An organic metal framework@graphene oxide composite material and its preparation method and application

Abstract

The present invention belongs to the field of environmental science and engineering materials, and discloses a kind of metal organic framework @ graphene oxide composite material and its preparation method and application. The method includes: (1) pyrazole 3,5-dicarboxylic acid monohydrate is added to water, stirring ultrasound is dissolved, and pyrazole 3,5-dicarboxylic acid monohydrate solution is obtained; (2) graphene oxide is added to the pyrazole 3,5-dicarboxylic acid monohydrate solution in step (1) and ultrasound is carried out to obtain mixed solution A; (3) aluminum-based metal compound is added to the mixed solution A in step (2), ultrasound is carried out to obtain mixed solution B; (4) alkali liquor is added to mixed solution B, after reaction in microwave reactor, after filtration, washing, heating activation, metal organic framework @ graphene oxide composite material is obtained. The inventive method is not only simple to prepare, short in time consumption and high in material stability, but also has high specific surface area and stronger adsorption capacity, and can be used as adsorbent to remove organic dyes in water.

Description

Technical Field

[0001] The present invention belongs to the field of environmental science and engineering materials, and discloses an organic metal framework@graphene oxide composite material and a preparation method and application thereof. Background Art

[0002] The discharge of organic matter in industrial wastewater has become one of the problems of environmental pollution to be solved. Artificial dyes are typical industrial organic pollutants and are widely used in the textile, leather, cosmetics, food and other industries. The printing and dyeing industry produces a huge amount of wastewater discharge. Many dyes are toxic and difficult to biodegrade, causing serious damage to the aquatic ecosystem and threatening human health. Therefore, the discharge of dye wastewater has become a global concern. The increasing demand for water quality and quantity has also promoted the development of purification and reuse technology for printing and dyeing wastewater. In comparison, adsorption technology is one of the most effective methods for removing odorous pollutants in wastewater. However, traditional adsorption materials have limited adsorption capacity and it is difficult to produce an adsorption effect on low-concentration organic pollutants. Therefore, it is crucial to study an adsorption material with good adsorption effect and low preparation cost.

[0003] Graphene oxide (GO) is a new type of two-dimensional inorganic nanomaterial with a large number of oxygen-containing functional groups such as hydroxyl, carboxyl, epoxy, and ester groups on its surface. It has good adsorption capacity and water dispersibility and is easy to functionalize and modify.

[0004] Metal Organic Frameworks (MOFs) are generally composed of two components: organic ligands and inorganic metal ions or metal clusters. MOFs offer many unique advantages, including high porosity, low density, large surface area, regular pore structures, adjustable pore size, and diverse topological structures, which have significantly increased their popularity. MOFs have shown great potential in the field of adsorption and separation. However, their poor water stability and dispersibility make them a serious drawback in the adsorption of organic pollutants.

[0005] There is an urgent need to research an adsorption material with good adsorption effect and low preparation cost, so that it can be better used in the adsorption of organic pollutants in water treatment. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing an organic metal framework@graphene oxide composite material.

[0007] Another object of the present invention is to provide an application of the above-mentioned metal organic framework@graphene oxide composite material in adsorbing organic dyes in water.

[0008] The present invention prepares a novel composite material through coordination reaction between metal ions on MOF and oxygen-containing functional groups of GO, which has the dual excellent properties of MOF and GO, and provides a new material for the adsorption of organic pollutants such as odors in water treatment.

[0009] The object of the present invention is to provide a method for preparing the above-mentioned metal organic framework@graphene oxide composite material, the specific steps of which are as follows:

[0010] A method for preparing an organic metal framework@graphene oxide composite material comprises the following steps:

[0011] (1) adding pyrazole-3,5-dicarboxylic acid monohydrate into water, stirring and ultrasonicating to dissolve it, to obtain a pyrazole-3,5-dicarboxylic acid monohydrate solution;

[0012] (2) adding graphene oxide to the pyrazole-3,5-dicarboxylic acid monohydrate solution in step (1), and dispersing by ultrasonication to obtain a mixed solution A;

[0013] (3) adding the aluminum-based metal compound to the mixed solution A in step (2), stirring and ultrasonicating to obtain a mixed solution B;

[0014] (4) adding the alkali solution to the mixed solution B in step (3), reacting in a microwave reactor, filtering, washing, and heating to activate, thereby obtaining an organic metal framework@graphene oxide composite material.

[0015] The present invention disperses graphene oxide in pyrazole-3,5-dicarboxylic acid monohydrate, adds an aluminum-based metal compound, and then reacts in an alkaline environment in a microwave reactor to produce a preliminary product of a metal skeleton@graphene oxide composite material. This product is then filtered, washed, and heated for activation to yield the final organometallic framework@graphene oxide product. This method not only offers simple preparation, short production times, and high material stability, but also possesses a high specific surface area and strong adsorption capacity, making it suitable as an adsorbent for removing organic dyes from water.

[0016] A further embodiment is that in step (1), the pyrazole-3,5-dicarboxylic acid monohydrate is pyrazole-3,5-dicarboxylic acid monohydrate.

[0017] In a further embodiment, the concentration of the pyrazole-3,5-dicarboxylic acid monohydrate solution is 0.010-0.015 g / mL.

[0018] A further solution is that in step (2), the ultrasonic time is 60 to 120 minutes. A further solution is that in step (3), the ultrasonic time is 10 to 20 minutes.

[0019] A further solution is that in step (3), the aluminum-based metal compound is at least one of aluminum chloride hexahydrate, aluminum sulfate and aluminum nitrate.

[0020] A further solution is that, in step (3), the mass ratio of pyrazole-3,5-dicarboxylic acid monohydrate, graphene oxide, and aluminum-based metal compound in the mixed solution B is 2-3:1.5-2.5:3-5

[0021] A further solution is that in step (4), the alkali solution is at least one of a NaOH solution and a KOH solution, the concentration of the alkali solution is 0.8 to 1.2 mol / L, and the volume ratio of the added alkali solution to the mixed solution B is 1:10 to 11.

[0022] A further solution is that in step (4), the conditions of the microwave reaction are: microwave power of 600-900W, reaction temperature of 90-110°C, and reaction time of 15-30min.

[0023] A further solution is that, in step (4), the washing and heating activation are specifically as follows: the reaction product is first washed with deionized water 2 to 4 times, then washed with methanol 2 to 4 times, and finally the reaction product is placed in an oven at 100 to 110° C. for heating activation for 24 to 48 hours.

[0024] An organic metal framework@graphene oxide composite material is prepared by the preparation method of the present invention.

[0025] The metal organic framework@graphene oxide composite material of the present invention is used in the preparation of an adsorbent for removing organic dyes from water.

[0026] Application of the metal organic framework@graphene oxide composite material of the present invention in adsorbing methylene blue, methyl orange and rhodamine B in water.

[0027] The mechanism of the present invention is:

[0028] The present invention utilizes the rich oxygen-containing functional groups on the surface of graphene oxide to coordinate with the metal ions in the center of MOFs, allowing them to stack with each other through chemical bonds to form new channels. At the same time, the dense carbon atoms on the surface of graphene enhance the dispersion force between the graphene and the guest molecules, significantly improving the adsorption performance of the composite material.

[0029] Among them, the present invention utilizes pyrazole-3,5-dicarboxylic acid monohydrate and aluminum-based metal compounds to form an xhh topological structure, and the octahedral coordinated aluminum ions are composed of four bridging carboxyl groups and two hydroxyl groups to form angle-sharing bonds, so that the clusters and ligands give MOF more hydrophilic sites and stronger water stability.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention provides a novel method for preparing an organic metal framework (MOF)@graphene oxide composite material. The present invention utilizes microwave energy in a microwave reactor to accelerate the reaction rate, thereby completing the synthesis reaction in a short time. Throughout the process, pyrazole-3,5-dicarboxylic acid monohydrate and an aluminum-based metal compound react rapidly under the action of a microwave field to generate MOFs, which simultaneously combine with graphene oxide, thereby preparing an organic metal framework@graphene oxide composite material with a high specific surface area, high stability, and high adsorption performance in a short time.

[0032] (2) The MOFs material in the present invention is MOF(Al(OH)(PZDC), which is a water-collecting adsorbent and has strong adsorption in water. It undergoes a coordination reaction with graphene oxide, which also has strong adsorption, thereby greatly improving the adsorption performance of the composite material for organic pollutants.

[0033] (3) The preparation method of the present invention is simple, has high yield, and short time consumption, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 (a, b, c) are SEM images of the MOF@GO composite materials prepared in Examples 1, 2 and 3, respectively.

[0035] Figure 2 (a, b) are XRD and FTIR graphs of the MOF@GO composite materials prepared in Examples 1, 2 and 3, respectively. In the figure, the three curves correspond to Example 1, Example 2, and Example 3 (i.e., Example 1, Example 2, and Example 3) from top to bottom.

[0036] Figure 2 c is the BET diagram of the MOF@GO composite material prepared in Example 1 (i.e., Example 1 in the figure). DETAILED DESCRIPTION

[0037] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0038] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0039] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0040] The graphene oxide in the examples of the present invention was purchased from Guosen Pilot Technology.

[0041] RO water: deionized water.

[0042] Example 1

[0043] (1) Dissolve 5.3 g of pyrazole-3,5-dicarboxylic acid monohydrate in 500 ml of RO water, stir and ultrasonicate to completely dissolve it, to obtain a pyrazole-3,5-dicarboxylic acid monohydrate solution;

[0044] (2) Then, 3.8 g of graphene oxide was added to the pyrazole-3,5-dicarboxylic acid monohydrate solution and ultrasonically dispersed for 1 h to obtain a mixed solution A;

[0045] (3) Then, 7.6 g of aluminum chloride hexahydrate (AlC13·6H2O) was dissolved in the mixed solution A, and the mixture was stirred and ultrasonicated for 10 min to obtain the mixed solution B;

[0046] (4) Finally, 50 mL of sodium hydroxide aqueous solution (1 mol / L) was carefully added dropwise to the resulting mixed solution B. The mixture was placed in a three-necked flask and placed in a microwave reactor at 90°C, 800W, and reacted for 30 min. After the reaction, the reaction product was collected by filtration using a sand core funnel, washed three times with deionized water, then three times with methanol, and finally heated in a vacuum oven at 105°C for 24 hours to obtain a composite material.

[0047] Example 2

[0048] (1) Dissolve 6.0 g of pyrazole-3,5-dicarboxylic acid monohydrate in 500 ml of RO water, stir and ultrasonicate to completely dissolve it, to obtain a pyrazole-3,5-dicarboxylic acid monohydrate solution;

[0049] (2) Then, 4.8 g of graphene oxide was added to the pyrazole-3,5-dicarboxylic acid monohydrate solution and ultrasonically dispersed for 1.5 h to obtain a mixed solution A;

[0050] (3) Then, 9.6 g of aluminum chloride hexahydrate (AlC13·6H2O) was dissolved in the mixed solution, stirred and ultrasonicated for 15 min to obtain mixed solution B;

[0051] (4) Finally, 50 mL of sodium hydroxide aqueous solution (1 mol / L) was carefully added dropwise to the resulting mixed solution B. The mixture was placed in a three-necked flask and placed in a microwave reactor at 100°C, 700W, and reacted for 25 min. After the reaction, the reaction product was collected by filtration using a sand core funnel, washed three times with deionized water, then three times with methanol, and finally heated in a vacuum oven at 105°C for 36 hours to obtain a composite material.

[0052] Example 3

[0053] (1) Dissolve 7.5 g of pyrazole-3,5-dicarboxylic acid monohydrate in 500 ml of RO water, stir and ultrasonicate to completely dissolve it, to obtain a pyrazole-3,5-dicarboxylic acid monohydrate solution;

[0054] (2) Then, 6.2 g of graphene oxide was added to the pyrazole-3,5-dicarboxylic acid monohydrate solution and ultrasonically dispersed for 2 h to obtain a mixed solution A;

[0055] (3) Then, 12.0 g of aluminum chloride hexahydrate (AlC13·6H2O) was dissolved in the mixed solution, and the mixture was stirred and ultrasonicated for 20 min to obtain mixed solution B;

[0056] (4) Finally, 50 mL of sodium hydroxide aqueous solution (1 mol / L) was carefully added dropwise to the resulting mixed solution B. The mixture was placed in a three-necked flask and placed in a microwave reactor at 110°C, 600W, and reacted for 15 min. After the reaction, the reaction product was collected by filtration using a sand core funnel, washed three times with deionized water, then three times with methanol, and finally heated in a vacuum oven at 105°C for 48 hours to obtain a composite material.

[0057] Test Example 1

[0058] 1. SEM analysis

[0059] like Figure 1 As shown in (a, b, c), GO presents a layered wrinkled structure, and MOFs crystals present a regular cubic structure, indicating that MOFs are successfully loaded on the GO sheets. Figure 1 It shows that the MOF@GO composite materials prepared in Examples 1, 2 and 3 all have complete and regular morphological structures. In fact, during the preparation of MOF@GO, Al 3+ It can react with oxygen-containing functional groups in GO sheets to form Al-O, and can also coordinate with pyrazole carboxylic acid to form Al 3+ It is fixed between GO layers, so that the formation of MOF occurs on the GO sheets, effectively reducing the layer stacking phenomenon of GO.

[0060] 2. XRD analysis

[0061] like Figure 2 As shown in a, MOF@GO exhibits a distinct diffraction peak at 2θ = 9.5°, which is the characteristic peak of -COOH and -OH. MOFs@GO also exhibits sharp characteristic peaks near 2θ = 9.6°, 13.6°, and 17.5°, indicating the high crystallinity of the material.

[0062] 3. FTIR analysis

[0063] Figure 2 b shows that the characteristic peaks of MOF@GO are: 1674 cm -1 C=O stretching vibration peak at 1573cm -1 and 1368cm -1 OCO groups in the metal ligands at 1500 cm-1 The characteristic peaks of MOF@GO prepared in Examples 1, 2 and 3 are consistent, indicating that MOF@GO was successfully synthesized in all three methods.

[0064] 4. N2 adsorption and desorption test

[0065] Before the adsorption / desorption experiments, MOF@GO was activated at 100 °C under vacuum for 24 h to ensure the removal of water molecules from the channels. Figure 2 c shows the adsorption-desorption curve of MOF@GO prepared in Example 1 at 77 K. It is worth noting that when the pressure is 0, MOF@GO still has a very high adsorption capacity, and its specific surface area is 1319.3261 m 2 / g, and the pore size is concentrated at 3nm.

[0066] In addition, in other embodiments, based on Example 1, aluminum chloride hexahydrate is replaced by aluminum sulfate or aluminum nitrate, and NaOH solution is replaced by KOH solution, which can also achieve the purpose of the present invention.

[0067] Comparative Example 1

[0068] This comparative example does not use pyrazole-3,5-dicarboxylic acid monohydrate, but uses terephthalic acid. Specific steps:

[0069] (1) Dissolve 5.3 g of terephthalic acid in 500 ml of water, stir and ultrasonicate to completely dissolve it, to obtain a terephthalic acid solution;

[0070] (2) Then, 3.8 g of graphene oxide was added and ultrasonicated for 1 h to obtain mixed solution A;

[0071] (3) Then, 7.6 g of aluminum chloride hexahydrate (AlC13·6H2O) was dissolved in the mixed solution and ultrasonicated for 10 min to obtain mixed solution B;

[0072] (4) Finally, 50 mL of sodium hydroxide aqueous solution (1 mol / L) was carefully added dropwise to the resulting mixed solution B. The mixture was placed in a three-necked flask and placed in a microwave reactor at 90°C, 800W, and reacted for 30 min. After the reaction, the reaction product was collected by filtration using a sand core funnel, washed three times with deionized water, then three times with methanol, and finally heated in a vacuum oven at 105°C for 24 hours to obtain a composite material.

[0073] Comparative Example 2

[0074] This comparative example does not use AlCl3·6H2O, but uses zinc nitrate hexahydrate (ZnNO3·6H2O). Specific steps:

[0075] (1) Dissolve 5.3 g of pyrazole-3,5-dicarboxylic acid monohydrate in 500 ml of water, stir and ultrasonicate to completely dissolve it, to obtain a pyrazole-3,5-dicarboxylic acid monohydrate solution;

[0076] (2) Then, 3.8 g of graphene oxide was added and ultrasonicated for 1 h to obtain mixed solution A;

[0077] (3) Then, 7.6 g of zinc nitrate hexahydrate (ZnNO3·6H2O) was dissolved in the mixed solution and ultrasonicated for 10 min to obtain mixed solution B;

[0078] (4) Finally, 50 mL of sodium hydroxide aqueous solution (1 mol / L) was carefully added dropwise to the resulting mixed solution B. The mixture was placed in a three-necked flask and placed in a microwave reactor at 90°C, 800W, and reacted for 30 min. After the reaction, the reaction product was collected by filtration using a sand core funnel, washed three times with deionized water, then three times with methanol, and finally heated in a vacuum oven at 105°C for 24 hours to obtain a composite material.

[0079] Test Example 2-Adsorption Performance Test

[0080] Test material: Composite materials of Examples 1-3 or Comparative Examples 1-2 (Test Groups 1-5)

[0081] 20 ml of each 20 mg / L methylene blue, methyl orange, and rhodamine B were added to a small beaker. 20 mg of the composite material from Examples 1-3 or Comparative Examples 1-2 was then added. The mixture was stirred on a magnetic stirrer for 12 hours and then centrifuged. The absorbance values ​​at wavelengths of 652 nm, 462 nm, and 554 nm were measured (i.e., the absorbance values ​​of methylene blue, methyl orange, and rhodamine B were measured at wavelengths of 652 nm, 462 nm, and 554 nm, respectively). A blank group was set up: no composite material was added. Compared to the blank group, the smaller the absorbance value measured in the test group, the lower the dye concentration in the water. The removal rates of the three dyes were calculated. The results are shown in Table 1-2.

[0082] Calculation formula: Dye removal rate = (blank group absorbance value - test group absorbance value) / blank group absorbance value * 100%.

[0083] Table 1 shows the absorbance values ​​of the composite materials of Examples 1-3 and Comparative Examples 1-2 after adsorption of 20 mg / L methylene blue, methyl orange and rhodamine B, and compares them with the blank group (ie before adsorption).

[0084] Table 1 Absorbance results

[0085] dye blank Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Methylene blue 1.400 0.584 0.436 0.550 0.840 0.950 Methyl orange 0.830 0.680 0.640 0.720 0.700 0.740 Rhodamine B 0.787 0.227 0.211 0.252 0.550 0.620

[0086] As shown in Table 2, Example 1 achieved removal efficiencies of 58.3%, 18.1%, and 71.2% for the three dyes, respectively; Example 2 achieved removal efficiencies of 68.9%, 22.9%, and 73.2%, respectively; and Example 3 achieved removal efficiencies of 60.7%, 13.2%, and 68.0%, respectively. Comparative Examples 1 and 2 achieved removal efficiencies of 40%, 15.7%, and 30.1%, and 32.1%, 10.9%, and 21.2%, respectively. Compared to Comparative Examples 1 and 2, Examples 1-3 all achieved improved removal efficiencies for the three dyes.

[0087] Table 2 Removal rate of three dyes

[0088] dye Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Methylene blue 58.3％ 68.9％ 60.7％ 40.0％ 32.1％ Methyl orange 18.1％ 22.9％ 13.3％ 15.7％ 10.8％ Rhodamine B 71.2％ 73.2％ 68.0％ 30.1％ 21.2％

[0089] In summary, it can be seen that the material prepared by the method of the present invention has important significance in the field of water treatment adsorption.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an organic metal framework@graphene oxide composite material, characterized in that: The following steps are involved: (1) adding pyrazole-3,5-dicarboxylic acid monohydrate into water, stirring and ultrasonicating to dissolve it, thereby obtaining a pyrazole-3,5-dicarboxylic acid monohydrate solution; (2) adding graphene oxide to the pyrazole-3,5-dicarboxylic acid monohydrate solution in step (1) and dispersing the mixture by ultrasonication to obtain a mixed solution A; (3) adding the aluminum-based metal compound to the mixed solution A in step (2), stirring and ultrasonicating to obtain a mixed solution B; (4) adding the alkali solution to the mixed solution B in step (3), reacting in a microwave reactor, filtering, washing, and heating to activate, thereby obtaining an organic metal framework@graphene oxide composite material; In step (1), the concentration of the pyrazole-3,5-dicarboxylic acid monohydrate solution is 0.010-0.015 g / mL; In step (3), the aluminum-based metal compound is at least one of aluminum chloride hexahydrate, aluminum sulfate, and aluminum nitrate, and the mass ratio of pyrazole-3,5-dicarboxylic acid monohydrate, graphene oxide, and the aluminum-based metal compound in the mixed solution B is 2-3:1.5-2.5:3-5; Step (4), the microwave reaction conditions are: microwave power of 600-900 W, reaction temperature of 90-110° C., and reaction time of 15-30 min.

2. The preparation method according to claim 1, characterized in that The ultrasonic time in step (2) is 60 to 120 minutes; the ultrasonic time in step (3) is 10 to 20 minutes.

3. The preparation method according to claim 1 or 2, characterized in that In step (3), the aluminum-based metal compound is at least one of aluminum chloride hexahydrate, aluminum sulfate and aluminum nitrate.

4. The preparation method according to claim 1, characterized in that In step (4), the alkali solution is at least one of a NaOH solution and a KOH solution, the concentration of the alkali solution is 0.8-1.2 mol / L, and the volume ratio of the added alkali solution to the mixed solution B is 1:10-11.

5. The preparation method according to claim 1, characterized in that Step (4), the washing and heating activation are specifically as follows: the reaction product is first washed with deionized water 2 to 4 times, then washed with methanol 2 to 4 times, and finally the reaction product is placed in an oven at 100 to 110°C for heating activation for 24 to 48 hours.

6. An organic metal framework@graphene oxide composite material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 4.

7. Use of the organic metal framework@graphene oxide composite material according to claim 6 in the adsorption of methylene blue and rhodamine B in water.

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