Method for promoting reconnection of graphene oxide after dye adsorption by doping MXene

Abstract

The invention discloses a method for promoting reconnection of graphene oxide after dye adsorption by doping MXene, which comprises the following steps: step 1, mixing Ti2C3 MXene and graphene oxide (GO) in proportion, and then preparing a graphene oxide-MXene composite material by adopting a dispensing method; 2, shearing or grinding the graphene oxide-MXene composite material obtained in the step 1, and adding the graphene oxide-MXene composite material into a dye solution; and step 3, standing for a period of time, finishing dye adsorption, reconnecting the graphene oxide-MXene composite material which is originally cut into pieces or ground into powder, and keeping stable connection without breaking during continuous shaking. According to the invention, material recovery and reutilization are realized, and secondary pollution of an adsorption material to a water body is avoided. The method is simple to operate and easy to use and popularize on a large scale.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and in particular to a method for promoting the reconnecting of graphene oxide after adsorbing dyes by doping MXene. Background Art

[0002] With the acceleration of the industrialization process, the treatment of dye wastewater has become an important topic in the field of environmental science. Dye wastewater usually contains a large number of organic dye molecules that are difficult to degrade, such as methylene blue (MB). These dyes have characteristics such as high chromaticity and high toxicity, causing serious pollution to water bodies and the ecological environment. At present, the treatment technologies of dye wastewater mainly include physical adsorption, chemical oxidation, and biodegradation, etc. Among them, the adsorption method is widely used due to its advantages such as high efficiency, simple operation, and low cost. Commonly used adsorption materials include activated carbon, graphene oxide (GO), metal-organic framework materials (MOFs), etc. These materials can effectively adsorb dye molecules through their rich pore structures and surface functional groups. However, existing adsorption materials still have some limitations in practical applications, such as slow adsorption rate, difficult recycling and reuse, and insufficient structural stability in complex water environments, etc.

[0003] In order to overcome the limitations of traditional adsorption materials, researchers have begun to explore the application of membrane materials in the treatment of dye wastewater. Membrane materials form a thin film with selective separation function by fixing adsorbents in the membrane matrix, showing significant advantages such as higher mechanical strength and stability, higher selectivity and permeability, convenience for recycling and reuse, and simple operation. However, existing membrane materials still face the problem of limited adsorption rate in practical applications, which is mainly due to the pore structure and the distribution of surface functional groups of the membrane materials restricting the diffusion rate of dye molecules. In order to further improve the adsorption performance of membrane materials, researchers have tried to increase the specific surface area and active sites of membrane materials by shearing treatment. This treatment method significantly improves the adsorption rate of membrane materials, making them show higher efficiency in treating complex wastewater. However, the sheared membrane materials are easy to break after adsorption, making it difficult to recycle and reuse, which limits their operability and economy in practical applications. Summary of the Invention

[0004] The present invention proposes a method for promoting the reconnecting of GO after adsorbing MB by doping MXene. By preparing GO and MXene materials into membrane materials, the present invention can not only improve their structural stability but also enhance the adsorption performance through the physical structure of the membrane. Further, the present invention improves the adsorption rate of the membrane material through shearing treatment and realizes the reconnecting and stable recycling of the membrane material after adsorption. This method not only overcomes the limitations of traditional adsorption materials but also significantly improves the adsorption efficiency and recyclability of the membrane material, reduces secondary pollution, and has important environmental and economic significance.

[0005] The technical solution of the present invention is as follows: A method for promoting the reconnection of graphene oxide after adsorbing dyes by doping MXene, comprising the following steps: Step 1: Mix a Ti 2 C 3 MXene dispersion and a graphene oxide solution in a certain proportion, and then prepare a graphene oxide-MXene composite material by the drop-coating method; In Step 1, mix Ti 2 C 3 MXene and graphene oxide (GO) in different mass ratios to form a uniform composite material. The above mixture is uniformly coated on an oil film by the drop-coating method. The drop-coating method is a simple and efficient preparation method suitable for large-scale production. The coated film material is placed in a blast drying oven for heat drying treatment to ensure the uniformity and stability of the film. In the method of the present invention, in Step 1, the mixture drop-coated on the oil film is placed in a drying oven and dried at 50 °C for 5 h, taken out and cooled. The composite material can be easily peeled off from the base oil film. The prepared film material is cut or ground to increase the specific surface area and active sites of the film material. The cut film material is added to the dye solution and left standing to allow the film material to adsorb dye molecules. The heat drying treatment is preferably carried out at 50 °C for a duration of 5 hours. This condition can ensure the uniform drying of the film material, avoid thermal damage to the material, and improve the mechanical strength and stability of the film.

[0006] Step 2: Cut or grind the graphene oxide-MXene composite material prepared in Step 1 into powder (the cut pieces of the graphene oxide-MXene composite film should be of similar size to avoid uneven local properties caused by excessive differences in fragment sizes), and then put it into a dye solution to adsorb the dye; leave it standing for a period of time. After the adsorption of the dye is completed, the originally cut or ground graphene oxide-MXene composite material reconnects together and can still remain stable and non-dispersed during continuous shaking.

[0007] Furthermore, the MXene used in Step 1 can also be TiAlC 3 doping.

[0008] Furthermore, the mass ratio of the graphene oxide and Ti 2 C 3 MXene in Step 1 is 1:9 to 9:1. Preferably, the ratio (mass ratio) of MXene and graphene oxide in Step 1 is 1:4. Under this ratio condition, the adsorption efficiency of the material is greatly improved, and the reconnected structure has higher stability.

[0009] Further, the dye used in the second step is one of methylene blue, methyl orange, or a mixed solution of methylene blue and methyl orange.

[0010] Further, the reconnecting in the second step occurs in a dye solution under acidic and weakly alkaline conditions. Under acidic conditions, the reconnecting effect is better.

[0011] Further, the reconnecting in the second step is carried out at room temperature or below 50 °C.

[0012] Further, the reconnecting in the second step occurs in a composite material of graphene oxide and MXene.

[0013] The present invention also provides an application of the above method for promoting the reconnecting of graphene oxide adsorbed with dyes by doping MXene.

[0014] By using the method of the present invention to adsorb dyes, through the shearing treatment, the specific surface area of the membrane material is significantly increased, the adsorption rate is greatly improved, and the adsorption time is shortened by more than about 50%. This characteristic makes the membrane material of the present invention show higher efficiency in treating dye wastewater; after adsorption, the sheared membrane material can be reconnected and form a stable structure, which is convenient for recycling and reuse. This characteristic not only reduces the fragmentation and loss of materials, but also avoids secondary pollution, and has remarkable environmental friendliness and economic feasibility; the method of the present invention is simple to operate, does not require complex equipment and high-pressure conditions, and the adsorption and reconnecting processes can be completed at room temperature or above room temperature. The preparation and recycling processes of the membrane material are suitable for large-scale industrial applications and have broad application prospects. Beneficial Effects

[0015] 1. High-efficiency adsorption and structural stability: By shearing the membrane material in the present invention, the specific surface area and active sites of the membrane material are significantly increased, thereby greatly improving the adsorption rate of dye molecules (such as methylene blue MB), and the adsorption time is shortened by more than about 50%. At the same time, after adsorption, the sheared membrane material can be reconnected and form a stable structure, which is convenient for recycling and reuse, reducing the fragmentation and loss of materials and avoiding secondary pollution.

[0016] 2. Economic and environmental benefits: The method of the present invention is simple to operate, does not require complex equipment and high-temperature and high-pressure conditions, and the adsorption process can be completed at room temperature, significantly reducing the treatment cost. In addition, through reconnecting and recycling, the membrane material can be reused multiple times, reducing material waste. The whole process does not require the use of chemical reagents, avoiding secondary pollution, and has remarkable environmental friendliness and economic feasibility. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the prepared graphene oxide-MXene composite film; Figure 2 Schematic diagram of the prepared shredded graphene oxide-MXene composite film; Figure 3 Schematic diagram of the reconnecting of the shredded graphene oxide-MXene composite film; Figure 4 Schematic diagram of the reconnecting of the graphene oxide-MXene composite films with different shredding degrees in Example 1; Figure 5 Schematic diagram of the reconnecting of the graphene oxide-MXene composite films with different mass ratios of MX and GO in Example 2; Figure 6 Schematic diagram of the reconnecting of the graphene oxide-MXene composite film in MB solution with different pH values in Example 3; Figure 7 Schematic diagram of the reconnecting of the graphene oxide-MXene composite film treated at high temperature in Example 4. Detailed implementation manners

[0018] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit scope of the technical solutions of the present invention shall be covered within the protection scope of the present invention.

[0019] Step 1: Mix Ti2C3 MXene and GO in proportion, and then prepare graphene oxide-MXene composite materials by the drop coating method; Step 2: Add the shredded or ground graphene oxide-MXene composite materials obtained in Step 1 into the dye solution; Step 3: Let it stand for a period of time. While the dye adsorption is completed, the originally shredded or ground graphene oxide-MXene composite materials are reconnected together, and can still maintain a stable connection without breaking during continuous shaking. Example 1

[0020] A method for promoting the reconnecting of graphene oxide after adsorbing MB by doping MXene, the method is: Step 1: Uniformly mix the Ti2C3 MXene (5 mg / ml) dispersion liquid and the GO (5 mg / ml) solution in a ratio of 1:4, and then drop the mixed solution onto the oil film and place it in a blast drying oven at 50 °C for 5 h to obtain the graphene oxide-MXene composite film as Figure 1 shown; Step 2: Perform different degrees of shredding treatment (very shredded, generally shredded, flakes) on the graphene oxide-MXene composite materials obtained in Step 1, and respectively take 20 mg and add them to 20 ml of 400 mg / L MB solution; Step 3: Let it stand for a period of time. When the degree of fragmentation of the composite material is very fine (such as Figure 2 ), while completing the dye adsorption, the originally fragmented graphene oxide-MXene composite material reconnects together again. During continuous shaking, it can still maintain stable connection without breaking. The reconnection phenomenon is as shown in Figure 3 . The comparison of the reconnection of composite membranes with different fragmentation treatments is as shown in Figure 4 . A small degree of membrane fragmentation (pieces) will affect the reconnection of the membrane. Example 2

[0021] The difference between this example and Example 1 is that in Step 1, the Ti2C3 MXene dispersion liquid and the GO solution are uniformly mixed in different mass ratios (1:4, 3:7, 2:3, 1:1, 3:2); in Step 2, the degree of fragmentation of the graphene oxide-MXene composite material is very fine; the reconnection of membranes with different mass ratios is as shown in Figure 5 . Among them, when the mass ratios are 1:4, 3:7 or 2:3 respectively, good reconnection can occur, but as the proportion of MXene increases (mass ratios 1:1 or 3:2), the reconnection effect becomes worse. Example 3

[0022] The difference between this example and Example 1 is that in Step 2, the degree of fragmentation of the graphene oxide-MXene composite material is very fine, and the MB solution environment is under different pH conditions (None, pH = 2, 4, 6, 8, 10, 11). The reconnection under different pH solution environments is as shown in Figure 6 . Under acidic or neutral conditions, good reconnection can occur; the reconnection effect of the membrane under alkaline conditions is very poor. Example 4

[0023] The difference between this example and Example 1 is that in Step 2, the graphene oxide-MXene composite material is heated at 200 °C for 3 h and then fragmented, and the degree of fragmentation is very fine. The reconnection after heat treatment is as shown in Figure 7 . It can be seen that although the adsorption effect on MB is not good, it can still be well connected together.

Claims

1. A method for promoting reconnection of graphene oxide after adsorption of dyes by doping MXene, characterized in that: The following steps are involved: Step 1: Mixing Ti2C3MXene dispersion and graphene oxide solution in a certain proportion, and then preparing graphene oxide-MXene composite material by drop coating method; Step 2: Cut or grind the graphene oxide-MXene composite material prepared in step 1 into pieces or into powder, and then put it into the dye solution to adsorb the dye; after standing for a period of time, after the dye is adsorbed, the graphene oxide-MXene composite material that was originally cut or ground into powder is reconnected together and can remain stable and not dispersed during constant shaking.

2. The method of doping MXene to promote reconnection of graphene oxide after adsorption of dyes according to claim 1, characterized in that: The MXene used in the step 1 may also be doped with TiAlC3.

3. The method of doping MXene to promote reconnection of graphene oxide after adsorption of dyes as claimed in claim 1, characterized in that: The mass ratio of graphene oxide and Ti2C3MXene described in step 1 is 1:9~9:

1.

4. The method of doping MXene to promote reconnection of graphene oxide after adsorption of dyes as claimed in claim 1, characterized in that: The dye used in step 2 is one of methylene blue, methyl orange or a mixed solution of methylene blue and methyl orange.

5. The method of doping MXene to promote reconnection of graphene oxide after adsorption of dyes according to claim 1, characterized in that: The reconnection in step 2 occurs under acidic and weakly alkaline conditions.

6. The method of doping MXene to promote reconnection of graphene oxide after adsorption of dyes according to claim 1, characterized in that: The reconnection in step 2 is performed at room temperature or below 50°C.

7. The method of doping MXene to promote reconnection of graphene oxide after adsorption of dyes according to claim 1, characterized in that: The reconnection in step 2 occurs in the composite material of graphene oxide and MXene.

8. Use of a method for promoting reconnection of graphene oxide after adsorption of dyes by doping MXene as described in any one of claims 1 to 7.

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