JPH01160820A - Composite carrier - Google Patents

Abstract

PURPOSE:To obtain a composite carrier with excellent solectively extracting and selectively carrying abilities for alkali metals esp. Li, transferable against concentration gradient, by mixing each specific cyclic polyether and phosphoric ester. CONSTITUTION:The objective carrier can be obtained by mixing (A) a dibenzo-14-crown-4 derivative as a cyclic polyether of formula I (R<1-2> are each H, alkyl or acyl) (e.g., dibenzo-14-crown-4) and (B) a phosphoric diester as a phosphoric ester of formula II (R<3-4> are each alkyl or alkenyl group) [e.g., di(2-ethyl-hexyl)phosphate] in any proportion (e.g., molar ratio: 1/1) in an organic solvent virtually immiscible to water (e.g., CHCl3).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel composite carrier. More specifically, the present invention relates to a composite carrier that has excellent characteristics such as a large selective extraction ability and selective transport ability for alkali metals, especially lithium, and the ability to transport against a concentration gradient. It is something.

BACKGROUND OF THE INVENTION In recent years, the demand for lithium has been increasing year by year as a raw material for ceramics and special alloys, and it is expected that the demand will increase rapidly in the near future as a fuel resource for lithium batteries and nuclear fusion reactors. Therefore, in order to secure this resource, in addition to the conventional extraction from pegmatite deposits, studies are underway to recover lithium from shrubs, geothermal water, and even seawater.

By the way, many metals other than lithium are dissolved in the shrubs, geothermal water, seawater, etc., so from these,
To separate and collect lithium, a carrier that can selectively extract and transport lithium is required. Crown ethers such as 12-crown-4 and benzo-15-crown-5 have been proposed as carriers [Journal of the American Chemical Society (J, Amer, Cbcm, Soc. ,
) J Vol. 89, p. 7017 (1967), Chemical Review (Chem, Rev,) J No. 74
Volume, page 351 (1974)].

However, these crown ethers have good selectivity toward sodium and potassium but low selectivity toward lithium, and although they exhibit carrier properties in the organic layer, they exhibit strong solvation ( hydration)
The ability to take in metal ions is low in the aqueous layer, making it unsuitable for the purpose of recovering lithium from an aqueous solution.

Problems to be Solved by the Invention An object of the present invention is to provide a new carrier that improves the drawbacks of conventional carriers and can be suitably used for recovering alkali metals, especially lithium, from aqueous solutions. It was made for the purpose of

Means for Solving the Problems The present inventors have conducted extensive research to develop a carrier that exhibits excellent selective extraction and selective transport ability for alkali metals, especially lithium. forms a stable complex, but the dibenzo-14-crown 4 derivative has a low ability to incorporate metal ions from the aqueous layer into the organic layer;
We discovered that by combining an oil-soluble phosphoric acid diester with an ionizable functional group, we could obtain a composite carrier that has both the ability to incorporate metal ions into the organic layer and the selective extraction of lithium. Based on this knowledge, we The present invention has now been completed.

That is, the present invention provides a compound represented by the general formula (R1 and R2 in the formula are each a hydrogen atom, an alkyl group, or an acyl group, and they may be the same or different from each other) Cyclic polyether and the general formula % (R3 and R4 in the formula are each a linear or branched alkyl group or alkenyl group, and they may be the same or different from each other) The present invention provides a composite carrier consisting of a combination with a phosphoric acid ester represented by the following formula.

The present invention will be explained in detail below.

The cyclic polyether used as a component of the composite carrier of the present invention is a dibenzo-14-crown-4 derivative represented by the general formula (I). An alkyl group or an acyl group may be bonded to the two benzene rings as desired, and the substituents bonded to the two benzene rings may be the same. It's okay and it can be different.

When such a dibenzo-14-crown-4 derivative is combined with the phosphoric acid diester represented by the general formula (If), a specific synergistic effect is exerted on the extractability and transportability of lithium. This synergistic effect is due to the fact that the crown ring of the crown ether used is 14
-4, crown ethers with other ring sizes, such as dibenzo-18-crown-6
This synergistic effect does not appear even if drugs such as benzo-15-crown-5 are used. In addition, the synergistic effect is 2
Dibenzo-14-crown- with unsubstituted benzene rings
In addition to 4, derivatives in which an alkyl group such as a methyl group or an ethyl group, or an acyl group such as an acetyl group or a propanoyl group is introduced into the benzene ring also exhibit a synergistic effect. The substituent in the derivative preferably has 1 to 20 carbon atoms.

In the present invention, one type of cyclic polyether represented by the general formula (I) may be used or two or more types may be used in combination, but particularly preferred is dibenzo-1
This is a case where 4-crown-4 is used alone.

In the composite carrier of the present invention, the phosphoric acid diester used as the other component has an ionizable functional group (P-OH group) having the structure represented by the general formula (n) above.
and an oil-soluble diester having a linear or branched alkyl group or alkenyl group, and those having an alkyl group or alkenyl group having 4 or more carbon atoms are particularly preferred.

In the present invention, one type of phosphoric acid diester represented by the general formula (n) may be used, or two or more types may be used in combination, but particularly preferred is di(2-ethylhexyl) phosphoric acid. This is the case when Fate is used alone.

The composite carrier of the present invention can be easily obtained by dissolving the cyclic polyether represented by the general formula (I) and the phosphoric acid diester represented by the general formula (If) in an appropriate organic solvent and mixing them uniformly. This solution can be used as is.

There is no particular restriction on the mixing ratio of the cyclic polyether and phosphoric acid diester, and they can be mixed at any ratio, but it is preferable to mix them at a molar ratio of 1:1 because the highest synergistic effect is expressed. .

Further, the organic solvent to be used is not particularly limited as long as it is substantially immiscible with water. Specifically, hydrocarbons such as benzene and halogenated hydrocarbons such as chloroform can be mentioned.

In order to collect metals such as lithium using the composite carrier of the present invention obtained in this way, a method commonly used when recovering metals from an aqueous solution, such as a solvent extraction method or a liquid membrane separation method, is used. The following methods can be used.

Next, an example of a method for collecting metals such as lithium by a liquid membrane separation method using the composite carrier of the present invention will be explained with reference to the attached drawings. A cell 1 used for liquid film separation has a structure in which the lower portions of cylindrical tubes 2.3 are connected by a cylindrical tube 4. 5 is a stirrer.

First, in cell 1, solution C in which the composite carrier of the present invention was dissolved.
(organic liquid film), then a solution A containing metal ions to be transported is placed in the cylindrical part 2, and a solution B that receives and takes away the transported metal ions is placed in the cylindrical part 3. As the solution B, an acidic solution is generally used.

The target metal ions are more selectively transported to the B layer through the 0 layer than the A layer and are collected.

Effects of the Invention The composite carrier of the present invention is a combination of a cyclic polyether having a specific structure and a phosphoric acid diester, and has excellent selective extraction properties for alkali metals, especially lithium, and a high rate of lithium uptake from an aqueous solution. It is also large and extremely useful as a carrier used in solvent extraction separation and liquid membrane separation of lithium.

EXAMPLES Next, the present invention will be explained in further detail by examples, but the present invention is not limited to these examples in any way.

Example 1 Using an apparatus with the structure shown in Fig. 1, by liquid membrane separation method,
A metal ion transport experiment was conducted. Solution A.

As B and C, use those having the following component compositions.

Solution A: LiOH 10mM, NaOH+nMS [
12020mlt(sourcephxse) Solution B: LiC1110mM, NaCQlOmM
, 1 regulation 111C920m1! (rscievin
g pass) solution C nidibenzo-14-crown-
45mM di(2-ethylhexyl)phosphate 5
40 ml of mM chloroform Transport experiments were performed at 25° C. with a stirrer rotating at a constant speed. Below, other experiments were conducted under similar conditions.

FIG. 2 shows the change over time in the metal ion concentration in both layers A and B due to metal ion transport. In FIG. 2, the horizontal axis represents time (1+t), and the vertical axis represents the ratio (CM+) of the metal ion concentration after one hour to the initial metal ion concentration (Mo).
Mt)/(Mo), solid lines indicate changes in lithium ions in each layer, and broken lines indicate changes in sodium ions in each layer.

As can be seen from this figure, lithium has a
It is transported at a high rate compared to sodium and concentrated in the B layer at a rate of about 5%/hr.

Comparative Example 1 Dibenzo-14-crown-4 and di(
A transport experiment was carried out in the same manner as in Example 1, except that dibenzo-14-crown-4 was used alone instead of the composite carrier with 2-ethylhexyl) phosphate. As a result, lithium could not be transported even after 20 hours.

Example 2 Using the composite carrier of the present invention, lithium was extracted from an aqueous lithium solution with an organic solvent. The compositions of the aqueous layer and organic solvent layer are as follows.

Aqueous layer: LiOH 15mM aqueous solution 201IIll Organic solvent layer Nidibenzo.14-crown-415mM.

Di(2-ethylhexyl) phosphate 15M chloroform solution 10d Put the superaqueous solution and chloroform solution in a centrifuge tube with a Teflon cap, shake at 25°C for 10 minutes, let stand, and extract into the organic solvent layer. When the amount of lithium was measured, it was found that 40% of the lithium in the aqueous layer was extracted.

Comparative Example 2 Instead of the composite carrier in Example 2, benzo-15
-Crown-5 and dibenzo-14-crown-4 were used alone, and an experiment was conducted in the same manner as in Example 2.
Only 3% lithium was extracted with 14-crown-4.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an example of a device for transporting metal ions using the composite carrier of the present invention, in which 1 is a cell for liquid membrane separation, 2, 3, and 4 are cylindrical tubes, 5 is a stirrer, A is a solution containing the metal to be transported, B is a solution that receives and receives metal ions,
C is a solution in which the composite carrier is dissolved. FIG. 2 is a graph showing changes in metal ion concentration in both layers A and B due to metal ion transport in an example of the present invention.

Claims (1)

[Claims] 1 General formula▲ Numerical formula, chemical formula, table, etc.▼ (R^1 and R^2 in the formula are a hydrogen atom, an alkyl group, or an acyl group, respectively, and they are the same. There are cyclic polyethers represented by the general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (in the formula, R^3 and R^4 are linear or A composite carrier consisting of a combination with a phosphate ester represented by a branched alkyl group or alkenyl group, which may be the same or different.