WO2021196864A1

WO2021196864A1 - Mxene composite gel material, preparation method and use

Info

Publication number: WO2021196864A1
Application number: PCT/CN2021/074815
Authority: WO
Inventors: 单光存; 李鑫; 谭昊易
Original assignee: 北京航空航天大学
Priority date: 2020-04-02
Filing date: 2021-02-02
Publication date: 2021-10-07
Also published as: CN111269516A; CN111269516B

Abstract

An MXene composite hydrogel material and a preparation method, the preparation method comprising: adding a polyacrylic acid solution and a sodium carbonate solution to an MXene dispersion in sequence to form a mixed solution; adding a calcium chloride solution to the mixed solution dropwise and stirring to generate a black MXene composite hydrogel. The Mxene material in the MXene composite hydrogel material has the characteristics of a large specific surface area, stable chemical properties and structure, resistance to radiation and so on, and can be used as a good adsorption material for radioactive substances.

Description

MXene composite gel material, preparation method and application

Technical field

The present disclosure relates to an adsorption material, in particular to an MXene composite gel material, a preparation method and application.

Background technique

The radionuclides strontium (strontium-90 and strontium-89) are nuclear fission products, among which strontium-90 accounts for a relatively high proportion of nuclear fission products, with a half-life of 29.1 years. After entering the human body, it is easy to accumulate in human bones and even induce bone cancer. After a nuclear accident, radionuclides diffuse rapidly and continue to accumulate in the water environment. If they are not handled in time, they will have a serious impact on the local ecological environment. If they are not handled properly, secondary pollution may occur. According to the "China's Nuclear Safety" white paper issued by the State Council Information Office in September 2019, as of June 2019, China had 47 nuclear power plants in operation, ranking third in the world; 11 nuclear power plants under construction, ranking first in the world, and these Most of the sites for nuclear power plants are located along the coast. The 2011 Fukushima nuclear accident in Japan caused direct pollution to the marine environment, and its impact on the marine ecological environment was immeasurable. Therefore, it is necessary and significant to design and prepare an adsorption material that can efficiently remove the radionuclide strontium in water.

Summary of the invention

According to an aspect of the present disclosure, there is provided an MXene composite hydrogel material, which includes:

Two-dimensional MXene material;

Polyacrylic acid; and

Amorphous calcium carbonate.

In a further embodiment, the chemical formula of the two-dimensional MXene material is Ti ₃ C ₂ Ti _x , a sheet-like structure, x is a natural number greater than 1, and the area of the single sheet is not less than 40,000 nm ² .

In a further embodiment, the weight average molecular weight M _w of the polyacrylic acid is 100,000-250,000 g/mol.

According to another aspect of the present disclosure, there is provided a preparation method of MXene composite hydrogel, which includes:

Add the polyacrylic acid solution and the sodium carbonate solution to the MXene dispersion in sequence to form a mixed solution;

The calcium chloride solution was added dropwise to the mixed solution and stirred to form a black MXene composite hydrogel.

In a further embodiment, the MXene dispersion is prepared by the following method: prepare the MXene dispersion, add deionized water and configure to a set concentration, and configure the MXene in the dispersion with the set concentration to have a lamellar structure , And the number of layers does not exceed 10, the chemical formula is Ti ₃ C ₂ Ti _x , T _x is a surface active end-capping group, and x is a natural number greater than 1.

In a further embodiment, the volume ratio of the polyacrylic acid solution, calcium chloride solution, MXene dispersion and sodium carbonate solution used is V ₁ :V ₂ :V ₃ :V ₄ =1:0.5 to 1:0.5 ～1:0.4～0.5; and the molar concentration of the polypropylene solution is 0.2M～0.4M, the molar concentration of the calcium chloride solution is 0.1M～0.2M, and the molar concentration of the sodium carbonate solution is 0.2M ~0.4M, the mass concentration of the MXene dispersion is 0.4~0.8mg/mL.

In a further embodiment, the weight average molecular weight M _w of the polyacrylic acid in the polyacrylic acid solution is 100,000-250,000 g/mol.

In a further embodiment, adding the calcium chloride solution dropwise to the mixed solution and stirring to form a black MXene composite hydrogel includes: adding dropwise to the mixed solution or injecting calcium chloride through a syringe pump The solution is continuously stirred during the addition process. With the dripping of the calcium chloride solution, the solution fades from black to form a black MXene composite hydrogel.

In a further embodiment, the preparation method further includes: taking out the MXene hydrogel, rinsing with deionized water, pressing into a sheet and then drying, after drying, it has a three-dimensional porous structure with a pore size of 2 μm-30 μm.

According to another aspect of the present disclosure, a method for using MXene composite hydrogel material is provided, which includes putting the above-mentioned dried MXene composite hydrogel material into a strontium-containing aqueous solution to be treated.

Description of the drawings

Figure 1 is a scanning electron micrograph of the MXene/PAA/ACC hydrogel obtained in Example 1.

Figure 2 shows the ICP test result of MXene/PAA/ACC hydrogel adsorbing strontium ions in Example 2.

Figure 3 shows the ICP test results of the strontium ion adsorption effect of different MXene/PAA/ACC hydrogel dosages in Example 3.

Detailed ways

In order to make the objectives, technical solutions, and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The purpose of the present disclosure is to provide a MXene composite gel material, preparation method and application, so as to at least partially solve the above-mentioned problems.

In view of the unsatisfactory adsorption effect of the existing radionuclide strontium adsorption materials, the inventor found that MXene, as a new type of two-dimensional material, specifically refers to two-dimensional transition metal carbides or nitrides. The chemical formula of MXene is M _n+1 X _n T _x , where M represents an early transition metal element (such as Ti, Sc, Zr, Hf, etc.), X is carbon or nitrogen, and T _x represents its surface functional group, for example by chemical liquid phase The surface of MXene prepared by peeling contains a large amount of -OH, -O, and -F. Among them, Ti ₃ C ₂ Ti _x is a typical MXene material. MXene material has the characteristics of large specific surface, stable chemical properties and structure, and resistance to radiation. In addition, the abundant surface functional groups make MXene have good hydrophilicity, and it is easy to recombine with other materials, which has great potential in the treatment of water environment polluted by nuclear radiation.

The embodiments of the present disclosure provide an MXene composite hydrogel material, which includes:

Two-dimensional MXene material;

Polyacrylic acid; and

Amorphous calcium carbonate.

Each component in the MXene composite hydrogel material can be detected by appropriate detection methods, including but not limited to X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (Fourier -transform infrared spectroscopy, FTIR) method. Among them, MXene is a two-dimensional transition metal carbon (nitride) compound, and the general formula of MXene material can be M _n+1 X _n T _x , where M represents a transition metal, X represents carbon or nitrogen, and n is 1, 2, 3 , T _x is a surface active end-capping group (including but not limited to -OH, -F or -O). MXene is generally prepared by selectively etching away the A atoms in the MAX phase. The MAX phase is a family of more than 70 layered ternary metal carbides. The general molecular formula is M _n+1 AX _n (n=1, 2, 3 ), M represents a transition metal, X represents carbon or nitrogen, and A represents an element of the III or IV main group. In the prior art, the A element (such as aluminum) in the MAX ceramic phase is dissolved by a chemical etching method to obtain a two-dimensional nano-MXene material with abundant active groups (such as F, O and OH groups) on the surface. In some embodiments, M _n+1 X _n T _x may be Ti ₃ C ₂ T _x , T _x is a surface active end-capping group, and x may be a natural number greater than 1.

In some embodiments, the volume mass concentration of the MXene dispersion liquid used as the raw material for the preparation is 0.4-0.8 mg/mL, and this ratio is the basis for preparing the composite material in a gel state. MXene dispersion can be obtained by directly purchasing commercial MXene dispersion and then adding deionized water to dilute it to the target concentration; or by purchasing MXene low-layer powder and then undergoing processing steps such as ultrasonic dispersion in deionized water and centrifugal extraction of the supernatant.

In some embodiments, the chemical formula of the two-dimensional MXene material is Ti ₃ C ₂ Ti _x , a lamellar structure, x is a natural number greater than 1, the number of layers does not exceed 10, and the area of a single sheet is not less than 40,000 nm ² .

Polyacrylic acid can be prepared by a known preparation method in the prior art, wherein the weight average molecular weight M _w of acrylic acid is 100,000 to 250,000 g/mol, and this molecular weight condition is the basis for preparing a composite material in a gel state.

For amorphous calcium carbonate, provide the concentration and volume of the sodium carbonate solution and calcium chloride solution used in the preparation process (as described above). The specific function of amorphous calcium carbonate is to provide Ca ²⁺ , connect the active groups of polyacrylic acid and MXene, and promote the formation of hydrogel.

In conjunction with the above-mentioned MXene composite hydrogel material, the embodiments of the present disclosure also provide a preparation method of MXene composite hydrogel, which includes:

S1: Add the polyacrylic acid solution and the sodium carbonate solution to the MXene dispersion in sequence to form a mixed solution;

S2: Add a calcium chloride solution dropwise to the mixed solution and stir to generate a black MXene composite hydrogel.

For the above polypropylene solution, the preparation method may be: preparing a polyacrylic acid deionized aqueous solution (Polyacrylic Acid, PPA) with a molar concentration of 0.2M to 0.4M through a conventional polyacrylic acid preparation process, with a weight average molecular weight _Mw of 100000～ 250000g/mol.

For the above-mentioned calcium chloride solution, the preparation method can be: prepare a calcium chloride (CaCl ₂ ) deionized aqueous solution with a molar concentration of 0.1 M to 0.2 M by adding calcium chloride medicine to deionized water, wherein the calcium chloride used The purity of the drug product is at least analytically pure (AR).

For the above sodium carbonate solution, the preparation method can be: prepare a sodium carbonate (Na ₂ CO ₃ ) deionized aqueous solution with a molar concentration of 0.2 M to 0.4 M by adding calcium chloride to the deionization, wherein the calcium chloride is used The purity of the drug product is at least analytically pure (AR).

For the MXene solution, the preparation method may be: adding the MXene dispersion to the deionized water to prepare the MXene (Ti ₃ C ₂ Ti _x ) deionized water dispersion with a mass concentration of 0.4-0.8 mg/mL. Optionally, to ensure the dispersion effect, the MXene dispersion can be sonicated for 30 minutes before the experiment. When sonicating, place ice cubes to keep the temperature low, and fill the MXene dispersion with inert gas (argon), bottle and seal.

For step S1, specifically, it may include: adding the polyacrylic acid solution and the sodium carbonate solution to the MXene dispersion in sequence, and using equipment such as magnetic stirring to make the solution fully stirred for at least 15 minutes.

For step S1, specifically, it can include: adding calcium chloride solution dropwise to the mixed solution in S1, stirring does not stop during the addition of the solution, as the calcium chloride solution is dripped, the solution fades to black, and black is formed The hydrogel MXene/PAA/ACC. If a syringe pump is used to add calcium chloride solution, a 10 mL disposable medical syringe is used, and the injection speed is 50 to 150 mL/h.

In some embodiments, after step S2, the black MXene/PAA/ACC hydrogel can be taken out and rinsed with deionized water. The washed MXene/PAA/ACC hydrogel can be pressed into a sheet and then dried and stored. Drying methods include drying at room temperature, oven drying (temperature not exceeding 80°C), vacuum drying (temperature not exceeding 80°C) and freeze drying.

In some embodiments, the volume ratio of the polyacrylic acid solution, calcium chloride solution, MXene dispersion and sodium carbonate solution used above is V ₁ :V ₂ :V ₃ :V ₄ =1:0.5～1:0.5～1: 0.4～0.5.

The embodiments of the present disclosure also provide a method for using the MXene composite hydrogel material, which includes putting the MXene composite hydrogel material in the above-mentioned embodiments into an aqueous solution containing strontium. The strontium in the strontium-containing aqueous solution here can come from the radionuclides strontium (strontium-90 and strontium-89) produced by nuclear fission. By this method, the corresponding strontium ions can be adsorbed to avoid nuclear pollution.

The preparation method of the hydrogel polymer and the effect of adsorbing nuclide strontium ions, the method has the characteristics of simple procedure, low cost, easy waste recovery and the like.

In order to further illustrate the above content, specific embodiments are described below, but it should be noted that the following specific embodiments are only used to explain the present disclosure, and those skilled in the art can combine, substitute or transform them, and the following content is not used To limit the scope of the claims of the present disclosure.

Example 1

MXene/PAA/ACC hydrogel preparation steps.

(1) Configure 30mL of PPA solution (0.2mol/L), 30mL of CaCl ₂ solution (0.1mol/L), 15mL of Na ₂ CO ₃ solution (0.2mol/L), 30mL of MXene (Ti3C2Tix) dispersion, spare;

(2) Take 30 mL of the PPA solution and 30 mL of the CaCl ₂ solution described in step (1) and sequentially add 30 mL of the MXene dispersion to obtain the black mixed solution A, and use magnetic stirring for 15 minutes;

(3) Use a syringe pump to add 15 mL of Na ₂ CO ₃ solution dropwise to the mixture described in step (2). The syringe pump uses a 10 mL disposable medical syringe, and the injection speed is set to 100 mL/h;

(4) With _{the dripping of the Na 2} CO ₃ solution, the black mixed solution A will gradually fade from black, and the black MXene/PAA/ACC hydrogel will gradually agglomerate and settle;

(5) Rinse the MXene/PAA/ACC hydrogel obtained in step (4) with deionized water, and the deionized water should be clean and free of impurities;

(6) Freeze-drying the MXene/PAA/ACC hydrogel for 12 hours can be used to remove the radionuclide strontium in water.

(7) SEM morphology and structure characterization of the freeze-dried MXene/PAA/ACC hydrogel. As shown in Figure 1, the freeze-dried hydrogel has a three-dimensional porous structure with a pore size of 2 μm-30 μm.

Example 2

The adsorption and removal of strontium ions in water by MXene/PAA/ACC hydrogel. The chemical properties of chemical elements depend on the number of protons. The radionuclide strontium and the non-radioactive isotope strontium ion have different neutron numbers but the same chemical properties. In the experiment, a non-radioactive strontium chloride (SrCl ₂ ) solution was used to prepare the required solution for a substitute experiment. The results of the adsorption experiment can be used to characterize the adsorption effect of the MXene/PAA/ACC hydrogel on the radionuclide strontium.

_{(1) Configure 1L of strontium chloride (SrCl 2} ) deionized water solution with a mass concentration of 100mg/L for use. The purity of the strontium chloride used is analytical grade (AR). Take 5mL and place it in a 10mL centrifuge tube for actual concentration measurement. Number B0;

(2) Weigh six MXene/PAA/ACC hydrogels obtained in Example 1, 50 mg each, and put them into six 10 mL centrifuge tubes, respectively numbered A1, A2, A3, A4, A5, A6;

(3) Take the SrCl ₂ solution of (1) and place it in the centrifuge tube of (2), 5 mL each;

(4) Place the centrifuge tube obtained in (3) in a constant temperature shaking box, and set the temperature to 25°C;

(5) After the start of the adsorption experiment described in (4), set the centrifuge tubes numbered A1, A2, A3, A4, A5, A6 at regular intervals of 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, and 6 hours. Take it out, take out the supernatant and put it into a 10mL centrifuge tube respectively labeled as B1, B2, B3, B4, B5, B6;

(6) Using Agilent ICPOES730 instrument to measure the concentration of B0-B5 sample, the test result is shown in Figure 2, which shows that the adsorption process basically reaches equilibrium after 2 hours, and the adsorption rate is above 80%.

Example 3

The effect of the dosage of MXene/PAA/ACC hydrogel on the removal of strontium ions in water.

(2) Weigh four parts of the MXene/PAA/ACC hydrogel obtained in Example 1, six parts with masses of 5 mg, 10 mg, 30 mg, and 50 mg, respectively, and put them into four 10 mL centrifuge tubes, respectively numbered A1, A2, A3, A4;

(5) From the beginning of the adsorption experiment described in (4) for 2 hours, take out the centrifuge tubes numbered A1, A2, A3, and A4, take out the supernatants and put them into 10 mL centrifuge tubes, respectively, labeled B1, B2, B3, and B4;

(6) Using Agilent ICPOES730 instrument to measure the concentration of B0-B4 sample, the test result is shown in Figure 3, which shows that when the adsorbent dosage is 50mg, the adsorption rate can reach 80%.

Based on the above disclosure of the embodiments of the present disclosure, it can be seen that the Mxene material of the embodiments of the present disclosure has at least the following significant technical effects:

The Mxene material in the present disclosure has the characteristics of large specific surface, stable chemical properties and structure, resistance to radiation, etc., and can be used as a better adsorption material for radioactive substances;

The Mxene in the present disclosure has abundant surface functional groups, has good hydrophilicity, and is easily compounded with polypropylene, sodium carbonate, and calcium chloride;

The MXene composite gel material in the present disclosure can efficiently remove the radionuclide strontium in the water body, and the adsorbent structure is stable after the nuclide adsorption is completed, and the recovery is simple.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in further detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Within the spirit and principle of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims

A MXene composite hydrogel material, which includes:

Two-dimensional MXene material;

Polyacrylic acid; and

Amorphous calcium carbonate.
The MXene composite hydrogel material according to claim 1, wherein the chemical formula of the two-dimensional MXene material is Ti 3 C 2 Ti x , a sheet structure, x is a natural number greater than 1, and the area of a single sheet is not less than 40,000 nm 2 .
The MXene composite hydrogel material according to claim 1, wherein the weight average molecular weight Mw of the polyacrylic acid is 100,000-250,000 g/mol.
A preparation method of MXene composite hydrogel, which includes:

Add the polyacrylic acid solution and the sodium carbonate solution to the MXene dispersion in sequence to form a mixed solution;

The calcium chloride solution was added dropwise to the mixed solution and stirred, and finally a black MXene composite hydrogel was formed.
The preparation method according to claim 4, wherein the MXene dispersion is prepared in the following manner:

Prepare MXene dispersion, and add deionized water to configure to set concentration. Configure to set concentration of MXene sheet in the dispersion with layered structure, and the number of layers does not exceed 10, the chemical formula is Ti 3 C 2 Ti x , T x It is a surface-active end-capping group, and x is a natural number greater than 1.
The preparation method according to claim 4, wherein the volume ratio of the polyacrylic acid solution, calcium chloride solution, MXene dispersion liquid and sodium carbonate solution used is V 1 :V 2 :V 3 :V 4 =1: 0.5～1:0.5～1:0.4～0.5; and the molar concentration of the polyacrylic acid solution is 0.2M～0.4M, the molar concentration of the calcium chloride solution is 0.1M～0.2M, and the volume of the sodium carbonate solution The molar concentration is 0.2M-0.4M, and the mass concentration of the MXene dispersion is 0.4-0.8 mg/mL.
The preparation method according to claim 4, wherein the weight average molecular weight Mw of polyacrylic acid in the polyacrylic acid solution is 100,000-250,000 g/mol.
The preparation method according to claim 4, wherein the step of adding a calcium chloride solution dropwise to the mixed solution and stirring to generate a black MXene composite hydrogel comprises:

Add the calcium chloride solution dropwise to the mixed solution or inject the calcium chloride solution through a syringe pump, and continue to stir during the adding process. With the drop of the calcium chloride solution, the solution fades from black to form a black MXene composite hydrogel.
The preparation method according to claim 4, further comprising:

The MXene composite hydrogel is taken out, washed with deionized water, pressed into a sheet shape and then dried. After drying, it has a three-dimensional porous structure with a pore size of 2 μm-30 μm.
A method for using MXene composite hydrogel material, comprising putting the dried MXene composite hydrogel material according to any one of claims 1 to 3 in an aqueous solution containing strontium.