Oxygen / nitrogen-rich graphene oxide composite material and preparation method and application thereof

Abstract

The invention belongs to the technical field of composite materials, and particularly discloses an oxygen / nitrogen-rich graphene oxide composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: uniformly dispersing graphene oxide in anhydrous N, N-dimethylformamide to obtain a graphene oxide dispersion liquid; and adding 2, 5-diaminobenzene-1, 4-diphenol into the graphene oxide dispersion liquid, uniformly mixing, carrying out amidation reaction under the action of a catalyst, and washing and drying the obtained product to obtain the oxygen / nitrogen-rich graphene oxide composite material. The graphene oxide-2, 5-diaminobenzene-1, 4-diphenol composite material prepared by the preparation method disclosed by the invention is stable in structure and good in reutilization performance, has excellent adsorption performance and selectivity on p-nitrophenol, and can realize enrichment and separation of p-nitrophenol in an aqueous solution.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to an oxygen / nitrogen-rich graphene oxide composite material and a preparation method and application thereof. Background Art

[0002] Phenol pollutants have become a prominent problem in today's environment. They mainly come from industrial emissions such as petrochemicals, oil refining, coke ovens and herbicides. Phenol pollutants have chemical and microbial stability, which allows them to persist and spread widely in the environment. Even at very low concentrations, phenolic pollutants can have negative effects on humans and aquatic organisms. In view of this, it is urgent to develop effective, cost-saving and simple methods to remove phenolic pollutants. There are many types of conventional technologies for removing phenolic pollutants in wastewater, such as extraction, membrane filtration, photocatalysis and adsorption. Among these technologies, adsorption has been widely studied and widely used in practice because of its many advantages such as simple operation, easy adjustment, high efficiency, low cost and time-saving and labor-saving.

[0003] Graphene oxide has rich functional groups on its surface and edges, which can produce adsorption with adsorbates through various intermolecular interactions. In addition, graphene oxide is widely used due to its advantages such as high mechanical strength, large specific surface area, and stable chemical properties. Chemical modification of graphene oxide using specific molecules can not only provide more active sites for the adsorption of phenolic compounds, but also improve its separation performance, showing a broader application prospect in the field of adsorption separation.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0005] In view of the above-mentioned shortcomings that currently exist, the present invention provides an oxygen / nitrogen-rich graphene oxide composite material, a preparation method and an application thereof. The present invention bonds 2,5-diaminobenzene-1,4-diphenol with graphene oxide through an amidation reaction to form a graphene oxide-based composite material with a stable structure and the ability to efficiently adsorb phenolic compounds. The modification of 2,5-diaminobenzene-1,4-diphenol can increase the active sites of the composite material for adsorbing phenolic compounds, and the composite material exhibits different adsorption capacities for phenolic compounds by virtue of multiple adsorption mechanisms, thereby improving the adsorption selectivity of the composite material.

[0006] In order to achieve the above object, the present invention provides a method for preparing an oxygen / nitrogen-rich graphene oxide composite material, comprising the following steps:

[0007] S1. uniformly dispersing graphene oxide in anhydrous N,N-dimethylformamide to obtain a graphene oxide dispersion;

[0008] S2. Add 2,5-diaminobenzene-1,4-diphenol to the graphene oxide dispersion and mix them evenly, perform an amidation reaction under the action of a catalyst, and obtain a composite graphene oxide composite material rich in oxygen / nitrogen after washing and drying the obtained product.

[0009] According to one aspect of the present invention, the mass ratio of the graphene oxide to the 2,5-diaminobenzene-1,4-diphenol is 1-15:5-20.

[0010] For example, 0.1-1.5 g of graphene oxide, 50-150 mL of anhydrous N,N-dimethylformamide, and 0.5-2 g of 2,5-diaminobenzene-1,4-diphenol are uniformly dispersed and mixed by ultrasonic dispersion.

[0011] It should be noted that the graphene oxide is a dry powdered solid; the purity of the 2,5-diaminobenzene-1,4-diphenol is higher than 90%.

[0012] According to one aspect of the present invention, the mass ratio of the catalyst to the graphene oxide is 12-40:10-15.

[0013] According to one aspect of the present invention, the catalyst is O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) in combination with N,N-diisopropylethylamine; the mass ratio of O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate to N,N-diisopropylethylamine is 1-10:5-10.

[0014] For example, 0.2-2.0 g of O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) and 1.0-2.0 mL of N,N-diisopropylethylamine are used as the catalyst, and the reactants are ultrasonically stirred until they are uniformly mixed.

[0015] According to one aspect of the present invention, in step S2, the equipment used for the amidation reaction is a moisture-proof reflux device, the reaction temperature is 100 to 160° C., and the reaction time is 12 to 36 hours.

[0016] According to one aspect of the present invention, in step S2, the amidation reaction is carried out under stirring, and after the reaction is completed, it is naturally cooled to room temperature, the obtained product is filtered, and the filter residue is repeatedly washed with ethanol and deionized water in turn, and after removing impurities, the filter residue is collected and freeze-dried.

[0017] For example, the amidation reaction is carried out under stirring. After the reaction is completed, the reaction solution is naturally cooled to room temperature, the obtained product is filtered, and the filter residue is repeatedly washed at least three times with 20-160 mL of ethanol and ultrapure water to collect the solid remaining on the filter membrane.

[0018] Based on the same inventive concept, the present invention also provides an oxygen / nitrogen-rich graphene oxide composite material, which is prepared by any of the above-mentioned preparation methods.

[0019] Based on the same inventive concept, the present invention also provides the use of the above-mentioned oxygen / nitrogen-rich graphene oxide composite material in the selective adsorption and separation of dyes and phenolic compounds in aqueous solution.

[0020] According to one aspect of the present invention, the dye includes at least one of methylene blue (MB) and alizarin yellow (AYR); the phenolic compound includes at least one of p-nitrophenol (PNP), m-nitrophenol (MNP), tert-butylhydroquinone (TBHQ), and hydroquinone (HQ); and the adsorbate concentration is 10 to 50 mg / L.

[0021] Beneficial effects of the present invention:

[0022] The graphene oxide of the present invention and 2,5-diaminobenzene-1,4-diphenol undergo an amidation reaction under catalytic conditions. Specifically, the amino groups of 2,5-diaminobenzene-1,4-diphenol and the abundant carboxyl groups on the graphene oxide are used to undergo an amidation reaction, thereby successfully synthesizing a composite material with a stable structure. This certain degree of bonding has many advantages. On the one hand, it makes the composite material easy to separate from the aqueous solution in practical applications. On the other hand, due to the difference in the magnitude of the intermolecular forces between the composite material and different adsorbates, different adsorption capacities are exhibited. This characteristic enables the composite material to selectively adsorb and enrich different phenolic compounds and achieve effective adsorption and separation. The adsorption results show that the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material provided by the present invention has a significant adsorption effect on p-nitrophenol, while the adsorption capacity for dyes is relatively weak, and the enrichment and separation of p-nitrophenol in aqueous solution can be achieved. In addition, the composite material has stable physical and chemical properties, which means that it can achieve good reusability in practical applications, reduce the cost of the adsorption process, and provide an efficient and economical solution for practical applications in related fields. The composite material of the invention has application potential in separation and enrichment of low-concentration p-nitrophenol in aqueous solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a comparison chart of the adsorption capacity of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material prepared in Example 1 of the present invention for dyes (methylene blue (MB) and alizarin yellow (AYR)) and phenolic compounds (p-nitrophenol (PNP), m-nitrophenol (MNP), tert-butylhydroquinone (TBHQ) and hydroquinone (HQ));

[0024] Figure 2 It is a Fourier transform infrared spectra of the products of Example 1 and Comparative Examples 1 to 2 of the present invention; wherein A is a Fourier transform infrared spectra of the graphene oxide (GO) of Comparative Example 1 and the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material (GO-DABD) of Example 1 before and after dye adsorption; B is a Fourier transform infrared spectra of 2,5-diaminobenzene-1,4-diphenol (DABD) of Comparative Example 2;

[0025] Figure 3 are scanning electron microscope images of the products of Example 1 and Comparative Example 1 of the present invention; wherein A is a scanning electron microscope image of the graphene oxide of Comparative Example 1; B is a scanning electron microscope image of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material of Example 1; and C is a scanning electron microscope image of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material of Example 1 after adsorbing p-nitrophenol;

[0026] Figure 4 The electronic scanning images, element mapping and EDS analysis images of the products of Example 1 and Comparative Example 1 of the present invention; wherein A is the electronic scanning image of the graphene oxide of Comparative Example 1 and the distribution image of the C and O elements; B is the electronic scanning image of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material of Example 1 and the distribution image of the C, O and N elements; C is the EDS analysis image of the graphene oxide of Comparative Example 1; and D is the EDS analysis image of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material of Example 1. DETAILED DESCRIPTION

[0027] To make the present invention easier to understand, the present invention is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in the field; unless otherwise specified, the raw materials and reagents involved in this article can be purchased from the market or prepared by known methods.

[0028] Example 1

[0029] A method for preparing an oxygen / nitrogen-rich graphene oxide composite material comprises the following steps:

[0030] 1.0 g of graphene oxide was weighed into a 250 mL round-bottom flask, 90 mL of anhydrous N,N-dimethylformamide solution was added thereto, and ultrasonication was performed for 30 min to ensure that the graphene oxide was uniformly dispersed in the anhydrous N,N-dimethylformamide solution.

[0031] 1.7511 g O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), 1.965 mL N,N-diisopropylethylamine and 0.45 g 2,5-diaminobenzene-1,4-diphenol were added to the graphene oxide dispersion in sequence, and the mixture was stirred continuously until the organic molecules no longer aggregated. The mixed solution was sealed with a film and set aside for later use.

[0032] The round-bottom flask was placed on a thermostatic magnetic stirrer and stirred at 160 °C for 36 h.

[0033] After the reaction was completed, the reaction solution was naturally cooled to room temperature, the obtained product was filtered, and the filter residue was repeatedly washed at least three times with 150 mL of ethanol and ultrapure water to collect the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material remaining on the filter membrane.

[0034] Example 2

[0035] A method for preparing an oxygen / nitrogen-rich graphene oxide composite material comprises the following steps:

[0036] 0.5 g of graphene oxide was weighed into a 250 mL round-bottom flask, 90 mL of anhydrous N,N-dimethylformamide solution was added thereto, and ultrasonication was performed for 30 min to ensure that the graphene oxide was uniformly dispersed in the anhydrous N,N-dimethylformamide solution.

[0037] 1.7511 g O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), 1.965 mL N,N-diisopropylethylamine and 0.45 g 2,5-diaminobenzene-1,4-diphenol were added to the graphene oxide dispersion in sequence, and the mixture was stirred continuously until the organic molecules no longer aggregated. The mixed solution was sealed with a film and set aside for later use.

[0038] The round-bottom flask was placed on a thermostatic magnetic stirrer and stirred at 160 °C for 12 h.

[0039] After the reaction was completed, the reaction solution was naturally cooled to room temperature, the obtained product was filtered, and the filter residue was repeatedly washed at least three times with 150 mL of ethanol and ultrapure water to collect the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material remaining on the filter membrane.

[0040] Example 3

[0041] A method for preparing an oxygen / nitrogen-rich graphene oxide composite material comprises the following steps:

[0042] 1.5 g of graphene oxide was weighed into a 250 mL round-bottom flask, 150 mL of anhydrous N,N-dimethylformamide solution was added thereto, and ultrasonication was performed for 40 min to ensure that the graphene oxide was uniformly dispersed in the anhydrous N,N-dimethylformamide solution.

[0043] 1.7511 g O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), 1.965 mL N,N-diisopropylethylamine and 0.45 g 2,5-diaminobenzene-1,4-diphenol were added to the graphene oxide dispersion in sequence, and the mixture was stirred continuously until the organic molecules no longer aggregated. The mixed solution was sealed with a film and set aside for later use.

[0044] The round-bottom flask was placed on a thermostatic magnetic stirrer and stirred at 100 °C for 36 h.

[0045] After the reaction was completed, the reaction solution was naturally cooled to room temperature, the obtained product was filtered, and the filter residue was repeatedly washed at least three times with 150 mL of ethanol and ultrapure water to collect the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material remaining on the filter membrane.

[0046] Comparative Example 1

[0047] Graphene oxide.

[0048] Comparative Example 2

[0049] 2,5-Diaminobenzene-1,4-diphenol.

[0050] Performance testing and result analysis

[0051] The graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material prepared in Example 1 was used as an adsorbent to adsorb dyes and phenolic compounds in aqueous solution; the chemical composition and bonding mode of the material were analyzed by Fourier transform infrared spectroscopy; and the morphological changes of graphene oxide and the composite material before and after adsorption were observed by SEM. The material adsorption results and material characterization are as follows:

[0052] from Figure 1It can be seen that the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material has an obvious adsorption effect on p-nitrophenol, but a poor adsorption effect on dyes, so it can be applied to the separation of p-nitrophenol from aqueous solution.

[0053] from Figure 2 It can be seen that the amidation of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material is successful. Due to the amidation reaction between the 2,5-diaminobenzene-1,4-diphenol molecules and the graphene oxide functional groups, there is a more obvious characteristic absorption peak of the modified molecule compared with the characteristic absorption peak of pure graphene oxide. At the same time, the C=O (1730.35cm -1 ) stretching vibration to the low wave number 1657.80cm -1 Move, in addition, at 1442.30cm -1 A new stretching vibration absorption peak is generated at 3430.68 cm-1, which is the stretching vibration of CN in the amide. Based on the above analysis, the successful preparation of the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material is confirmed. After adsorbing p-nitrophenol, the stretching vibration of OH / NH and the vibration of the aromatic ring skeleton increase from 3430.68 cm-1 to 3430.68 cm-1, respectively. -1 and 1628.35cm -1 Move to 3439.12cm -1 and 1633.64cm -1 , indicating that hydrogen bonding and π-π stacking occurred between the composite material and p-nitrophenol.

[0054] from Figure 3 It can be seen that the synthesis of graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material is successful. Figure 3 Graphene oxide ( Figure 3 A), graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material ( Figure 3 B), graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material after adsorption ( Figure 3 C) SEM morphology. Figure 3As shown in the figure, the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material retains the lamellar structure of graphene oxide, and due to the covalent coupling of 2,5-diaminobenzene-1,4-diphenol molecules on the surface of graphene oxide, its surface becomes thicker and rougher. After adsorbing p-nitrophenol, its surface properties did not change significantly. The element distribution and component content of the surface of graphene oxide and graphene oxide-2,5-diaminobenzene-1,4-diphenol composite materials were analyzed by element mapping and EDS. It was found that C (72.88wt.%), O (14.29wt.%) and N (12.84wt.%) can be detected for the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material. The appearance of N element further indicates the successful modification of 2,5-diaminobenzene-1,4-diphenol molecules, and the N and O elements are more evenly distributed on the surface of the composite material, which is conducive to the adsorption of p-nitrophenol.

[0055] In summary, the graphene oxide-2,5-diaminobenzene-1,4-diphenol composite material prepared by the present invention has a stable structure and good reusability, has excellent adsorption performance and selectivity for p-nitrophenol, and can achieve the enrichment and separation of p-nitrophenol in aqueous solution.

[0056] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing an oxygen / nitrogen-rich graphene oxide composite material, characterized in that: The following steps are involved: S1. uniformly dispersing graphene oxide in anhydrous N,N-dimethylformamide to obtain a graphene oxide dispersion; S2. Add 2,5-diaminobenzene-1,4-diphenol to the graphene oxide dispersion and mix them evenly, perform an amidation reaction under the action of a catalyst, and obtain a composite graphene oxide composite material rich in oxygen / nitrogen after washing and drying the obtained product.

2. The method for preparing the oxygen / nitrogen-rich graphene oxide composite material according to claim 1, characterized in that: The mass ratio of the graphene oxide to the 2,5-diaminobenzene-1,4-diphenol is 1-15:5-20.

3. The method for preparing the oxygen / nitrogen-rich graphene oxide composite material according to claim 1, characterized in that: The mass ratio of the catalyst to the graphene oxide is 12-40:10-15.

4. The method for preparing the oxygen / nitrogen-rich graphene oxide composite material according to claim 1, characterized in that: The catalyst is a combination of O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine; the mass ratio of the O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate to N,N-diisopropylethylamine is 1-10:5-10.

5. The method for preparing the oxygen / nitrogen-rich graphene oxide composite material according to claim 1, characterized in that: In step S2, the equipment used for the amidation reaction is a moisture-proof reflux device, the reaction temperature is 100 to 160° C., and the reaction time is 12 to 36 hours.

6. The method for preparing the oxygen / nitrogen-rich graphene oxide composite material according to claim 1, characterized in that: In step S2, the amidation reaction is carried out under stirring. After the reaction is completed, the mixture is naturally cooled to room temperature. The obtained product is filtered and the filter residue is repeatedly washed with ethanol and deionized water in turn. After impurities are removed, the filter residue is collected and freeze-dried.

7. An oxygen / nitrogen-rich graphene oxide composite material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the oxygen / nitrogen-rich graphene oxide composite material as claimed in claim 7 in selective adsorption and separation of dyes and phenolic compounds in aqueous solution.

9. The use according to claim 8, characterized in that: The dye comprises at least one of methylene blue and alizarin yellow; the phenolic compound comprises at least one of p-nitrophenol, m-nitrophenol, tert-butylhydroquinone and hydroquinone; and the adsorbent concentration is 10-50 mg / L.

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