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Separation of lanthanides using micro solvent extraction system

Nishihama S., Tajiri Y., Yoshizuka K.

Ars Separatoria Acta

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2006

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No. 4

18-26

EN

A micro solvent extraction system for the separation of lanthanides has been investigated. The micro flow channel is fabricated on a poly(methyl methacrylate) (PMMA) plate, and solvent extraction progresses by feeding aqueous and organic solutions into the channel simultaneously. The extraction equilibrium is quickly achieved, without any mechanical mixing, when a narrow channel (100 µm width and 100 µm depth) is used. The results of solvent extraction from the Pr/Nd and Pr/Sm binary solutions revealed that both lanthanides are firstly extracted together, and then, the lighter lanthanide extracted in the organic solution alternatively exchanges to the heavier one in the aqueous solution to achieve the extraction equilibrium. The phase separation of the aqueous and organic phases after extraction can also be successively achieved by contriving the cross section of the flow channel, and the extractive separation of Pr/Sm is demonstrated.

2

Selective recovery of lithium from seawater using a novel MnO2 type adsorbent III - benchmark evaluation

Yoshizuka K., Kitajou A., Holba M.

Ars Separatoria Acta

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2006

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No. 4

78-85

EN

The granulation method of λ-MnO2 adsorbent employing chitin-based binder, which has efficient selectivity towards lithium ion, has been developed. The granules of ca. 1 – 2 mm with high resistance to the column operation for seawater (pH = 8.1) can be achieved. The laboratory scale column separation with the granulated adsorbent shows that lithium ions from seawater can be selectively recovered against the majority of co-existing cations. In addition, the elution of Mn from the adsorbent can be prevented. The benchmark column separation plant with seawater intake 200 L/h has been built and the whole process was verified and evaluated. The composition analysis of dried precipitated salts showed ca. 35 % efficiency of lithium recovery in the benchmark plant. In order to enhance the lithium recovery efficiency the following recovery steps are expected when routine techniques are applied.

3

Selective recovery of lithium from seawater using a novel MnO2 type adsorbent. II – Enhancement of lithium ion selectivity of the adsorbent

Kitajou A., Suzuki T., Nishihama S., Yoshizuka K.

Ars Separatoria Acta

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2003

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No. 2

97-106

EN

A novel spinel-type manganese dioxide adsorbent has been developed for the selective recovery of Li+ from seawater. The adsorbent can be prepared from a lithium-rich component of spinel-type lithium dimanganese tetraoxide Li1.5Mn2O4, followed by ion exchange of Li+ by H+ with diluted hydrochloric acid. The X-ray analysis of the adsorbent suggests the adsorption-elution cycle of Li+ progresses under γ expansion-shrinking mechanism of the adsorbent. The adsorption of Li+ progresses via cation exchange, and the selective recovery of Li+ can be carried out, even when the large amount of Na+ coexists in seawater. The chromatographic selective recovery of Li+ from the artificial seawater shows that Li+ can be selectively adsorbed with remaining most of Na+ in the feed solution in the break through step, while Li+ of high purity can recover and concentrate into the elutant in the elution step.

4

Selective recovery of lithium from seawater using a novel MnO2 type adsorbent

Yoshizuka K., Fukui K., Inoue K.

Ars Separatoria Acta

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2002

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No. 1

79-86

EN

A novel ?-type manganese dioxide (?-MnO2) adsorbent has been developed for selectively recovering Li+ from seawater. This adsorbent can be prepared from spinel-type lithium di manganese tetra-oxide (LiMn2O4) using ion exchange of Li+ by hydrogen ion. In batch adsorption, ?-MnO2 adsorbent can effectively adsorb Li+ at elevated pH (like seawater; pH=8.1) with quite high selectivity for Li+ vs. Na+ (molar ratio of Li+/Na+ exceeding 800). In chromatographic separation, Li+ can be effectively adsorbed on the adsorbent packed into column, while Na+ is only scarcely adsorbed. In elution stage, Li+ can be concentrated more than 75 times compared to its initial concentration in the feed solution of adsorption stage, while little Na+ was eluted. The molar selectivity coefficient of Li+/Na+ to 2300 can be achieved.