Sulfur-doped MXene hydrogel adsorbent as well as preparation method and application thereof

Abstract

The invention provides a sulfur-doped MXene hydrogel adsorbent as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing MXene in deionized water, adding a sulfur source, carrying out an ion exchange reaction, and after the reaction is finished, carrying out centrifugal separation, washing and drying to obtain sulfur-doped MXene; the preparation method comprises the following steps: dissolving an acrylic monomer in deionized water, adding a cross-linking agent and an initiator, and uniformly mixing to obtain an acrylic acid prepolymerization solution; and dispersing the sulfur-doped MXene in deionized water, adding an acrylic acid prepolymerization solution, uniformly stirring, and carrying out polymerization reaction to obtain the sulfur-doped MXene hydrogel adsorbent. According to the preparation method, MXene is doped with sulfur, and additional adsorption sites are introduced, so that the adsorption capacity of cesium ions can be remarkably improved. As a carrier, the acrylic acid-based hydrogel can improve the dispersibility and stability of MXene in water and enhance the mechanical strength of the material.

Description

Technical Field

[0001] This invention belongs to the field of water treatment materials technology, specifically relating to a sulfur-doped MXene hydrogel adsorbent for adsorbing and removing cesium ions from water, its preparation method, and its application. Background Technology

[0002] cesium ion (Cs) + Cesium is a common radioactive nuclide widely found in nuclear wastewater, posing a serious threat to the environment and human health. Cesium ions have a long half-life (e.g., cesium-137 has a half-life of approximately 30 years), and their chemical properties are similar to those of potassium ions, making them prone to accumulation in organisms through the food chain, leading to radioactive contamination. Therefore, effectively removing cesium ions from water is of great significance for the treatment of nuclear wastewater and environmental protection.

[0003] Traditional methods for cesium ion removal mainly include chemical precipitation, ion exchange, and adsorption. Chemical precipitation involves adding chemical reagents to form insoluble precipitates of cesium ions, thus achieving separation. However, this method typically requires large amounts of chemical reagents, and the resulting precipitates can cause secondary pollution. Ion exchange utilizes materials such as ion exchange resins or zeolites to remove cesium ions through ion exchange reactions. While this method offers high selectivity, the adsorption capacity of ion exchange materials is limited, and the regeneration process is complex and costly. Adsorption removes cesium ions through physical or chemical adsorption at active sites on the surface of adsorbent materials. Adsorption methods are simple to operate and relatively inexpensive, but traditional adsorbent materials such as activated carbon and clay have poor adsorption capacity for cesium ions, making them unsuitable for practical applications.

[0004] In recent years, MXene materials have shown great potential in the field of adsorption due to their high specific surface area, abundant surface functional groups, and excellent conductivity. MXenes are two-dimensional materials obtained by exfoliating transition metal carbides or nitrides, possessing a layered structure and tunable surface chemistry. The surface of MXenes typically contains functional groups such as hydroxyl and oxygen groups, which can coordinate with metal ions, thereby achieving the adsorption of metal ions. However, the adsorption selectivity and capacity of pure MXene for cesium ions still need further improvement. Furthermore, MXenes exhibit poor dispersibility and stability in aquatic environments, easily agglomerating, which limits their application in practical water treatment.

[0005] To overcome the limitations of MXene, researchers have attempted to combine it with other functional materials to enhance its adsorption performance. Polyacrylic acid-based hydrogels, a polymer material with a three-dimensional network structure and high hydrophilicity, can effectively improve the material's dispersibility and stability. The three-dimensional network structure of the hydrogel not only provides a good dispersion environment for MXene but also allows for the introduction of more adsorption sites through functionalization modification, thereby enhancing its adsorption capacity for cesium ions. Furthermore, the high hydrophilicity of the hydrogel helps improve the material's stability in water and prevents MXene aggregation.

[0006] Sulfur (S) 2- Doping is another effective strategy to improve the adsorption performance of MXene. Sulfur doping can introduce additional adsorption sites on the MXene surface, enhancing the selective adsorption of cesium ions. Sulfur atoms have a large atomic radius and strong electronegativity, enabling them to form strong chemical bonds with cesium ions, thereby increasing the adsorption capacity. In addition, sulfur doping can also improve the conductivity and chemical stability of MXene, further enhancing its application potential in water treatment.

[0007] In summary, developing a sulfur-doped MXene hydrogel adsorbent is of significant practical importance. This adsorbent not only combines the high adsorption performance of sulfur-doped MXene but also improves the dispersibility and stability of the material through the introduction of hydrogel, thereby achieving efficient removal of cesium ions from water. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] This invention proposes a sulfur-doped MXene hydrogel adsorbent, its preparation method, and its application. This adsorbent has high adsorption capacity, excellent selectivity, and good stability, thus solving the technical problem of how to efficiently remove cesium ions from water.

[0010] (II) Technical Solution

[0011] To address the aforementioned technical problems, this invention proposes a method for preparing a sulfur-doped MXene hydrogel adsorbent, which includes the following steps:

[0012] S1. Disperse MXene in deionized water, add sulfur source, carry out ion exchange reaction, centrifuge after reaction, wash and dry to obtain sulfur-doped MXene;

[0013] S2. Dissolve the acrylic monomer in deionized water, add the crosslinking agent and initiator, mix well to obtain an acrylic prepolymer solution;

[0014] S3. Disperse sulfur-doped MXene in deionized water, add acrylic acid prepolymer solution, stir evenly, and carry out polymerization reaction to obtain sulfur-doped MXene hydrogel adsorbent.

[0015] Furthermore, in step S1, MXene is Ti3C2T x .

[0016] Furthermore, in step S1, the sulfur source is Na2S or H2S.

[0017] Furthermore, in step S1, the ion exchange reaction is carried out under an inert gas atmosphere at a temperature of 50–80°C for a time of 2–6 hours.

[0018] Furthermore, in step S2, the crosslinking agent is N,N'-methylenebisacrylamide; the initiator is ammonium persulfate or potassium persulfate.

[0019] Further, in step S3, the mass-to-volume ratio of sulfur-doped MXene to acrylic acid prepolymer solution is 1:(20-30).

[0020] Furthermore, in step S3, the polymerization reaction temperature is 60–80°C, and the reaction time is 1–3 h.

[0021] In addition, the present invention also proposes a sulfur-doped MXene hydrogel adsorbent, which is prepared by the above method.

[0022] Furthermore, the present invention also proposes an application of the above-mentioned sulfur-doped MXene hydrogel adsorbent in the treatment of cesium-contaminated wastewater. The application method is to add the sulfur-doped MXene hydrogel adsorbent to the cesium-contaminated wastewater.

[0023] Further, the application method includes the following: adding sulfur-doped MXene hydrogel adsorbent to cesium-polluted wastewater with a cesium ion content of 10-500 mg / L, the dosage of sulfur-doped MXene hydrogel adsorbent being 1-10 g / L, and shaking at a speed not exceeding 300 r / min at 10-40℃ for 1-2 hours.

[0024] (III) Beneficial Effects

[0025] This invention proposes a sulfur-doped MXene hydrogel adsorbent, its preparation method, and its application. The preparation method includes dispersing MXene in deionized water, adding a sulfur source, and carrying out an ion exchange reaction. After the reaction, centrifuge, wash, and dry to obtain sulfur-doped MXene. Then, dissolve acrylic acid monomer in deionized water, add a crosslinking agent and an initiator, and mix thoroughly to obtain an acrylic acid prepolymer solution. Next, disperse the sulfur-doped MXene in deionized water, add the acrylic acid prepolymer solution, stir thoroughly, and carry out a polymerization reaction to obtain the sulfur-doped MXene hydrogel adsorbent. This invention introduces additional adsorption sites by doping MXene with sulfur, significantly improving the adsorption capacity for cesium ions. The acrylic-based hydrogel, as a carrier, improves the dispersibility and stability of MXene in water, while also enhancing the mechanical strength of the material. Detailed Implementation

[0026] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying examples.

[0027] This embodiment proposes a method for preparing a sulfur-doped MXene hydrogel adsorbent, which specifically includes the following steps:

[0028] S1. Add 1g of Ti3C2T x Dispersed in 100 mL of deionized water, 0.5 g of Na2S was added, and an ion exchange reaction was carried out under nitrogen protection at a temperature of 60 °C for 4 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain sulfur-doped MXene.

[0029] S2. Dissolve 10g of acrylic acid monomer in 100mL of deionized water, add 0.1g of N,N'-methylenebisacrylamide and 0.05g of ammonium persulfate, mix well to obtain an acrylic acid prepolymer solution.

[0030] S3. Disperse 0.5g of sulfur-doped MXene in 50mL of deionized water, add 10mL of acrylic acid prepolymer solution, stir evenly, and carry out polymerization reaction at 70℃ for 3h to obtain sulfur-doped MXene hydrogel adsorbent.

[0031] The prepared sulfur-doped MXene hydrogel adsorbent was used to remove cesium ions from water. 100 mL of an aqueous solution containing 50 mg / L of cesium ions was taken, and 0.1 g of the sulfur-doped MXene hydrogel adsorbent was added. The pH was adjusted to 7, and the solution was shaken at 120 rpm for 2 hours at room temperature. After adsorption was complete, the adsorbent was separated by filtration, and the concentration of cesium ions in the solution was measured. The results showed that the sulfur-doped MXene hydrogel adsorbent prepared in this invention could achieve a cesium ion removal rate of over 95%.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a sulfur-doped MXene hydrogel adsorbent, characterized in that, The preparation method includes the following steps: S1. Disperse MXene in deionized water, add sulfur source, carry out ion exchange reaction, centrifuge after reaction, wash and dry to obtain sulfur-doped MXene; S2. Dissolve the acrylic monomer in deionized water, add the crosslinking agent and initiator, mix well to obtain an acrylic prepolymer solution; S3. Disperse sulfur-doped MXene in deionized water, add acrylic acid prepolymer solution, stir evenly, and carry out polymerization reaction to obtain sulfur-doped MXene hydrogel adsorbent.

2. The method for preparing the sulfur-doped MXene hydrogel adsorbent as described in claim 1, characterized in that, In step S1, MXene is Ti3C2T x .

3. The method for preparing the sulfur-doped MXene hydrogel adsorbent as described in claim 1, characterized in that, In step S1, the sulfur source is Na2S or H2S.

4. The method for preparing the sulfur-doped MXene hydrogel adsorbent as described in claim 1, characterized in that, In step S1, the ion exchange reaction is carried out under an inert gas at a temperature of 50–80°C for 2–6 hours.

5. The method for preparing the sulfur-doped MXene hydrogel adsorbent as described in claim 1, characterized in that, In step S2, the crosslinking agent is N,N'-methylenebisacrylamide; the initiator is ammonium persulfate or potassium persulfate.

6. The method for preparing the sulfur-doped MXene hydrogel adsorbent as described in claim 1, characterized in that, In step S3, the mass-to-volume ratio of sulfur-doped MXene to acrylic acid prepolymer solution is 1:(20-30).

7. The method for preparing the sulfur-doped MXene hydrogel adsorbent as described in claim 1, characterized in that, In step S3, the polymerization reaction temperature is 60–80°C, and the reaction time is 1–3 hours.

8. A sulfur-doped MXene hydrogel adsorbent, characterized in that, The sulfur-doped MXene hydrogel adsorbent is prepared by the method described in any one of claims 1 to 7.

9. The application of the sulfur-doped MXene hydrogel adsorbent according to claim 8 in the treatment of cesium-contaminated wastewater, characterized in that, The application method involves adding the sulfur-doped MXene hydrogel adsorbent to cesium-contaminated wastewater.

10. The application of the sulfur-doped MXene hydrogel adsorbent as described in claim 9 in the treatment of cesium-contaminated wastewater, characterized in that, The application method includes the following: adding the sulfur-doped MXene hydrogel adsorbent to cesium-polluted wastewater with a cesium ion content of 10-500 mg / L, wherein the dosage of the sulfur-doped MXene hydrogel adsorbent is 1-10 g / L, and shaking at a speed not exceeding 300 r / min at 10-40℃ for 1-2 hours.