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Homogeneous liquid-liquid extraction of metal cations at near neutral pH

Thesis/Dissertation ·
OSTI ID:7252406

Solvent extraction performed at low pH to prevent hydrolysis of cations has been studied in conjunction with homogeneous liquid-liquid solvent extraction into propylene carbonate, which forms a homogeneous solution with an aqueous phase when heated above 71/sup 0/C. Extraction is achieved with heating and cooling upon which the phases separate. Also, propylene carbonate yields a homogenous phase with water and ethanol in the ratio, propylene carbonate/water/ethanol 2:2:1; thus permitting direct comparison by e.g., absorption spectrophotometry of aqueous phase, organic phase and calibration standards. Thenoyltrifluoroacetone chelates of Fe(III), Co(II), and Cu(II) have been extracted from an aqueous phase containing tartrate, at pH values from 6 to 8, into propylene carbonate by the homogeneous liquid-liquid extraction technique. The extractions were very rapid, and quantitative under optimum conditions. Iron(III) was also quantitatively and rapidly extracted with acetylacetone under these same conditions. Normal extraction technique into propylene carbonate and toluene also gave rapid and quantitative results for Fe(III)-TTA from this aqueous medium. These results, attributed to the significantly higher ratio of enolate ion, suggest an alternative mechanism for the synergic effect of various organic gases in TTA extractions. Acid-base reactions in the organic phase yield similar higher concentrations of enolate ion in the aqueous phase. A method was developed to extract uranium from ores and fuel elements using homogeneous liquid-liquid solvent extraction.

Research Organization:
City Univ. of New York, NY (USA)
OSTI ID:
7252406
Country of Publication:
United States
Language:
English