Aminated modified hydrothermal carbon, preparation method thereof and application of aminated modified hydrothermal carbon in removal of hexavalent chromium in water

Abstract

The invention discloses amination modified hydrothermal carbon, a preparation method of the amination modified hydrothermal carbon and application of the amination modified hydrothermal carbon to removal of hexavalent chromium in water, and belongs to the technical field of hexavalent chromium removal. Uniformly stirring the garden waste raw material powder and the acidic mixed solution, and then adding a nicotinamide modifier to obtain a uniformly mixed solution; and transferring the uniformly mixed solution into a hydrothermal reaction kettle, carrying out hydrothermal carbonization reaction, naturally cooling to room temperature after the reaction is finished, and carrying out suction filtration, washing, drying, grinding and sieving to obtain the amination modified hydrothermal carbon. Through the mode, the amination modified hydrothermal carbon prepared by the method shows efficient removal capacity on hexavalent chromium in a water body, the maximum adsorption rate reaches 99%, and the adsorption capacity reaches 165.4 mg / g.

Description

Technical Field

[0001] The invention relates to the technical field of hexavalent chromium removal, and in particular to amination-modified hydrothermal carbon, a preparation method thereof and application thereof in removing hexavalent chromium from water. Background Art

[0002] With the rapid development of mining, chemical, electroplating, electronics, leather and other industries, the problem of heavy metal pollution is becoming increasingly serious. There are a large number of chromium-containing and antimony-containing pollutants in various industrial wastewaters such as natural surface water, drinking water, and electroplating wastewater. Chromium (Cr), as a typical heavy metal, has serious harm to human health and other organisms in the environment. Among them, there are two main forms of chromium in the environment: trivalent chromium Cr (III) and hexavalent chromium Cr (VI). Among them, excessive intake of trivalent chromium can cause damage to human chromosomes. Compared with trivalent chromium, hexavalent chromium is more toxic and more harmful to the human body. Hexavalent chromium is easily absorbed by the human body and can enter the human body through the digestive tract, respiratory tract and skin contact. A small amount of hexavalent chromium can cause vomiting, diarrhea, nosebleeds and skin allergies. Long-term exposure to hexavalent chromium leads to a large amount of hexavalent chromium accumulation in the human body, which can cause chronic headaches, allergic asthma, liver failure, skin cancer, etc. In addition, hexavalent chromium is also teratogenic and reproductive toxic.

[0003] Hydrothermal carbonization can convert cheap and readily available biomass into solid carbon materials. Hydrothermal carbon is a solid product obtained by hydrothermal carbonization at 150℃-350℃ using low-cost biomass waste as raw materials. Hydrothermal carbon has the characteristics of low cost, low energy consumption, environmental friendliness, and rich surface functional groups. However, due to its underdeveloped pore structure, small porosity and specific surface area, its wide application in the adsorption field is limited. Studies have shown that by grafting amino, carboxyl and other functional groups on the surface of hydrothermal carbon, the adsorption capacity of hydrothermal carbon for heavy metals can be significantly improved. However, the currently widely used functional modification methods such as post-grafting method and chemical oxidation method have the disadvantages of cumbersome processing process and high cost. It is necessary to further find suitable modifiers, simplify the modification process, and prepare low-cost functionalized hydrothermal carbon.

[0004] Based on this, the present invention designs an amination-modified hydrothermal carbon, a preparation method thereof and an application thereof in removing hexavalent chromium from water to solve the above-mentioned problems. Summary of the invention

[0005] In view of the above shortcomings of the prior art, the present invention provides an amination-modified hydrothermal carbon, a preparation method thereof and an application thereof in removing hexavalent chromium from water. The present invention successfully improves the hydrothermal carbon yield through a one-step hydrothermal method, and also introduces a large number of N-containing functional groups, significantly improving the hydrothermal carbon's ability to remove hexavalent chromium from water, thereby solving the problems of the existing hydrothermal carbon functionalization modification process being complex, high cost and low resource utilization rate of garden waste.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The preparation method of amination-modified hydrothermal carbon comprises the following steps:

[0008] (1) crushing garden waste raw materials;

[0009] (2) stirring the garden waste raw material powder and the acidic mixed solution uniformly, and adding the nicotinamide modifier after stirring to obtain a uniformly mixed solution;

[0010] (3) The uniformly mixed solution is transferred to a hydrothermal reactor for hydrothermal carbonization reaction. After the reaction is completed, the solution is naturally cooled to room temperature, and the amino-modified hydrothermal carbon is obtained after filtration, washing, drying, grinding, and sieving.

[0011] Furthermore, in step (2), the concentration of the nicotinamide modifier is 1 M; and the volume ratio of the acidic mixed solution to the nicotinamide modifier is 1:1.

[0012] Furthermore, in step (2), the weight ratio of the total volume of the acidic mixed solution and the nicotinamide modifier to the garden waste raw material powder is 60 ml:5 g.

[0013] Furthermore, in step (2), the acidic mixed solution is a mixed solution of tannic acid and nitric acid.

[0014] Furthermore, in step (3), the temperature of the hydrothermal carbonization reaction is 130-250° C., and the time is 6-14 hours.

[0015] Furthermore, in step (3), vacuum filtration is used, and the product is washed 3-4 times with water and anhydrous ethanol during the filtration process; the product is dried in a drying oven at a temperature of 80±5°C for 24±8h, and after constant weight is reached, the black powder obtained by grinding through a 80-100 mesh sieve is the amino-modified hydrothermal charcoal.

[0016] In order to better achieve the purpose of the present invention, the present invention also provides an amination-modified hydrothermal carbon prepared according to the preparation method.

[0017] In order to better achieve the purpose of the present invention, the present invention also provides a use of the amination-modified hydrothermal carbon in removing heavy metal pollutants in water.

[0018] Furthermore, the amination-modified hydrothermal carbon was used as an adsorbent to remove hexavalent chromium from water.

[0019] In order to better achieve the purpose of the present invention, the present invention also provides a method for removing hexavalent chromium from water, using the amination-modified hydrothermal carbon, and performing the following steps:

[0020] Add the amino-modified hydrothermal carbon with a concentration of 0.2-0.4 g / L into water containing hexavalent chromium with a concentration of 5-100 mg / L, adjust the solution pH to 4, the temperature to 303-313 K, adsorb for 6 hours, and then filter out the adsorbent; the maximum adsorption rate of hexavalent chromium in water reaches 99%, and the adsorption amount reaches 165.4 mg / g.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention selects garden waste with huge output (mainly pruned branches and leaves, fallen leaves and lawn residues, etc.) as raw materials, uses tannic acid, nitric acid and nicotinamide, which have been industrially produced and are low-priced, as modifiers, and successfully increases the output of hydrothermal carbon through a simple one-step hydrothermal method. In addition, a large number of nitrogen-containing functional groups are introduced, which significantly improves the ability of hydrothermal carbon to remove hexavalent chromium in water.

[0022] 2. The preparation method of the present invention has the characteristics of simple process, abundant raw materials, low cost and scalable production. At the same time, it opens up a new way for the resource utilization of garden waste and realizes waste treatment.

[0023] 3. The amino modified hydrothermal carbon prepared by the present invention shows a high efficiency in removing hexavalent chromium from water, with a maximum adsorption rate of 99% and an adsorption amount of 165.4 mg / g. It can be used in the treatment of wastewater containing hexavalent chromium such as electroplating, printing and dyeing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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 or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 This is a graph showing the adsorption of hexavalent chromium in water by the amination-modified hydrothermal carbons prepared in Examples 1 to 12 of the present invention, the original hydrothermal carbon prepared in Comparative Example 1, and commercial activated carbon (AC).

[0026] Figure 2 The adsorption rate graph of hexavalent chromium in water by the amination-modified hydrothermal carbon prepared in Examples 1 to 12 of the present invention, the original hydrothermal carbon prepared in Comparative Example 1, and commercial activated carbon (AC) and the preparation yield graph;

[0027] Figure 3 The SEM images of the amino-modified hydrothermal carbon prepared in Example 3 of the present invention (Figure b) and the original hydrothermal carbon prepared in Comparative Example 1 (Figure a);

[0028] Figure 4The present invention provides a technical roadmap for preparing amination-modified hydrothermal carbon. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 this field without creative work are within the scope of protection of the present invention. For those embodiments of the present invention that do not specify specific conditions, they are carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials, reagents, etc. used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0030] Embodiment 1: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0031] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0032] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0033] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 6 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH6-220.

[0034] Example 2: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0035] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0036] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0037] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 8 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH8-220.

[0038] Embodiment 3: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0039] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0040] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0041] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH10-220.

[0042] Embodiment 4: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0043] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0044] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0045] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 12 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH12-220.

[0046] Embodiment 5: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0047] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0048] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0049] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 14 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH14-220.

[0050] Example 6: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0051] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0052] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0053] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 130°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH10-130.

[0054] Embodiment 7: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0055] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 60 mesh;

[0056] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0057] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 160°C for 10 h. After the reaction was completed, the mixture was naturally cooled to room temperature, washed with water and anhydrous ethanol for 4 times during vacuum filtration, and dried in a drying oven at 75°C for 16 h. After constant weight, the black powder obtained by grinding through an 80-mesh sieve was amino-modified hydrothermal carbon, named N3MSH10-160.

[0058] Embodiment 8: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0059] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 80 mesh;

[0060] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0061] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 190°C for 10 h. After the reaction was completed, the mixture was naturally cooled to room temperature, washed with water and anhydrous ethanol for 4 times during vacuum filtration, and dried in a drying oven at 85°C for 32 h. After constant weight, the black powder obtained by grinding through an 80-mesh sieve was amino-modified hydrothermal carbon, named N3MSH10-190.

[0062] Embodiment 9: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0063] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0064] (2) The garden waste raw material powder was stirred evenly with 30 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 30 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0065] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 250°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times, and dried in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N3MSH10-250.

[0066] Embodiment 10: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0067] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0068] (2) The garden waste raw material powder was stirred evenly with 20 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 20 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0069] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N1MSH10-220.

[0070] Example 11: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0071] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0072] (2) The garden waste raw material powder was stirred evenly with 25 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 25 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0073] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained by grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N2MSH10-220.

[0074] Example 12: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0075] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0076] (2) The garden waste raw material powder was stirred evenly with 35 ml of a mixed solution of tannic acid and nitric acid for 12 h, and then 35 ml of a nicotinamide modifier (concentration 1 M) was added to obtain a mixed solution;

[0077] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times, and dried in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained after grinding through a 100-mesh sieve was amino-modified hydrothermal carbon, named N4MSH10-220.

[0078] Comparative Example 1: A method for preparing amination-modified hydrothermal carbon, comprising the following steps:

[0079] (1) 5 g of garden waste materials (mainly trimmed branches and leaves, fallen leaves and lawn residues, etc.) were washed, dried, crushed and sieved through 100 mesh;

[0080] (2) Mix the garden waste raw material powder with 60 ml of water for 12 h;

[0081] (3) The mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal carbonization reaction at 220°C for 10 h. After the reaction was completed, it was naturally cooled to room temperature. During the vacuum filtration process, it was washed with water and anhydrous ethanol for 3 times. It was placed in a drying oven at 80°C for 24 h. After constant weight, the black powder obtained after grinding through a 100-mesh sieve was the modified hydrothermal carbon, named SH10-220.

[0082] The specific surface area and pore structure distribution results of the amination-modified hydrothermal carbon prepared in Example 10 and the original hydrothermal carbon prepared in Comparative Example 1 are shown in Table 1.

[0083] Table 1 Specific surface area and pore structure distribution of samples before and after modification

[0084]

[0085] Experimental example

[0086] Usage method: add 0.2-0.4 g / L amino-modified hydrothermal carbon (prepared by any one of Examples 1 to 12) into water containing 5-100 mg / L hexavalent chromium, adjust the solution pH to 4, the temperature to 303-313 K, adsorb for 6 hours, and filter out the adsorbent.

[0087] For example, a 0.3 g / L amination-modified hydrothermal carbon (prepared by the scheme of Example 1) was added to water containing hexavalent chromium at a concentration of 100 mg / L, and the solution pH was adjusted to 4, the temperature was 310 K, and after adsorption for 6 hours, the adsorbent was filtered out. Results: The maximum adsorption rate of hexavalent chromium in water reached 99%, and the adsorption amount reached 165.4 mg / g.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing amination-modified hydrothermal carbon, characterized in that: The following steps are involved: (1) crushing garden waste raw materials; (2) stirring the garden waste raw material powder and the acidic mixed solution uniformly, and adding the nicotinamide modifier after stirring to obtain a uniformly mixed solution; (3) The uniformly mixed solution is transferred to a hydrothermal reactor for hydrothermal carbonization reaction. After the reaction is completed, the solution is naturally cooled to room temperature, and the amino-modified hydrothermal carbon is obtained after filtration, washing, drying, grinding, and sieving.

2. The method for preparing amination-modified hydrothermal carbon according to claim 1, characterized in that: In step (2), the concentration of the nicotinamide modifier is 1 M; and the volume ratio of the acidic mixed solution to the nicotinamide modifier is 1:

1.

3. The method for preparing amination-modified hydrothermal carbon according to claim 1, characterized in that: In step (2), the weight ratio of the total volume of the acidic mixed solution and the nicotinamide modifier to the garden waste raw material powder is 60 ml:5 g.

4. The method for preparing amination-modified hydrothermal carbon according to claim 1, characterized in that: In step (2), the acidic mixed solution is a mixed solution of tannic acid and nitric acid.

5. The method for preparing amination-modified hydrothermal carbon according to claim 1, characterized in that: In step (3), the temperature of the hydrothermal carbonization reaction is 130-250° C., and the time is 6-14 hours.

6. The method for preparing amination-modified hydrothermal carbon according to claim 1, characterized in that: In step (3), vacuum filtration is performed, and the product is washed 3-4 times with water and anhydrous ethanol during the filtration process; the product is placed in a drying oven at a temperature of 80±5°C and dried for 24±8h. After constant weight is reached, the black powder obtained by grinding through a 80-100 mesh sieve is the amino-modified hydrothermal charcoal.

7. An amination-modified hydrothermal carbon prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the aminated hydrothermal carbon according to claim 7 in removing heavy metal pollutants from water.

9. The use of the aminated modified hydrothermal carbon according to claim 8 in removing heavy metal pollutants in water, characterized in that: Aminated modified hydrothermal carbon was used as adsorbent to remove hexavalent chromium from water.

10. A method for removing hexavalent chromium from water, using the amination-modified hydrothermal carbon according to claim 7, characterized in that: Follow these steps: The amino-modified hydrothermal carbon with a concentration of 0.2-0.4 g / L was added to water containing hexavalent chromium with a concentration of 5-100 mg / L, the solution pH was adjusted to 4, the temperature was 303-313 K, and after adsorption for 6 hours, the adsorbent was filtered out; the maximum adsorption rate of the amino-modified hydrothermal carbon for hexavalent chromium in water reached 99%, and the adsorption amount reached 165.4 mg / g.

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