Enhancement in Extraction Rates by Addition of Organic Acids to Aqueous Phase in Solvent Extraction of Rare Earth Metals in Presence of Diethylentriamine-Pentaacetic Acid.

Using a two-level factorial design, a study was undertaken to change the parameters impacting the recovery of rare earth from rare earth mixture. The experimental design was used to screen and identify the major contributing aspects to rare earth recovery. The experiment aims to isolate samarium from a mixture of samarium, europium, and gadolinium. Factors involved consist of pH (pH 1 and pH 6), acid type (nitric acid and hydrochloric acid) and concentration (1.0M and 5.0M), mixing duration (30 min and 120 min), feed composition (20% samarium and 80% samarium), type of diluent (hexane and chloroform), temperature (room temperature and 60°C) and organic to aqueous phase ratio (1:1 and 2:1). The results showed that the samarium recovery was in the range of 0.98% to 90.88%. Based on analysis variance (ANOVA), five factors significantly affect the samarium recovery out of eight factors explored. The five factors according to the most significant order are pH> feed composition> organic to aqueous phase ratio>acid concentration>acid type>mixing duration>type of diluent> temperature. Statistical analysis shows that the linear model is significant, with the value of R2 is 0.9886. Based on the statistical data, five significant variables influence the separation of samarium. This research shows that two-level factorial design can anticipate significant variables impacting rare earth separation, particularly samarium, in the solvent extraction process.

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EXTRACTION OF RARE EARTH METALS WITH 2-ETHYLHEXYL PHOSPHONIC ACID MONO-2-ETHYLHEXYL ESTER IN THE PRESENCE OF DIETHYLENETRIAMINEPENTAACETIC ACID IN AQUEOUS PHASE

Solvent Extraction and Ion Exchange ◽

10.1080/07366299308918165 ◽

1993 ◽

Vol 11 (3) ◽

pp. 437-453 ◽

Cited By ~ 48

Author(s):

Fukiko Kubota ◽

Masahiro Goto ◽

Fumiyuki Nakashio

Keyword(s):

Rare Earth ◽

Aqueous Phase ◽

Phosphonic Acid ◽

Rare Earth Metals ◽

Diethylenetriaminepentaacetic Acid

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Solvent extraction of rare-earth metals with bis(2-ethylhexyl)phosphinic acid

Fresenius Journal of Analytical Chemistry ◽

10.1007/s002160050226 ◽

1997 ◽

Vol 357 (6) ◽

pp. 635-641 ◽

Cited By ~ 18

Author(s):

Y. Nagaosa ◽

Yao Binghua

Keyword(s):

Rare Earth ◽

Solvent Extraction ◽

Rare Earth Metals ◽

Phosphinic Acid

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Liquid-liquid solvent extraction of rare earths: a crystallographic analysis.

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314089931 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1006-C1006

Author(s):

Jeroen Jacobs ◽

Koen Binnemans ◽

Luc Van Meervelt

Keyword(s):

Crystal Structure ◽

Ionic Liquid ◽

Ionic Liquids ◽

Rare Earth ◽

Solvent Extraction ◽

Aqueous Phase ◽

Rare Earths ◽

Structural Information ◽

Side Chain ◽

Anionic Complex

Liquid-liquid solvent extraction has become the primary research topic for separating mixtures of rare-earths. [1] Current research on this topic focuses on extraction processes involving ionic liquids as basic extracting agents. In the aqueous phase, the rare-earth is coordinated by the anionic entities of the ionic liquid, forming an anionic complex. The large organic cation of the ionic liquid neutralizes the complex (ion-pair complex) and migrates the entity to an organic phase. The choice of these agents is solely based on the calculation of thermodynamical extraction parameters, whilst structural information about these compounds is rare or even non-existent. Our research focuses on obtaining structural information via crystallography on the above-mentioned molecules and relating the interactions between anion and cation to the stability of the complexes. A difference in stability between the anionic complex and cation can give a different extractability. Different rare-earth chloride salts were dissolved in an aqueous phase, containing ionic liquids with β-diketonate anions and 1-alkyl-3-methylimidazolium cations. After the extraction, crystals of the formed compounds are grown from the organic phase and measured. Current results show us that an intermolecular non-classical C-H ... O hydrogen bond is persistent across the different molecules, whilst small interactions between the cation side chain and halogens on the β-diketonate add extra stability to the crystal structure. Structures formed with 2-thenolytrifluoroactylacetonate anions have no intention to form side chain interactions, leaving the alkyl chain of the 1-alkyl-3-methylimidazolium in a void, whilst structures formed with hexafluoroacetylactonate have strong side chain interactions, which leads to a better packing. The different solubility of both compounds can be related to the different interactions and stability in the crystal structure.

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