阅读说明：本技术 基于磁性Janus颗粒的萃取稀土元素的方法 (Method for extracting rare earth elements based on magnetic Janus particles ) 是由 徐建鸿 杨振忠 梁福鑫 于 2020-05-28 设计创作，主要内容包括：本发明涉及一种基于磁性Janus颗粒的萃取稀土元素的方法。本发明的萃取稀土元素的方法包括以下步骤：a)在含稀土元素的待萃取水溶液中,混合萃取用组合物和磁性Janus颗粒,在动态条件下形成乳液,其中所述萃取用组合物的至少一部分形成为由所述磁性Janus颗粒稳定的分散相,其中每个所述磁性Janus颗粒同时具有亲水性部分和疏水性部分；b)施加外部磁场A,形成富集有所述分散相的富集乳液部分,进而分离所述富集乳液部分；c)使得分离出所述富集乳液部分后得到的萃取体系分层,进而分离。(The invention relates to a method for extracting rare earth elements based on magnetic Janus particles. The method for extracting rare earth elements comprises the following steps: a) mixing an extraction composition and magnetic Janus particles in an aqueous solution to be extracted containing a rare earth element to form an emulsion under dynamic conditions, wherein at least a portion of the extraction composition forms as a dispersed phase stabilized by the magnetic Janus particles, wherein each of the magnetic Janus particles has both a hydrophilic portion and a hydrophobic portion; b) applying an external magnetic field A to form an enriched emulsion fraction enriched with the dispersed phase, and further separating the enriched emulsion fraction; c) and layering the extraction system obtained after separating the enriched emulsion part, and further separating.)

1. A method for extracting rare earth elements, comprising the steps of:

a) mixing an extraction composition and magnetic Janus particles in an aqueous solution to be extracted containing a rare earth element under dynamic conditions such that at least a portion of the resulting extraction system forms an emulsion, wherein at least a portion of the extraction composition forms a dispersed phase stabilized by the magnetic Janus particles, wherein each of the magnetic Janus particles has both a hydrophilic portion and a hydrophobic portion;

b) applying an external magnetic field A to form an enriched emulsion fraction enriched with the dispersed phase, and further separating the enriched emulsion fraction;

c) and layering the extraction system obtained after separating the enriched emulsion part, and further separating.

2. The method according to claim 1, wherein the amount of the magnetic Janus particles used in step a) is 0.001 to 5 wt% based on the total weight of the aqueous solution to be extracted containing a rare earth element and the composition for extraction.

3. The method according to claim 1 or 2, wherein in step a), the ratio of the rare earth element-containing aqueous solution to be extracted and the composition for extraction is 1:10000000 to 1000000:1 by volume.

4. A method for extracting rare earth elements according to any one of claims 1 to 3, wherein the content of rare earth elements in the aqueous solution to be extracted containing rare earth elements is 100ppm or less.

5. The method for extracting rare earth elements according to any one of claims 1 to 4, wherein in the step b), the magnetic field strength of the external magnetic field A is 0.05 to 2T.

6. A method for extracting rare earth elements according to any one of claims 1 to 5, further comprising the steps of:

d) applying an external magnetic field B having a greater magnetic field strength than the external magnetic field A to the separated enriched emulsion portion enriched in the dispersed phase, thereby breaking the emulsion and recovering the magnetic Janus particles.

7. The method according to claim 6, wherein in step d), the magnetic field strength of the external magnetic field B is 0.1-5.0T.

8. The method according to any one of claims 1 to 7, wherein the combination of the hydrophilic portion and the hydrophobic portion of the magnetic Janus particles is selected from silica/polystyrene, silica/poly (meth) acrylate-based monomer, silica/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomer-divinylbenzene, silica/polystyrene-di (meth) acrylate-based monomer, silica/poly (meth) acrylate-, At least one of silicon dioxide/polystyrene- (methyl) acrylate monomer-di (methyl) acrylate monomer, titanium dioxide/polystyrene, titanium dioxide/poly (methyl) acrylate monomer, titanium dioxide/polystyrene-divinylbenzene, titanium dioxide/poly (methyl) acrylate monomer-divinylbenzene, titanium dioxide/polystyrene-di (methyl) acrylate monomer, and titanium dioxide/poly (methyl) acrylate monomer-di (methyl) acrylate monomer.

9. A method for extracting rare earth elements according to any one of claims 1 to 8, wherein the magnetic Janus particles are snowman-shaped.

Technical Field

The present invention relates to extraction processes, and in particular to a process for enhanced extraction of rare earth elements by employing magnetic Janus particles as solid particle emulsifiers.

Background

Rare earth elements include lanthanides (lanthanum (L a), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er)), thulium (Tm), ytterbium (Yb), lutetium (L u)), and scandium (Sc) and yttrium (Y) in the iiib group of the periodic table of chemical elements.

Solvent extraction is one of the widely used separation methods in view of the current worldwide production of single rare earths. The solvent extraction method selectively separates and purifies the rare earth elements by utilizing the difference of the distribution ratio of certain components in the water phase in the organic phase. The organic phase formed by the extractant and the organic solvent is fully contacted with the aqueous phase containing the rare earth element to be separated without being fully mixed, thereby realizing the distribution of unequal concentration of the rare earth components in the two phases and achieving the purposes of separating and purifying the rare earth element. The solvent extraction method has the advantages of large processing capacity, high reaction speed and good separation effect, so that the solvent extraction method cannot be replaced by other methods. However, the conventional method for extracting rare earth elements by liquid-liquid extraction has the disadvantages of long extraction time, low extraction efficiency, difficulty in extracting rare earth elements with extremely low concentration (100ppm) and the like.

For example, patent document 1 discloses a method for extracting, enriching and recovering rare earth from a low-concentration rare earth solution. Carrying out centrifugal extraction on the low-concentration rare earth solution by adopting a non-saponified organic extractant to obtain a rare earth-loaded organic phase and raffinate; and (4) carrying out centrifugal back extraction on the loaded organic phase by adopting inorganic acid to obtain the rare earth enrichment liquid. Performing coupling centrifugal extraction once or twice according to the concentration of the actual rare earth solution, enriching all rare earths or light rare earth and medium-heavy rare earth into a rare earth loaded organic phase, and performing centrifugal back extraction by inorganic acid to obtain rare earth enriched liquid containing all rare earths or mainly light rare earth or medium-heavy rare earth. However, the extraction method is complicated in operation and long in extraction time. Patent document 2 discloses a method for separating rare earth elements using an acidic-alkaline composite extractant. In the extraction process, leading out the water phase at the middle stage of the extraction section, extracting and separating the water phase by using an alkaline extractant, and returning the water phase to the extraction section for continuous extraction; and introducing the water phase discharged from the washing section into the middle stage of the extraction section for extraction, and returning the water washing liquid discharged from the washing section to the washing section, the washing section and the back extraction section for use or preparing acid for dissolving the rare earth ore. However, this extraction method is also complicated in operation and requires a long extraction time. Patent document 3 provides a method for continuous extraction separation of a medium-heavy rare earth chloride solution. In the method, the medium-heavy rare earth chloride solution after impurity removal, an extracting agent and a diluting agent are mixed in a mixing chamber, flow into a clarifying chamber for clarification, and an organic phase and a water phase are separated. Although the extraction process can be continuously and stably carried out, the occupied area is large, the extraction efficiency is low, and the purification, enrichment and recovery of rare earth ions with extremely low concentration are difficult.

To increase extraction efficiency, it is one of the effective ways to reduce the size of the extract phase droplets to increase the contact area of the extract phase droplets. Accordingly, one skilled in the art sometimes contemplates adding a surfactant, such as an emulsifier, to the extraction system. However, such methods have significant technical drawbacks. Especially for aqueous-organic extraction systems, the use of conventional emulsifiers often makes separation of the two phases after extraction difficult. Specifically, the emulsifier reduces the interfacial tension of the components in the mixed system and forms a relatively strong film on the surface of the droplets or forms an electric double layer on the surface of the droplets due to the electric charge given by the emulsifier, preventing the droplets from aggregating with each other, thereby maintaining the emulsion to be uniform. In this case, the aqueous solution phase to be extracted and the extraction liquid phase are difficult to separate thoroughly, greatly adversely affecting the extraction effect, and also causing environmental pollution and resource waste.

Therefore, in the prior art, there is still room for research on an extraction technique capable of simultaneously improving extraction efficiency and separation efficiency, particularly extracting rare earth elements from an aqueous solution to be extracted having a very low concentration of rare earth ions.

Janus particles are a new material and are widely noticed due to their wide application prospect caused by unique properties in structure and performance. Typically, Janus particles have two partitions that differ in structure, morphology, or composition, e.g., having both a hydrophilic portion and a lipophilic portion. This property allows Janus particles to be used as solid emulsifiers. Particularly, after the magnetic responsiveness modification, the enrichment can be realized by using a magnetic field, and the enrichment can be recycled. For example, patent document 4 discloses magnetic Janus particles that can be used as a solid emulsifier in oil-water separation technology. The enrichment and separation of emulsion droplets stabilized by magnetic Janus particles can be realized through an external magnetic field, so that rapid liquid separation is realized. However, patent document 1 does not pay attention to the application of the magnetic Janus particles in the extraction field, particularly the extraction field of rare earth elements.

Patent document

Patent document 1: CN107699715B

Patent document 2: CN109554556A

Patent document 3: CN110331303A

Patent document 4: WO 2016/026464A1

Disclosure of Invention

Problems to be solved by the invention

In view of the above-mentioned drawbacks in the art, the technical problem to be solved by the present invention is to provide a method for extracting rare earth elements from an aqueous solution to be extracted containing rare earth elements, which can be widely applied to extraction of rare earth elements from an aqueous solution to be extracted containing rare earth elements, and particularly, can be applied to extraction of rare earth elements from an aqueous solution to be extracted containing rare earth elements in a low content (e.g., 100ppm or less), and has the advantages of improved extraction efficiency, simple and convenient liquid separation operation, high flexibility, and excellent environmental friendliness and economy.

Means for solving the problems

According to the intensive research of the inventor of the present invention, it is found that the technical problems can be solved by implementing the following technical scheme:

[1] a method of extracting rare earth elements comprising the steps of:

a) mixing an extraction composition and magnetic Janus particles in an aqueous solution to be extracted containing a rare earth element under dynamic conditions such that at least a portion of the resulting extraction system forms an emulsion, wherein at least a portion of the extraction composition forms a dispersed phase stabilized by the magnetic Janus particles, wherein each of the magnetic Janus particles has both a hydrophilic portion and a hydrophobic portion;

b) applying an external magnetic field A to form an enriched emulsion fraction enriched with the dispersed phase, and further separating the enriched emulsion fraction;

c) and layering the extraction system obtained after separating the enriched emulsion part, and further separating.

[2] The method for extracting a rare earth element according to [1], wherein the amount of the magnetic Janus particles used in the step a) is 0.001 to 5% by weight based on the total weight of the aqueous solution to be extracted containing a rare earth element and the composition for extraction.

[3] The method for extracting a rare earth element according to [1] or [2], wherein in the step a), the ratio of the aqueous solution to be extracted containing a rare earth element to the composition for extraction is 1:10000000 to 1000000:1 by volume.

[4] The method for extracting a rare earth element according to any one of [1] to [3], wherein the content of the rare earth element in the aqueous solution to be extracted containing a rare earth element is 100ppm or less.

[5] The method for extracting a rare earth element according to any one of [1] to [4], wherein in the step b), the magnetic field strength of the external magnetic field A is 0.05 to 2.0T.

[6] The method for extracting a rare earth element according to any one of [1] to [5], further comprising the steps of:

d) applying an external magnetic field B having a greater magnetic field strength than the external magnetic field A to the separated enriched emulsion portion enriched in the dispersed phase, thereby breaking the emulsion and recovering the magnetic Janus particles.

[7] The method for extracting a rare earth element according to [6], wherein in the step d), the magnetic field strength of the external magnetic field B is 0.1 to 5.0T.

[8] The method for extracting a rare earth element according to any one of [1] to [7], wherein the combination of the hydrophilic portion and the hydrophobic portion of the magnetic Janus particle is selected from the group consisting of silica/polystyrene, silica/poly (meth) acrylate-based monomer, silica/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomer-divinylbenzene, silica/polystyrene-di (meth) acrylate-based monomer, silica/poly (meth) acrylate-based monomer-di (meth) acrylate-based monomer, silica/polystyrene- (meth) acrylate-based monomer-di (meth) At least one of an acrylate monomer, titanium dioxide/polystyrene, titanium dioxide/poly (meth) acrylate monomer, titanium dioxide/polystyrene-divinylbenzene, titanium dioxide/poly (meth) acrylate monomer-divinylbenzene, titanium dioxide/polystyrene-di (meth) acrylate monomer, titanium dioxide/poly (meth) acrylate monomer-di (meth) acrylate monomer.

[9] The method for extracting a rare earth element according to any one of [1] to [8], wherein the magnetic Janus particle is snowman-shaped.

ADVANTAGEOUS EFFECTS OF INVENTION

Through the implementation of the technical scheme, the invention can obtain the following technical effects:

(1) the magnetic Janus particles play a role of a solid emulsifier, so that the two-phase contact area can be increased and the extraction efficiency can be improved through emulsification in the extraction method, and therefore, the extraction method can be widely used for solvent extraction of rare earth elements in industry, and is particularly suitable for enhanced extraction of rare earth ions with extremely dilute concentration.

(2) The magnetic Janus particles have magnetism, so that the extraction method disclosed by the invention can realize quick and efficient liquid separation under the action of a magnetic field.

(3) The extraction method of the invention has mild operation conditions, simple and convenient operation and small occupied area of required equipment, thereby having strong flexibility.

(4) The magnetic Janus particles can be recovered and recycled, especially the amount of magnetic Janus particles added can be low. Therefore, the extraction method of the invention is green, economical and free of secondary pollution.

Drawings

FIG. 1 is a scanning electron microscope image of magnetic Janus particles.

Fig. 2 is an optical microscope picture of emulsion droplets stabilized by magnetic Janus particles.

Detailed Description

The present invention will be described in detail below. The technical features described below are explained based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

in the present specification, the term "Janus particle" refers to a Janus particle in the broad sense of the art, i.e., a particle that is not only asymmetric (anisotropic) in structural morphology, but also asymmetric in compositional properties, or both.

In the present specification, the "(meth) acrylate" used includes the meanings of "methacrylate" and "acrylate"; the "(meth) acrylic acid" used includes the meaning of "methacrylic acid" as well as "acrylic acid".

In the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, the numerical ranges indicated by "above" or "below" mean the numerical ranges including the numbers.

In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

As used herein, the term "optional" or "optional" is used to indicate that certain substances, components, performance steps, application conditions, and the like are used or not used.

In the present specification, the unit names used are all international standard unit names, and the "%" used means weight or mass% content, if not specifically stated.

In the present specification, the term "particle diameter" as used herein means an "average particle diameter" if not specifically stated, and can be measured by a commercially available particle sizer or an electron scanning microscope.

In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

The method for extracting rare earth elements comprises the following steps: a) mixing an extraction composition and magnetic Janus particles in a rare earth element-containing aqueous solution to be extracted (hereinafter sometimes simply referred to as an aqueous solution to be extracted), under dynamic conditions such that at least a portion of the resulting extraction system forms an emulsion, wherein at least a portion of the extraction composition forms a dispersed phase stabilized by the magnetic Janus particles, wherein each of the magnetic Janus particles has both a hydrophilic portion and a hydrophobic portion; b) applying an external magnetic field A to form an enriched emulsion fraction enriched with the dispersed phase, and further separating the enriched emulsion fraction; c) and layering the extraction system obtained after separating the enriched emulsion part, and further separating.

The extraction method is suitable for the aqueous solution to be extracted containing the rare earth elements from different sources, so the extraction rate of the rare earth elements is not particularly limited, and generally, the extraction rate is 20.0-99.9 wt%. In some preferred embodiments, the residual amount of rare earth elements in the aqueous solution after extraction (raffinate) is preferably less than 30ppm, more preferably less than 15ppm, less than 1.0 ppm. In other preferred embodiments, the extraction time is preferably from 2 to 60 minutes.

The term "extraction yield" as used in the present invention means that, when an extract to be extracted in an aqueous solution to be extracted is extracted with an extracting composition, the extraction yield is equal to the percentage of the total amount of the extract to be extracted in the extracting composition to the total amount of the extract to be extracted in both phases. As described above, in the case of a rare earth element compound as an extract to be extracted, both the extraction rate and the residual amount are values in terms of rare earth elements.

The above steps will be described in detail below.

a) Step of emulsification and extraction

In this step, an extraction composition and magnetic Janus particles are mixed in an aqueous solution to be extracted, at least a portion of the resulting extraction system is formed into an emulsion and extracted under dynamic conditions, wherein at least a portion of the extraction composition is formed into a dispersed phase stabilized by the magnetic Janus particles.

In the present invention, "at least a part of the composition for extraction is formed into a dispersed phase stabilized by the magnetic Janus particles" means a state in which at least a part of the composition for extraction is formed into stable emulsion droplets in the extraction system (as shown in fig. 2) because the magnetic Janus particles function as a solid emulsifier.

The amount of the magnetic Janus particles is not particularly limited and may be appropriately adjusted according to the specific composition of the extraction system. In some specific embodiments, the amount of the magnetic Janus particles is preferably 0.001 to 5% by weight, more preferably 0.01 to 3% by weight, and still more preferably 0.02 to 1% by weight, relative to the total weight of the aqueous solution to be extracted and the composition for extraction, from the viewpoint of better obtaining the technical effects of the present invention. In some embodiments, the amount of the magnetic Janus particles is preferably 0.02 to 1% by weight relative to the total weight of the composition for extraction, from the viewpoint of better obtaining the technical effect of the present invention.

The ratio of the aqueous solution to be extracted and the composition for extraction is not particularly limited and may be appropriately selected depending on the actual application. In some specific embodiments, the ratio of the aqueous solution to be extracted and the composition for extraction (aqueous solution to be extracted: composition for extraction) is preferably 1:10000000 to 1000000:1, more preferably 1:100000 to 100000:1, still more preferably 1:80000 to 80000:1, and even more preferably 1:50000 to 50000:1 by volume.

The order of charging the magnetic Janus particles and the extraction composition is not particularly limited, and the magnetic Janus particles and the extraction composition may be charged simultaneously; or the magnetic Janus particles are put into the container firstly, and then the composition for extraction is put into the container; or the composition for extraction is put in first, and then the magnetic Janus particles are put in.

In the present invention, the dynamic conditions may be applied by means known in the art, for example, oscillations, vortexes, ultrasound, electric or magnetic fields, or the like may be applied. In some preferred embodiments, the dynamic conditions are preferably applied by means of oscillation from the viewpoint of ease of operation. In this case, the frequency of oscillation is preferably 50 to 300r/min, more preferably 80 to 250 r/min.

In the invention, the extraction temperature in the emulsification extraction step is preferably in the range of 0-60 ℃. When the extraction temperature is too low, the energy required for cooling tends to be too high. When the extraction temperature is too high, the extraction efficiency tends to deteriorate.

In the present invention, the extraction pressure in the emulsification extraction step may be any of atmospheric pressure, elevated pressure and reduced pressure, but atmospheric pressure is preferable from the viewpoint of ease of operation.

In the present invention, the extraction time is not particularly limited and may be appropriately selected depending on the composition and amount of the aqueous solution to be extracted and the composition for extraction, the amount of the magnetic Janus particles, the extraction temperature, the extraction pressure, and the like. However, the time for the emulsification extraction is usually 1 to 100 minutes from the viewpoint of improving the extraction efficiency and increasing the production efficiency.

In the present invention, the extraction means may employ any one of the extraction means commonly used in the art, such as batch extraction, continuous extraction and continuous countercurrent extraction.

The aqueous solution to be extracted containing a rare earth element, the composition for extraction, and the magnetic Janus particles are described in detail below.

(1) Aqueous solution to be extracted containing rare earth elements

The source of the aqueous solution to be extracted in the present invention is not particularly limited, and for example, it may be any of industrially acceptable aqueous solutions containing a rare earth element, such as various wastewaters, acidic leachate containing a rare earth element (e.g., from wastes, fly ash, etc.), and various liquid intermediate products containing a rare earth element, and the like.

Specifically, the rare earth elements to which the extraction method of the present invention is applicable include lanthanides (lanthanum (L a), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er)), thulium (Tm), ytterbium (Yb), lutetium (L u)), and scandium (Sc) and yttrium (Y).

In the present invention, there is no particular limitation on the content of the rare earth element in the aqueous solution to be extracted containing the rare earth element, and in some preferred embodiments, the extraction method of the present invention is preferably applied to an aqueous solution to be extracted having a content of the rare earth element of 100ppm or less.

In some more preferred embodiments, as previously described, the residual amount of rare earth elements in the raffinate can be less than 1.0ppm, even for aqueous solutions to be extracted having a rare earth element content of 100ppm or less.

(2) Composition for extraction

The specific composition of the composition for extraction of the present invention is also not particularly limited.

In some embodiments, the extraction composition of the present invention preferably comprises at least an ionic liquid. In other specific embodiments, the extraction composition of the present invention preferably comprises at least an extractant and a water-insoluble organic solvent.

The ionic liquid may be generally appropriately selected in accordance with the specific composition of the aqueous solution to be extracted (specific kind of rare earth element, and other substances contained in the aqueous solution to be extracted, etc.). Examples of ionic liquids include, without limitation: 1-butyl-3-methylimidazol perfluorobutane sulfonic acid, trioctylmethylammonium chloride monoisooctyl phosphate ([ A336] [ P507]), trioctylmethylammonium chloride diisooctyl phosphate ([ A336] [ P204]), and the like.

The organic solvent may be generally appropriately selected in accordance with the specific composition of the aqueous solution to be extracted (specific kind of rare earth element, and other substances contained in the aqueous solution to be extracted, etc.). Examples of organic solvents include, without limitation, kerosene, light white oil, mineral spirits, and the like.

In the extraction process of the present invention, various extractants known in the art can be used. Examples of extractants in the present invention include, without limitation: neutral extractants, for example, neutral oxygen-containing extractants, neutral phosphorus-containing extractants (e.g., tributyl phosphate (TBP), di-sec-octyl methylphosphonate (P350), di-2-ethylhexyl isopropylphosphonate, di-sec-octyl isopropylphosphonate, trioctylphosphine oxide, tri-n-butylphosphine oxide, and the like), neutral sulfur-containing extractants, and the like; acidic extractants, for example, acidic phosphate extractants (e.g., diisooctyl phosphate (P204), di-sec-octyl phosphate (P215), monolauryl phosphate (P501), monoisooctyl phosphate (P507), diisooctyl phosphonic acid, bis (2,4, 4-trimethylpentyl) phosphinic acid, etc.), carboxylic acid extractants (e.g., naphthenic acid, versatic acid, n-hexanoic acid, diethylhexanoic acid, etc.); amine-based extractants, for example, primary amine-based extractants, secondary amine-based extractants, tertiary amine-based extractants (e.g., trialkylamines, etc.), quaternary amine salt-based extractants (e.g., methyltrialkylammonium chloride, etc.); amide extractants, such as monoamides, bisamides, imides, 3-oxoglutaramides; a synergistic extractant; complexing an extractant; and the like. In some preferred embodiments, the extractant is preferably at least one selected from the group consisting of a neutral phosphorus-containing extractant, an acidic phosphate-based extractant, an amine-based extractant, and an amide-based extractant, and more preferably an acidic phosphate-based extractant. In addition, in some preferred embodiments, the content of the extractant in the composition for extraction is preferably 10 to 40% by weight, and more preferably 15 to 35% by weight.

The extraction composition of the present invention may further contain other additives such as complexing agents, extraction promoters, extraction inhibitors, phase transfer catalysts, stabilizers, diluents, and the like, in an arbitrary amount as required.

(3) Magnetic Janus particles

A portion of each of the magnetic Janus particles of the present invention has a hydrophilic property and another portion has a hydrophobic property, in other words, each of the magnetic Janus particles of the present invention has both a hydrophilic part and a hydrophobic part. The specific chemical composition of the magnetic Janus particles of the present invention is not particularly limited as long as they have both a hydrophilic portion and a hydrophobic portion, and can be adjusted according to the composition and ratio of the aqueous solution to be extracted and the composition for extraction.

In some embodiments, the hydrophilic portion of the magnetic Janus particles of the present invention can have hydroxyl groups (including alcoholic hydroxyl groups, silicon hydroxyl groups, phenolic hydroxyl groups, and the like), ether groups, amide groups, carboxyl groups, anhydrides or salts thereof, and the like. In some embodiments, the hydrophilic portion of the magnetic Janus particles of the present invention can be comprised of organic materials, inorganic materials, or both. Examples of the forming monomer of the organic substance constituting the hydrophilic portion include, but are not limited to, acrylic monomers, pyrrolidone monomers, acrylamide monomers, (poly) ethylene glycol monomers, (poly) propylene glycol monomers, and the like. These monomers may be used alone or in combination of two or more. Examples of the inorganic substance constituting the hydrophilic portion include, without limitation, silicon monoxide, silicon dioxide, titanium dioxide, aluminum oxide, and the like. These inorganic substances may be used alone or in combination of two or more. In some preferred embodiments, the hydrophilic portion of the magnetic Janus particles of the present invention preferably comprises an inorganic substance, more preferably comprises silica.

In some embodiments, examples of the organic substance forming monomers constituting the hydrophobic portion include, but are not limited to, styrenic monomers (e.g., styrene, p-methylstyrene, α -methylstyrene, etc.), (meth) acrylate monomers (e.g., methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, etc.), silane monomers, silicone monomers, olefin monomers, acetal monomers, etc. these resins may be used alone or in combination of two or more.

Furthermore, the hydrophobic portion of the magnetic Janus particles of the present invention can be hollow, porous, or solid, as desired.

In some preferred embodiments, the magnetic Janus particles of the present invention are preferably magnetic mineral/polymer Janus particles or magnetic polymer/polymer Janus particles, more preferably magnetic mineral/polymer Janus particles.

In some preferred embodiments, the combination of hydrophilic and hydrophobic portions (hydrophilic/hydrophobic portions) of the magnetic Janus particles of the present invention is preferably selected from the group consisting of silica/polystyrene (as described in WO 2016/026464a 1), silica/poly (meth) acrylate-based monomers, silica/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomers-divinylbenzene, silica/polystyrene-di (meth) acrylate-based monomers, silica/poly (meth) acrylate-based monomers-di (meth) acrylate-based monomers, silica/poly (meth) acrylate-di (meth) acrylate-based monomers, and mixtures thereof, At least one of silicon dioxide/polystyrene- (methyl) acrylate monomer-di (methyl) acrylate monomer, titanium dioxide/polystyrene, titanium dioxide/poly (methyl) acrylate monomer, titanium dioxide/polystyrene-divinylbenzene, titanium dioxide/poly (methyl) acrylate monomer-divinylbenzene, titanium dioxide/polystyrene-di (methyl) acrylate monomer, and titanium dioxide/poly (methyl) acrylate monomer-di (methyl) acrylate monomer. In some more preferred embodiments, the combination of hydrophilic and hydrophobic portions (hydrophilic/hydrophobic portions) of the magnetic Janus particles of the present invention is more preferably selected from the group consisting of silica/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomer-divinylbenzene, silica/polystyrene-di (meth) acrylate-based monomer, silica/poly (meth) acrylate-based monomer-di (meth) acrylate-based monomer, silica/polystyrene- (meth) acrylate-based monomer-di (meth) acrylate-based monomer, titania/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomer-di (meth) acrylate-based monomer, silica/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomer, and mixtures thereof, At least one of titanium dioxide/poly (meth) acrylate monomer-divinylbenzene, titanium dioxide/polystyrene-di (meth) acrylate monomer, and titanium dioxide/poly (meth) acrylate monomer-di (meth) acrylate monomer.

The magnetic Janus particles of the present invention include a magnetic component, such as, for example, iron (Fe) trioxide₂O₃) Ferroferric oxide (Fe)₃O₄) Iso-iron oxide, chromium dioxide (CrO)₂) Magnetic ferrite (MFe)₂O₄) Magnetic spinel (MR)₂O₄) Magnetic hexaferrite (MFe)₁₂O₁₉) Magnetic orthoferrite (RFeO)₃) Magnetic garnet M₃R₂(AO₄)₃Wherein M represents a divalent metal, R represents a trivalent metal and a represents a tetravalent metal. From the viewpoint of easy availability, the magnetic component is preferably ferroferric oxide. The magnetic component may optionally be present on the hydrophilic portion, the hydrophobic portion, or both of the magnetic Janus particles. In some preferred embodiments, to better achieve the technical effects of the inventionFrom the viewpoint of the present invention, the magnetic component of the present invention is present at least in the hydrophobic portion of the magnetic Janus particle, and more preferably, the magnetic component of the present invention is supported on the hydrophobic portion of the magnetic Janus particle.

In the present invention, the structural morphology of the magnetic Janus particles of the present invention is not particularly limited, and for example, the magnetic Janus particles of the present invention have a spherical shape, a rod shape, a butterfly shape, a mushroom shape, a bullet shape, a cone shape, a cylinder shape, a disk shape, a hamburger shape, a dumbbell shape, a chain shape, a half raspberry shape, a raspberry shape, or a snowman shape, and the like, and can be appropriately selected depending on the composition and the ratio of the aqueous solution to be extracted and the composition for extraction. From the viewpoint of better achieving the technical effects of the present invention, the magnetic Janus particles of the present invention are preferably magnetic particles that are asymmetric (anisotropic) in structural morphology, and more preferably magnetic particles having a snowman shape. In the present invention, the term "snowman-like" refers to a three-dimensional structure (as shown in fig. 1) in which two spheres (or approximate spheres) of the same or different sizes are stacked in a partially overlapping manner. In the case where the magnetic Janus particles of the present invention are snowman-shaped magnetic particles, the ratio of the diameters of the two spheres constituting "snowman-shaped" is preferably 1:4 to 4: 1.

The size of the magnetic Janus particles of the present invention is not particularly limited as long as it can function as an emulsifier for solid particles, and can be appropriately adjusted according to the composition and ratio of the aqueous solution to be extracted and the composition for extraction. In some embodiments, the size of the magnetic Janus particles of the present invention is preferably 150 to 800nm, more preferably 250 to 600nm, from the viewpoint of better achieving the technical effects of the present invention. The size of the magnetic Janus particles of the present invention can be measured by means well known in the art, for example by Scanning Electron Microscopy (SEM).

In the present invention, the magnetic Janus particles may be prepared by a method generally used in the art, for example, may be prepared by emulsion polymerization, seeded emulsion polymerization, dispersion polymerization-seeded emulsion polymerization, phase separation, microfabrication, self-assembly, and the like.

b) Magnetic fertilizerStep of Collection and separation

Applying an external magnetic field A to the extraction system obtained in the step a), and enriching a dispersed phase stabilized by the magnetic Janus particles in the extraction system, thereby forming an enriched emulsion part enriched with the dispersed phase, and further separating the enriched emulsion part.

The magnetic field strength of the external magnetic field a is generally selected as appropriate depending on the kind of the magnetic Janus particles used, the composition for extraction, and the composition of the aqueous solution to be extracted. In some embodiments, the magnetic field strength of the external magnetic field A is preferably 0.05T to 2T, more preferably 0.08T to 1.5T. When the magnetic field strength of the external magnetic field a is less than this range, it tends to be difficult to achieve enrichment of the dispersed phase. When the magnetic field strength of the external magnetic field a is larger than this range, the dispersed phase stabilized by the magnetic Janus particles tends to be difficult to maintain stable.

In some embodiments, the application time of the external magnetic field a is preferably 1 second to 30 minutes, preferably 10 seconds to 20 minutes, and more preferably 2 minutes to 10 minutes, from the viewpoint of better achieving the technical effects of the present invention. When the application time of the external magnetic field a is less than this range, it tends to be difficult to achieve enrichment of the dispersed phase. When the application time of the external magnetic field a is longer than this range, a further improvement effect cannot be obtained, and a reduction in production efficiency is caused.

Generally, the external magnetic field a may be applied by means known in the art. The external magnetic field a may be applied, for example, by an electromagnet or a permanent magnet. These magnets may be a single magnet or any combination of magnets.

The method for separating the enriched emulsion fraction is not particularly limited, and means generally known in the art, such as magnetic adsorption, suction, and the like, may be used.

Further, the separated enriched emulsion portion may be subjected to oil-water separation, refining, extraction, distillation, etc. processes known in the art to obtain the desired product, or may be directly discarded, as desired.

c) Liquid separation step

In this step, after the enriched emulsion fraction is separated, the treated extraction system is layered to form an oil phase layer (i.e., an organic phase from which the rare earth element is extracted) and an aqueous phase layer (i.e., a raffinate phase). Further, the oil phase layer and the water phase layer are separated.

Any liquid separation device known in the art may be used in this step as desired. The standing time in this step is not particularly limited and may be appropriately selected depending on the composition and ratio of the aqueous solution to be extracted and the composition for extraction. In general, the standing time is preferably 1 minute to 3 hours, and more preferably 5 minutes to 1 hour.

Further, each of the separated oil phase and aqueous phase may be further subjected to processes of oil-water separation, refining, extraction, back extraction, washing, distillation, etc. known in the art, or may be directly discarded, as necessary.

d) Recovery procedure for magnetic Janus particles

The extraction process of the present invention may further comprise a recovery step of the magnetic Janus particles as desired. In this step, an external magnetic field B of greater magnetic strength than the external magnetic field a is applied to the separated enriched emulsion fraction enriched in the dispersed phase, thereby breaking the emulsion and recovering the magnetic Janus particles.

The magnetic field strength of the external magnetic field B is greater than the magnetic field strength of the external magnetic field a. In some preferred embodiments, the magnetic field strength of the external magnetic field B is preferably 0.1T to 5T, more preferably 0.2T to 4T. When the magnetic field strength of the external magnetic field B is less than the above range, it tends to be difficult to achieve good demulsification. When the magnetic field strength of the external magnetic field B is larger than the above range, the demulsifying effect tends to be not further improved and the cost tends to be increased.

Generally, the external magnetic field B may be applied by means known in the art. The external magnetic field B may be applied by an electromagnet or a permanent magnet, for example. These magnets may be a single magnet or any combination of magnets.

The isolated magnetic Janus particles can be reused in the extraction process of the present invention after being subjected to washing, drying, etc., as desired.

Further, the separated product obtained after separation of the magnetic Janus particles (demulsification) may be subjected to oil-water separation, refining, extraction, distillation, etc. processes known in the art to obtain the desired product, or may be directly discarded, as desired.