Modified activated carbon for removing perchlorate in water of sheep farm and preparation method of modified activated carbon

Abstract

The invention provides modified activated carbon for removing perchlorate in water of a sheep farm and a preparation method of the modified activated carbon, and relates to the field of water treatment.The method comprises the steps that activated carbon reacts in a citric acid aqueous solution, a carboxyl layer is evenly loaded on the surface of the activated carbon, and preliminarily modified activated carbon is obtained; reacting the primarily modified activated carbon in an alkaline polydimethyldiallylammonium chloride aqueous solution, and adsorbing strong cation quaternary ammonium salt on the surface of a carboxyl layer through electrostatic interaction to obtain re-modified activated carbon; the activated carbon modified again reacts in a triethylene tetramine aqueous solution, triethylene tetramine molecules are further combined to the strong cation quaternary ammonium salt through the electrostatic adsorption effect, the modified activated carbon for removing perchlorate in the water of the sheep farm is obtained, the adsorption capacity of the activated carbon to negatively charged solutes is remarkably enhanced, and the perchlorate in the water of the sheep farm is removed. The perchlorate treatment efficiency of the whole farm environment is improved.

Description

Technical Field

[0001] The invention relates to the field of water treatment, and in particular to a modified activated carbon for removing perchlorate in water used in sheep farms and a preparation method thereof. Background Art

[0002] Perchlorate (ClO4 - ) is a new type of pollutant that is highly water-soluble and persistent, and can directly affect human health through drinking water. Perchlorate can interfere with the thyroid gland's absorption of iodine, thereby affecting the normal secretion of thyroid hormones, especially causing significant harm to the brain development of fetuses and infants. For dairy products, how to effectively control perchlorate pollution has become an important issue that needs to be solved urgently.

[0003] At present, the removal technology of perchlorate in sheep farm water is mainly based on adsorption. Among them, activated carbon has become the most widely used adsorbent to solve the pollution problem of perchlorate in sheep farms because of its low cost, simple operation and no secondary pollution. Activated carbon has a large specific surface area and good pore structure, and can adsorb a variety of harmful substances. It is widely used in the field of water treatment. However, for the treatment of perchlorate, the adsorption efficiency of traditional activated carbon is limited in many aspects and cannot fully meet the requirements of perchlorate removal. In addition, other removal methods such as ion exchange, membrane filtration and chemical reduction can achieve a certain degree of perchlorate removal, but their high cost and complex process make it difficult to be widely promoted in large-scale farms. Therefore, at this stage, activated carbon is still an important choice for farms to treat perchlorate.

[0004] However, there are still many defects in the direct use of traditional activated carbon to treat perchlorate in farms. On the one hand, the electrostatic adsorption capacity of unmodified activated carbon is weak, and the removal effect of perchlorate is limited; on the other hand, although modified activated carbon can effectively improve the adsorption performance, its preparation process is complicated and the cost is high, which makes it difficult to meet the actual needs of large farms. At the same time, the current modified activated carbon is prone to adsorption saturation and shedding during use, resulting in a shortened actual service life and low utilization value. Therefore, there is currently no efficient, safe, low-cost modified activated carbon material suitable for sheep farms. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a modified activated carbon for removing perchlorate in water used in sheep farms and a preparation method thereof, so as to solve the problems that the current activated carbon has limited effect in removing perchlorate in water used in sheep farms, complicated preparation process, high cost and short service life, and significantly enhances the adsorption capacity of activated carbon for negatively charged solutes, thereby improving the treatment efficiency of perchlorate in the overall farm environment.

[0006] The present invention is achieved through the following technical solutions: A method for preparing modified activated carbon for removing perchlorate from water used in sheep farms comprises the following steps: S1, reacting the activated carbon in a citric acid aqueous solution, uniformly loading a carboxyl group on the surface of the activated carbon, and obtaining a preliminarily modified activated carbon; S2, reacting the initially modified activated carbon in an alkaline polydimethyldiallyl ammonium chloride aqueous solution, and adsorbing the strong cationic quaternary ammonium salt on the surface of the carboxyl group through electrostatic action to obtain a second modified activated carbon; S3, reacting the modified activated carbon in a triethylenetetramine aqueous solution, so that the triethylenetetramine molecules are further bound to the strong cationic quaternary ammonium salt through electrostatic adsorption, thereby obtaining modified activated carbon for removing perchlorate in water used in sheep farms.

[0007] A further improvement of the present invention is: S1: adding activated carbon to the citric acid aqueous solution and mixing evenly, then stirring at 40-60°C for 2-4h, and then removing the unadsorbed citric acid to obtain a preliminarily modified activated carbon.

[0008] The mass ratio of citric acid to deionized water in the citric acid aqueous solution is (1.92-4.8):50, and the mass ratio of activated carbon to citric acid is 1:(1.92-4.8).

[0009] S2: adding the initially modified activated carbon to the aqueous solution of polydimethyldiallylammonium chloride, adjusting the pH of the solution to alkaline, stirring at 40-60° C. for 3-5 hours, and then removing the unadsorbed polydimethyldiallylammonium chloride to obtain a second modified activated carbon.

[0010] The volume ratio of polydimethyldiallylammonium chloride to deionized water in the polydimethyldiallylammonium chloride aqueous solution is 1:(2-4), and the ratio of the initially modified activated carbon to the polydimethyldiallylammonium chloride aqueous solution is 1g:30mL.

[0011] S2: adjusting the pH of the solution to 8.5-11, and then stirring at 40-60°C for 3-5h.

[0012] S3 adds the modified activated carbon to the triethylenetetramine aqueous solution, then stirs for 3-5 hours at 20-40°C, removes the unbound triethylenetetramine, and finally dries to obtain modified activated carbon for removing perchlorate in sheep farm water.

[0013] The volume ratio of triethylenetetramine to deionized water in the triethylenetetramine aqueous solution is 1:(2-7), and the ratio of the re-modified activated carbon to the triethylenetetramine aqueous solution is 1g:50mL.

[0014] The stirring intensity in S1 is 40-80 r / min, and the stirring intensity in S2 and S3 is 60-80 r / min.

[0015] A modified activated carbon obtained by any one of the above-mentioned methods for preparing modified activated carbon for removing perchlorate in water used in sheep farms.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a method for preparing modified activated carbon for removing perchlorate in water used in sheep farms. The method comprises modifying the surface of activated carbon in multiple steps, sequentially introducing carboxyl groups, quaternary ammonium salts and hierarchical modifiers, and enhancing the adsorption function of activated carbon. A citric acid solution is reacted with activated carbon, carboxyl groups are introduced by citric acid, citric acid molecules are combined with oxygen-containing groups on the surface of activated carbon through hydrogen bonds, carboxyl groups are uniformly loaded on the surface of activated carbon, oxygen-containing functional groups on the surface of activated carbon are increased, and the binding force of subsequent modification is improved. On this basis, a polydimethyldiallylammonium chloride solution is reacted with the preliminarily modified activated carbon, so that a strong cationic quaternary ammonium salt is adsorbed on the carboxyl group on the activated carbon through an electrostatic action monomolecular layer. A triethylenetetramine solution is reacted with the activated carbon modified again, so that the triethylenetetramine molecules are further combined with the strong cationic quaternary ammonium salt layer through electrostatic adsorption. The quaternary ammonium salt polymer polydimethyldiallylammonium chloride and the hierarchical modifier triethylenetetramine are subjected to electrostatic adsorption modification, and strong cationic functions and more adsorption sites are introduced. On the one hand, the positively charged nitrogen-containing functional groups in the quaternary ammonium salt have a strong electrostatic adsorption effect on the negatively charged perchlorate, and can effectively adsorb the perchlorate in the aqueous solution; on the other hand, the hierarchical modifier is introduced to form a stronger electrostatic interaction with the strong cationic quaternary ammonium salt layer, further enhancing the electrostatic adsorption attraction on the surface of the activated carbon, and the overall removal effect of negatively charged pollutants such as perchlorate is greatly improved. The adsorption amount of the modified activated carbon is 36.24-40.01 mg / L, that is, the maximum can reach 40.01 mg / L, achieving efficient adsorption while being efficient, safe and suitable for perchlorate pollution problems in sheep farms. Citric acid dissociates into negative charges under alkaline conditions, so that it can form a stronger electrostatic interaction with the positively charged quaternary ammonium group, increasing the adhesion and stability of the quaternary ammonium salt polymer on the surface of the activated carbon. The preparation method is simple in process, low in production cost, and suitable for on-site use in farms. At the same time, activated carbon can be reused multiple times through simple regeneration, reducing operating costs. The preparation process uses water as the reaction medium, avoiding the emission of harmful substances, being friendly to the environment around the sheep farm and in line with the concept of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a graph showing the adsorption capacity of modified activated carbon of Examples 1-6. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0019] The present invention provides a method for preparing modified activated carbon for removing perchlorate in water used in sheep farms, comprising the following steps: The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water are mixed to prepare a citric acid solution, activated carbon is added to the citric acid solution, mixed evenly, and stirred at 40-60° C. for 2-4 hours.

[0020] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0021] Use magnetic stirring and control the magnetic stirring intensity at 40-80r / min.

[0022] The mass ratio of citric acid to deionized water is (1.92-4.80):50 to prepare the citric acid solution, and the mass ratio of activated carbon to citric acid is 1:(1.92-4.80).

[0023] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: Polydimethyldiallylammonium chloride is mixed with deionized water to prepare a polydimethyldiallylammonium chloride solution, the modified activated carbon is added to the polydimethyldiallylammonium chloride solution, the pH of the solution is adjusted to alkaline, and the solution is stirred at 40-60° C. for 3-5 hours.

[0024] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0025] Use magnetic stirring and control the magnetic stirring intensity at 60-80r / min.

[0026] The pH value of the polydimethyldiallylammonium chloride solution is 8.5-11.

[0027] The volume ratio of polydimethyldiallylammonium chloride to deionized water is 1:(2-4) to prepare polydimethyldiallylammonium chloride solution, and the ratio of modified activated carbon to the prepared polydimethyldiallylammonium chloride aqueous solution is 1g:30mL.

[0028] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: Triethylenetetramine and deionized water are mixed to prepare a triethylenetetramine solution, and the modified activated carbon is added to the triethylenetetramine solution and stirred at 20-40° C. for 3-5 hours.

[0029] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0030] Use magnetic stirring and control the magnetic stirring intensity at 60-80r / min.

[0031] The volume ratio of triethylenetetramine to deionized water is 1:(2-7) to prepare triethylenetetramine solution, and the ratio of modified activated carbon to the prepared triethylenetetramine solution is 1g:50mL.

[0032] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0033] The activated carbon is selected from coal-based activated carbon, coconut shell activated carbon or wood activated carbon. Preferably, the activated carbon is selected from coconut shell activated carbon.

[0034] Example 1 The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water were mixed in a mass ratio of 1.92:50 to prepare a citric acid solution. 1 g of coconut shell activated carbon was added to 50 mL of the citric acid solution, mixed evenly, and then magnetically stirred at 60 ° C and 60 r / min for 2 hours.

[0035] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0036] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: The volume ratio of polydimethyldiallylammonium chloride to deionized water was 1:2 to prepare polydimethyldiallylammonium chloride solution, 1 g of the modified activated carbon was added to 30 mL of the polydimethyldiallylammonium chloride solution, the pH of the solution was adjusted to 8.5, and magnetic stirring was carried out at 60 ° C and 60 r / min for 3 hours.

[0037] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0038] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: The volume ratio of triethylenetetramine to deionized water was 1:2 to prepare a triethylenetetramine solution, 1 g of the modified activated carbon was added to 50 mL of the triethylenetetramine solution, and magnetic stirring was performed at 80 r / min at 20 °C for 3 h.

[0039] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0040] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0041] Example 2 The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water were mixed in a mass ratio of 3.36:50 to prepare a citric acid solution. 1 g of wood activated carbon was added to 50 mL of the citric acid solution, mixed evenly, and then magnetically stirred at 60 °C and 60 r / min for 2 h.

[0042] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0043] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: The volume ratio of polydimethyldiallyl ammonium chloride to deionized water was 1:2 to prepare polydimethyldiallyl ammonium chloride solution, 1 g of the modified activated carbon was added to 30 mL of the polydimethyldiallyl ammonium chloride solution, the pH of the solution was adjusted to 9, and magnetic stirring was carried out at 60 ° C and 60 r / min for 3 hours.

[0044] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0045] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: The volume ratio of triethylenetetramine to deionized water was 1:3 to prepare a triethylenetetramine solution, 1 g of the modified activated carbon was added to 50 mL of the triethylenetetramine solution, and magnetic stirring was performed at 80 r / min at 20 °C for 3 h.

[0046] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0047] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0048] Example 3 The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water were mixed in a mass ratio of 4.80:50 to prepare a citric acid solution. 1 g of coal-based activated carbon was added to 50 mL of the citric acid solution, mixed evenly, and then magnetically stirred at 70 r / min at 50 °C for 3 h.

[0049] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0050] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: The volume ratio of polydimethyldiallyl ammonium chloride to deionized water was 1:2 to prepare polydimethyldiallyl ammonium chloride solution, 1 g of the modified activated carbon was added to 30 mL of the polydimethyldiallyl ammonium chloride solution, the pH of the solution was adjusted to 9.5, and magnetic stirring was carried out at 70 r / min at 50 ° C for 4 hours.

[0051] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0052] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: The volume ratio of triethylenetetramine to deionized water was 1:4 to prepare a triethylenetetramine solution, 1 g of the modified activated carbon was added to 50 mL of the triethylenetetramine solution, and magnetic stirring was performed at 70 r / min at 30 °C for 4 h.

[0053] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0054] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0055] Example 4 The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water were mixed in a mass ratio of 1.92:50 to prepare a citric acid solution. 1 g of coconut shell activated carbon was added to 50 mL of the citric acid solution, mixed evenly, and then magnetically stirred at 70 r / min at 50 °C for 3 h.

[0056] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0057] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: The volume ratio of polydimethyldiallyl ammonium chloride to deionized water was 1:4 to prepare polydimethyldiallyl ammonium chloride solution, 1 g of the modified activated carbon was added to 30 mL of the polydimethyldiallyl ammonium chloride solution, the pH of the solution was adjusted to 10, and magnetic stirring was carried out at 70 r / min at 50 °C for 4 h.

[0058] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0059] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: The volume ratio of triethylenetetramine to deionized water was 1:5 to prepare a triethylenetetramine solution, 1 g of the modified activated carbon was added to 50 mL of the triethylenetetramine solution, and magnetic stirring was performed at 70 r / min at 30 °C for 4 h.

[0060] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0061] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0062] Example 5 The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water were mixed in a mass ratio of 3.36:50 to prepare a citric acid solution. 1 g of coconut shell activated carbon was added to 50 mL of the citric acid solution, mixed evenly, and then magnetically stirred at 80 r / min at 40 °C for 4 h.

[0063] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0064] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: The volume ratio of polydimethyldiallylammonium chloride to deionized water was 1:4 to prepare polydimethyldiallylammonium chloride solution, 1 g of the modified activated carbon was added to 30 mL of the polydimethyldiallylammonium chloride solution, the pH of the solution was adjusted to 10.5, and magnetic stirring was carried out at 80 r / min at 40 °C for 4 h.

[0065] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0066] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: The volume ratio of triethylenetetramine to deionized water was 1:6 to prepare a triethylenetetramine solution, and 1 g of the modified activated carbon was added to 50 mL of the triethylenetetramine solution, and magnetic stirring was performed at 40 °C and 60 r / min for 5 h.

[0067] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0068] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0069] Example 6 The first step is to modify the surface of activated carbon with citric acid: Citric acid and deionized water were mixed in a mass ratio of 4.80:50 to prepare a citric acid solution. 1 g of coconut shell activated carbon was added to 50 mL of the citric acid solution, mixed evenly, and then magnetically stirred at 80 r / min at 40 °C for 4 h.

[0070] After the reaction was completed, the mixture was filtered and rinsed with deionized water until the pH of the filtrate was neutral to remove the unadsorbed citric acid.

[0071] The second step is to introduce quaternary ammonium salt polymer to increase the electrostatic adsorption capacity of activated carbon: The volume ratio of polydimethyldiallylammonium chloride to deionized water was 1:4 to prepare polydimethyldiallylammonium chloride solution, 1 g of the modified activated carbon was added to 30 mL of the polydimethyldiallylammonium chloride solution, the pH of the solution was adjusted to 11, and magnetic stirring was carried out at 80 r / min at 40 °C for 4 hours.

[0072] After the reaction is completed, the mixture is filtered and rinsed with deionized water until the pH of the filtrate is neutral to remove the unadsorbed polydimethyldiallylammonium chloride.

[0073] The third step is to use layer modifiers to further increase the electrostatic adsorption capacity of activated carbon: The volume ratio of triethylenetetramine to deionized water was 1:7 to prepare a triethylenetetramine solution, 1 g of the modified activated carbon was added to 50 mL of the triethylenetetramine solution, and magnetic stirring was performed at 40 °C and 60 r / min for 5 h.

[0074] After the reaction, the sample was filtered and rinsed thoroughly with deionized water until the pH of the filtrate was neutral to remove unbound triethylenetetramine and ensure the stability of the surface modification.

[0075] Step 4: Drying: The modified activated carbon was obtained by drying the product in a vacuum drying oven at 50°C for 24 hours.

[0076] Adsorption performance test of Examples 1-6 The modified activated carbon prepared in the above Examples 1-6 was used for adsorption in a perchlorate solution to examine the adsorption performance. The specific steps are as follows: Prepare 50 mg / L perchlorate solution: Take 1000 mg / L standard concentration perchlorate solution and place it in a beaker, dilute it with a volume ratio of 1:19 perchlorate solution to acetonitrile to obtain a 50 mg / L perchlorate solution. Use a disposable needle filter to inject the prepared perchlorate solution into the sample tube as a blank group.

[0077] Simulate the adsorption process: Take 1g of activated carbon and fill it into a 5mL syringe and compact it. Add 50mg / L perchlorate solution from the top of the syringe. Use a disposable needle filter to inject the adsorbed perchlorate solution into the sample tube and detect the perchlorate concentration of the sample solution.

[0078] The modified activated carbons of Examples 1-6 were used to adsorb perchlorate, and each sample was measured three times in parallel. The maximum adsorption capacity of each modified activated carbon was taken as the final adsorption capacity.

[0079] The experimental results are shown in Figure 1 , where the adsorption capacity refers to the maximum content of perchlorate adsorbed by modified activated carbon per unit dose (per gram) (in mg / L): from Figure 1 It can be seen that the maximum adsorption capacity of the scheme of the present invention reaches 40.01 mg / L, and the perchlorate removal rate reaches 80.02% relative to the perchlorate solution without adsorption. It can be seen that the method of the present invention can effectively remove perchlorate, and has a large adsorption capacity and good adsorption effect.

Claims

1. A method for preparing modified activated carbon for removing perchlorate from water used in sheep farms, characterized in that: The following steps are involved: S1, reacting the activated carbon in a citric acid aqueous solution, uniformly loading a carboxyl group on the surface of the activated carbon, and obtaining a preliminarily modified activated carbon; S2, reacting the initially modified activated carbon in an alkaline polydimethyldiallyl ammonium chloride aqueous solution, and adsorbing the strong cationic quaternary ammonium salt on the surface of the carboxyl group through electrostatic action to obtain a second modified activated carbon; S3, reacting the modified activated carbon in a triethylenetetramine aqueous solution, so that the triethylenetetramine molecules are further bound to the strong cationic quaternary ammonium salt through electrostatic adsorption, thereby obtaining modified activated carbon for removing perchlorate in water used in sheep farms.

2. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 1, characterized in that: S1: adding activated carbon to the citric acid aqueous solution and mixing evenly, then stirring at 40-60°C for 2-4h, and then removing the unadsorbed citric acid to obtain a preliminarily modified activated carbon.

3. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 2, characterized in that: The mass ratio of citric acid to deionized water in the citric acid aqueous solution is (1.92-4.8):50, and the mass ratio of activated carbon to citric acid is 1:(1.92-4.8).

4. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 3, characterized in that: S2: adding the initially modified activated carbon to the aqueous solution of polydimethyldiallylammonium chloride, adjusting the pH of the solution to alkaline, stirring at 40-60° C. for 3-5 hours, and then removing the unadsorbed polydimethyldiallylammonium chloride to obtain a second modified activated carbon.

5. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 4, characterized in that: The volume ratio of polydimethyldiallylammonium chloride to deionized water in the polydimethyldiallylammonium chloride aqueous solution is 1:(2-4), and the ratio of the initially modified activated carbon to the polydimethyldiallylammonium chloride aqueous solution is 1g:30mL.

6. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 5, characterized in that: S2: adjusting the pH of the solution to 8.5-11, and then stirring at 40-60°C for 3-5h.

7. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 6, characterized in that: S3 adds the modified activated carbon to the triethylenetetramine aqueous solution, then stirs for 3-5 hours at 20-40°C, removes the unbound triethylenetetramine, and finally dries to obtain modified activated carbon for removing perchlorate in sheep farm water.

8. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 7, characterized in that: The volume ratio of triethylenetetramine to deionized water in the triethylenetetramine aqueous solution is 1:(2-7), and the ratio of the re-modified activated carbon to the triethylenetetramine aqueous solution is 1g:50mL.

9. The method for preparing modified activated carbon for removing perchlorate from water used in sheep farms according to claim 7, characterized in that: The stirring intensity in S1 is 40-80 r / min, and the stirring intensity in S2 and S3 is 60-80 r / min.

10. A modified activated carbon obtained by the preparation method of modified activated carbon for removing perchlorate in water used in sheep farms as described in any one of claims 1 to 9.

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