been investigated for the first time. The extraction of Pd(II) has been studied by CPC and batch solvent extraction. The distribution ratios for Pd(II) determined by both methods agree well. In low HCl concentrations (<0.1 M), the extracted species was PdCl2.(TOPO)2, irrespective of the chloride concentration, while at acid concentrations above 0.1 M, the Pd was extracted as the ion pair, 2(TOPO.H+).PdCl42-. Base line separation of Pd(II) and Pt(II) in CPC was obtained under a variety of chloride and HCl concentration with the average number of theoretical plates being 390 ± 40 at a flow rate of 0.47 ± 0.05 mL/min.

ISSN:0736-6299    

DOI:10.1080/07366299108918041

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

1-(4-Alkylphenyl)-3-hydroxy-2-methyl-4-pyridones (AHMP or HL) having 1 to 12 carbon atoms in their alkyl chains were synthesized and used for the extraction of indium(III) from aqueous solutions into 1,2-dichloroethane. The extracted species were InL3for all AHMP. The partition coefficients, KDof AHMP and the distribution constants, KDCof indium(III)-AHMP complexes increased with an increase in the carbon number in the alkyl chain. The increments of log KDand log KDCwere 0.52 and 1.67 per a carbon atom, respectively. The proton dissociation constants of AHMP and the extraction constants and the formation constants of their indium(III) complexes were also determined.

ISSN:0736-6299    

DOI:10.1080/07366299108918042

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In a series of accelerated tests, using tetradecane as a model diluent, cobalt was shown to catalyse the oxidation of aliphatic solvent extraction diluents to raonocarboxylic acids,

ISSN:0736-6299    

DOI:10.1080/07366299108918043

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Equilibrium data are presented for the separation of selected rare earths Including La, Dy, Yb and Y, using solvent extraction from a chloride system. The solvents examined are Naphthenlc acid, Versatic acid and D2EHPA In shellsol 2016 at 15°C. The data presented show that Yttrium has a similar distribution co-efflclent to the heavy rare earths In D2EHPA but the distribution co-efflclent is similar to the light rare earths In the carboxyllc acid systems (Versatic and Naphthenlc acid). This Indicates that carboxyllc acids could be used to separate yttrium from heavy rare earths and In combination with D2EHPA for the separation from materials containing all the rare earths.

ISSN:0736-6299    

DOI:10.1080/07366299108918044

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

With an appropriate liquid cation exchanger, ammonia can be extracted selectively from sour waters, thereby greatly reducing the energy requirement for stripping the acid gas(es) from the water. The ammonium form of the liquid cation exchanger is then decomposed thermally, yielding product ammonia and the ion exchanger for recycle. Such a process purifies the water and provides the ammonia and acid gases as separate products. For energy efficiency it is desirable to use a liquid cation exchanger of optimal acidity, strong enough to form the ammonium ion pair, but weak enough to allow ready regeneration. Di-2, 4, 4-trimethylpentyl phosphinic acid (DTMPPA) in the form of Cyanex 272 (American Cyanamid Co.) has been confirmed as an effective extractant through measurements of extraction equilibria and vapor-liquid equilibria for ammonia solutions of as-received and purified Cyanex 272. Preliminary evidence has also been obtained on thermal stability of DTHPPA at regeneration temperatures.

ISSN:0736-6299    

DOI:10.1080/07366299108918045

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Partition of citric acid, 2-butanol and water between the aqueous and alcoholic phases is reported. Distribution of citric acid is expressed in terms of, H3Cit (2-BuOH)5, complex formation in the organic phase. Detailed thermodynamic analysis of the investigated system is presented.

ISSN:0736-6299    

DOI:10.1080/07366299108918046

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The kinetics and mechanism of extraction of radioactive Eu(III) by thenoyltrifluoroactone (HTTA) and triphenylarsine oxide (Ph3AsO) in chloroform from aqueous perchlorate medium at ionic strength 0.1(H+, NaCIO4) has been studied using a stirred Lewis cell.

ISSN:0736-6299    

DOI:10.1080/07366299108918047

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The aggregation behavior of didodecylnaphthalenesulfonic acid (HDDNS) in carbon tetrachloride at 25.0 °C has been investigated by interfacial tension measurements, FT1R spectrophotometry, Karl Fischer titrations, and computer-aided analysis of the extraction of Zn(ll) ion from nitric acid solution. HDDNS forms hydrated aggregates at analytical HDDNS concentrations greater than 4.4 x 10-6 M up to at least 0.1 M. Slope analysis of the extraction of Zn(ll) up to ca. 5% loading with 0.001-0.1 M HDDNS solutions indicates that the size of the aggregates lies in the range 5-8 and increases gradually with increasing HDDNS concentration. By use of the computer programs SXLSQ and SXLSQA the extraction of Zn(ll) up to ca. 40% loading may be described to within twice the experimental precision by formation of the three species HnAnZnAnHn-2, and Zn2AnHn-4 (A = DDNS-anion) characterized by a common aggregation number n in the range 5-8. Under the conditions employed, organic-phase nonideality effects as estimated by the Hildebrand-Scott treatment applied in the program SXLSQA are much less useful in understanding the extraction behavior than mass-action and speciation effects.

ISSN:0736-6299    

DOI:10.1080/07366299108918048

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor