Nitrogen-rich organic molecule modified graphene oxide composite material as well as preparation method and application thereof

Abstract

The invention provides a nitrogen-rich organic molecule modified graphene oxide composite material as well as a preparation method and application thereof. The method comprises the following steps: adding graphene oxide into a polar organic solvent, and performing ultrasonic dispersion and uniform mixing to obtain a graphene oxide dispersion liquid; the nitrogen-rich organic molecule modified graphene oxide composite material is prepared by the following steps: adding graphene oxide into a reaction kettle, adding 3, 5-diamino-1, 2, 4-triazole, uniformly mixing, carrying out nucleophilic reaction under a weakly acidic heating condition, repeatedly washing a product with ethanol and pure water, and freeze-drying to obtain the nitrogen-rich organic molecule modified graphene oxide composite material, and the composite material is used as an adsorbent, has a stable structure and can efficiently adsorb heavy metal ions. Through modification of the nitrogen-rich organic matter, the adsorbent obtains richer groups and adsorption sites, and can show different adsorption capacities on inorganic metal cations through multiple adsorption mechanisms. An adsorption result shows that the adsorbent has excellent adsorption selectivity on low-concentration copper ions in an aqueous solution. Through multiple adsorption-desorption experiments, the composite material still shows excellent reutilization performance.

Description

Technical Field

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

[0002] Copper is a common heavy metal with low cost and is widely used in life. With the continuous discharge of industrial wastewater, a large amount of heavy metal ions are released and bioaccumulated through the food chain. Their highly toxic and non-biodegradable physical and chemical properties seriously affect the ecological environment. A variety of treatment processes such as chemical precipitation, reverse osmosis, coagulation, electrolysis, adsorption, etc. have been developed and applied to efficiently and selectively remove copper ions from aqueous solutions. Compared with other methods, adsorption is widely used due to its cost-effectiveness, simple operation, good removal effect and reusability.

[0003] Graphene oxide has the characteristics of rich functional groups, high specific surface area and high mechanical strength. Its derivative composite materials have been widely used in the field of adsorption of heavy metal ions. Using graphene oxide as a base material and chemically modifying it with specific molecules can not only enrich the functional groups coordinated with specific heavy metal ions, but also improve the separation performance of the composite material. In the field of efficient and selective adsorption and separation of copper ions, functionalized graphene oxide composite materials have broader application prospects.

[0004] Therefore, the present invention designs a nitrogen-rich organic molecule modified graphene oxide composite material and a preparation method and application thereof. Summary of the invention

[0005] Based on this, the present invention provides a nitrogen-rich organic molecule modified graphene oxide composite material and its preparation method and application. The method couples 3,5-diamino-1,2,4-triazole with graphene oxide through nucleophilic reaction under heating conditions to construct a graphene oxide-based composite material with high efficiency in adsorbing heavy metal ions and stable structure. The modification of 3,5-diamino-1,2,4-triazole can increase the amount of nitrogen elements in the composite material and increase the adsorption active sites. The modification of nitrogen-rich organic matter enables the new adsorbent to obtain more abundant groups and adsorption sites, and can show different adsorption capacities for inorganic metal cations with multiple adsorption mechanisms, thereby improving the efficient adsorption performance of the composite material and enhancing the adsorption selectivity of the composite material. The adsorption results show that it shows excellent adsorption selectivity for low-concentration copper ions in aqueous solution. After multiple adsorption-desorption experiments, the composite material still shows excellent reusability, so the composite material of the present invention is expected to be used in the separation and enrichment of low-concentration copper ions in aqueous solution.

[0006] An embodiment of the present invention provides a method for preparing a nitrogen-rich organic molecule modified graphene oxide composite material, comprising the following steps:

[0007] S1: adding graphene oxide to a polar organic solvent, and uniformly dispersing and mixing by ultrasonication to obtain a graphene oxide dispersion;

[0008] S2: Add 3,5-diamino-1,2,4-triazole to the graphene oxide dispersion and mix evenly, and perform nucleophilic reaction under weak acid heating conditions, and the product is repeatedly washed with ethanol and pure water, and freeze-dried to obtain the nitrogen-rich organic molecule modified graphene oxide composite material. The weak acid stirring is controlled until the organic molecules no longer agglomerate.

[0009] According to one aspect of an embodiment of the present invention, the graphene oxide is a dry powdered solid; the 3,5-diamino-1,2,4-triazole is a colorless crystal with a purity higher than 90%; and the polar organic solvent is at least one of ethanol, N,N-dimethylformamide, and dimethyl sulfoxide.

[0010] According to one aspect of an embodiment of the present invention, the added amount of graphene oxide is 0.3 to 1.0 g; the added amount of 3,5-diamino-1,2,4-triazole is 1.0 to 3.0 g; and the added amount of the polar organic solvent is 80 to 120.0 mL.

[0011] According to one aspect of the embodiment of the present invention, the weak acidity is achieved by adding 1.0 to 4.0 mL of glacial acetic acid to make the pH value of the system 4 to 6.

[0012] According to one aspect of an embodiment of the present invention, the nucleophilic reaction uses a reflux device and is heated to reflux at 80-120° C. for 8 hours.

[0013] According to one aspect of an embodiment of the present invention, the nucleophilic reaction is always carried out under stirring. After the reaction is completed, the reaction solution is naturally cooled to room temperature. After the obtained product is filtered, the filter residue is repeatedly washed with 40 to 100 mL of ethanol for 5 times or more, and then repeatedly washed with deionized water for 5 times or more until the supernatant is neutral, and the solid remaining on the filter membrane is collected.

[0014] Based on a general concept of the invention, an embodiment of the present invention provides a nitrogen-rich organic molecule modified graphene oxide composite material obtained by the above-mentioned preparation method.

[0015] The embodiments of the present invention also provide the use of the nitrogen-rich organic molecule modified graphene oxide composite material obtained by the above-mentioned preparation method for selectively adsorbing and separating inorganic ions in aqueous solution.

[0016] According to one aspect of an embodiment of the present invention, the inorganic ions are derived from soluble sulfates and nitrates thereof.

[0017] According to one aspect of an embodiment of the present invention, the inorganic ions include copper, lead, neodymium, cadmium, silver and yttrium, and the adsorption concentration is 10 to 50 mg / L.

[0018] The above scheme of the present invention has the following beneficial effects:

[0019] The present invention innovatively uses 3,5-diamino-1,2,4-triazole and graphene oxide to undergo nucleophilic reaction, and utilizes the amino group on 3,5-diamino-1,2,4-triazole to undergo nucleophilic reaction with the carbonyl group on graphene oxide to construct a functional composite material with stable structure. 3,5-diamino-1,2,4-triazole can increase the number of chemical reaction sites due to its rich nitrogen-containing functional groups, while enhancing the thermal stability of the material. Therefore, the present invention introduces nitrogen-rich organic molecules as nucleophilic reagents to effectively improve the adsorption capacity of the composite material. Secondly, a certain degree of difference in bonding and adsorption mechanism enables the composite material to exhibit different adsorption capacities for different inorganic ions, so as to achieve the excellent performance of selective adsorption and separation of the material. The adsorption results show that the 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material provided by the present invention has excellent adsorption performance for copper ions and good hydrophobic properties, and can achieve selective adsorption of specific heavy metal ions and recycling after adsorption. In addition, after multiple adsorption-desorption experiments, the composite material exhibited stable physical and chemical properties, achieved good reusability, and had high cost-effectiveness in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a comparison chart of the adsorption capacity of the 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material of the embodiment of the present invention for inorganic ions (copper, lead, neodymium, cadmium, silver, yttrium);

[0022] Figure 2 is a Fourier transform infrared spectrum of different materials of the embodiments of the present invention; Figure 2 (a) Fourier transform infrared spectra of graphene oxide and 3,5-diamino-1,2,4-triazole coupled graphene oxide composites before and after adsorption, Figure 2 (b) is the Fourier transform infrared spectrum of 3,5-diamino-1,2,4-triazole.

[0023] Figure 3is a scanning electron microscope image of different materials of the embodiments of the present invention; Figure 3 (a) is the SEM of graphene oxide. Figure 3 (b) is the SEM of 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material. Figure 3 (c) is the SEM of the composite material after adsorption of copper ions.

[0024] Figure 4 It is the element mapping (EDS) diagram of different materials of the present invention and the distribution diagram of each element C, O, and N; Figure 4 (a) is the element mapping (EDS) diagram of the composite material and the distribution diagram of each element C, O, and N. Figure 4 (b) is the element mapping (EDS) diagram of the composite material after adsorbing copper ions and the distribution diagram of each element C, O, N, and Cu.

[0025] Figure 5 It is the element mapping analysis diagram of different materials of the present invention; Figure 5 (a) is the elemental mapping analysis diagram of 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material. Figure 5 (b) is the elemental mapping analysis diagram of the composite material after adsorption of copper ions. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0027] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0029] In view of the existing problems, the present invention provides a nitrogen-rich organic molecule modified graphene oxide composite material and a preparation method and application thereof.

[0030] Example 1

[0031] This embodiment provides a method for preparing a nitrogen-rich organic molecule modified graphene oxide composite material.

[0032] The method of this embodiment specifically includes the following steps:

[0033] Weigh 1.0 g of graphene oxide into a 250 mL round-bottom flask and add 100.0 mL of ethanol. Mix evenly by ultrasonication for 40 minutes to obtain a graphene oxide dispersion. Seal the flask for later use.

[0034] Weigh 2 g of 3,5-diamino-1,2,4-triazole into the above round-bottom flask, add 1.0 mL of glacial acetic acid, and stir slowly with a glass rod until the organic molecules no longer aggregate to obtain a mixed reaction solution, which is sealed for later use.

[0035] Under the condition of room temperature of about 25°C, when the temperature in the oil bath is raised to 95°C, the round-bottom flask is combined with a reflux device and placed in the oil bath for reaction for 8 hours with continuous magnetic stirring.

[0036] After the reaction is completed, the reaction solution is naturally cooled to room temperature, the obtained product is filtered under reduced pressure, and the filter residue is repeatedly rinsed with 40-100 mL of ethanol for 5 times and then repeatedly rinsed with deionized water for 5 times until the supernatant is neutral. The solid remaining on the filter membrane is collected and dried to obtain a composite material.

[0037] Example 2

[0038] This embodiment provides a method for preparing a nitrogen-rich organic molecule modified graphene oxide composite material.

[0039] The method of this embodiment specifically includes the following steps:

[0040] Weigh 1.0 g of graphene oxide into a 250 mL round-bottom flask and add 100.0 mL of N,N-dimethylformamide. Mix evenly by ultrasonication for 40 minutes to obtain a graphene oxide dispersion. Seal the flask for later use.

[0041] Weigh 1 g of 3,5-diamino-1,2,4-triazole into the above round-bottom flask, add 1.0 mL of glacial acetic acid, and stir slowly with a glass rod until the organic molecules no longer aggregate to obtain a mixed reaction solution, which is sealed for later use.

[0042] Under the condition of room temperature of about 25°C, when the temperature in the oil bath is raised to 95°C, the round-bottom flask is combined with a reflux device and placed in the oil bath for reaction for 8 hours with continuous magnetic stirring.

[0043] After the reaction is completed, the reaction solution is naturally cooled to room temperature, the obtained product is filtered under reduced pressure, and the filter residue is repeatedly rinsed with 40-100 mL of ethanol for 5 times and then repeatedly rinsed with deionized water for 5 times until the supernatant is neutral. The solid remaining on the filter membrane is collected and dried to obtain a composite material.

[0044] Example 3

[0045] This embodiment provides a method for preparing a nitrogen-rich organic molecule modified graphene oxide composite material.

[0046] The method of this embodiment specifically includes the following steps:

[0047] Weigh 1.0 g of graphene oxide into a 250 mL round-bottom flask and add 100.0 mL of dimethyl sulfoxide. Mix evenly by ultrasonication for 40 minutes to obtain a graphene oxide dispersion. Seal the flask for later use.

[0048] Weigh 3 g of 3,5-diamino-1,2,4-triazole into the above round-bottom flask, add 2.0 mL of glacial acetic acid, and stir slowly with a glass rod until the organic molecules no longer aggregate to obtain a mixed reaction solution, which is sealed for later use.

[0049] Under the condition of room temperature of about 25°C, when the temperature in the oil bath is raised to 95°C, the round-bottom flask is combined with a reflux device and placed in the oil bath for reaction for 8 hours with continuous magnetic stirring.

[0050] After the reaction is completed, the reaction solution is naturally cooled to room temperature, the obtained product is filtered under reduced pressure, and the filter residue is repeatedly rinsed with 40-100 mL of ethanol for 5 times and then repeatedly rinsed with deionized water for 5 times until the supernatant is neutral. The solid remaining on the filter membrane is collected and dried to obtain a composite material.

[0051] The composite material prepared in the above embodiment is used as an adsorbent to adsorb inorganic ions in aqueous solution (wherein, the inorganic ions selected are copper ions, lead ions, neodymium ions, cadmium ions, silver ions, and yttrium ions for adsorption experiments). Fourier transform infrared spectroscopy is used to analyze the chemical composition and bonding mode of the material; SEM is performed to characterize graphene oxide and the composite material before and after adsorption in order to observe the changes in surface morphology. The material adsorption results and material characterization are as follows:

[0052] from Figure 1 It can be seen that the 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material has an excellent adsorption effect on copper ions, but almost no adsorption capacity for rare earth ions. Therefore, it can be applied to the selective adsorption and separation of copper ions from aqueous solutions.

[0053] from Figure 2 It can be seen that the synthesis of 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material is successful. Due to the nucleophilic reaction between 3,5-diamino-1,2,4-triazole molecules and graphene oxide functional groups, there is a more obvious modified molecule characteristic absorption peak CN (1370cm) compared with the characteristic absorption peak of pure graphene oxide. -1 ) and C=N(1547cm -1 ) appears. At the same time, the characteristic absorption peak of the carbonyl group of the original graphene oxide C=O (1731cm -1 ) intensity decreased and the wave number 1688cm -1The shift indicates that the primary amine on the modified molecule reacts with the carbonyl group to form hydroxylamine, which immediately loses H2O to form C=N (1547 cm -1 ), which confirms that the 3,5-diamino-1,2,4-triazole-coupling graphene oxide material is successfully composited through nucleophilic reaction. Secondly, after the adsorption of copper ions, the stretching vibration of CN and COC in the composite material changes from 1370 cm -1 and 1055cm -1 Move to 1378cm respectively -1 and 1052cm -1 , and the stretching vibration of amino group is red-shifted to 3205cm -1 and 3139cm -1 , which indicates that the composite material has good adsorption of copper ions.

[0054] from Figure 3 It can be further seen that the synthesis of 3,5-diamino-1,2,4-triazole coupled graphene oxide material is successful. Figure 3 They are graphene oxide ( Figure 3 (a)), 3,5-diamino-1,2,4-triazole coupled graphene oxide composite material ( Figure 3 (b)) SEM morphology of the composite material after adsorption of copper ions. Figure 3 As shown in (a), graphene oxide has a relatively smooth surface without curling. Figure 2 (b) It can be observed that the 3,5-diamino-1,2,4-triazole-coupled graphene oxide material retains the layered characteristics of the initial GO, but the surface has obvious wrinkles and curling. 2+ After that, the composite surface still has some wrinkles and is relatively rough ( Figure 3 (c)). Through EDS and elemental mapping, it can be observed that C, O, and N elements are evenly distributed on the surface of 3,5-diamino-1,2,4-triazole-coupled graphene oxide materials ( Figure 4 ). EDS analysis showed that the composite material contained 0.97% Cu by weight, which confirmed that the Cu element was successfully adsorbed onto the composite material ( Figure 5 ).

[0055] The 3,5-diamino-1,2,4-triazole coupled graphene oxide material prepared by the present invention has a stable structure and good reusability, has excellent adsorption performance and selectivity for copper ions, and can realize efficient selective adsorption and separation of copper ions in aqueous solution.

[0056] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a nitrogen-rich organic molecule modified graphene oxide composite material, characterized in that: The following steps are involved: S1: adding graphene oxide to a polar organic solvent, and uniformly dispersing and mixing by ultrasonication to obtain a graphene oxide dispersion; S2: adding 3,5-diamino-1,2,4-triazole to the graphene oxide dispersion and mixing evenly, and performing a nucleophilic reaction under weakly acidic heating conditions, and repeatedly washing the product with ethanol and pure water, and freeze-drying to obtain the nitrogen-rich organic molecule modified graphene oxide composite material.

2. The method for preparing the nitrogen-rich organic molecule modified graphene oxide composite material according to claim 1, characterized in that: The graphene oxide is a dry powdered solid; the 3,5-diamino-1,2,4-triazole is a colorless crystal with a purity higher than 90%; and the polar organic solvent is at least one of ethanol, N,N-dimethylformamide and dimethyl sulfoxide.

3. The method for preparing the nitrogen-rich organic molecule modified graphene oxide composite material according to claim 1 or 2, characterized in that: The added amount of graphene oxide is 0.3 to 1.0 g; the added amount of 3,5-diamino-1,2,4-triazole is 1.0 to 3.0 g; and the added amount of polar organic solvent is 80 to 120.0 mL.

4. The method for preparing the nitrogen-rich organic molecule modified graphene oxide composite material according to claim 1, characterized in that: The weak acidity is achieved by adding 1.0-4.0 mL of glacial acetic acid to a pH value of 4-6.

5. The method for preparing the nitrogen-rich organic molecule modified graphene oxide composite material according to claim 1, characterized in that: The nucleophilic reaction adopts a reflux device and is heated to reflux at 80-120° C. for 8 hours.

6. The method for preparing the nitrogen-rich organic molecule modified graphene oxide composite material according to claim 1, characterized in that: The nucleophilic reaction is always carried out under stirring. After the reaction is completed, the reaction solution is naturally cooled to room temperature. After the obtained product is filtered, the filter residue is repeatedly washed with 40-100 mL of ethanol for 5 times or more, and then repeatedly washed with deionized water for 5 times or more until the supernatant is neutral, and the solid remaining on the filter membrane is collected.

7. A nitrogen-rich organic molecule modified graphene oxide composite material obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the nitrogen-rich organic molecule-modified graphene oxide composite material obtained by the preparation method according to any one of claims 1 to 6 for selectively adsorbing and separating inorganic ions in aqueous solution.

9. The use according to claim 8, characterized in that: The inorganic ions are derived from their soluble sulfates and nitrates.

10. The use according to claim 8, characterized in that: The inorganic ions include copper, lead, neodymium, cadmium, silver and yttrium, and the adsorption concentration is 10-50 mg / L.

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