Modified graphene adsorbent and preparation process thereof

Abstract

The invention relates to the technical field of graphene adsorbents, in particular to a modified graphene adsorbent and a preparation process thereof. Graphene oxide is modified through choline chloride, a strong alkali solution and a green solvent, and the modified graphene adsorbent is prepared; and the green solvent is one or more of 3-nitrophthalic acid, 6-aminoquinoxaline, 4-nitro-o-phenylenediamine, 3, 4-dichloroaniline, pentachloroaniline, 2-carboxyl-3-ethyl nitrobenzoate, 1, 3, 5-triethynylbenzene and 6-amino-5-bromoquinoxaline. The preparation method comprises the following steps: preparing the green solvent, and preparing the green solvent from one or more of 3-nitrophthalic acid, 6-aminoquinoxaline, 4-nitro-o-phenylenediamine and 3, 4-dichloroaniline. The modified graphene adsorbent which is high in adsorption capacity, easy to separate and reusable is prepared, and the problems that graphene oxide is difficult to separate and magnetic graphene oxide is low in adsorption capacity are solved.

Description

Technical Field

[0001] The invention relates to the technical field of graphene adsorbents, and more specifically, to a modified graphene adsorbent and a preparation process thereof. Background Art

[0002] In the process of rapid urbanization and industrialization, a large amount of heavy metals are discharged into the environment. Due to the toxicity, non-degradability and easy accumulation of heavy metal ions in organisms, the increasingly serious heavy metal pollution in the global freshwater system has become one of the major environmental problems facing human society. At present, many technologies for removing heavy metal ions from water have been developed, including ion exchange, electrochemical treatment, chemical precipitation, membrane separation, etc., but these methods have problems such as high cost, low removal efficiency and complex operation. Therefore, it is necessary to develop a wastewater treatment material with high removal efficiency, simple operation and easy separation. Due to its simple operation, high efficiency in treating wastewater and low cost, the adsorption method has received widespread attention and has become one of the most commonly used wastewater treatment technologies.

[0003] With the advancement of large-scale industrial production, water pollution has faced an extremely severe situation. Among them, dye wastewater has the characteristics of high chroma, potential "three-cause" effects and difficulty in treatment, which has become a difficulty in the field of water treatment. Adsorption technology, as a green water pollution control technology without secondary pollution, has begun to receive widespread attention in the field of dye wastewater treatment. The preparation and research of adsorption materials have also become a hot topic in the field of materials. Graphene materials have been widely studied due to their unique physical and chemical properties. Among them, the excellent surface activity of graphene oxide can further improve its adsorption performance after modification.

[0004] Currently, research on graphene materials is in full swing in various countries, and research on the physicochemical modification, surface modification and biological derivative changes of modified graphene materials is becoming increasingly in-depth. Summary of the invention

[0005] The invention provides a modified graphene adsorbent and a preparation process thereof, and prepares a modified graphene adsorbent with high adsorption capacity, easy separation and reusability, thereby solving the problems of difficult separation of graphene oxide and low adsorption capacity of magnetic graphene oxide.

[0006] In a first aspect, the present invention provides a modified graphene adsorbent, wherein graphene oxide is modified by choline chloride, a strong alkaline solution and a green solvent to obtain the modified graphene adsorbent; the green solvent is one or more of 3-nitrophthalic acid, 6-aminoquinoxaline, 4-nitro-o-phenylenediamine, 3,4-dichloroaniline, pentachloroaniline, 2-carboxy-3-nitrobenzoic acid ethyl ester, 1,3,5-triethynylbenzene and 6-amino-5-bromoquinoxaline.

[0007] Preferably, the concentration of the strong alkaline solution is 3-6 mol / L.

[0008] Preferably, the composition further comprises a dispersant, which is one of a quaternary ammonium salt, a quaternary phosphate salt and an amino acid.

[0009] In a second aspect, the present invention provides a process for preparing a modified graphene adsorbent, comprising the following steps:

[0010] (1) dispersing graphene oxide in deionized water and continuously ultrasonicating to obtain a uniform graphene oxide suspension;

[0011] (2) adding choline chloride to the graphene oxide suspension obtained in step (1), and continuing ultrasonication to obtain a uniform mixed solution; wherein the mass ratio of choline chloride to graphene oxide is 1:2;

[0012] (3) heating the mixed solution obtained in step (2) to 50-60° C. and maintaining it for 2-3 hours, then adding a strong alkaline solution and a green solvent, and continuously stirring to generate a graphene nanosheet suspension;

[0013] (4) Then, poly(p-vinylbenzyltrimethylammonium chloride) or poly(p-styrene sodium sulfonate) aqueous solution is added dropwise into the graphene nanosheet suspension, reacted, and washed to obtain a modified graphene adsorbent.

[0014] Preferably, the ultrasonic dispersion time of step (1) and step (2) is 40 min to 60 min.

[0015] Preferably, the concentration of the graphene oxide suspension in step (1) is 1 mg / L to 3 mg / L.

[0016] Preferably, the stirring time of step (3) is 30 min to 60 min.

[0017] Preferably, in step (3), the mass ratio of the strong alkaline solution to the green solvent is (0.5-2):1.

[0018] In summary, the present invention has the following beneficial effects:

[0019] 1. The graphene oxide in the present invention is a derivative of graphene, containing oxygen-containing groups such as hydroxyl and carboxyl, and has good hydrophilicity, high specific surface area and mechanical strength;

[0020] 2. The choline chloride of the present invention contains more groups and is charged choline chloride. The introduction of choline chloride will affect the electron distribution and the interaction force between graphene sheets, and affect the stacking between graphene sheets. CNT can be easily dispersed between graphene sheets through π-π interaction force, thereby serving as a better spacer between graphene sheets;

[0021] 3. The preparation process of the present invention will not pollute the environment, and the structure of graphene oxide itself will not be destroyed during the modification process.

[0022] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the scope of protection of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0024] Example

[0025] Example 1

[0026] A modified graphene adsorbent is prepared by modifying graphene oxide with choline chloride, a strong alkali solution and a green solvent; the concentration of the strong alkali solution is 6 mol / L; and the green solvent is 3-nitrophthalic acid.

[0027] A preparation process of a modified graphene adsorbent comprises the following steps:

[0028] (1) dispersing graphene oxide in deionized water and continuously ultrasonicating to obtain a uniform graphene oxide suspension; the concentration of the graphene oxide suspension is 3 mg / L; and the ultrasonic dispersion time is 40 min;

[0029] (2) adding choline chloride to the graphene oxide suspension obtained in step (1), and continuing ultrasonication to obtain a uniform mixed solution; wherein the mass ratio of choline chloride to graphene oxide is 1:2; and the ultrasonic dispersion time is 40 min;

[0030] (3) heating the mixed solution obtained in step (2) to 50° C. and maintaining it for 2 h, then adding a strong alkali solution and a green solvent, and continuously stirring to generate a graphene nanosheet suspension; the stirring time is 30 min to 60 min; the mass ratio of the strong alkali solution to the green solvent is 0.5:1;

[0031] (4) Then, poly(p-vinylbenzyltrimethylammonium chloride) or poly(p-styrene sodium sulfonate) aqueous solution is added dropwise into the graphene nanosheet suspension, reacted, and washed to obtain a modified graphene adsorbent.

[0032] Example 2

[0033] A modified graphene adsorbent is prepared by modifying graphene oxide with choline chloride, a strong alkali solution and a green solvent; the concentration of the strong alkali solution is 4 mol / L; and the green solvent is 6-aminoquinoxaline.

[0034] A preparation process of a modified graphene adsorbent comprises the following steps:

[0035] (1) dispersing graphene oxide in deionized water and continuously ultrasonicating to obtain a uniform graphene oxide suspension; the concentration of the graphene oxide suspension is 1 mg / L; and the ultrasonic dispersion time is 40 min;

[0036] (2) adding choline chloride to the graphene oxide suspension obtained in step (1), and continuing ultrasonication to obtain a uniform mixed solution; wherein the mass ratio of choline chloride to graphene oxide is 1:2; and the ultrasonic dispersion time is 40 min;

[0037] (3) heating the mixed solution obtained in step (2) to 60° C. and maintaining it for 2 h, then adding a strong alkali solution and a green solvent, and continuously stirring to generate a graphene nanosheet suspension; the stirring time is 30 min; the mass ratio of the strong alkali solution to the green solvent is 1:1;

[0038] (4) Then, poly(p-vinylbenzyltrimethylammonium chloride) or poly(p-styrene sodium sulfonate) aqueous solution is added dropwise into the graphene nanosheet suspension, reacted, and washed to obtain a modified graphene adsorbent.

[0039] Example 3

[0040] A modified graphene adsorbent is prepared by modifying graphene oxide with choline chloride, a strong alkali solution and a green solvent; the concentration of the strong alkali solution is 5 mol / L; and the green solvent is 6-amino-5-bromoquinoxaline.

[0041] A preparation process of a modified graphene adsorbent comprises the following steps:

[0042] (1) dispersing graphene oxide in deionized water and continuously ultrasonicating to obtain a uniform graphene oxide suspension; the concentration of the graphene oxide suspension is 3 mg / L; and the ultrasonic dispersion time is 40 min;

[0043] (2) adding choline chloride to the graphene oxide suspension obtained in step (1), and continuing ultrasonication to obtain a uniform mixed solution; wherein the mass ratio of choline chloride to graphene oxide is 1:2; and the ultrasonic dispersion time is 40 min;

[0044] (3) heating the mixed solution obtained in step (2) to 60° C. and maintaining it for 2 h, then adding a strong alkali solution and a green solvent, and continuously stirring to generate a graphene nanosheet suspension; the stirring time is 30 min; the mass ratio of the strong alkali solution to the green solvent is 2:1;

[0045] (4) Then, poly(p-vinylbenzyltrimethylammonium chloride) or poly(p-styrene sodium sulfonate) aqueous solution is added dropwise into the graphene nanosheet suspension, reacted, and washed to obtain a modified graphene adsorbent.

[0046] Comparative Example 1

[0047] 12.09 g of trimethylolpropane triglycidyl ether, 2.44 g of hydroxyethylamine, 1.5 g of resorcinol and 0.64 g of tetrabutylammonium bromide were stirred at 100 ° C for 48 h, then cooled to room temperature, 50 mL of tetrahydrofuran was added, and then ultrapure water was added to precipitate it to obtain a precipitate; 1.1 g of the precipitate and 10 g of graphene oxide were dispersed in 40 mL of DMF, ultrasonicated at room temperature for 30 min, 0.05 g of tetrabutylammonium bromide was added, and stirred at 80 ° C for 10 h. After stirring, it was washed with DMF and freeze-dried to obtain a hyperbranched polyetheramine-modified graphene oxide adsorbent.

[0048] Comparative Example 2

[0049] Graphene oxide was dispersed in ethanol at room temperature and ultrasonicated for 1 hour to make it evenly dispersed. Then, polyphenylene dendrimer was added and stirred continuously at 80°C for 24 hours. The mass ratio of the reactants was graphene oxide: polyphenylene dendrimer: ethanol = 1:3:120. The reaction product was filtered under reduced pressure and washed with ethanol three times, and freeze-dried to obtain a polyphenylene dendrimer-modified graphene oxide adsorbent.

[0050] Comparative Example 3

[0051] EDTA adsorbent.

[0052] Comparative Example 4

[0053] The method is basically the same as Example 1, except that the green solvent is replaced with dodecyldimethylbenzylammonium chloride to obtain a modified graphene adsorbent.

[0054] Comparative Example 5

[0055] The method is basically the same as Example 1, except that the graphene oxide is replaced with activated carbon to obtain a modified activated carbon adsorbent.

[0056] Application Example 1

[0057] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 1 were uniformly mixed in a mass ratio of 5g:100g:8g, and metal ions were adsorbed and removed at 40°C and 101kPa for 20 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0058] Application Example 2

[0059] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 2 were uniformly mixed in a mass ratio of 5g:100g:8g, and metal ions were adsorbed and removed at 40°C and 101kPa for 20 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0060] Application Example 3

[0061] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 3 were uniformly mixed in a mass ratio of 5g:100g:8g, and metal ions were adsorbed and removed at 40°C and 101kPa for 20 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0062] Application Example 4

[0063] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 2 were uniformly mixed in a mass ratio of 5g:100g:10g, and metal ions were adsorbed and removed at 40°C and 101kPa for 15 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0064] Application Example 5

[0065] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 2 were uniformly mixed in a mass ratio of 5g:100g:10g, and metal ions were adsorbed and removed at 40°C and 101kPa for 20 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0066] Application Example 6

[0067] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 2 were uniformly mixed in a mass ratio of 5g:100g:12g, and metal ions were adsorbed and removed at 40°C and 101kPa for 20 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0068] Application Example 7

[0069] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 1 were uniformly mixed in a mass ratio of 5g:100g:10g, and metal ions were adsorbed and removed at 40°C and 101kPa for 25 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0070] Application Example 8

[0071] Poly(p-hydroxystyrene) and its copolymer, propylene glycol methyl ether acetate, and the modified graphene adsorbent of Example 2 were uniformly mixed in a mass ratio of 5g:100g:12g, and metal ions were adsorbed and removed at 50°C and 101kPa for 20 minutes. After the adsorption was completed, PGMEA was removed, and the metal ion content in the target was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0072] The above is only an exemplary 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 a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A modified graphene adsorbent, characterized in that: Graphene oxide is modified by choline chloride, a strong alkaline solution and a green solvent to obtain a modified graphene adsorbent; the green solvent is one or more of 3-nitrophthalic acid, 6-aminoquinoxaline, 4-nitro-o-phenylenediamine, 3,4-dichloroaniline, pentachloroaniline, 2-carboxy-3-nitrobenzoic acid ethyl ester, 1,3,5-triethynylbenzene and 6-amino-5-bromoquinoxaline.

2. The modified graphene adsorbent according to claim 1, characterized in that: The concentration of the strong alkaline solution is 3-6 mol / L.

3. The modified graphene adsorbent according to claim 1, characterized in that: The invention also includes a dispersant, which is one of a quaternary ammonium salt, a quaternary phosphate salt and an amino acid.

4. The preparation process of the modified graphene adsorbent according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) dispersing graphene oxide in deionized water and continuously ultrasonicating to obtain a uniform graphene oxide suspension; (2) adding choline chloride to the graphene oxide suspension obtained in step (1), and continuing ultrasonication to obtain a uniform mixed solution; wherein the mass ratio of choline chloride to graphene oxide is 1:2; (3) heating the mixed solution obtained in step (2) to 50-60° C. and maintaining it for 2-3 hours, then adding a strong alkaline solution and a green solvent, and continuously stirring to generate a graphene nanosheet suspension; (4) Then, poly(p-vinylbenzyltrimethylammonium chloride) or poly(p-styrene sodium sulfonate) aqueous solution is added dropwise into the graphene nanosheet suspension, reacted, and washed to obtain a modified graphene adsorbent.

5. The method for preparing the modified graphene adsorbent according to claim 4, characterized in that: The steps The ultrasonic dispersion time of step (1) and step (2) is 40 min to 60 min.

6. The method for preparing the modified graphene adsorbent according to claim 4, characterized in that: The concentration of the graphene oxide suspension in step (1) is 1 mg / L to 3 mg / L.

7. The method for preparing the modified graphene adsorbent according to claim 4, characterized in that: The stirring time of step (3) is 30 min to 60 min.

8. The method for preparing the modified graphene adsorbent according to claim 4, characterized in that: In step (3), the mass ratio of the strong alkaline solution to the green solvent is (0.5 ~ 2):1.