CN112742220B

CN112742220B - Polymer containing film and preparation method and application thereof

Info

Publication number: CN112742220B
Application number: CN202011534182.2A
Authority: CN
Inventors: 王勇; 齐涛; 陆雅萌; 李阳
Original assignee: Jiangxi Rare Earth Research Institute Chinese Academy Of Sciences; Institute of Process Engineering of CAS
Current assignee: Jiangxi Rare Earth Research Institute Chinese Academy Of Sciences; Institute of Process Engineering of CAS
Priority date: 2020-12-22
Filing date: 2020-12-22
Publication date: 2023-05-30
Anticipated expiration: 2040-12-22
Also published as: CN112742220A

Abstract

The invention provides a polymer containing membrane, a preparation method and application thereof, wherein the material of the polymer containing membrane comprises a combination of a base polymer and an extractant; the extractant is any one of a neutral extractant, a carboxylic acid extractant or a chelating extractant; the polymer containing film has good selectivity to rare earth elements by selecting any one of a neutral extractant, a carboxylic acid extractant or a chelating extractant; the preparation method of the polymer containing film is simple and environment-friendly, and the extractant contained in the prepared polymer containing film can hardly run off in the use process, so that the stability and the service life of the polymer containing film are improved.

Description

Polymer containing film and preparation method and application thereof

Technical Field

The invention belongs to the technical field of separation membranes, and particularly relates to a polymer containing membrane and a preparation method and application thereof.

Background

In recent years, rare earth or a compound thereof has the characteristics of excellent photoelectromagnetism and the like, can greatly improve the quality and performance of products, and is widely applied to the fields of national defense, metallurgy, chemical industry, aerospace and the like. However, in nature, rare earth elements are mostly dispersed in minerals in the form of accompaniment, and the difficulty of separation and extraction is great. In the process of separating rare earth elements, not only the associated rare earth elements with similar physical properties and chemical properties are considered, but also a plurality of associated impurity elements are separated, so that the difficulty of the process flow is greatly improved. Today, the economic development is rapid, and the consumption of rare earth elements is increasing year by year, so how to effectively separate each element in rare earth has important practical significance.

In the traditional liquid-liquid solvent extraction process, oil-water two phases are directly contacted, so that the problems of entrainment, easy emulsification and the like of the oil-water two phases are caused. The liquid membrane separation technology combines the advantages of liquid-liquid extraction and membrane separation, and performs extraction separation under the condition that oil-water two phases are not in direct contact, so that the solvent loss and emulsification conditions can be reduced.

The liquid membranes used in conventional liquid membrane separation techniques mainly include Emulsion Liquid Membranes (ELMs) and Supported Liquid Membranes (SLMs). There are many studies and reports on these two membranes. CN104831068A discloses an emulsion liquid film for separating calcium and magnesium ions, which consists of an organic film phase and an internal phase back extractant, wherein the film phase consists of a film solvent, a double-flow carrier and a surfactant, the film phase is mixed with an internal water phase and sheared at high speed under an emulsifying machine to obtain a stable emulsion liquid film, which has the advantages of being capable of being used for effectively separating calcium and magnesium ions, good in selectivity for calcium ions compared with magnesium ions, beneficial to improving extraction rate, providing technical reference for the emulsion liquid film in metal ion separation application, and strong in practicability. The emulsion film has the advantages of larger interface contact area, small consumption of extractant and the like, but also has the problems of low stability, difficult emulsion preparation and demulsification and the like.

CN105597556a discloses a high heat conduction composite supported liquid film and a preparation method thereof. Comprising the following steps: a porous membrane; a supported liquid film on the porous membrane; the supported liquid film consists of a supporting layer and a film liquid; the hydrophilicity and hydrophobicity of the porous membrane are opposite to those of the membrane; the film liquid contains 20-45% of LiCl by mass and 5-10% of high heat conduction material by mass. In order to strengthen the heat conducting capacity of the film, the film is doped with a high heat conducting filler in the preparation process. The composite supported liquid film has three preparation methods, namely a bonding method, a dry solution deposition method and a wet solution deposition method, and has simple process and low equipment cost, and the prepared composite supported liquid film has ultrathin cortex. The obtained composite supported liquid film and product can be widely applied to the fields of water treatment technology, fresh air total heat recovery technology, air conditioner energy saving technology, chemical metallurgy, environmental protection, biochemical engineering and the like, and has simple steps, convenient operation and strong practicability. However, the supported liquid film still has the defects of easy blocking of film holes, unavoidable direct contact of oil phase and water phase, short service life and the like.

The polymer-enclosed membrane (PIM) is a novel extraction membrane, and is usually formed by dissolving a base polymer, an extractant and a plasticizer or a modifier in a solvent and pouring. CN108261930a discloses a polymer-contained liquid film of indium, a preparation method and application, wherein the preparation raw materials of the liquid film comprise polymer, volatile solvent and carrier, and the preparation method of the liquid film comprises solvent volatilization method. The polymer containing liquid film separates the liquid phase from the back extraction phase solution, and indium is extracted from the low-concentration liquid by adjusting the proper acidity environment of the liquid phase and the back extraction phase and is resolved in the back extraction phase, so that the purposes of separating and enriching indium are achieved. But the polymer containment membrane cannot separate rare earth elements.

Therefore, the development of a polymer containing membrane capable of selectively separating and enriching one or more rare earth elements has important research significance.

Disclosure of Invention

In view of the shortcomings of the prior art, the invention aims to provide a polymer containing film, a preparation method and application thereof, wherein the material of the polymer containing film comprises a combination of a base polymer and an extractant, and the polymer containing film has good selectivity for rare earth elements by selecting any one of a neutral extractant, a carboxylic acid extractant or a chelating extractant, so that specific one or more rare earth elements can be effectively separated from an aqueous solution containing the rare earth elements; the preparation method of the polymer containing membrane is simple and environment-friendly, and the extractant contained in the membrane can hardly be lost in the use process of the prepared polymer containing membrane, so that the stability and the service life of the polymer containing membrane are improved.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a polymer containment membrane, the material of which comprises a combination of a base polymer and an extractant;

the extractant is any one of a neutral extractant, a carboxylic acid extractant or a chelating extractant.

The polymer containing membrane provided by the invention comprises a combination of a base polymer and an extractant, and the polymer containing membrane has good selectivity on one or more rare earth elements by selecting any one of a specific neutral extractant, a carboxylic acid extractant or a chelating extractant, so that the polymer containing membrane can be selectively separated and enriched; and the extractant contained in the polymer containing film can hardly run off in the use process, so that the service life of the polymer containing film is prolonged, the use cost is saved, and the polymer containing film is suitable for mass industrialized production and application.

Preferably, the polymer-containing film has a thickness of 29 to 31 μm, such as 29.2 μm, 29.4 μm, 29.6 μm, 29.8 μm, 30 μm, 30.2 μm, 30.4 μm, 30.6 μm or 30.8 μm, and specific point values between the above point values, are limited in length and for brevity, the invention is not intended to be exhaustive of the specific point values included in the range.

Preferably, the polymer-containing film material comprises from 35 to 80% by mass of base polymer, such as 37%, 39%, 42%, 46%, 49%, 52%, 56%, 59%, 62%, 65%, 69%, 72%, 76% or 79%, and specific point values between the above, are for brevity and for simplicity the invention is not intended to be exhaustive.

Preferably, the base polymer is any one of polyvinyl chloride, polyvinylidene fluoride, cellulose triacetate or polyvinylidene fluoride-hexafluoropropylene.

Preferably, the base polymer is polyvinylidene fluoride-hexafluoropropylene.

As a preferable technical scheme of the invention, the base polymer is vinylidene fluoride-hexafluoropropylene, and the polyvinylidene fluoride-hexafluoropropylene has the characteristics of high hydrophobicity, strong heat resistance, good mechanical strength and the like, has lower solubility, and can reduce the cost of film preparation.

Preferably, the polymer containment film material has an extractant content of 20 to 45% by mass, such as 20%, 23%, 26%, 29%, 35%, 38% or 40%, and specific point values between the above point values, which are limited in space and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values comprised in the range.

Preferably, the neutral extractant comprises dioctylsulfoxide or dimethylheptyl methylphosphonate (P350).

Preferably, the carboxylic acid-based extractant comprises cinnamic acid.

Preferably, the chelating extractant comprises benzoyl trifluoroacetone.

Preferably, the material of the polymer containment film further comprises a plasticizer.

Preferably, the mass percent of plasticizer in the material of the polymer-containing film is 0.1-35%, such as 3%, 6%, 9%, 12%, 15%, 18%, 21%, 24%, 27%, 30% or 33%, and specific point values between the above point values, are limited in space and for simplicity, the invention is not exhaustive of the specific point values included in the range.

Preferably, the plasticizer comprises tributyl phosphate.

In a second aspect, the present invention provides a method for preparing a polymer containment film according to the first aspect, the method comprising the steps of:

(1) Mixing an extractant, optionally a plasticizer, and an organic solvent to obtain a mixed solution;

(2) Mixing the base polymer with the mixed solution obtained in the step (1), stirring, and drying to obtain the polymer containing film.

The preparation method of the polymer containing film provided by the invention comprises the steps of firstly mixing an extracting agent, optionally a plasticizing agent and an organic solvent, fully and uniformly mixing the extracting agent, optionally the plasticizing agent and the organic solvent, then mixing the mixture with a base polymer, oscillating the mixture by an oscillator, facilitating swelling of the polymer so as to be fully dissolved in the organic solution, then stirring the polymer, and finally drying the polymer containing film in a mould with a fixed size.

Preferably, the organic solvent of step (1) comprises tetrahydrofuran.

Preferably, the temperature of the mixture of step (1) and step (2) is each independently from 25 to 50 ℃, such as 27 ℃, 29 ℃, 31 ℃, 33 ℃, 36 ℃, 39 ℃, 41 ℃, 45 ℃ or 49 ℃, and specific point values between the above point values, for the sake of brevity and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values comprised in the range.

Preferably, the mixing in step (1) and step (2) is performed under shaking conditions.

Preferably, the rotational speed of the oscillations is each independently 200-350 rpm, such as 220rpm, 240rpm, 260rpm, 280rpm, 300rpm, 320rpm or 340rpm, and specific point values between the above point values, are limited in space and for the sake of brevity, the invention is not exhaustive of the specific point values comprised in the range.

Preferably, the mixing time in step (1) is 10-20 min, such as 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min or 19min, and the specific point values between the above point values, which are limited in space and for brevity, the present invention is not exhaustive.

Preferably, the stirring time in step (2) is 3 to 8 hours, such as 3.3 hours, 3.6 hours, 3.9 hours, 4.1 hours, 4.5 hours, 4.9 hours, 5.2 hours, 5.6 hours, 5.9 hours, 6.2 hours, 6.6 hours, 6.9 hours or 7.5 hours, and the specific point values between the above point values, are limited in length and for brevity, the present invention is not exhaustive list of the specific point values included in the range.

Preferably, the temperature of the agitation in step (2) is 30 to 50 ℃, such as 32 ℃, 34 ℃, 36 ℃, 38 ℃, 40 ℃, 42 ℃, 44 ℃, 46 ℃ or 48 ℃, and specific point values between the above point values, limited in space and for the sake of brevity, the present invention is not exhaustive of the specific point values comprised in the range.

Preferably, the stirring of step (2) is performed under water bath conditions.

Preferably, the stirring in step (2) is carried out at a speed of 500 to 2100rpm, such as 600rpm, 700rpm, 800rpm, 900rpm, 1200rpm, 1400rpm, 1600rpm, 1800rpm or 2000rpm, and specific point values between the above point values, which are limited in space and for the sake of brevity, the invention is not intended to be exhaustive.

Preferably, the drying temperature in step (2) is 20-30 ℃, such as 21 ℃, 22 ℃, 23 ℃, 24 ℃,25 ℃, 26 ℃, 27 ℃, 28 ℃ or 29 ℃, and specific point values between the above point values, limited in space and for the sake of brevity, the invention is not exhaustive of the specific point values comprised in the range.

Preferably, the drying time of step (2) is greater than 48h, such as 50h, 53h, 55h, 57h, 60h, 63h, 65h, 69h, 70h or 72h, and the specific point values between the above point values, are for brevity and for brevity the present invention is not intended to be exhaustive.

As a preferable technical scheme, the preparation method comprises the following steps:

(1) Mixing an extractant, optionally a plasticizer and an organic solvent for 10-20 min under the shaking condition of the rotation speed of 200-350 rpm at the temperature of 25-50 ℃ to obtain a mixed solution;

(2) Mixing the base polymer and the mixed solution obtained in the step (1) for 2-4 hours at 25-50 ℃ under the vibration condition of 200-350 rpm, stirring for 3-8 hours at the water bath temperature of 30-50 ℃ and the rotation speed of 500-2100 rpm, and drying for more than 48 hours at 20-30 ℃ to obtain the polymer containing film.

In a third aspect, the present invention provides the use of a polymer containment membrane according to the first aspect for separation and recovery of rare earth elements.

Preferably, the rare earth element is any one or a combination of at least two of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, or europium.

Compared with the prior art, the invention has the following beneficial effects:

(1) The polymer containing film provided by the invention has good selectivity to one or more rare earth elements by selecting the combination of the base polymer and the extractant and selecting any one of the specific neutral sulfur-containing extractant, the carboxylic acid extractant or the chelating extractant, and can effectively separate the specific one or more elements from the aqueous solution containing the rare earth elements.

(2) The preparation method of the polymer containing film is simple, environment-friendly, low in cost and suitable for mass industrialized production; the prepared polymer containing membrane hardly loses the extractant contained in the membrane in the using process and can be repeatedly used for many times; and the application range is wide, and the water-based paint can be used in the temperature range of 16-50 ℃ and the pH value of 3-7.

Drawings

FIG. 1 is a physical view of a polymer containment film provided in example 2.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

A polymer containment membrane made of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) (Sigma-Aldrich, 427160) and extractant P350;

the preparation method comprises the following steps:

(1) Mixing 0.2g extractant and 15.5mL Tetrahydrofuran (THF) at 25 ℃ with shaking at 300rpm for 15min to obtain mixed solution;

(2) Mixing 0.6g PVDF-HFP and the mixed solution obtained in the step (1) at 25 ℃ with shaking at 300rpm for 3h, stirring at 1500rpm for 5h in a water bath at 40 ℃ and drying at 25 ℃ for 48h to obtain the polymer containing film.

Example 2

A polymer containment membrane, the materials of which are PVDF-HFP (Sigma-Aldrich, 427160), extractant P350 and tributyl phosphate (TBP);

the preparation method comprises the following steps:

(1) Mixing 0.2g extractant, 0.12g TBP and 15.5mL THF at 25deg.C with shaking at 300rpm for 15min to obtain mixed solution;

(2) Mixing 0.48g PVDF-HFP and the mixed solution obtained in the step (1) at 25 ℃ with shaking at 300rpm for 3h, stirring at 1500rpm for 5h in a water bath at 40 ℃ and drying at 25 ℃ for 48h to obtain the polymer containing film.

The physical diagram of the polymer containing film obtained in this example is shown in fig. 1, and it can be seen from fig. 1 that the polymer containing film obtained in this example is uniform and transparent.

Example 3

A polymer containing film was distinguished from example 2 only in that PVDF-HFP was replaced with polyvinylidene fluoride (PVDF) (Sigma-Aldrich, 427160), and the other components, amounts and preparation methods were the same as in example 2.

Example 4

A polymer-containing film was different from example 2 only in that the amount of extractant P350 added was 0.12g, the amount of PVDF-HFP added was 0.56g, and the other components, amounts and preparation methods were the same as in example 2.

Example 5

A polymer-containing film was different from example 2 only in that the amount of extractant P350 added was 0.2g, and the amount of PVDF-HFP added was 0.48g, and the other components, amounts and preparation methods were the same as in example 2.

Example 6

A polymer-containing film was different from example 2 only in that the amount of extractant P350 added was 0.36g, the amount of PVDF-HFP added was 0.32g, and the other components, amounts and preparation methods were the same as in example 2.

Comparative example 1

A polymer containing membrane is prepared from PVDF-HFP (Sigma-Aldrich, 427160) and extractant P350;

the preparation method comprises the following steps:

0.28g of extractant P350, 0.12g of TBP, 0.39g of PVDF-HFP and 15.5mL of THF were stirred at 1500rpm for 8h under water bath conditions of 40℃and dried at 25℃for 48h to give the polymer-containing film.

Performance test:

extraction rate, membrane flux and permeability coefficient: placing a polymer containing film in the middle of an extraction experiment module for clamping, selecting 250mL of acidic solution containing lanthanum and praseodymium rare earth ions with the concentration of 100mg/L from a material phase in a cavity on the right side of the extraction experiment module, selecting 250mL of inorganic acid solution with the concentration of 1M from a back extraction phase on the left side, simultaneously conveying the solution to two sides of the module at the speed of 100mL/min under the room temperature condition, respectively testing the concentration of lanthanum and praseodymium ions in the material phase and the back extraction phase before and during 72h of extraction by a peristaltic pump, obtaining the extraction rate according to a formula I, obtaining the permeability coefficient according to formulas II and III, and obtaining the film flux according to a formula IV; the formulas I, II, III and IV are respectively shown as follows:

/>

J ₀ ＝P×C ₀

a formula IV;

wherein: c (C) _t Representing the elemental concentration obtained from the 72 hour test; c (C) ₀ Representing the element concentration initially obtained by the test; t represents time; p represents the permeability coefficient; j (J) ₀ Represents membrane flux; v represents the volume of the material phase; a represents the area of the containing film; e represents the extraction rate.

The polymer containing films prepared in examples 1 to 6 were tested according to the test methods described above, and the test results are shown below:

TABLE 1

As can be seen from the data in table 1, the polymer containing film provided by the invention has a good separation effect on lanthanum and praseodymium in rare earth elements; specifically, the polymer-enclosed membranes obtained in examples 1 to 6 can achieve an extraction rate of praseodymium element of 64.98 to 76.28% within 72 hours, and a permeability coefficient of 2.84×10 ^-3 ～4.27×10 ^-3 Membrane flux was 5.64×10 ^-8 ～7.60×10 ^-8 J ₀ /mol m ^-2 s ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The extraction rate of lanthanum element is 10.04-17.87%, and the permeability coefficient is 0.36 multiplied by 10 ^-3 ～0.67×10 ^-3 Membrane flux was 0.65X10 ^-8 ～1.21×10 ^-8 J ₀ /mol m ^-2 s ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The polymer-containing film obtained in comparative example 1 had uneven film surface, remained solid particles of PVDF-HFP, and PVDF-HFP was not completely dissolved in tetrahydrofuran, and a transparent polymer-containing film could not be produced with uniform mixing.

The applicant states that the present invention has been described by way of the above examples as a polymer-containing film and a method of making and using it, but the invention is not limited to, i.e. it is not meant that the invention must be practiced in dependence upon, the above process steps. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of selected raw materials, addition of auxiliary components, selection of specific modes, etc. fall within the scope of the present invention and the scope of disclosure.

Claims

1. A method for preparing a polymer containment membrane for separating rare earth elements lanthanum and praseodymium, which is characterized by comprising the following steps:

(1) Mixing an extractant, an organic solvent and a plasticizer to obtain a mixed solution;

(2) Mixing the base polymer with the mixed solution obtained in the step (1), stirring, and drying to obtain the polymer containing film;

the mixing in the step (1) and the mixing in the step (2) are carried out under the condition of shaking, and the rotating speeds of the shaking are respectively and independently 200-350 rpm;

the material of the polymer-containing film comprises a combination of a base polymer and an extractant;

the extractant is a neutral extractant;

the neutral extractant comprises dioctyl sulfoxide or methyl dimethyl heptyl phosphate;

the base polymer is polyvinylidene fluoride-hexafluoropropylene;

the mass percentage of the basic polymer in the material of the polymer containing film is 35-79%;

the mass percentage of the extractant in the material of the polymer containing membrane is 20-45%;

the mass percentage of the plasticizer in the material of the polymer containing film is 0.1-35%.

2. The method of claim 1, wherein the polymer containment film has a thickness of 29 to 31 μm.

3. The method of claim 1, wherein the plasticizer comprises tributyl phosphate.

4. The method of claim 1, wherein the organic solvent of step (1) comprises tetrahydrofuran.

5. The process of claim 1, wherein the temperature of the mixing in step (1) and step (2) is each independently 25 to 50 ℃.

6. The method according to claim 1, wherein the mixing time in the step (1) is 10 to 20 minutes.

7. The method according to claim 1, wherein the mixing time in the step (2) is 2 to 4 hours.

8. The method according to claim 1, wherein the stirring time in the step (2) is 3 to 8 hours.

9. The method according to claim 1, wherein the temperature of the stirring in the step (2) is 30 to 50 ℃.

10. The method of claim 1, wherein the stirring in step (2) is performed in a water bath.

11. The method according to claim 1, wherein the stirring in step (2) is carried out at a rotational speed of 500 to 2100rpm.

12. The method according to claim 1, wherein the drying temperature in step (2) is 20 to 30 ℃.

13. The method of claim 1, wherein the drying in step (2) is performed for a period of time greater than 48 hours.

14. The preparation method according to claim 1, characterized in that the preparation method comprises the steps of:

(1) Mixing an extractant, a plasticizer and an organic solvent for 10-20 min at 25-50 ℃ under the vibration condition of 200-350 rpm to obtain a mixed solution;